P ESk/ . I PT I O N

Saccharoascorbi c Acid Esters, Production and Use Thereof

This invention relates to saccharoascorb i c acid esters and salts thereof, and production and use of the same. More particularly, the invention relates to saccharoascorbi c acid esters represented by the general formula of

namely, esters of D- g 1 ucosaccharoascorb i c acid or D-erythro- hexo-2-enaro- 1 , - 1 ac tone, and esters of L-gul osaccharoascorbic acid or L- threo-hexo-2-enaro- 1 , 4- lac tone, both being esterifie at the 6-position carboxylic group, and salts thereof, and further to a method of producing the same and use of the same.

The invention relates further to an electroconductive coating composition which contains a saccharoascorbic acid ester or a salt thereof.

L-Ascorbic acid, D-erythorbic acid, their derivatives, and L-gu 1osaccharoascorb ic acid (described in U.S. Patent Nos. 2,428,438 and 2,438,251; Carbohydrate Research,. £0* 251-258 (1978) ; Vitamine, 5£, 117-131 (1982)) are already known to have antioxidant activity.

In the course of intensive investigation of sacc aro- ascorbic acids, their derivatives and use, the present inventors have obtained, as novel compounds, esters of L- gulo- and D-glucosaccharoascorbic acids having the 6-positiόn carboxylic group esterified. The inventors further found that these compounds have excellent antioxidant activity, so that they have various uses, and are in particular useful as an antioxidant in an electroconducti e coating composition which contains a metal powder sensitive to air oxidation. An electroconductive coating composition is used for, for example, surface coating of a synthetic resin casing which contains therein electronic circuit devices. This surface coating renders the surface electroconductive, and prevents the permeation of electromagnetic waves through the casing, and thus erroneous operation of the circuit device.

An electroconductive coating composition is usually composed of an organic solvent, a binder resin such as an acrylic resin, and an electroconducti e metal powder such as

•a silver, nickel or copper dispersed therein. It is generally , needed that the composition retains not only high workability as a composition but also high electroconduc ti vi y as an electroconductive film over a long ^" period of time. It is further needed that the composition is inexpensive.

Thus a variety of electroconductive coating compositions have been recently proposed which contain a less expensive copper powder therein. However, since copper is very sensitive to surface oxidation with the air, an electroconduc¬ tive film formed therewith is remarkably reduced in electro- conductivity with time. It has been therefore proposed to add a compound which has antioxidant activity to an electroconductive coating composition. There are already known as such an additive, for example, anthranilic acid (Japanese Patent Laid-open Ko. 58-97892) , and a combination of a reducing compound such as hydroquinone and a chelatable compound with copper ions

such as ace tyl ace tone . However, the electroconducti e fi lm formed with a composition that contains such an additive as above is still found unsatisfactory in a long period stabili ty of elec troconduc t i vi ty . Meanwhile, an adhesive composition is already known which contains ascorbic acid or an ester thereof as a rust inhibitor (Japanese Patent Publication No. 54-9613) . However, since an electroconductive coating composition usually contains an organic solvent as beforedescribed, ascorbic acid which is only slightly soluble therein is not suitable for use as an antioxidant in an electroconductive coating composi tion. An carboxylic acid ester of ascorbic acid is soluble in many organic solvents, but it is difficult to obtain the ester in a pure form, which makes it difficult to produce a composition having a stable and constant quality.

The present inventors have found that the use of saccharoascorbi c acid esters and salts thereof, which have bot reducing ability and chelating abili ty wi th metal ions, as an antioxidant additive, provides an electroconducti e coating composition which forms a film whose e1 ec troconduc t i i ty is retained high over a long period of time.

It is, therefore, an object of the invention to provide novel compounds, L-gulo- and D- g1 ucosaccharoascorbi c acid esters and salts thereof. It is another object of the invention to provide a method of producing L-gulo- and D- l ucosaccharoascorbi c acid esters and salts thereof.

It is still an object of the invention to provide an electroconductive coating composition containing the novel saccharoascorbi c acid esters or salts thereof.

According to the invention, there is provided a novel saccharoascorb i c acid ester, and a salt thereof. The saccharoascor ic acid ester is represented by the general formula of

wherein R represents an organic residue of a molecular weight of 15-500, preferably 15-300, and OH has either an S- or an R- configuration , as designated herein by a wavelike line.

In the general formula (I), R is preferably a hydrocarb residue of 1-24 carbons, which include an alkyl, an alkenyl or an alkynyl, either linear or branched, a cycloalkyl, an aryl or an arylalkyl. The alkyl of 1-24 carbons includes, fo example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobuty sec. -butyl, tert. -butyl, n-pentyl, isoamyl, sec. -amyl, tert.- amyl, neopentyl,. n-hexy1, n-heptyl, n-octyl, sec.-octyl, n- nonyl, isononyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n- tetradecyI , n-pen tadec 1 , n-hexadecyl, n-heptadecy1 , n- octadecyl, isooctadecyl , n-nonadecyl, n-eicosyl, n-heneicosy1 , n-docosyl, n-tricosyl and n- tetracosy1. These alkyls may hav substituents thereon, for example, a halogen such as chlorine, bromine, iodine or fluorine, cyano, hydroxyl, carboxyl or its ester, aminocarbonyl , ether group as represented by -0-alkyI wherein the alkyl is preferably of 1-8 carbons or -0-aryl wherein the aryl is preferably phenyl, acyl as represented by -CO-alkyl wherein the alkyl is preferably of 1-8 carbons, or aroyl represented by -CO-aryl wherein the aryl is preferably phenyl, such as benzoyl.

The alkenyl is preferably of 2-20 carbons, and includes, for example, vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl,

tridecenyl , te tradeceny 1 , pen tadeceny 1 , hep tadeceny 1 , octadecenyl , nonedecenyl and eicosenyl . These alkenyls may have substi tuents thereon as be foremen t i oned or an alkyl of preferably 1-3 carbons. The alkynyl is also preferably of 2-20 carbons, and includes, for example, ethynyl , propynyl, butynyl, pentynyl , hexynyl , heptynyl , octynyl, nonynyl, decynyl , undecynyl , dodecynyl , tridecynyl , te tradecyny 1 , pen tadecyny 1 , hepadecynyl octadecynyl, nonadecynyl and eicosynyl. These alkynyls may have substi tuents thereon as beforemen t ioned or an alkyl of preferably 1-3 carbons.

The cycloalkyl is preferably of 3-8 carbons, and there may be mentioned as examples, cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl, cycloheptyl and cyclooctyl . The cycloalkyl also may have substi tuents thereon as before- mentioned or an alkyl of preferably 1-3 carbons.

There may be mentioned as the aryl, for example, phenyl , furyl , thienyl , pyridyl or naphthyl , and these aryls may have substi tuents thereon as beforemen t i oned or an alkyl of prefe- rably 1-3 carbons..

The arylalkyl is exempl i fied by an alkyl preferabl of 1-4 carbons having substi tuents thereon such as aryl as above mentioned, i .e. , phenyl , furyl , thienyl, pyridyl or naphthyl The arylalkyl may have substituents thereon as beforemen t ioned or an alkyl of preferably 1-3 carbons. More specific examples of the arylalkyl include benzyl, phenethyl, 1- phenyl e thy 1 , 1- heny 1 prop 1 , 3- pheny 1 propy 1 , 1 - me thy 1 - 3- pheny 1 propy 1 and 4-ρhenylbutyl .

The saccharoascorb ic acid ester (I) of the invention may be produced by use of a saccharoascorb i c acid as represented by the formula

as a starting material. In the formula (II) , the compound having a 5-ρosition OH on the right hand (absolute configu¬ ration of R) is L- gu 1 osaccharoascorbic acid. This compound is already known, as described in U.S. Patent No. 2,428,438. However, the compound having a 5-posi tion OH on the left hand (absolute configuration of S) is D- g 1 ucosaccharoascorb ic acid, and is a novel compound. The D-gl ucosaccharoascorb ic acid may be produced by -treating 2-ke to-D-gl ucari c acid or D-arabino- 2-hexulosaric acid, or its 2,3-0-acetal or ketal with an acid.

The saccharoascorb i c acid esters of the invention may be produced by a variety of methods. Preferred examples of the methods will now be described.

Method (A) :

The saccharoascorbic acid ester (I) of the invention is produced by the reaction of the saccharoascorbic acid (II) with an alcohol having the general formula of

R-OH (III) wherein R is the same as before.

This reaction is one- of the most popular ester synthesizing reactions, namely a dehydration reaction between the carboxylϊc acid and the alcohol. The reaction is an equilibrium reaction, and proceeds in the absence of a

catalyst, however, i t is preferred that the reaction be carrie out in the presence of a catalyst. Any known esterification catalyst may be used, and mineral acids, organic acids or Lewis acids are usually used. More speci f.ical ly, there may be used, as mineral acids, hydrogen hal ides such a s hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen fluoride perchloric acid; sulfuric acid; f 1 uorosu 1 fur i c acid; phosphori acid or boric acid. There may be used, as organic acids, arenesulfonic acids such as p- toluenesulfonic acid or ben ene- sul fonic acid; alkanesulfonic acids such as methanesul fonic acid or trifluoromethanesul fonic acid ; al iphatic carboxyl ic acids such as acetic acid or propionic acid; halogenated aceti acids such as tr i f 1 uoroace t ic acid or tr i ch 1 oroace t i c acid ; or ll ⁺ -form ion exchange resins. The Lewis acids usable include, for example, boron trifluoride, boron trifluoride- ether complexes, boron trich lor ide , boron tribromide, boron tri iodide, aluminum chloride, ti tanium te rach 1 or i de , zinc chloride, stannous chloride and stannic chloride. These acids may be used as they are, or as solutions or suspensions in water or organ i c • so 1 ven ts , if desired. Further, the acids may be used singly or as a mixture of two or more.

The acids are used usually in- amounts of about 0.001-5 % preferably about 0.01-2 % by weight based on the amount of the saccharoascorbic acid (II) used as a starting material . The saccharoascorbic acid (II) as a starting material is used usually in the form of a free acid, which may or may not contain water of crystal l ization. However, the acid ma be used in the form of a sal t such as an alkali metal sal t, e.g. , li thium sal t, sodium sal t or potassium sal t; an alkal ine earth metal sal t, e.g. , magnesium sal t, calcium sal t or barium sal t; or an ammoinium sal t. When the sal ts are used as a starting material , the sal ts are reacted wi th an acid in about s to i ch i ome tr i c amounts or in sl ight excess amounts, usual ly up to 1.5 moles per mole of the sal ts, prior to the esteri fication reaction, so that the sal ts are converted to

free acids.

The esterification of the saccharoascorbic acid or its salt is carried out usually in a solvent. Any solvent which does not adversely affect the reaction may be used, such as acetone, methyl ethyl ketone, cyclohexanone, hexane, cyclo- hexane, aceton i trϊ 1 e, propion i tri le, benzoni tri le, nitromethan nitroethane, nitrobenzene, d ich loro e thane, chloroform, carbon tetrach lorxde, 1 , 1-dich loroethane, 1, 2-dich1oroe thane, 111, 1- trϊchloroethane, 1, 1, 2-trichloroethane, trichloroethylen tetrachl oroe thyIene , benzene, toluene, xylene, formamide, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, hexame thy 1 hsphora ide, sulfolane, dioxane, tetrahydrofuran , ethyl ether, d i methoxyethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, or water. These solvents may be used singly or as a mixture. The afore¬ said alcohols as a reactant as represented by the general formula (III) may be used also as a solvent.

In the esteri ication reaction, the alcohol (III) may be used in from equimolar amounts to large excess amounts to the saccharoasco-rb i c acid (II) . For instance, when the alcoho is u.sed also as a solvent, the amount may be about 300 times in moles as much as the acid.

Since the esterification reaction is an equilibrium reaction, i t is preferred that the water generated in the reaction or the water contained in the reaction mixture be removed from the reaction mixture during the reaction by a conventional method to increase the yield of the esters. The water may be removed by distillation, preferably by azeotropic distillation with a solvent. When azeotropic distillation is employed, the azeotropic vapor may be cooled to separate the water therefrom, and the recovered solvent may be returned to the reaction mixture. lterna ively, the azeotropic vapor may be removed from the reaction mixture, while a dried fresh solvent may be added to the reaction mixture in amounts equal to that of the solvent removed therefrom. However, water only

may be removed depending on the alcohol (I II) or solvents used when t e alcohol (I I I) or solvents have higher boi l ing points than water.

The water may also be removed wi th a dehydrating or drying agent. For example, the azeotropic vapor as i t is or after cool ing to condensates may be dried over a drying agent such as anhydrous calcium sulfate, anhydrous sodium sulfate, anhyd ous magnesium sulfate, molecular sieves, si l ica gel or alumina, and then returned to a reaction vessel . Orthoformates or 1, 1-dialkoxyρroρane may be used, for example, as a dehydra ting agent. A dehydrating agent may be added to the reaction mixture to remove the water therein.

The reaction temperature is usually in the range of from abou t 0°C to about 150°C, preferably from about 20°C to about 120 °C . The reaction is carried out usual ly under normal pressures, however, the reaction may be carried out under reduced pressures to accelerate the distillative or azeotropic removal of w ter from the reaction mixture.

Further, the reaction time may vary depending upon the alcohols (I I I) used, catalysts and other reaction condi tions employed, but i t is usual ly in the range of about 0.5-24 hours, preferably of about 1-15 hours, al though not cri tical.

Method (B) : The saccharoascorbic acid ester (I) of the invention is obtained by the reaction of a saccharoascorbic acid ester having the general formula of

C00R

( I V )

wherein R ¹ represents a hydrocarbon residue of 1-12 carbons, with the aforesaid alcohol (III) . This reaction is an ester exchange reaction.

In the general formula (IV) , R ¹ is a hydrocarbon residue of 1-12 carbons, and includes, for example, an alkyl, an alkenyl or an alkynyl, either linear or branched, a cycloalkyl, an aryl or an arylalkyl. The alkyl of 1-12 carbons includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec. -butyl, tert. -butyl, n-pentyl, isoamyl, sec. -amyl, tert.-amyl, neopentyl, n-hexyl, n-heptyl, n-octyl, sec.-octyl, n-nonyl, isononyl, n-decyl, n-undecyl and n-dodecyl. The alkenyl is of 2-12 carbons, and includes, for example, vinyl, propcnyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl and dodecenyl. Similarly the alkynyl is of 2-12 carbons, and includes, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl and dodecynyl.

The cycloalkyl is preferably of 3-8 carbons, and there may be mentioned as examples, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.

There may be mentioned as the aryl, for example, phenyl, furyl, thienyl, pyridyl or naphthyl, and the arylalkyl is preferably of 7-10 carbons, and may be exemplified by an alkyl preferably of 1-4 carbons having substituents thereon such as aryl as above mentioned, i.e. , phenyl, furyl, thienyl, pyridyl or naphthyl. More specific examples of the arylalkyl include benzyl, phenethyl, 1- phenylethyl , 1-ρhenyIpropy 1 , 3-phenyl- propyl, 1-me th 1-3-phenyIpropy 1 and 4-ρhenyl butyl .

The ester compound (IV) as a starting material may be produced by the reaction of the saccharoascorbic acid (II) with an alcohol represented by the general formula of R ^l -0H

wherein R ¹ is the same as before, in accordance i th the method (A) as described hereinbefore.

Simi larly to the esteri fication reaction - (A) as herein before mentioned, this reaction is also an equi l ibrium reaction, and is carried out usual ly in the presence of a catalyst, usual ly mineral acids, organic acids or Lewis acids. More specifical ly, there may be used, as mineral acids, hydrogen hal ides such as hydrogen chloride, hydrogen bromide, hydrogen iodide or hydrogen fluoride; perchloric acid; sul fu ic acid; f 1 uoros u 1 fur i c acid; phosphoric acid or boric acid. There may be used, as organic acids, arenesulfonic acids such as p- to 1 uenesu 1 fon i c acid or benzenesu 1 fon i c acid; a 1 kanesu 1 fon i c acids such as me thanesu 1 fon i c acid or tri fluoromethanesulfonic acid; aliphatic carboxyl ic acids such as acetic acid or propionic acid; halogenated acetic acids such as trifluoroacetic acid or trichloroacetic acid; or H ⁺ -form ion exchange resins. The Lewis acids usable include, for example, boron trifluoride, boron tr i f 1 uor i de- e ther complexes, boron trichloride, boron tribromide, boron tri iodide, aluminum chloride, ti tanium tetrachloride, zinc chloride, s tannous chloride and stannic chloride. These acids may be used as they are, or as solutions or suspensions in water or organic solvents, if desired. Further, the acids may be used singly or as a mixture of two or more. The acids are used usually in amounts of about 0.001-5 % , preferably about 0.01-2 % by weight based on the amount of the saccharoascorbic acid ester (IV) used as a starting material .

The reaction is carried out ei ther in a solvent or wi thout a solvent. Any solvent which does not adversely affect the reaction may be used, such as hexane, cyclohexane, ace ton i tri 1 e, prop i on i tr i 1 e , benzon i tr i 1 e, ni tromethane, ni troethane, ni trobenzene, d i ch 1 oro e thane , chloroform, carbon tetrachloride, 1, 1-dichloroethane, 1, 2-dichloroethane-, 1, 1, 1- trichloroethane, 1, 1, 2- trichloroethane, trichloroethylene, tetrachloroethylene, benzene, toluene, xylene, for amide,

dimethylforma ide, dϊ ethylacetamide, dimethyl sulfoxide, hexamethy I phsphoram ide, sulfolane, dioxane, tetrahydrofuran, ethyl ether, dimethoxyethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, or water. These solvents may be used singly or as a mixture. The aforesaid alcohols as represented by the general formula (III) may be used as a solvent, too.

In the reaction of the method (B) , ester exchange reactions take place between the saccharoascorbic acid ester (IV) and the alcohol (III) in the presence of an acid catalyst, to produce equilibrium mixtures. Therefore, it is preferred that the alcohol (III) be used in large excess amounts, as a reactant but also as a solvent, usually in amounts of about 300 times in moles as much as the saccharoascorbic acid ester used, to increase the yield of the desired saccharoascorbic acid ester. As a further method, it is also preferred that a by-produced alcohol be removed from the reaction mixture when the by-produced alcohol have low boiling points, thereby to shift the equilibrium to the side of desired saccharoascorbic acid ester. In this method, the alcohol (III) may be used in amounts ranging from an equivalent to 5 times as much as equivalent to the saccharoascorbic acid ester (IV).

The reaction temperature Is usually in the range of from about 0°C to about 150°C, preferably from about 20°C to about 120°C. The reaction may be carried out under reduced pressures to accelerate the distillative removal of the by- produced alcohol, i.e., R'-OH, from the reaction mixture.

The reaction time may vary depending upon the saccharo¬ ascorbic acid ester (IV) and the alcohols (III) used, catalyst used and other reaction conditions employed, but it is usually in the range of about 0.5-24 hours, preferably of about 1-15 hours, although not critical.

Method (C) : The saccharoascorbic acid ester (I) of the invention

is obtainable by reacting a saccharoascorbic acid sal t havinj the general formula of

wherein M represents an alkali metal, an alkaline earth metal, an ammonium, a substi tuted ammonium or pyridinum, either with

15 a compound having the general formula of

R-X

(VI) wherein R is the same as before, and X represents a halogen, an a 1 ky 1 s u 1 fony 1 oxy or an ar 1 su 1 fony I ox , or wi th a compound

20 having the general formula of

(RO) _S0z (VII) wherein R is the same as before.

In the general formula (V) , M is an alkali metal such

25 as lithium, sodium or potassium; an alkaline earth metal such as magnesium, calcium or barium; an ammoinium or a substituted ammonium (>N ⁺ <) preferably having at least one substituent of an alkyl of 1-6 carbons, a cycloalkyl, preferably cyclo- hexyl, or an aryl, preferably benzyl or phenyl ; or having at

30 least one 5- or 6-membered carbon or heterocyclic ring formed wi th the ni trogen atom of the ammonium, optionally further with ni trogen or oxygen atoms contained therein; or pyridinium.

More specifically, there may be mentioned as examples of th e substituted ammonium, methylammonium, ethylammnoium, propy I

U a lammnoium, butylammonium, pentylammoni , hexylammonium, anili

nium, benzy 1 ammon i um, d ime thy1ammon ium, d iethylammon ium , dipro pylammnoium, d ϊ bu ty 1 am oniu , d i pen tylammon ium, dihexyl- ammon ium, dianilinium, p i peri dini um, orphol in i um, pyridazin ium, pyrro 1 i di n i um , d i benzyI ammonium, tri ethyl- ammonium, tri e thy 1ammnoium, tri propy1ammnoi um, tributyl- ammonium, tr i pen ty 1 ammon ium, tri hexylammon ium, tribenzyl- ammonium, te tramethy1 ammon i um, te trae hy1ammnoium, tetrapropyl- ammnoium, tetrabutylammonium, tetrapentylammonium, tetrahexyl- ammonium, tri me thy 1 phenyl ammon i um, trimethyl benzylammon ium, tri ethy1pheny 1 ammon i u , tri ethy1 benzylammon ium, tripropyl- phenylammonium, tripropylbenzylammonium, tribu ylphenylammoniu or tribu ty1 benzy I ammonium.

In turn, in the general formula (VI) , X is a halogen such as chlorine, bromine, iodine or fluorine; an alkyl- sulfonyloxy such as methanesulfonyloxy, ethanesulfonyloxy, tr ich lorome thanesu 1 fony loxy or tri fluoromethanesu 1 fonyloxy; or an ary lsul fony 1 oxy such as ben ^' zenesul fόnyloxy, p-toluene- sulfonyloxy, o- to 1 uenesu 1 fonyl oxy , p-chlorobenzenesu 1 fony1 oxy , o-ni tro to luene.su I fony1 oxy , m-n i tro toluenesul fonyloxy or p- n i tro tol uenesu 1 fony loxy .

The saccharoascorbic acid salt (V) used as a starting material in the method may be produced by a known method as, for example, described in Vita ine, 5j5, 117-131 (1982), or any method similar thereto. The salt (V) may also be produced by the reaction of the saccharoascorbic acid (II) with an appropriate base material exemplified by, for example, hydroxides, carbonates or hydrogen carbonates of alkali metals or alkaline earth metals, or pyridine, tertiary amines or substituted ammonium hydroxides having a partial structure of =N ⁺ 0H ^" . More specifically with hydroxides, carbonates or hydrogen carbonates of alkali metals or alkaline earth metals, there may be mentioned as examples, lithium hydroxide, lithium hydrogen carbonate, lithium carbonate, sodium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydroxide, potassium hydrogen carbonate, potassium carbonate,

magnesium hydroxide, magnesium carbonate, calcium hydroxide, calcium carbonate, barium hydroxide and barium carbonate. These base materials may be used in amounts of from about equivalent to 1.5 times as much as an equivalent to the saccharoascorbic acid (II) .

The esterifica ion reaction according to the method (C) is carried out usually in the presence of a solvent. Any solvent which does not adversely affect the reaction may be used, but a polar solvent is preferred, such as aceton i tri 1 e , prop i on i tr i 1 e , benzon i tr i 1 e , formamide, d i e thy 1 formam i de , dimethylacetamide, dimethyl sulfoxide, sulfolane, hexamethyl- phosphoram i de , acetone, methyl ethyl ketone, dioxane, tetra- hydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or water. These solvents may be used singly or as a mixture.

The compounds (VI) or (VII) may be used in amounts of about 1-20 moles, prefera-bly in amounts of about 1.2-10 moles, per mole of the saccharoascorbic acid salt (V) used.

The reaction temperature is usually in the range of from about 0°C to about 100°C, preferably from about 10°C to about 80°C. The reaction time may vary depending upon the saccharoascorbic acid sal t (V) and -the other reactants used, but it is usual ly in the range of about 0.5-24 hours, preferabl of about 1-15 hours, al though not critical.

Method (D) :

The saccharoascorbic acid ester (I) of the invention is produced by subjecting a saccharoascorbic acid ester having the general formula of

(VIII)

wherein R is the same as before; R ^z represents a hydrogen or a protective group of a hydroxyl group; R ³ represents a protec¬ tive group of a hydroxyl group; and R ⁴ represents a hydrogen, an acyl or a protective group of a hydroxyl group, to an elimination reaction of the protective group and the acyl group .

In the general formula of (VIII), the hydroxyl protective group represented by R ^z , R ³ and R ⁴ are those which are elimi¬ nated by reduction. Such protective groups are already known, and include, for example, benzyl and a substituted benzyl, preferably with a lower alkoxy, a nitro, a halogen or a cyano, such as p-methoxybenzy 1 , o-ni troben_y1 , p-ni trobenzyI , p- chlorobenzy 1 , p-bromobenzy1 or p-cyanobenzy1. A diphenyl- ethyl is also an example of a preferred protective group. The acyl group is preferably of 1-12 carbons, and is most preferably a lower acyl of 1-7 carbons, which includes, for example, formyl, acetyl, propionyl, butyryl, valeryl, isovaleryl, pyvaloyl or benzoyl.

In this method, the acyl group may be first eliminated, and then the hydroxyl protective group may be eliminated; or the hydroxyl protective group may be first eliminated, and then the acyl group may be eliminated. When the R ^z , R ³ and R ⁴ are all hydroxyl protective groups, they are all eliminated in a single elimination reaction.

The acyl group of 5-ρosition carbon may be eliminated

by hydrolysis thereof wi th an acid or a base. hen the acyl group of 5-posi tion carbon only is to be hydrolyzed in high yields whi le the ester group of the 6-ρosi tion carbon is to be remained unaffected, i t is preferred that the reaction be carried out under conditions as mi ld as possible. The 5- posi tion acyl group may be selectively el iminated since the 5-posi tion acyl is usually more readi ly hydrolyzed, al though somewhat depending upon the ester structure of the 6-posi tion carbon and the acyl structure R ⁴ of the 5-posi tion carbon. The acid used in the hydrolysis is not specifical ly l imi ted, but any acid usable in hydrolysis in general may be used also in this method. Therefore, among others are usable mineral acids and organic acids. More specifical ly, there may be used, as mineral acids, hydrogen halides such as hydrogen chloride, hydrogen bromide, hydrogen iodide or hydrogen fluoride; perchloric acid; sulfuric acid; f 1 uoros u 1 f ur i c acid, phosphoric- acid or boric acid. There may be used as organic acids, arenesulfonic acids such as p- tolueιιesulfonic acid or benzenes u 1 f on i c acid; a 1 kanes u 1 f on i c acids such as ethane- sulfonic acid or tr i f 1 uorome thanesu 1 fon i c acid; aliphatic carboxyl ic acids such as acetic acid or propionic acid; halogenated acetic acids such as trif 1 uoroace t i c acid or tr i ch 1 oroace t i c acid; or H ⁺ -form ion exchange resins. These acids may be used as they are, or as solutions or suspensions in water or organic solvents, if desired. Further, the acids may be used singly or as a mixture of two or more.

The base used in the hydrolysis also is not specifical ly l imi ted, but any base usable in hydrolysis in general may be used in this method. Therefore, there may be mentioned as examples of the bases usable, hydroxides, carbonates or hydrogen carbonates of alkal i metals or alkaline earth metals, such as l i thium hydroxide, l i thium hydrogen carbonate, l i thium carbonate, sodium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydroxide, potassium hydrogen carbonate, potassium carbonate, magnesium hydroxide, magnesium carbonate,

calcium hydroxide, calcium carbonate, barium hydroxide or barium carbonate; organic bases such as pyridine, or primary, secondary or tertiary amines.

Any solvent which does not adversely affect the reaction may be used in the reaction, but a solvent which has a high affinity with water is preferred, such as acetone, methyl ethyl ketone, methanol, ethanol, n-propanol, isopropanol, tert. -bu tanol , aceton i tri 1 e, propi on i tri le, dioxane, tetra- hydrofuran, ethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethyl- forma ide, dimethylacetamide, dimethyl sulfoxide or hexamethyl* phosphorami de. Water also may be used as a solvent. These solvents may be used singly or as a mixture.

The reaction temperature is usually in the range of from about -20°C to about 120°C, preferably from about 0°C to about 100°C, although depending upon the compound (VIII) used and other reaction conditions employed. Similarly the reaction time may vary depending upon the compound ^" (VIII) used and other reaction conditions employed, but it is usually in the range of about 1-10 hours.

As above described, the compound (VIII) which has an acyl group R ⁴ at 5-posi tion carbon can be converted to a compound represented by the general formula of

(IX)

wherein R, R ² and R ³ are the same as before, by deacylation of the 5-ρosition acyl group by hydrolysis.

Then, the el imiation of t e hydroxyl protective group at the 2- and 3-ρosi tion carbon provides the saccharoascorbic acid ester (I) of the invention. The el imiation is usual ly accompl ished by catalytic reduction using hydrogen in the presence of a catalyst such as pal ladium chloride, platinum oxide or platinum black. These may be supported on activated carbon, as exempl ified by Pd/C, alumina, or si l ica gel .

The catalytic reduction reaction is carried out usually in a solvent, such as methanol , ethanol , n-propanol , isopropanol , acetic acid, ace ton i tr i 1 e , pro i on i tr i 1 e, dioxane te trahydro f uran , ethyl ether, 1 , 2 - d i me thoxye thane , ethylene glycol dimethyl ether, chloroform, dichloromethane, benzene, toluene, or water. These solvents may be used singly or as a mi ture. The reaction is carried out usual ly at temperatures in the range of about 10- 100°C, ei ther under normal or increased pressures .

On the other hand, when the hydroxyl protective groups R ^z and R ³ at the 2- and 3-ρosi tion carbons, respectively, are first to be liminated, prior to the deacylation, the method which is used to convert the compound (IX) to the saccharoascorbic acid ester (I) may be employed as i t is. Namely, the catalytic reduction of the ester (IX) wi th hydrogen in a reaction solvent in the presence of a catalyst provides a compound having an acyl group R ⁴ at the 5-ρosition carbon and having the general formula of

wherein R is the same as before.

Then, the application to the above compound (X) of the hydrolysis method which is used to convert the compound (VIII) to the compound (IX) can eliminate the acyl group R ⁴ selecti¬ vely, thereby to provide the saccharoascorbic acid ester (I) .

When R ^z , R ³ and R ⁴ in the compound (VIII) are all hydroxyl protective groups, the aforesaid catalytic reduction of such compounds provides the ester (I) in a single step. As above set forth, the saccharoascorbic acid ester (I) of the invention is obtainable by the method (A) , (B), (C) or (D) , among others, usually in the form of free acids, while the method (D) may provide the ester (I) in the form of sal ts as wel 1. The saccharoascorbic acid ester (I) of the invention may be isolated and purified by a conventional method. Namely, after the reaction, solvents and low boiling temperature materials are removed in a conventional manner from the reaction mixture, and the resultant residue is subjected to extraction, chromatography using, for example, silica gel, polystyrene resins or activated carbon, distillation or recrys tal 1 i za tion . The saccharoascorbic acid ester (I) may be isolated either an anhydrous or hydrated compound.

The saccharoascorbic acid ester (I) in the form of free acids may be converted to the correspondi g salts by the reaction of the acid with a base material such as an alkali metal oxide, an alkali metal hydroxide, an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkaline earth metal oxide, an alkaline earth metal hydroxide or an alkaline earth metal carbonate, an amine or an ammonium hydroxide. The ester (I) in the form of free acids may be converted to salts also by putting the ester in the form of free acids into contact with a cation exchange resin substituted with an alkali metal ion, an alkaline earth metal ion or an ammonium ion.

If desired, after the reaction, there is added to the reaction mixture, wi thout isolating the saccharoascorbic acid ester, an appropria te base material such as an alkal i metal oxide, an alkal i metal hydroxide, an alkal i metal carbonate, an alkal i metal hydrogen carbonate, an alkal ine earth metal oxide, an alkal ine earth metal hydroxide or an alkaline earth metal carbonate, an amine or an ammonium hydroxide, or the reaction mixture is pu t into contact wi th a cation exchange resin having an appropriate alkal i metal ion, an alkal ine earth metal ion or an ammonium ion substi tuted, thereb to convert the ester(I) directly to sal t forms. The salts are then isolated and puri fied in a conventional manner such as recrys ta 11 i za t i on , reprec i p i ta t i on or the l ike.

The saccharoascorbic acid ester (I) and a sal t thereof may contain water of crystal l ization.

The sal t of the saccharoascorbic acid ester (I) of the invention includes, for example, an alkal i metal sal t such as li thium, sodium or pota sium sal t; an alkaline earth metal salt such as magnesium, calcium or barium sal t; and an ammonium, a substi tuted ammonium or a pyridinium salt. There may be mentioned as examples of substi tuted ammonium sal ts, me thy 1 ammon i um , e thy 1 ammno i u , prop 1 ammno i um , bu ty 1 ammon i u , pen t 1 ammon i um , hexy 1 ammon i um , ani l inium, benzy 1 ammon i u , d i me thy 1 ammon i um , d i e thy 1 ammon i um, dipropyl- ammnoium, d i bu ty 1 ammon i um , d i pen ty 1 ammon i u , d i hexy 1 ammon i um , diani l inium, p i per i d i n i u , morpho 1 i n i um , pyr i daz i n i u , pyrro 1 i d i n i u , d i benzy 1 ammon i u , tr i e thy lammon i um , triethyl- am noium, tr i propy 1 ammno i um , tr i bu ty 1 ammoni um , tripentyl- ammonium, tr i hexy 1 ammon i um , tr i benzy 1 ammon ium , tetra ethyl- ammonium, te trae thy 1 ammno i um , te trapropy 1 ammno ium , tetrabutyl- ammonium, te trapen ty 1 ammon i um , te trahexy 1 ammon i u , trimethyl- pheny lammon i um, tr i e thy 1 benzy 1 ammon i um , tr i e thy 1 pheny 1 - ammonium, triethylbenzylammonium, tripropylphenylammoniu , tri rop lbenzylammonium, tributylphenylammonium or tributyl- benzy 1 ammon i um sal t.

The aforementioned saccharoascorbic acid ester (VIII) is also a novel compound, and may be produced in accordance with the scheme shown below:

R

(IX)

The ester (VI I I) may be produced ei ther b Method I or I I.

Method I The ester (XIII) is a compound wherein R ^z , R ³ and R ⁴ ar the same as before, and R ⁴ ' represents a hydrogen or is the same as R ⁴ which is the same as beforementioned. The ester (XI I I) wherein R ⁴ is an acyl may be produced by appl ication of a conventional acylation reaction to the compound (XII) . Namely, the reaction of the compound (XI I) wi th a conventional acylation agent such as an al iphatic or aromatic acid anhydride, inclusive of a mixed acid anhydride, of 1-12 carbons, or an acid hal ide t ereof such as an acid chloride, acid bromide, acid iodide or acid fluoride, in the presence of an acid or a base catalys t, provides the acylated compound (XII I) .

In the acylation reaction, however, two kinds of compounds are produced depending upon the reaction condi tions or reagents used since the starti ng ma terial (XII) is an - hydroxy - carboxy 1 i c acid. One is a compound in which only the 5-posi tion hydroxyl has been acylated, i , e. , the compound (XIII) in which R ^4' is hydrogen, and the other is a compound in which both of the 5-ρosi tion hydroxyl and the 6-ρosi tion carboxyl have been acylated to form a mixed acid anhydride at the 6-posi tion carbon, i .e. , the compound (XII I) in which both of R ⁴ ' and R ⁴ are acyl groups. Al though depending upon the reaction condi tions, methods of after- treatment, or the stabil i ty of the compound (XI II) , ei ther or both of the compound (XIII) in which R ^{4 '} is hydrogen or acyl may be isolated, if needed. Further i f needed, the C00R ⁴ ' (wherein R ⁴ ' is acyl) at the 6-ρosi tion carbon only is hydrolyzed to carboxyl , to provide the compound (XI I I) wherein R ⁴ ' is hydrogen .

On the other hand, the compound (XI I I) in hich R ⁴ is a hydroxyl protective group which is el iminated by a reduction

reaction may be produced by a kno n benzy lation reaction of the compound (XII) . For instance, the reaction of the compound (XII) with an appropriate benzyl halide such as benzyl chloride, benzyl bromide or benzyl iodide, in the presence of a dehydrohalogena tion agent in the absence or presence of a solvent, provides the compound (XIII) in which R ⁴ and R ^4' are hydroxyl protective groups which are capable of being eliminated by a reduction reaction.

In this reaction, a base material is used as a dehydro- halogenation agent, such as sodium hydride, sodium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydride potassium carbonate, potassium hydrogen carbonate, pyridine, or tertiary amines, e.g. , tri ethylam ine, tr i propy 1 a i ne, die thy1propylamine or 4-di me thy laminopyri d i ne. Silver oxide or silver carbonate are also usable as a dehydroha logena t i on agent. When the reaction is carried out in a solvent, there may be usually used as a solvent, acetone, methyl ethyl ketone acetoni tri le, propion i tri le, nitromethane, nitroethane, nitrobenzene, ethyl acetate, dich 1 oromethane, chloroform, carbon te rachloride, dioxane, te trahydrofuran , 1 , 2-d i me thoxy- ethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethyl carbonate, formamide, di ethyl- formamide, dimethyl sulfoxide, sulfolane, or hexa ethyl- phosphoramide. The reaction temperature is usually in the range of from about 0°C to about 120°C, althogh depending upon the reactants and reagents used and the reaction conditions employed. Similarly the reaction time may vary, however, it is usually in the range of about 1-24 hours. The application of conventional esterification reactions to the thus obtained compound (XIII) provides the compound (VIII) .

More specifically, the compound (XIII) in which R ^4* is hydrogen is esterified by a conventional method to provide the compound (VIII) . Such conventional es tero f ica tion methods

include, for example, a so-called direct es terifica ion method in hich the compound (XI II) is reacted wi th the alcohol (I I I) in the presence of an acid catalyst; a method via carboxylates in which the compound (XI I I) is reacted wi th the aforesaid compounds, RX (VI) or (R0) ₂ S0 ₂ (VI I) in the presence of a base material ; a method in which the compound (XIII) is reacted wi th the aforesaid alcohol (I II) in the presence of a dehydration condensation agent exempl ified by dicyclohexylcarbodi imide; a method in which the compound (XIII) is reacted wi th an olefin compound exempl i fied by isobutylene in the presence of an acid catalys t; a method in which the compound (XI I I) is reacted wi th an O-alkylating agent exempl ified by i azo e thane or or ho or a tes ; or the compound (XI II) is first converted to active ester compounds, which is then subjected to alcoholysis by the alcohol (III) . When the compound .(XIII) has an acyl group as R ⁴ ' , i t corresponds to an active ester compound as above mentioned. Therefore, the reaction of the compound (XI I I) wi th the alcohol (III) in the presence of a base catalyst provide's the saccharoascorbic acid ester (VI I I) . When the compound (XI I I) has a hydroxyl protective group as R ^4' , the appl ica¬ tion of ester exchange reaction thereto provides the compound (VIII) .

Method II:

In the steps of from the compound (XI I) wherein R ^z and R ³ are the same as before to the compound (IX) wherein R, R ^z and R ³ are the same as before, a conventional esterification method may be adoptable. Such conventional esterification methods include, for instance, a direct esterification method in which the compound (XII) is reacted wi th the alcohol (III) in the presence of an acid catalyst; a method via carboxylates in which the compound (XII) is reacted wi th the aforesaid compounds, RX (VI) or (R0) _z S0 ₂ (VI I) in the presence of a base material ; a method in which the compound (XI I) is reacted with

the aforesaid alcohol (III) in the presence of a dehydration- condensation agent exemplified by dicycl ohexy lcarbod i i ide ; a method in which the compound (XII) is reacted with an olefin compound exemplified by isobutylene in the presence of an acid catalyst; or a method in which the compound (XII) is reacted with an O-alkylating agent exemplified by diazomethane or or thoforma tes .

In the step of from the compound (IX) to the compound (VIII) wherein R ⁴ is not hydrogen, conventional acylation methods are applicable to the step when R ⁴ is an acyl group. The acylation may be carried out by the reaction of the compound (IX) with an acylating agent such as an acid anhydride of an aliphatic carboxylic acid of 1-12 carbons or an aromatic carboxylic acid, inclusive of a mixed acid anhydride, or an acid halide such as acid chloride, acid bromide, acid iodide or acid fluoride in the presence of an acid catalyst or a basic condensation agent.

On the other hand, when the compound (XII) has a hydroxy protective group as R ⁴ which is eliminated by a reduction reaction, the re-action of thereof with a benzyl halide such as benzyl chloride, benzyl bromide or benzyl iodide, in the presence of a base material or a dehydroha 1 ogena t ion agent such as silver oxide or silver carbonate, provides the compound (VIII) .

The aforesaid compound (XII) used as a starting material in the production of the compound (VIII) as above described is also a novel compound. The compound (XII) may be produced in accordance with the steps shown below:

(XVII) (XVIII) (XIX)

(XX) (XII)

The step 1 is a ketal or an acetal formation reaction of the saccharoascorbic acid (II) for the production of the compound (XIV) in which R ⁵ and R ⁶ are the same or different from each other, and represent independently hydrogen, methyl, ethyl or phenyl, or R ⁵ and R ⁶ combinedly form a divalent polymethylene group represented by -(CHz)n wherein n is 4 or 5 Namely, the saccharoascorbic acid (II) is reacted with an aldehyde or a ketone, or a ketal or an acetal of an aldehyde or a ketone, such as formaldehyde, acetaldehyde, acetone, pro ionaldehyde, methyl ethyl ketone, diethyl ketone, cyclo- pentanone, cyclohexanone or benzaldehyde, in the presence of an acid catalyst, to provide the compound (XIV) . The reaction is carried out usually in the presence of

a solvent. Any solvent which does not adversely affect the reaction may be used, such as ace ton i tr i 1 e , pro i on i tr i 1 e , benzon i tr i 1 e , ni tromethane, ni troethane, ni trobenzene, chloroform, carbon tetrachloride, 1 , 1 - d i ch 1 oroe thane , 1, 2- d i ch 1 oroe thane , hexane, cyclohexane, benzene, toluene, xylene, dioxane, te trahydrofuran , 1 , 2- d i me thoxye thane , ethylene glycol dimethyl ether, diethyl carbonate, d i me thy 1 formam i de , or dimethyl sulfoxide. If desired, the aforementioned ketones or aldehydes, or their ketals or acetals, may be used also as a solvent. These solvents may be used singly or as a mixture. The acid catalyst usable includes, for example, mi neral acids such as hydrogen hal ides, e.g. , hydrogen chloride, hydrogen bromide, hydrogen iodide or hydrogen fluoride; perchloric acid; sulfuric acid; fluorosul furic acid; phosphori acid or boric acid; organic acids such as a renes u 1 fon i c acids, e.g. , p- to 1 uenesu 1 fon i c acid or benzenesu 1 fon i c acid; alkane- s u 1 fon i cac i ds , e.g. , me thanesu 1 fon i c acid or tr i f 1 uorome thane- sulfonic acid; halogenated acetic acids, e. g. , trifluoro- acetic acid or trichloroacetic acid; or H ^* - form ion exchange resins; or Lewis acids such as boron trifluoride, boron trichloride, boron tribromide, boron tri iodide, aluminum chloride, ti tanium tetrachloride, zinc chloride, stannous chloride or stannic chloride.

The reaction temperature is usual ly in the range of from about 0-100°C, and the reaction time is usual ly in the range of about 1-24 hours.

The step 2 is a reaction for the production of the compound (XV) wherein R ^z , R ³ , R ^s and R ⁶ are the same as before from the compound (XIV) . In this step the compound (XIV) is reacted wi th a benzyl halide such as benzyl chloride, benzyl bromide or benzyl iodide, in the presence of a base material or a dehydrohalogenation agent such as si l er oxide or si lver carbonate. The benzyl halide is usual ly used in amounts of about 1-8 moles, preferably in amounts of about 1-6 moles, per mole of the compound (XIV) . The dehydrohalogenation

agent is used usually in amounts of about 1.5-20 moles per mole of the compound ( IV) .

The reaction is carried out usually in a solvent. Any solvent which does not adversely affect the reaction may be used. Such solvents include, for example, acetone, methyl ethyl ketone, ace toni tri le, propioni tri le, nitromethane, ni troethane, nitrobenzene, ethyl acetatre, dioxane, tetrahydro- furan, 1 , 2-d i methoxyethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethyl carbonate, formamide, dime thy 1 formam ide, dimethyl sulfoxide, sulfolane, or hexa- me thy 1 phosphoram ide. These solvents may be used singly or as a mixture of two or more.

The reaction temperature is usually in the range of from about 0-120°C. The reaction time is usually in the range of about 1-24 hours, although depending upon the reactants, dehydrohalogenation agent and solvents used, and the reaction conditions employed.

The step 4 from the compound (II) to the compound (IV) is described hereinbefore with regard to the production of the latter. The step 5 from the compound (IV) to the compound (XVI) may be carried out in the same manner as in the production of the compound (XVI) from the compound (XIV), as described hereinbefore.

The step 3 from the compound (XV) to the compound (XJI) may be carried out by hydrolysis of the acetal or ketal group at the 5- and 6-ρosition carbons under acidic or alkaline conditions. Similarly to the above, the step 6 from the compound (XVI) to the compound (XII) may be carried out by hydrolysis of the ester group at the 6-position carbon under acidic or alkaline conditions.

In the above hydrolysis reactions, there may be used as an alkaline material, for example, sodium hydroxide, sodium hydrogen carbonate,, sodium carbonate, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, barium hydroxide, ammonia, sodium methoxide, or sodium

ethoxide. There may be used as an acid, for example, hydrogen hal ides uch as hydrogen chloride, hydrogen bromide, hydrogen iodide or hydrogen fluoride, perchloric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, tr i f 1 uoroace t i c acid tr i ch 1 oroace t i c acid, p- to 1 uenesu 1 fon i c acid, me thanesu 1 fon i c acid or H ⁺ -form ion exchange resins. The alkaline or acid materials may be used as they are, or as a solution or a suspension in a solvent. Further they may be used singly or as mixture of two or more. The amount of the alkaline or acid materials used may range from a catalytic amount to large excess where they are used as a solvent as wel l . Accordingly, the amount may preferably range from about 0.01 -500 % by weight based on the compound (XV) and (XVI) , respectively.

T e hy rolysis reaction is carried out usually in a so 1 ve n which includes, for instance, water, acetoni trile methanol , ethanol, n-propanol , isopropanol , n-butanol, ter t . - butanol, acetone, methyl ethyl ketone, benzene, toluene, xylene, dioxane, te trahydrof uran, ethyl ether, 1 , 2-d i me thoxy- ethane. e h y 1 ene • g I yco 1 dimethyl ether, diethylene glycol dimethyl ether, formamide, dimethylformamide, or dimethyl sul foxide. These solvents may be used singly or as a mixture of two or more.

The reaction temperature is usually in the range of from about -20°C to 100°C, while the reaction time is usually in the range of about 1-10 hours, although depending upon the reactants, reagents and solvents used, and the reaction condi tions employed.

Meanwhi le, the step 7 is for the production of the compound (XVI II) wherein R ⁵ and R ⁶ are the same as before, and an acetal or ketal formation reaction of the hydroxyls at the 5- and 6-ρosi tion carbons either of L-ascorbic acid (XVII) in which the 5-ρosi tion hydroxyl is on the right hand or has an absolute configuration S, or erythorbic acid (XVII) in which the 5-ρosi tion hydroxyl is on the left hand or has an

absolute configuration R. This acetal or ketal formation reaction may be accomplished by a method known per se, as described, for example, in Japanese Patent Laid-open No. 0- 69079. The step 8 from the compound (XVIII) to the compound (XIX) may be carried out in the same manner as in the step 5 as hereinbefore described. The step 9 from the compound (XIX) to the compound (XX) may be carried out by hydrolysis in the same manner as in the step 3 or 6 as ereinbefore descr i bed.

For the step 10, namely, for the selective oxidation of the thus obtained compound (XX) to the compound (XII) , Heyns" oxidation method may be preferably employed. This oxidation method is a catalytic oxidation with the air or oxygen in the presence of a catalyst such as platinum or palladium which may be supported on activated carbon, alumina or silica gel. The reaction is carried out in the presence of a solvent such as water, dioxane, tetrahydrofuran , 1, 2-dimethoxye thane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone, aceto- nitri le, propionitrile or dimethylformamide. These solvents may be used singly or as a mixture of two or more.

In this oxidation reaction, the reaction mixture becomes acidic as the reaction proceeds since the product (XII) is an acid. Therefore, it is preferred that an alkaline material, such as sodium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydroxide, potassium hydrogen carbonate or potassium carbonate, either as it is or as a solution, be added dropwise to the reaction mixture in accordance with the progress of the reaction to maintain the mixture nearly neutr for example, at a pH of about 5.5-8.5.

The reaction temperature is usually in the range of from about 20°C to 100°C, while the reaction time is usually in the range of about 2-48 hours, although depending upon the reactants and solvents used, and the reaction conditions

emp 1 oyed .

According to the above oxidation reaction, the compound (XI I) is obtained usual ly as a sal t of an alkaline material used in the neutral ization. If needed, the sal t may be converted into free acids (XI I) by the appl ication of mineral acids such as hydrochloric acid or sulfuric acid or H ⁺ -form cation exchange resins to the sal t.

The saccharoascorbic acid ester (I) and a sal t thereof of the invention ha e an excel lent antioxidant activi ty on account of the reductive endiol group in the molecule, and therefore they are useful as antioxidants in a variety of fields. For instance, the ester (I) and a sal t thereof of the invention improve the durabi l i ty of an electroconductive coating composi tion when being contained therein as an an tioxidant. They are also useful as antioxidants for food, and oi l and fat. Further the ester (I) and a sal t thereof of the invention serve as a deodoring agent or deoxygen agent in combination wi th metal sal ts such as iron sal ts, and as a corrosion inhibi tor in sealants such as butyl sealants. Further, the saccharoascorbic acid es ter (I) and a sal t thereof of the invention are useful as intermediates in organic synthesis. In particular, the ester (I) has two optical ly active carbons at the 4- and 5-ρosi tion, so that i t is useful in the synthesis of a variety of optically active products such as natural compounds, medicines, agricul tural chemicals or functional compounds al l of increasing importance.

In addi tion, the saccharoascorbic acid ester derivative (VII I) but also the compounds (IX) , (XII) , (XIII) , (XIV) , (XV) and (XVI) as set forth as intermediates for the production of the compound (VI I I) are al l novel compounds, and they are useful as intermediates for the production of the saccharo ^¬ ascorbic acid ester (I) of the invention.

The electroconductive coating composi tion of the

invention will now be described.

The electroconducti e coating composi tion of the invention comprises: an organic solvent, a resin, an electro¬ conductive metal powder, and saccharoascorbic acid ester or a salt thereof.

In the invention, the saccharoascorbic acid esters are especially preferred as an antioxidant since they have in general a high solubility in many organic solvents but also they are chemically stable. Further, the esters are readily obtained in a pure form contrary to ascorbic acid esters. Ascorhic acid has two endiol type hydroxyls and two non- endiol type hydroxyls, so that it is very difficult to esterify the non-endiol type hydroxyls selectively with a carboxylic acid, resulting in the formation of mixtures of esters. However, since the saccharoascorbic acid has only one carboxylic group therein, the esterification thereof with an alcohol readily provides a single ester in a high yield, not a mixture of esters.

The antioxidant activity of the saccharoascorbic acid esters derives from reducing ability and chelating ability with metal ions, as hereinbefore described, so that any ester may be used as an antioxidant in the electroconduc i e coating composition of the invention. However, methyl, -ethyl, isopropyl, isobutyl, tert. -butyl, octyl, decyl, cetyl, oleyl, stearyl, phenyl, benzyl, allyl or propargyl esters may be preferred.

The electroconductive coating composition of the invention contains the saccharoascorbic acid ester, an ester or a mixture of these, in amounts of about 0.01-10 % by weight, preferably of about 0.05-5 % by weight, most preferably of about 0.1-3 % by weight, based on the weight of an electroconductive metal powder in the composition.

A variety of electroconductive metals are usable in the invention, and there may be mentioned as examples, powders of copper, silver, aluminum, nickel, cromium, or alloys of two

or more of these metals. Al though the metal powders usable in the invention are not limi ted to the above exempl ified, however, a copper powder may be used as one of the most preferred metal powders since the saccharoascorbic acid esters prevent very effectively the surface oxidation of copper powders. Electroconductive substances such as carbon black may be also usable in place of an electroconducti e metal powder. The electroconductive substances, ei ther metal powders or carbon black, are contained usually in amounts of about from 10 % to about 80 % by eigh t based on the co posi tion.

The electroconductive coating composi tion of the invention contains a resin which may be any one used in the conventional electroconductive coating composi tions, and includes among others, for example, acryl ic resins, polyester resins, epoxy resins, urethane resins, oi l base alkyd resins, or emulsions of synthetic rubbers or resins. The resin is contained in the composi tion usual ly in amounts of about 20-90 % by weight based on the composi tion. The electroconducti e coating composi tion of the invention further contains an organic solven t. The solvent usable also is not specifically l imi ted, however, ketones, esters, chlorinated hydrocarbons, hydrocarbons, alcohols, ethers, or mixtures of two or more are usually used.

The invention will now be described wi th reference to examples, which follows.

Reference Example 1 A PYG medium containing 0.5 % of peptone, 0.5 % of yeast extract, 1.0 % of glucose and 0.1 % of K _z HP0 ₄ was placed in a 200 ml capaci ty Erlenmeyer flask, and s team- s ter i 1 i zed at 120°C for 20 minutes. This flask was inoculated wi th one loopful of fresh cells of Pseudomonas aeruginosa IF0 3448 gtown at 28°C for 2 days on a slant medium prepared by supple-

menting PYG medium with 2.0 % of agar. Cultivation was conducted at 30°C for 24 hours with rotation for shaking to give a seed cu 1 ture.

After preliminary pH adjustment to 7.0 with NaOH and bacterial filtration using a 0.45 micron filter, onopo tass i u D-glucarate (by __ Sigma) was added to PYG medium to a concentra- tion of 1 % . To a 200 ml capacity Erlenmeyer flask containing 20 ml of this medium was transferred 1 ml of the above seed culture, and shake culture was performed at 30°C for 24 hours. According to high performance liquid chromatography using a sulfonated polystyrene gel column (by Shimadzu, SCR- 101H column of 7.9 mm x 30 cm; mobile phase: diluted sulfuric acid, ph 2.2; flow rate: 0.5 ml/min. ; detector: differential di f fractometer) , the thus obtained culture broth was found to contain 9.02 mg/ml of 2-keto-D-gI ucaric acid.

The cells were removed from 590 ml of the culture broth by cen tri fugati on to give 580 ml of a supernatant. Cation ^' s in the s uperna tant-were removed by passing through a column of Amberlite cation exchange resin IR120 (H ^* -form, 200 ml) and washing with 150* ml of deionized water, and then the supernata was decolorized by passing through a column of activated carbo (70 ml) and washing with 50 ml of deionized water.

The thus decolorized effluent in amounts of 780 ml was adjusted at pH to 6.5 with Ca(0H) ₂ , filtered to remove turbidity and then concentrated to about 20 ml under reduced pressures, so that white amorphous crystals formed in the concentrate. The crystals were collected on a glass filter, washed with small amounts of cold water, methanol and then ethyl ether, and dried under reduced pressures to give 5.04 g of dlcalcium 2-keto-D-gl ucara te 3.5 hydrate. The analytical data for the crystals were shown below.

Melting point: 152-157°C (decomposed) Elemental analysis (%) for C ₆ H ₆ 0 _B Ca ^• 3.5H ₂ 0

Calculated: C, 23.30; H, 4.24; Ca, 12.96 Found: C, 23.15; H, 4.18; Ca, 14.00

Specific rotation: [ αr] _D ²⁵ = - 11.0° (c =1.075 %, 0.1N HCl, immediately after dissolution) [ c_ ] _D ²⁵ = +9.0° (c = 1.075 % , 0.1N HCl, after equilibration) IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3590, 3500, 3400-2700 (br) , 1650, 1600, 1430, 1380, 1360, 1300, 1250, 1240, 1220, 1125, 1095, 1065, 1040, 1005, 995, 955, 900, 840, 800, 765, 725.

I t was found that the dicalcium 2- ke to - D- g 1 ucara te varied in the amount of hydrated water. The elemental analys study showed that the salt ranged from monohydrate to tetra- hyd ra te .

Reference Example 2

To a stirred suspension of 5.0 g (0.0167 mole) of dicalcium 2- ke to- D- g 1 ucara te trihydrate in 250 ml of acetone was add ^~ ed gradually 2.5 ml of concentrated sulfuric acid. After completion of the addition, stirring was continued for another 3 hours. ^' Insoluble materials were then filtered off using about 20 g of Hyflo Super Cel (Johns-Manville, U.S.A.) as fil ter aids, and then washed with about 1000 ml of acetone.

The filtrate and the washings were combined and concen¬ trated under reduced pressures, and the crystalline precipi- tates were collected by filtration, washed with small amounts of ethyl acetate and then dried in a desiccator, to provide 3.80 g of 2, 3- 0- isopropy 1 idene-2-ke to-D-gl ucar i c acid as colorless needles. The yield was found 91.7 % . The analytica data were shown below. Mel ting point: 180-210°C (recrys ta 11 i zed from acetone/ether, decomposed)

Elemental analysis ( % ) for C 9H ι 20 ₈

Calculated: C, 43.56; H, 4.87

Found: C, 43.57; H, 4.99 I spectrum (ma imum absorptions, cm ^{" 1} , KBr) :

3400, 3300-2800, 1750, 1690.

1.30(s, 3H), 1.39(s, 3H) , 4.35-4.7 Cm, 310 , 8-10(br, 3H) ¹ C-NMR (D ₂ 0, δ ) :

25.3(q), 25.5(q), 76.7(d) , 86.7(d) , 111.8 (s) , 116.7(s) ,

170. (s), 173.0(s).

Reference Example 3

A mixture of 24.8 g (0.1 mole) of 2,3-0-isoρroρylidene- 2- eto-D-g lucaric acid and 50 ml of concentrated hydrochloric acid was stirred at 50°C for 20 minutes. The resultant reaction mixture was concentrated to dryness under reduced pressures, 10 ml of distilled water were added to the residue, and the resultant solution was passed through a column having 50 ml of a special grade activated carbon for chromatography (Shirasagi, registered trademark, by Takeda Chemical Industries, Ltd.) packed with the aid of di ^' stilled water.

After being eluted with water, the elute was concentrate under reduced pressures. To the residue was added a small amount of dichlorα ethane, and the resultant insoluble materials were collected by filtration and dried, to provide 19.0 g of crude D-glucosaccharoascorbic acid (D-ery hro-hex- 2-enaro-l, 4- lactone) hydrate. The purity and the yield were found 98.5 % and 90.0 %, respec ively. Recrys ta11 iza tion from dried acetonitrile provided pure D-glucosaccharoascorbic acid. The analytical data were shown below. Melting point: 188-189°C (decomposed) Elemental analysis (%) for C&H_0.

Calculated: C, 37.91; H, 3.16 Found: C, 37.80; H, 3.21

ΪR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3580, 3500, 3400-3000, 1770, 1720, 1690, 1590.

4.42(d, 1H) , 4.95 (d, III), 6.5-9.5(br, 2H) , 9.5-13(br, 2H).

¹³ C-NMR (d ₆ -DMS0, δ ) :

69.5(d, 5-position C) , 77.2 (d, 4-posi tion C) , 118.9 (s, 2-posi tion C) , 152.3 (s , 3-posi tion C) , 170.5(s, 1- position C) , 171.7(s, 6-ρosi tion C) .

Reference Example 4

A suspension of 500 g of crude dicalcium 2-keto-D- glucarate, which was found to contain 85.1 % or 1.417 mole of dicalcium salt as trihydrate (C6H6θ ₈ Ca-3H ₂ 0) as determined by high performance liquid chromatography, in 1500 ml of distilled water, was stirred at room temperature i le there were added thereto dropwise slowly 214.9 g (2.126 mole) of 97 % sulfuric acid, and after the completion of the addi tion, the mixture was stirred overnight at room tempera ures. The resultant insoluble materials were fil tered off and washed wi th about 1000 ml of disti lled water. The ashings and the fil trate were combined, and concentrated under reduced pressures on a water bath at 55°C to about an amount of -300 ml. After cooling, the resultant insoluble materials were fi l tered off. The filtrate was warmed for 8 hour on a water bath at 55°C, and concentrated under reduced pressures. To the concen¬ trate were added 200 ml of distilled water and the insoluble material formed was filtered off.

The thus obtained solution was passed through a column having 300 ml of a special grade activated carbon for chromato¬ graphy (Shirasagi, registered trademark, b Takeda Chemical Industries, Ltd.) packed with the aid of distilled water. The elution was carried out with distilled water. The eluate was concentrated under reduced pressures, and the precipi tated crystals were collected by filtration, and dried to give the first crude crystals.

The filtrate was again passed through an activated carbon column, and the eluate as concentrated under reduced pressures, and the precipitated crystals were collected by fil tration, and dried to give the second crude crystals. The fil trate was

further treated in the same manner as above, to provide the third crude crystals.

The first, second and third crude crystals were combined and mixed together, to provide 247 g of crude D-glucosaccharo¬ ascorbic acid monohydrate. The purity and the yield were found 96.8 % and 81.1 % , respectively.

Pure D-glucosaccharoascorbic acid monohydrate was obtained by recrys tal 1 iza tion from distilled water. The analytical data were shown below. Melting point: 134-138°C Elemental analysis (%) for C_H ₆ 0 _B :

Calculated: C, 34.63; H, 3.87

Found: C, 34.52; H, 3.89 IR spectrum (maximum absorptions, cm ^{- 1} , KBr) :

3580, 3500, 3400-3000, 1770, 1720, 1690, 1590.

In order to remove water of crystallization from D- g I ucosaccharoascorbic acid monohydrate, recrys ta11 iz ing from anhydrous organic solvents or drying under reduced pressures fay be employed. ^• However, azeotropic dehydration is preferred, as described below.

An amount of 100 ml of acetoπ-rtri le was added to 10.0 g of D-glucosaccharoascorbic acid monohydrate. The acetonitrile was distilled under normal pressures from the mixture while acetonitrile in amounts equal to the acetonitrile distilled was added to the mixture continuously, and in this manner 250 ml of acetonitrile were distilled in total. With the distillation of acetonitril , anhydrous D-glucosaccharoascorbi acid began to precipitate. After the distillation of aceto- nitrile, the precipitates were collected by filtration and dried to provide 8.8 g of D-glucosaccharoascorbic acid in a yield of 96.3 . This product was completely identical with the melting point, IR spectrum, 'H-NMR spectrum, ¹³ C-NMR spectrum, and retention time in high performance liquid chromatography.

Reference Exa p 1 e 5

D- i soascorb i c acid was reacted wi th acetone in accor¬ dance with the description in Japanese Patent Laid-open No. 60-69079 to pro ide 5,6-0-isoρroρylidene-D-isoascorbic acid. Melting point: 167-169°C (recrystallyzed from acetonitrile, decomposed) Elemental analysis ( ) for CgHizOβ

Calculated: C, 50.00; H, 5.60

Found: C, 50.10; H, 5.85 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3550-3300, 1760, 1665, 1650. ^■ H-NMR (d ₆ -DMS0, δ ) :

1.32(s, 3H) , 4.20-4.55(m, 1H) , 4.82(d, J=3Hz, 1H) , ca.

9(br, 2H).

Reference Example 6

An amount of 86.5 g of 5 , 6- 0- isopropy 1 i dene- D- i soascorbi acid was dissolved in 400 ml of dimethyl sulfoxide, and to the resultant solution were added gradually 110.6 g of potassium carbonate under stirring. An amount of 106.3 g of benzyl chloride was added dropwise to the mixture and stirred at room temperatures for 24 hours.

After the completion of the reaction, 2 liters of water were added to the reaction mixture, and the mixture was extracted with dichl oromethane three times wi th 1 liter in total. The extract was washed with water and dried over sodium sulfate. The solvent was distilled off from the extract, and the residue was subjected to silica gel chromatography using chloroform as a solvent, to provide 88.3 g of 2, 3-d i -0- benzy1 - 5,6-0-isopropylidene-D-isoascorbic acid as an oi ly ma erial in a yield of 55.7 1 .

Elemental analysis ( % ) for C 23H _z 40 Calculated: C, 69.68; H, 6.10 Found: C, 69.50; H, 6.18

1.31(s, 3H) , 1.40(s, 3H), 3.6-4.9(m, 2H) , 4.1-4.4(m, 1H) 4.70(d, 110, 5.0-5.3 (m, 4H) , 7.1-7.4(m, 10H) .

Reference Example 7

An amount of 1 liter of 0.1 hydrochloric acid was added to 39.6 g of 2, 3-d i-0-benzyl -5, 6-0- i sopropy 1 i dene-D- Isoascorbi acid, and the mixture was heated at 80°C for 2 hours. The reaction mixture was extracted with chloroform twice each with 0.5 liter. The extract was washed with water and dried over sodium sulfate. The solvent was distilled off, and the residu was subjected to silica gel chromatography using chloroform as a solvent to provide 29.4 g of 2, 3-d i -0-benzy 1 - D- i soascorb i acid as an oily material in a yield of 82.5 %. IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) 3600-3100, 1760, 1670.

3.4-4.2(m, 510, 4.7(d, HI), 5.0(s, 211), 5.15(s, 210,

7.1-7.4(m, 10H)

Reference Example 8

To a mixture of 15.0 g of D-glucosaccharoascorbic acid, 20.55 g of 2, 2-d i me thoxypropane and 150 ml of acetone were added three drops of concentrated sulfuric acid, and the mixture was stirred at room temperatures for 4 hours. After the completion of the reaction, a small amount of pyridine (about ten drops) was added to the mixture, and low boiling temperature materials were distilled off. The residue was then subjected to silica gel chromatography using ethyl acetat as a solvent, and the solvent was removed from the eluate to provide solid materials. The solid materials were recrysta- llized from acetone/dichloromethane (1/10) to provide 16.1 g of 5, 6-0- isopropy1 idene-D-gl ucosaccharoascorbi c acid in a yield of 88.7 %. Melting point: 162-163°C

Elemental analysis ( % ) for C9H10O7 Calculated: C, 46.96; II, 4.38 Found: C, 46.84; II, 4.32

IR spectrum (maximum absorptions, cm ^{" 1} , KBr) 3300, 3200, 1775, 1750, 1700, 1670.

^■ H-NMR (d ₆ -DMS0, δ ) :

1.58(s, 6H) , 4.97(s, 2H) .

The OH group was too broad to determine,

Reference Exa p 1 e 9

To a mixture of 0.40 g of L-gulosaccharoascorbic acid, 1.09 g of 2, 2-d i e thoxypropane and 10 ml of acetone were added one drop of concentrated sulfuric acid, and the resultant mixture was stirred at room temperatures for 3 hours. After the completion of the reaction, four drops of pyridine were added to the mixture, and low boiling temperature materials were distilled off. The residue was then subjected to silica gel chromatography using ethyl acetate as a solvent, _, and the solvent was removed from the eluate. The resultant product was recrys ta 11 i zed from ethyl ace ta te/d i ch 1 orome thane (1/10) to provide 0.231 g of 5 , 6- 0- i sopro y 1 i dene- L- gu 1 osaccharo¬ ascorbic acid crystals in a yield of 47.7 %. Mel ting point: 158- 159 °C Elemental analysis (%) for C9H10O7 Calculated: C, 46.96; H, 4.38

Found: C, 46.42; H, 4.33

IR spectrum (maximum absorptions, cm ^{" 1} KBr)

3500-3100, 1765, 1705. ^■ H-NMR (d.-DMSO, δ ) :

1.47(s, 3H) , 1.55(s, 3H) , 4.95( 2H) . The OH group was too broad to determine.

Reference Example 10

A mixture of 3.0 g of D-glucosaccharoascorbic acid, 60 ml of cyclohexanone di ethylacetal and three drops of

concentrated sulfuric acid was stirred at room temperatures overnight. Low boiling temperature materials were distilled off from the reaction mixture, and the residue was subjected to silica gel chromatography using dichlome thane/ethy1 acetate as a solvent, and the solvent was removed from the eluate by distition. The resultant product was recrys tal 1 i zed from dichloromethane/n-hexane to provide 1.53 g of 5,6-0-cyclo- hexy 1 idene-D-gl ucosaccharoascorb ic acid 0.5 hydrate in a yield of 34.7 % . Melting point: 80-85°C Elemental analysis (%) for C _{t 2} H ι 4O7 -0.5H ₂ 0 :

Calculated: C, 51.61; H, 5.41

Found: C, 51.48; H, 5.18 IR spectrum (maximum absorptions, cm ^" ' , KBr)

3500-3100, 1770, 1690.

1.20-2.00(m, 10H) , 5.06(s, 2H) , ca. 8.5 (br, 1H) , ca. ll.Kbr, 1H).

Reference Example 11

An amount of 2.00 g of 5 , 6-0- isopropy1 idene-D-gluco- saccharoascorbi c acid was dissolved in 15 ml of dimethyl sulfoxide. To the resultant solution were added 1.20 g of potassium carbonate, and then 1.49 g of benzyl bromide dropwise, and the mixture was stirred at room temperatures for 1 hour.

After the completion of the reaction and removal of the remaining insoluble salts by filtration, 200 ml of water were added to the filtrate, which was then extracted with dichloro- methane three times. The extract was washed with water four times, dried and concentrated under reduced pressures. The residue was subjected to silica gel chromatography using ethyl acetate/n-hexane (1/1) as a solvent to provide 1.67 g of 3-0- benzy1-5, 6-0- isopropy1 idene- D- lucosaccharoascorb ic acid as pasty material in a yield of 59.9 %.

The product as found to crystal lize in part in e her/ n-hexane (1/4) to give 0.55 g of crystals. Mel ting point: 137- 139 °C IR spectrum (maximum absorptions, cm ^" ', KBr)

3430, 1805, 1770, 1705. ^■ H-NMR (CDC1 a, δ ) :

1.55(s, 6H), 4.81 (d , 1H, J=2Hz) , 5.00(d, 1H, J=2Hz) ,

5.40(br, OH) , 5.51(s, 2H) , 7.38(s, 5H) . Mass spectrum (m/e)

320 (M ⁺ )

Reference Example 12

An amount of 10.00 g of 5, 6-0- isopropy lidene-D-gluco- saccharoascorbi.c acid was dissolved in 130 ml of dimeth l sulfoxide. To the resultant solution were added 13.2 g of potassium carbonate, and then 11.0 g of benzyl chloride drop- wise, and the mixture was stirred at room temperatures for 16 hours .

After completion of the reaction, - the remaining insolubl salts were removed by filtration, and 800 ml of water ere added to the filtrate. The fil trate was then extracted wi th dichloro ethane three times. The extract was washed wi th water four times, dried and concentrated under reduced pressures. The residue was subjected to silica gel chromato- graphy using ethyl ace ta te/n- hexane (1/2) as a solvent, to provide 6.22 g of 2, 3- i -0- benzy 1 -5, 6- 0- i sopropy 1 i dene- D- gl ucosaccharoascorb i c acid as an oily material in a yield of 34.9 % .

IR spectrum (maximum absorptions, cm ^" ', liquid film) 1800-1760, 1670.

1.53 (s, 6H) , 4.77(d, 1H, J=2Hz) , 4.96(d, HI, J=2Hz) , 5.14(s, 2H), 5.19(s, 1H) , 5.23(s, 1H) , 7.07-7. 3 ( , 10H) . Mass spectrum (m/e)

410 (H , 395.

Reference Example 13

An amount of 3.0 g of 5 , 6-0- isopropy1 idene- D- l uco- saccharoascorbic acid was dissolved in 20 ml of dimethyl sulfoxide. To the resultant solution were added 4.49 g of potassium carbonate, and the mixture was stirred at room temperatures to liberate carbon dioxide. After about 5 minutes, 4.48 g of benzyl bromide was added dropwise to the reaction mixture, and then the mixture was stirred at room temperatures for 2 hours.

After completion of the reaction, the insoluble materials formed were removed by filtration, and the filtrate was poured into about 30 ml of ice water, followed by extraction with about 200 ml of dichloro e thane. The extract was washed with water, dried over anhydrous sodium sulfate, and concentrated by removing the solvent by distillation unde reduced pressures. The residue was then subjected to silica gel chromatography using ethyl ac tate/n-hexane (1/2) as a solvent, to provide 2.36 g of 2, 3-d i -0- benzy 1 -5, 6- 0- isopropylidene-D-glucosaccharoascorbic acid as an oily material in a yield of 44.5 %.

Reference Example 14 An amount of 10.0 g of 2, 3-di -O-benzyl-D- isoascorb i c acid was dissolved in 300 ml of d ioxane/water (1/2) , and there were added thereto 10 g of 5 % Pd/C, followed by heating at 60°C. The air was bubbled into the mixture at a rate of 900 ml/min. while an aqueous solution of NaHC0 ₃ was added to the mixture through a pH controller to maintain the mixtureat a pH of about 7.

After the reaction for 4 hours, the catalyst was remove from the reaction mixture by filtration, and washed with a small amount of d ioxane/wa ter, and the washings were combined with the filtrate. The filtrate was concentrated under reduc

pressures, and the resultant precipi tates ere col lected by filtration, and washed wi th a small amount of ethyl acetate, to provide 5.4 g of white powders.

The powders were dissolved in 200 ml of ater, and the solution was washed with 60 ml of ethyl acetate. Di luted hydrochloric acid was added to an aquous layer to adjust the pH to about 2-3, and the aqueous layer was extracted i th ethyl acetate twice each with 120 ml. The extract was ashed wi h water, dried over anhydrous sodium sulfate, and concen- trated by removing the solvent by distil lation under reduced pressures. The resultant solids were recrystal l ized from hot water to provide 3.66 g of 2 , 3- d i - 0- benzy 1 - D- g 1 ucosaccharo - ascorbic acid in a yield of 35.2 % . Melting point: 123-124°C (decomposed) IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3400, 1770, 1740, 1680. 'H-NMR (CDCls, δ ) :

4.67(d, 110 , 5.06(s, 3H) , 5.15 (s, 2H) , ca. 6.5(br, 210 ,

7.1-7.4(m, 10H) . ¹³ C-NMR (d ₆ -DMS0, δ ) :

69.1(d) , 72.9(0 , 73.9(0 , 76.6(d) , 121.4(s) , 127.3(d) ,

128.2, 128.4(d) , 128.5, 128.7(d) , 135.6 (s) , 136.2(s) ,

156.8(s) , 168.8(s) , 171.0(s) .

Reference Example 15

An amount of 22.2 g of methyl D- g 1 ucosaccharoascorba te monohydrate was dissolved in 200 ml of dimethyl sulfoxide. an to the resultant solution were added gradually 18.0 g of potassium carbonate under stirring. An amount of 27.9 g of benzyl chloride was added dropwise to the mixture and stirred at room temperatures for 24 hours.

After completion of the reaction, 500 ml of ice ater were added to the reaction mixture, and the mixture as extracted with 2 liters of ether, and further with 500 ml of ethyl acetate. The extracts were combined together, washed

with water, dried over anhydrous sodium sulfate, and concen¬ trated by removing the solvent by d i s ti 11 a trion under reduced pressures. The residue was subjected to silica gel chromato¬ graphy using chloroform as a solvent to, provide 24.1 g of methyl 2, 3-d i -0-benzy 1 - D-gl ucosaccharoascorba te as an oily material in a yield of 62.6 % . IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) :

3450, 1760, 1690, 1675. 'H-NMR (CDCla, δ ) :

3.63(s, 3H) , 4.6-4.8(m, 110 , 5.05-5.3 , 5H) , άa. 6.5

(br, 1H) , 7.2-7.6(m, lOH) .

Reference Example 16

An amount of 56.15 g of methyl 2, 3-di -0-benzyl -D-gluco- saccharoascorba te was added to a mixture of 110 ml of 2N hydrochloric acid and 200 ml of acetonitrile, and then refluxed for 8 hours.

After completion of the reaction, the reaction mixture was concentrated to dryness, A small amount of n-hexane/ ethyl acetate wa.s added to the residue, the remaining insoluble materials were collected by filtration, and dried, to give 38.2 g of 2, 3-d i -0-benzy1 -D-glucosaccharoascorbic acid in a yield of 70.6 % .

Reference Example 17

An amount of 4.07 g of 2, 3-di -0-benzy1-5, 6-0- isopropy1 idene-D-glucosaccharoascorbic acid was heated at 60°C in a mixture of 20 ml of water/acetic acid (1/1) for 1.5 hours .

After completion of the reaction, the reaction mixture was concentrated under reduced pressures, and the residue was recrys tal 1 ized .from ethyl aceta te/n-hexane to provide 3.50 g of 2, 3-di -0-benzy1 -D-glucosaccharoascorb i c acid in a yield of 94.0 I .

Reference Example 18

An amount of 7.13 g of 2 , 3- d i - 0- benzy 1 - L- ascorb i c acid was dissolved in 250 ml of a mixture of dioxane and water (1/2) , and there were added thereto 7 g of 5 % Pd/C, followed by heating at 60°C. The air was bubbled into the mixture at a rate of 900 ml/min. while an aqueous solution of NaHC0 ₃ was added to the ixture through a pH controller to maintain the mixture at a pH of about 7.

After the reaction for 5 hours, the catalyst was remove from the reaction mixture by filtration, and washed ith a small amount of dioxane/water, and the ashings were combined wi th the fi l trate. The filtrate was concentrated under reduc pressures, and t e resul tant precipitates were collected by fil tration, and washed with a small amount of ethyl acetate, to provide 4.8 g of colorless powders.

The powders were dissolved in 150 ml of water, and the solution was washed with 60 ml of ethyl acetate. The resul tan aqueous layer was separated, and there was added thereto diluted hydrochloric acid to adjust the pH of the aqueous layer to about 1.-2. Then the aqueous layer was extracted with ethyl acetate twice each wi th 120 ml. The extract as washed wi th water, dried over anhydrous sodium sulfate, and concen¬ trated by removing the solvent by distillation under reduced pressures. The resul tant residue was purified by silica gel chromatography using chloroform as a solvent to provide 4.20 g of 2, 3- d i -0- benzy 1 -L-gulosaccharoascorbi c acid as an oily material in a yield of 56.7 % . Elemental analysis (%) for C ₂ oH ι s07 • 0.2H ₂ 0 Calculated: C, 64.24; H, 4.96 Found: C, 64.21; H, 4.98

IR spectrum (maximum absorptions, cm ^" ' , liquid film) :

3550-3150, 3060, 3040, 2950-2750, 1760, 1735, 1680, 1660. 'H-NMR (d ₆ -DMS0, δ ) : 4.30 (d , 1H) , 4.95(s, 2H) , 5.20 (d, 111) , 5.25(q, 2IO ,

7.20-7.45(m, 5H The signals of the OH and COOH proton were too broad to determine.

Reference Example 19 A mixture of 196 g of L-gulosaccharoascorb i c acid mono- hydratre, 5 ml of concentrated hydrochloric acid and 800 ml of methanol was refluxed under heating for 4 hours. After completion of the reaction, low boiling temperature materials were distilled off under reduced pressures, to provide crude methyl L-gu 1 osaccharoascorba te as a viscous liquid. The crude product was dissolved in 800 ml of dimethyl sulfoxide, and there ere added to the resultant solu ion 276 g of potassium carbonate and 242 g of benzyl chloride, followed by stirring at room temperatures for 16 hours. After completion of the reaction, about 500 ml of water were added to the reaction mixture, and the mixture was extracted three times with dichloro ethane in amounts of 3 liters. The extract was dried over anhydrous sodium sulfate, and concentrated by removing the solvent by distillation under reduced pressures. The resultant residue was separated and purified by silica gel chromatography using dichloromethane as a solvent to provide 48.7 g of nrethyl 3-0-benzy1-L-gulo- saccharoascorba te in an overall yield of 17.6 % and 142 g of methyl 2, 3-d i -0-benzy1 -L-gu losaccharoascorbate in an overall yield of 39.2 %, both as oily materials.

The analytical data of these esters are shown below.

Methyl 3-0- benzyl -L-gu losaccharoascorbate: Elemental analysis (%) for C . ₄ H i 4.0? Calculated: C, 57.14; H, 4.80 Found: C, 56.87; H, 4.53 IR spectrum (maximum absorptions, cm ^{- 1} , liquid film) :

3600-3100, 3050, 1760, 1690. ^■ H-NMR (CDCla, δ ) : 2.94(d, 110 , 3.87(s, 3H) , 4.50(m, 1H) , 4.88(br, 1H) ,

4 . 99 ( d , 1 H ) , 5 . 38 - 5 . 55 ( q , 2 H ) , 7 . 2 - 7 . 45 (m , 5 H ) .

Met yl 2,3-di-O-benzyl-L-gulosaccharoascorbate: Elemental analysis (%) for C21HZ0O7 Calculated: C, 65.62; H, 5.24 Found: C, 65.68; H, 5.32 IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) :

3600-3200, 3100-2850, 1760, 1680. 2.95 (d, 111) , 3.84(s, 3H) , 4.35-4.50 (q , 1H) , 4.94 (d , Hi) 5.09(s, 210 , 5.05-5.35 (q, 2H) , 7.20-7.40 (m, 10H) .

Reference Examp 1 e 20

To a solution of 122 g of methyl 2 , 3- d i - 0- benzy 1 - L- gulosaccharoascorbate in 500 ml of acetoni trile were added

200 ml of 3 hydrochloric acid, and the solution was refluxed under heating for 6 hours.

After completion of the reaction, the reaction mixture was concentrated under reduced pressures, and the residue as purified by silica gel chromatography using chloroform as a solvent to provide 79 g of 2,3-di-0-benzyl-L-gulosaccharo- ascorbic acid in a yield of 67.2 % ^~ . "

Reference Example 21 To a mixture of 25.0 g of 2, 3-d i -0- benzy I - D- g1 uco¬ saccharoascorb i c acid, 20 ml of anhydrous acetic acid and 200 ml of dichloromethane was added one drop of concentrated sulfuric acid, and the mixture was stirred at room tempera¬ tures for 15 hours. After completion of the reaction, low boiling point materials were removed by distillation under reduced pressure and the resultant residue was subjected to silica gel chroma ^¬ tography using di ch 1 orome thane/me thano 1 (95/5) as a solvent to provide 23.75 g of 2, 3-d i -0- benzy 1 -5- ace ty 1 -D-g 1 ucosacchar ascorbic acid in a yield of 85.3 %.

Melting point: 85-92°C

Elemental analysis (%) for C ₂₂ H ₂ oθ8

Calculated: C, 64.07; H, 4.89

Found: C, 63.97; H, 4.95 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3200, 1770, 1760, 1745, 1660. ^f H-NMR (CDC1 ₃ , δ ) :

2.09(s, 310, 5.09(s, 210, 5.12(d, 110, 5.18(s, 210,

5.56 (d, 110, 7.05-7.4(m, 10H) . The COOH was too broad to determine.

Reference Example 22

To a solution of 4.26 g of methyl 2, 3-di -0-benzy1-D- glucosaccharoascorba te in 40 ml of dichlorome hane were added 1.81 g of anhydrous acetic acid and then one drop of concentrated sulfuric acid, and the mixture was stirred at room temperatures for 4 hours.

After completion of the reaction, low boiling point materials were removed by distillation under reduced pressure and the resultant residue was subjected to silica gel chroma¬ tography using ethyl acetate/n-hexane (1/2) as a solvent to provide 4.39 g of methyl 2, 3-di-O-benzyl -5-0-acety1-D-gluco- saccharoascorbate as an oily material in a yield of 92.9 %. IR spectrum (maximum absorptions, cm ^{" 1} , liquid film): 1780-1740, 1680.

2.11(s, 3IO, 3.52(s, 3H) , 5.12(s, 1H) , 5.14(110, 5.17 (s, 2IO, 5.57(d, 1H, J=3Hz) , 7.06-7.40(m, 10H) . Mass spectrum (m/e) : 426(M ⁺ ), 335, 320, 260.

Reference Example 23

To a solution of 2.06 g of 2, 3-di-0-benzy1-5-acety1-D- glucosaccharoascorbic acid in 30 ml of ether were added in small portions an ether solution of diazomethane. The

reaction was stopped unti l the yellow color of diazomethane came to remain in the reaction mixture.

A small amount of acetic acid was added to the reactio mixture to disappear the yellow color, and then the solvent was removed by distillation under reduced pressures, to provide 2.14 g of methyl 2, 3-d i -0- benzy 1 - 5-0-ace ty 1 -D- gl uco¬ saccharoascorba te in a yield of 100 X .

Reference Example 24 To a solution of 10.0 g of 2 , 3- d i -0- benzy 1 - D-g 1 uco- saccharoascorbic acid in 20 ml of dimethyl for amide were added 5.58 g of potassium carbonate, and then 14.7 g of tert. -butyl bromide, follo ed by stirring at 40°C for 16 hours . After completion of the reaction, 500 ml of ether and 80 ml of water were added to obtain an ether extract. The ether extract was washed with water, dried, and the e her was removed by distillation under reduced pressures. The residu was subjected to silica gel chromatography using dichloro- methane/ethyl acetate (1/1) as a solvent. The product was recrys tal 1 i zed from dich 1orome thane/n- hexane to provide 2.66 g of t-butyl 2.3-di -0- benzy 1 - D- g 1 ucosaccharoascorba te in a yield of 23.1 % . Melting point: 103- 105°C Elemental analysis (% ) for C24lI _Z 6θ ₇ : Calculated: C, 67.59; H, 6.15 Found: C, 67.65; H, 6.17 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) : 3500, 1770, 1720, 1680. 'H-NMR (CDCl ₃ , δ ) :

1.33(s, 910 , 3.00(m, 1H) , 4.45(t, 111) , 4.94(m, 1H), 5.11 (s, 410, 7.37(s, 101O.

Reference Example 25 To a solution of 792 mg of 2, 3-d i -0- benzy 1 - 5- ace ty 1 -

D-glucosaccharoascorbic acid in 40 ml of dried dichloromethan were added 844 mg of triphenyIdibromophosphine, and the mixture was stirred at room temperatures for 5 minutes. Then 3.76 g of phenol were added to the mixture and the mixture was stirred for 10 minutes, and then there were added 158 mg of pyridine, followed by stirring at room temperatures for another 10 minutes and then standing overnight.

After completion of the reaction, dichlorome hane and water were added to obtain an organic extract. The extract was dried, and the solvent was removed by distillation under reduced pressures. The residue was subjected to silica gel chromatography using chloroform as a solvent to provi e 720 rag of phenyl 2.3-d i -0-benzy1-5-acetyl -D-g lucosaccharoascorba t as an oily material in a yield of 73.8 %. IR spectrum (maximum absorptions, cm ^"1 , liquid film) :

1780, 1765, 1750, 1675. Ml-NMR (CDC1 ₃ , δ ) :

2.17(s, 310, 5.15(s, 210, 5.23(s, 210, 5.30(d, 110,

5.79 (d, 111), 6.60-7.40(m, 1510.

Reference Example 26

An amount of 300 mg of phenyl 2, 3-di-0-benzy1-5-acety1- D-glucosaccharoascorbate was dissolved in a mixture of 2N hydrochloric acid and acetonitrile (1/9), and the solution was stirred at 80°C for 4 hours.

After completion of the reaction, acetonitrile was removed by distillation under reduced pressures, and ether and water were added to obtain an ether extract. The extract was dried, and the ether was removed by distillation under reduced pressures. The residue was subjected to silica gel chromatography using chloroform as a solvent to provide 50 mg of phenyl 2, 3-di-0-benzyl-D-glucosaccharoascorba te as an oily material in a yield of 18.7 %. IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) : 3650-3200, 1770, 1765, 1675.

55

2.93 (d, 111) , 4.85 (dd, HO, 5.33-5.92 ( , 510 , 6.55-7.43 (m, 1510.

Reference Example 27

To a solution of 3.17 g of 2, 3-di -0-benzy 1 -5-0-ace ty 1 - D-glucosaccharoascorbic acid in 80 ml of dried dichloromethan were added 3.38 g of d i bromo tri phenylphosphorane, and the mixture was stirred at room temperatures for 10 minutes. Then 9.93 g of p-methoxyphenol was added to the mixture, and the mixture as stiired for 10 minutes, and then there ere added gradually 0.65 ml of pyridine, followed by stirring at room temperatures for 1 hour and standing overni ht.

After completion of the reaction, the reaction mixture was added to 100 ml of water, and the mixture was extracted three ti e i th dichloromethane. The extract was dried over sodium sulfate, and the solvent was removed by distillation therefrom. The thus obtained residue was subjected to silica gel chromatography using chloroform as a solvent to provide 1.31 g of p-me thoxypheny1 2, 3-d i -0-benzy1 -5-0-acetyl -D-gl uco¬ saccharoascorba te as an oily material in a yield of 31.6 %. IR spectrum (maximum absorptions, c ^{" 1} , liquid film) :

. 1770-1750, 1680. 'H-NMR (CDC1 ₃ , δ ) : 2.16(s, 310, 3.76(s, 3H) , 5.15(s, 2H) , 5.22(s, 210, 5.29 (d, 1H), 5.77(d, 1H) , 6.67(s, 4H) , 7.10-7.46(m, 10IO.

Reference Example 28 An amount of 1.02 g of p-methoxypheny1 2, 3- di - 0- benzy1 5- ace ty 1 - D- g 1 ucosaccharoascorba te was dissolved in a mixture of 2 ml of 2N hydrochloric acid and 18 ml of acetonitrile, and the solution was stirred at 80°C for 8 hours.

After completion of the reaction, acetonitrile was removed by distillation, and 80 ml of water were added to

the reactiion mixture. The mixture was extracted three limes with ether, and the ether extract was dried over magnesium sulfate, followed by removing the ether by distillation. The residue was then subjected to silica gel chromatography using chloroform as a solvent to provide 510 mg of p-methoxypheny1 2, 3-di -0- benzy1 -D-glucosaccharoascorba te as an oily material in a yield of 49.0 %. IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) :

3700-3150, 1780-1740, 1675.

2.95(d, 110, 3.77(s, 310, 4.83(dd, HO, 4.93-5.30(m,

510, 6.65 (d, 410, 7.10-7.43 (m, lOH) .

Reference Example 29 To a solution of 6.0 g of 2, 3-di-0-benzyl-D-gluco- saccharoascorbic acid in 35 ml of di ethy1formamide were added 1.79 g of potassium carbo'nate at room temperatures unde stirring. After ceasing of generation of carbon dioxide gas, 5.40 g of stearyl bromide were added to the mixture, and the mixture was stirred at 50°C for 7 hours.

After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted three times with ether in amounts of 500 ml. The ether extract was washed with water, dried over sodium sulfate, and the ether was removed by distillation under reduced pressures. The residue was subjected to silica gel chromatography using ethyl acetate/n-hexane (1/3) as a solvent to provide 8.16 g of n-octadecyl 2, 3-di-0-benzy1-D-glucosaccharoascorbate in a yield of 80.9 %.. Melting point: 42-42.5°C (recrys tal 1 ized from methanol) Elemental analysis (%) for C38H5 O7: Calculated: C, 73.28; H, 8.74 Found: C, 73.29; H, 8.79 IR spectrum (maximum absorptions, cm ^" ', KBr) : 3500, 1770, 1740, 1680.

0.75-0.95 (t, 310, 1.0-1.6 , 3210 _ 2.94(d, HO , 3.95 (t, 210, 4.5-4.62(m, HI), 4.95-5.15 (m, 1H + 4H), 7.0- 7.4(m, lOH) .

Reference Example 30

An amount of 5.37 g of dicalcium 2-keto-D-glucarate was suspended in 400 ml of methanol. To the suspension were added 2.4 g of sulfuric acid, and the mixture was refluxed under heating for 90 minute .

After completion of t e reaction, sodium hydrogen carbonate was added to the reaction mixture until the mixture became neutral, and then insoluble calcium sulfate and sodium bicarbonate were removed by fi l tration. The filtrate was concentrated under reduced pressures, and acetone was added to the concentrate to remove insoluble salts therefrom by filtration. T e solvent was removed by distillation under reduced pressures from the filtrate, and water was added to the filtrate, followed by freeze-drying, to provide 2.1 g of dimethyl 2- ke to- D- g 1 ucara te as a syrupy material in a yield of 44.5 %. IR spectrum (maximum absorptions, cm ^" ' , liquid film) :

3600-3200, 1760-1720, 1630. 'H-NM (d_-DMS0, δ ) : 3.62(s, 3IO , 3.65(s, 310 , 3.9-4.2(m, 3H) , 5.6(br, 2H) , 6.8(br, HO . ^{I 3} C-NMR (d ₆ -DMS0, δ ) :

51.53(q) , 52.02(q), 76.64(d), 77.89(d), 78.24(d), 70.03 (d), 79.69(d) , 82.61(d), 99.99(s), 103.85(s) , 168.59 (s) , 169.25 (s) , 169.90 (s) , 170.35(a) .

Example 1

An amount of 100 g of D-glucosaccharoascorbic acid monohydrate was dissolved in 1 l iter of methanol. To the solution were added 3 drops of concentrated sulfuric acid,

and the mixture was refluxed under heating for 5 hours on a wa ter bath.

After completion of the reaction, low boiling point materials were removed by distillation under reduced pressures and 300 ml of d ich 1orometane were added to the concentrate. Crystallization took place gradually. After standing over¬ night in a refrigerator, the resultant precipitates were collected by filtration, washed with a small amount of ether, and dried under reduced pressures, to provide 101.9 g of methyl D- g 1 ucosaccharoascorba te monohydrate in a yield of 95.5 I . Mel ting point: 76.5-77.5°C (recrys tal 1 ized ftom methanol/ di hloromethane (1/1)) . Elemental analysis (_) for C ₇ Haθ7*H ₂ 0: Calculated: C, 37.85; H, 4.54 Found: C, 37.75; H, 4.57 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3560, 3500-3100(br) , 1760-1740, 16&0. 'H-NMR (d ₆ -DMS0, δ ) : 3.63(s, 310 , 4.50 (d, HI, J=3Hz) , 4.93(d, 1H, J=3Hz) , ca. 6-9(br, 3H) .

Example 2

To a mixture of 4.0 g of methyl iodide, 1.46 g of D- gl ucosaccharoascorb i c acid monohydrate and 10 ml of dimethyl formamide were added 1.07 g of potassium carbonate under stirring, and the reaction was carried out at room temperature overnigh t.

After completion of the reaction, the reaction mixture was concentrated under reduced pressures. An amount of 5 ml of water was added ^' to the concentrate and then the mixture was neutralized with diluted hydrochloric acid. The mixture was then extracted three times with ether in amounts of 300 ml. The ether extract was washed with water, dried over sodium sulfate, and the ether was removed by distillation

under reduced pressures to prvide sol id materials. T e solids were recrys ta 11 i zed from me thano 1 /d i ch 1 orome tha ne , to provide 0.47 g of methyl D-glucosaccharoa corbate monohydrate in a yield of 30.2 % .

ExampI e 3

An amount of 4.03 g of me hyl 2, 3-di-0-benzyl-5-acetyl- D-glucosaccharoascorbate was dissolved in 40 ml of methanol, and there were added thereto 200 mg of 2 % Pd/C, hus carryin out hydrogena t i on reaction at normal temperatures under normal pressures .

After completion of the reaction, t e catalyst as removed from the reaction mixture by fi ltration, and methanol was removed by distillation, to provide crystalline solids. The solids were recrystallized from ethyl acetate/n-hexane

(2/1) to provide 2.18 g of methyl 5- 0- ace ty 1 - D- g I ucosaccharo- ascorbate in a yield of 93.7 % . Mel ting point: 135.5-143°C Elemental analysis ^' (%) for C 9 H • o0 ₈ : Calculated: C, 43.91; H, 4.09 Found: . ^' C, 43.81; H, 4.04 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3370, 3200-2950, 1765, 1730, 1670. 'H-NMR (d ₆ -DMS0, δ ) : 2.11(s, 310 , 3.65(s, 3H) , 5.16(d, 1H, J=3Hz) , 5.47 (d, 1H, J=3Hz) . The OH was too broad to determine.

Examp e 4

An amount of 10.2 g of methyl D-glucosaccharoascorbate monohydrate was dissolved in 150 ml of methanol, and cooled with ice water. There were added dropwise to the solution 1.8 g of a solution of sodium hydroxide in 70 ml of methanol. After completion of the reaction, methanol was removed from the reaction mixture by distillation under reduced pressures, and 200 ml of acetone were added to the concentrate

to provide precipitates. The precipi tates were collected by filtration and dried under reduced pressures, to provide 10.3 g of Na salt of methyl D-glucosaccharoascorbate in a yield of

91.5 % .

Melting point: ca. 110°C (decomposed)

Elemental analysis (%) for C ₇ H ₇ 07 a • H ₂ 0:

Calculated: C, 34.44; H, 3.72

Found: C, 34.20; H, 3.80 IR spectrum (maximum absorptions, cm ^" ' , KBr) :

3700-2800, 1740, 1630-1590.

Example 5

An amount of 10.0 g of methyl D-g1 ucosaccharoascorba te monohydrate was dissolved in 200 ml of methanol. A solution of 6.4 g of barium hydroxide octahydrate in 200 ml of methanol was added dropwise to the solution under stirring. After removing insoluble materials by filtration, the filtrate was concentrated to form precipitates. An amount of 300 ml of acetone was added to the concentrate, the precipi tates were collected by filtration, washed with acetonece, and dried, to provide 9.7 g of Ba salt of methyl D-glucosaccharoascorbate in a yield of 74.4 L

Melting point: ca. 150°C (decomposed) Elemental analysis (%) for C ₇ H ₇ 0 ₇ Ba • 0.5H ₂ 0 : Calculated: C, 29.01; H, 3.13 Found: C, 28.92; H, ^" 3.09 IR spectrum (maximum absorptions, cm ^" ', KBr) :

3700-2500(br) , 1750(sh) , 1740(sh) , 1730, 1720(sh) , 1600 (very strong) .

Example 6

To a solution of 10.0 g of L-gu losaccharoascorbic acid in 400 ml of methanol were added 0.5 ml of concentrated hydrochloric acid, and the mixture was refluxed under heating for 3 hours.

After completion of the reaction, methanol was removed from the reaction mixture by distillation under reduced pressures, to provide pasty materials, which became semi-sol id after standing overnight at room temperatures. The materials were dissolved in hot ethyl acetate, and recrys ta 11 ized therefrom to provide methyl L-gulosaccharoascorbate 0.5 hydrat in a yield of 61.5 % . Melting point: 100- 101 °C (decomposed) Elemental analysis { % ) for C7Hsθ7-0.5H ₂ 0:

Calculated: C, 39.45; H, 4.26

Found: C, 39.30; H, 4.25 IR spectrum (maximum absorptions, cm ^" ' , KBr) :

3520, 3500-3000(br) , 1765, 1750, 1735, 1690, 1670. 'H-NMR (d„-DMS0, δ ) :

3.70(s, 3H) , 4.43(br, HI) , 4.95(d, 1H, J=3Hz) , 5.7(br,

1H) . 8.4(br, HO , ll.Kbr, 1H) .

Example 7

A mixture of 10.4 g of D-glucosaccharoascorbic acid monohydrate, 30 ml of ethylene glycol and and one drop of sulfuric acid .was heated under stirring for 4 hours on an oil bath at 100°C.

One tenth of the resultant reaction mixture was subjecte to activated carbon chromatography using acetone/water (1/1) as an eluent, the fractions containing the products were collected, and purified by use of 400 ml of Sefadex G-10. The fractions were then concentrated under reduced pressures, to provide 0.85 g of β - hydroxye thy 1 D-glucosaccharoascorbate 0.5 hydrate as powders in a yield of 69.9 % . Elemental analysis (%) for C ₈ H , _o 0 ₈ ^• 0.5H ₂ 0 : Calculated: C, 39.51; H, 4.56 Found: C, 39.91; H, 4.76 IR spectrum (maximum absorptions, cm ^{" 1} KBr) 3600-2800, 1770-1740, 1700-1670. 'H-NMR (dβ-DMSO, δ ) :

3.3-3.7 (t, 2H), 3.8-4.3(t, 210 , 4.50 Cd, HI, J=3Hz), 4.97 (d, 1H, J = 3Hz), ca. 4-7(br, 3H) , ca. 11.0(br, HO .

Example 8 A mixture of 10.4 g of D-glucosaccharoascorbic acid monohydrate, 200 ml of isopropyl alcohol and one drop of concentrated sulfuric acid was refluxed under stirring and heating for 4 hours.

The resultant reaction mixture was concentrated under reduced pressures, and the residue was dissolved in 500 ml of ethyl acetate and washed with water. After drying over sodium sulfate, the solvent was removed from e mixture b distillation under reduced pressures, and the residue was subjected to silica gel chromatography using ethyl acetate/ dichloromethane as a solvent to provide 8.5 g of isopro l D-glucosaccharoascorbate monohydrate as an oi ly material in a yield of 67.8 %.

Elemental analysis (%) for C9Hι ₂ 0 ₇ -H ₂ 0: Calculated: C, 43.20; H, 5.64 Found: , C, 43.21; H, 5.59

I.R spectrum (maximum absorptions, cm ^{" 1} , l iquid fi lm) :

3600-3000(br) , 1760(sh) , 1740, 1720, 1690. ^■ H-NMR (d_-DMS0, δ ) :

1.05-1.3 (6H) , 4.03(q, 1H, J=7Hz) , 4.43(d, 111, J=3Hz) , 4.87(d, 1H, J=3Hz) , 6.4-8.5(br, 2H) , ca. ll.OCbr, 1H)

Example 9

To a mixture of 3.4 g of isopropyl iodide, 2.08 g of D- g lucosaccharoascorbic acid monohydrate and 30 ml of dimethyl sulfoxide were added under stirring 1.52 g of potassium carbonate, and the reaction was carried out at room tempera¬ tures for 15 hours.

After completion of the reaction, the reaction mixture was added to 70 mi of water, neutralized wi th diluted hydro- chloric acid, and extracted three times wi th ethyl acetate

in total of 500 l. The extract was washed wi th water, dried over anhydrous sodium sulfate, and the solvent was removed by distillation under reduced pressures. The residue was then subjected to si l ica gel chromatography using ethyl acetate as a solvent to provide 0.25 g of isopropyl D-glucosaccharo¬ ascorbate mono ydrate in a yield of 10.0 % .

Examp 1 e 10

A mixture of 10.4 g of D-glucosaccharoascorbic acid, 200 ml of al ly] alcohol and one drop of concentrated sulfuric acid as reflu ed under eating on an oi l bath at 105- 110°C for 6 hours.

After completion of the reaction, the reaction mixture was concentrated under reduced pressures, and the residue was subjected to si l ica gel chro a ogr phy using ethyl acetate as a solvent to pro ide 10.1 g of allyl D-glucosaccharo¬ ascorbate as an oi ly material in a yield of 87.7 % . Elemental analysis (%) for Cv H i o0 ₇ : Calculated: C, 46.96; II, 4.38 Found: . C, 47.24; II, 4.70

IR spectrum (ma imum absorptions, cm ^" ' , liquid fi lm) :

3600- 2800 (br) , 1760- 1680 (br) . 'H-NMR (d _t -DMS0, δ ) :

4.4-4.7 (m, 310 , 4.92(d, III, J=3Hz) , 5.1-5.5(m, 2H) , 5.5-6.2 , 1H + 1H) , ca. 8.3(br, 1H) , ca. ll. Kbr, 1H) .

Exam 1 e 11

A mixture of 10.4 g of D-glucosaccharoascorbic acid monohydrate, 25 ml of propargyl alcohol and one drop of concentrated sulfuric acid was refluxed under heating on an oil bath at 120 - 130°C for 4 hours.

After completion of the reaction, low boiling tempera ^¬ ture materials were removed by distillation under reduced pressures. The residue was subjected to silica gel chromato- graphy using ethyl acetate as a solvent to provide 8.3 g of

propargyl D-glucosaccharoascorbate 0.5 hydrate as an oily material in a yield of 70.0 % .

Elemental analysis (%) for C ₉ H ₈ 0 ₇ - 0.5H-.0 :

Calculated: C, 45.58; H, 3.82

Found: C, 45.74; H, 4.13 IR spectrum (maximum absorptions, cm ^{" 1} , liquid film) :

3600-2800(br) , 1770-1740 (br) , 1730-1670 (br) . 'H-NMR (d ₆ -DMS0, δ ) :

3.5-3.35(110 , 4.57 (d, HI, J=3Hz) , 4.6-4.8(210 , 4.95

(d, 1H, J=3Hz) , 5.0-6.6(br, 111) , ca. 8. (br, 1H) , ca, ll.Kbr, 111) .

Example 12

A mixture of 10.4 g of D-glucosaccharoascorbic acid monohydrate, 50 ml of isobutanol and one drop of concentrated sulfuric acid was refluxed with tirring under heating for 4 hours .

After completion of the reaction, the reaction mixture was concentrated under reduced pressures, and the residue was dissolved in 500 ml of ethyl acetate, washed with water, and dried over anhydrous sodium sulfate. fter removing thε solvent by distillation, the residue was recrys ta 11 ized from ether/ethyl acetate, to provide 9.0 g of isobutyl D-gluco¬ saccharoascorbate in a yield of 73.1 %. Melting point: 131-132°C Elemental analysis (%) for C10H.4O7:

Calculated: C, 48.78; H, 5.73

Found: C, 48.77; H, 5.79 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-3000, 1760, 1750(sh) , 1710, 1685.

0.90(d, 6H, J=6Hz) , 1.65-2.05 (m, 1H) , 3.86(d, 211, J=6Hz

4.51(d, IH, J=3Hz) , 4.95 (d, HI, J=3Hz) . The OH was too broad to determine.

Example 13

An amount of 2.38 g of tert. -butyl 2, 3-di-0-benzy] -D- glucosaccharoascorbate was dissolved in 80 ml of ethyl acta te, and there re added to the solution 200 mg of 5 % Pd/C , and then hydrogenation reaction was carried out at normal temperature under normal pressures. f ter completion of the reaction, the catalys t was removed from the reaction mixture by fi l tration. The ethyl aceta te was removed by disti l lation from the fi l tra te, and the re idue was recrystal l ized from dichloromethane/n- hexane, to provide 1.0 g of tert. -butyl D-glucosaccharoascorbatc 0.2 hydra te i n a ield of 72.8 % . Mel ti n poin t: 53 - 55 °C El emen a l anal ysis (%) for Cι oHi 4θ ₇ -0.2H ₂ 0:

Calcu lated: C, 48.43; H, 5.81

Found : C, 48.24; H, 5.86 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

1770, 1730, 1680.

1.37 (s, 910 , 4.35(br, HI) , 4.86 (d, 1H) 5.60(br, 111) ,

3.37 ( b r , III) , 11.02 (br , 1H) .

Example 14

A i ture of 10.4 g of D-glucosaccharoascorbic acid, 50 g of cyclohexanol and one drop of concentrated sul furic acid was he ted at 100 °C wi th stirring for 3 hours.

Af ter completion of the reaction, low boil ing tempera¬ ture materials were removed by disti l lation under reduced pressures of not more than 3 mmHg. The residue was dissolved in 400 ml of ethyl acetate, washed wi th water, and dried over anhydrous sodium sul fate. After removing the solvent by disti l lation under reduced pressures, the residue was subjecte to si l ica gel chromatography using dichloromethane/isopropyl ether as a solvent to provide 11.25 g of cyclohe yl D-gl uco- saccharoascorbate in a yield of 82.6 % .

Melting point: 112-114°C (recrys ta I 1 i zed from ethyl acetate/ n-hexane) Elemental analysis ( ) for Cι ₂ Hι ₆ 0 ₇ :

Calculated: C, 52.94; H, 5.92

Found: C, 53.31; H, 5.95 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-3000, 1765, 1740, 1700. ^■ H-NMR (d_-DMS0, δ ) :

1.0-1.9(br. 10H) , 4.44 (d , HI) , 4.5-4.9 (br, 1H) , 4.90

(d, 1H) , 6.54(br, 1H) , 8.4(br, 1H) , 11.5(br, 1H) .

Example 15

An amount of 50 mg of phe yl 2,3-di-0-benzyl-D-gluco- saccharoascorbate was dissolved in 20 ml of ethyl actate, and there were added to the solution 5 mg of 5 % Pd/C, to carry out hydrogena tion under normal temperatures and pressures.

After completionn of the reaction, the catalyst was removed from the reaction mixture by fi l tration. The ethyl acetate was removed by distil lation from the filtrate, 'and the residue was subjected to silica gel chromatography using - ethyl acetate as a solvent to provide 24 g of phenyl D- gl ucosaccharoascorba te as an oi ly material in a yield of 82 %. Elemental analysis (%) for Cι ₂ Hιo0 ₇ : Calculated: C, 56.70; H, 3.96 Found: C, 57.02; H, 4.14

IR spectrum (maximum absorptions, cm ^" ', liquid film) :

3680-3000, 1780, 1760, 1680. 'H-NMR (d ₆ -DMS0, δ ) :

4.82 (d, 1H) , 5.13(d, 1H) , 6.20(br, 1H), 6.60-7.58(m, 5H) 8.50(br, 1H) , 11.53(br, 1H) .

Example 16

A mixture of 20.8 g of D- g 1 ucosaccharoascorbic acid monohydrate, 54.1 g of benzyl alcohol and one drop of concentrated sulfuric acid was heated under reduced pressures

of 20-30 mllg on an oi l bath at about 80°C for 4 hours.

After completion of the reaction, excess amounts of benzyl alcohol ere removed by distil lation under reduced pres ures of 1-2 m ll . The residue was then subjected to si l ica gel chromatography using chloroform/ethyl acetate as a solvent to provide 19.9 g of benzyl D-glucosaccharoascorbat in a yield of 67.8 %. el ting point: 145- 146°C (recrystal l ized from acetoni trile) Elemental anal sis (X) for C13H12O7:

Calculated: C, 55.72; H, 4.32

Found: C, 55.61; H, 4.32 IR ectrum ( a i u absorptions, cm ^" ' , KBr) :

3600-2800 (br) , 1770, 1745, 1680. 'H-NMR (d ₆ - DMS0 , δ ) :

4.58(d, HI, J=3Hz) , 4.94(d, 111, J=3Hz) , 5.08(211) , 7.2-

7.45(510 , 7.4-7.8 (br , HO , 8.4(br, 1H) , 11.2(br, 111) .

Example 17

An amount of 510 mg of p-methoxyphenyl 2.3-di-0-benzyl D-glucosaccharoascorbate was dissolved in 30 ml of ethyl actate. Ther were dded to the solution 50 mg of 5 % Pd/C, and a ydrogenation reaction as carried out at normal te pe ratures and under normal pressures.

After completion of the reaction, the catalyst was removed from the reaction mixture by fi l tration. The ethyl acetate was removed by distillation from the fil trate, to provide 260 mg of p-me hoxy hen l D-glucosaccharoascorbate as a pasty material in a yield of 73.0 %. IR spectrum (maximum absorptions, cm ^" ' , liquid film) : 3650-3000, 1780-1750, 1690. 'H-NMR (d _- DMS0, δ ) :

3.75 (s , 310 , 4.77 (d , 1H) , 5.10 (d , 1H) , 6.95(s, 4H) , 8. 5 (br , 1H) , 11.35 (br , HO . The OH was too broad to determine.

Example 18

A mixture of 5.0 g of methyl D- lucosaccharoascorba e monohydrate, 50 ml of n-octyl alcohol and one drop of concentrated sulfuric acid was heated under stirring on an oi bath at 110-ll5°C for 4 hours.

After completion of the reaction, excess amounts of n-octyl alcohol were removed by distil lation under reduced pressures of not more than 3 mmHg. The residue was dissolved in 500 ml of ethyl acetate, washed with water, and dried over anhydrous sodium sulfate. After removing the solvent by distillation under reduced pressures, the residue wa subjected to silica gel chromatography usin e hyl acetate/ tetrahydrofuran as a solvent to provide 4.9 g of n-octyl D-glucosaccharoascorbate in a yield of 72.1 %. Melting point: 89-90°C (recrystal l ize fr e hyl acetate/ n- hexane) Elemental analysis (%) ^" for *Ci4H22θ ₇ : Calculated: C, 55.62; H, 7.33 Found: C, 55.59; H, 7.33 I spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-3000(br) , 1780, 1760(sh) , 1730, 1705, 1690. 'H-NMR (CDC1 ₃ > δ ) :

0.75-1.0 (3H) , 2.1-2.7Q2H) , 4.23(t, 2H) , 4.79(d, 1H, J=3Hz) , 5.13(d, 1H, J=3Hz) . The OH was too broad to determine.

Example 19

An amount of 10.0 g of D-glucosaccharoascorbic acid monohydrate was added to 200 ml of bu toxye thoxyethy I alcohol, and there was added to the mixture one drop of concentrated sulfuric acid. The resultant mixture was stirred under reduce pressures for 6 hours while water was removed by distillation at 100°C.

After completion of the reaction, excess amounts of bu toxye thoxyethy 1 alcohol were removed by distil lation under

reduced pressures. The residue was subjected to si l ica el chromatography using dichloromethane/ethyl aceta e (1/1) as a solvent to provide 8.77 g of butoxyethoxye hyl D-gluco¬ saccharoascorbate as an oi ly material in a yield of 54.7 % . Elemental analysis ( ) for Ci 4H ₂₂ 0 ₉ -0.3H ₂ 0:

Calculated: C, 49.50; H, 6.70

Found: C, 49.67; H, 7.01 IR spectrum (maximum absorptions, c l i ui fi l )

3600-3000, 2950, 1750, ^' 1690. 'H-NMR (d ₆ ^' -DMS0, δ ) :

1.00-0.73(m, 310 , 1.10- 1.70 (m, 410 , «) . 1 U 0--3J ^' 0(m, SH) ,

4.03-4.26(m, 2H) , 4.51 (d, 1H) 4.93(d, 1H) . 5.88(br,

1H) , 8.37(br, 111) , 11.05 (br , 111) . The 011 was too broad to determine.

Exampl e 20

To a mixture 'of 5.0 g of phenacyl bromide, 5.2 g of D- glucosaccharoascorbic acid monohydrate and 100 ml of dimethyl formamide were added under stirring 3.8 g of potassium carbonate, and the reaction was carried out at room tempera¬ tures for 15 hours .

After completion of the reaction, the reaction mixture was concentrated under reduced pressures. To the residue was added 10 ml of water, and the mixture was neutralized with diluted hydrochloric acid, and extracted three times wi th ethyl acetate in amounts of 300 ml. The extract was washed with water, dried, and the solvent was removed by distillation under reduced pressures. The residue was recrystal lized from ethyl acetate/chloroform (2/3) to provide 0.58 g of phenacyl D-glucosaccharoascorbate 0.4 hydrate in a yield of 7.3 %. Melting point: 158- 160°C

Elemental analysis (%) for C • ₄ H • ₂ 0 ₈ ^• 0.4 H ₂ 0 : Calculated: C, 53.31; H, 4.09 Found: C, 53.35; H, 4.35 I spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-2800, 1765, 1750, 1700. ^■ H-NMR (d ₆ -DMS0, δ ) :

4.65(d, HI, J=3Kz) , 5.03 (d , HI, J=3Hz) , 4.5-5.6(br, HO , 5.3-5.7(210 , 7.4-8. Km, 5H-H1H) , ca. ll.Kbr, 1H) .

Examp 1 e 21

A mixture of 41.6 g of D- lucosaccharoascorbic acid monohydrate, 220 ml of n-decyl alcohol and one drop of concentrated sulfuric acid was heated under stirring under reduced pressure of 20-30 m llg on an oil bath at 110-120 °C for 2 ours.

After completion of the reaction, the reaction mixture . was dissolved in 1 li ter of ethyl acetate, washed with water, and dried over anhydrous sodium sulfate. After removing low boi ling temperature materials by distillation under reduce pressures, excess amounts of n-decyl alcohol were removed by ' distillation under highly reduced pressures of not more than 2 m Hg. The residue was recrystallized from ethyl acetate/ n-hexaπe to provide 51.4 g of n-decyl D-glucosaccharoascorbate in a yield of 77.8 % . Mel ting point: 95-96°C Elemental analysis (%) for Cι _H ₂ 6θ*r:" Calculated: C, 58.17; H, 7.93 Found: C, 58.37; H, 7.94 I spectrum (maximum absorptions, cm ^{- 1} , KBr) : 3550-3050, 1775, 1740, 1718. 'H-NMR (d.-DMSO, δ ) :

0.75-1.0 (3H) , l. l-1.8(br, 16H) , 4.03 (t, 2H) , 4.48(d, 1H, J=3Hz) , 4.92(d, 1H, J=3Hz) , 5.0-6.0(br, 1H) , ca. 8.3 (br, HI) , ca. 11.15(br, 1H) .

Example 22

A mixture of 41.6 g of L- gu 1 osaccharoascorb i c acid, 300 ml of n-decyl alcohol and one drop of concentrated sulfuri acid was heated at 110°C under stirring for 3 hours while the

by-produced water was removed by distillation under reduced pre ures .

Immediately after completion of the reaction, the reaction mixture as poured into 2 li ters of n- hexane, and the resul ant precipi tates were collected wi th excess amounts of n-decyl aocohol removed. The precipitates were dissolved in 200 ml of thyl acetate, and the solution was added to 800 ml of n-hexane. The resultant precipitates ere collec ed, and di solved in 500 ml of acetoni trile. To the solution was added n- exane, ^' and the separated acetoni tri le layer was dried to p o ide 9.5 g of n-decyl L-gulosaccharoascorbate in a yi l of 74.9 %.

Mel ting point: 67-70°C Elemental analysis (%) for C ■ &H ₂₆ 07 :

Calculated: C, 58.17; H, 7.93

Found: C, 58.46; H, 8.21 IR spectrum ( aximum ^' absOrptions, cm ^{" 1} , KBr) :

3550-3100 (br) , 2930, 2860, 1775, 1750, 1705, 1660. 'H-NMR (d ₆ -DMS0. δ ) :

0.85 ( t , 310., 1.25 (s , 16H) , 4.12(t, 210 , 4.40 (d , 110 ,

4.94 (d , 1H) , ca. 5.7(br, 1H) , 8.41 (br, 1H) , 11.0 (br , 111) .

Examp I e 23

A mixture of 5.0 g of methyl D-glucosaccharoascorbate monohydrate, 16.8 g of n-dodecyl alcohol and one drop of concentrated sulfuric acid was heated under stirring for 4 hours on an oil bath at 110-115°C.

After completion of the reaction, the reaction mixture was poured into 100 ml of n-hexane, and the resul tant preci- pi tates ere collected. After drying, the precipitates were passed through a silica gel column of about 10 cm in length using ethyl acetate/tetrahydrofuran as a solvent. The re o a of the solvent from the eluate provided 6.6 g of n-dodecyl D-glucosaccharoascorbate in a yield of 81.4 % . Mel ting point: 101-102°C (recrystall ized from ethyl acetate/

2

n-hexane) Elemental analysis (%) for Cι ₈ H ₃ oθ7:

Calculated: C, 60.32; H, 8.44

Found: C, 60.30; H, 8.47 IR spectrum (maximum absorptions, cm ^" ', KBr) :

3600-3050(br), 1770, 1740, 1710.

0.75-0.95(3H) , 2.1-2.7(2011) , 4.02(t, 210 , 4.46(d, 1H,

J=3Hz) , 4.89(d, 1H, J=3Hz) , 7.5-9(very br, 2H) , ca. 11.1

(br, 1H) .

Example 24

A mixture of 10.4 g of D-glucosaccharoascorbic acid monohydrate, 21.4 g of n- tetradecano 1 and one drop of concentrated sulfuric acid was heated under stirring under reduced pressures of 20-30 mmHg for 3 hours on an oil bath at about 110°C.

After completion of the reaction, the reaction mixture was poured into 100 ml of n-hexane, and the resultant preci- pitates were collected. After washing with petroleum ether and drying, the precipitates were recrystallized from ethyl aceta te/n-hexane to provide 14.0 g ^~ of n-tetradecyl D-gluco¬ saccharoascorbate in a yield of 72.4 %. Melting point: 110-111°. Elemental analysis (%) for C ₂₀ H ₃ θ7:

Calculated: C, 62.16; H, 8.87

Found: C, 62.13; H, 8.90 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-3050(br) , 1780(sh) , 1770, 1740, 1710. 'H-NMR (d ₆ -DMS0, δ ) :

0.75-0.95C3H) , 2.15-2.65(2410, 4.02U, 210, 4.46(d, 1H,

J=3Hz), 4.92 (d, 1H, J=3Hz) , ca. 11.1 (br, 1H) . The OH was too broad to determine.

Example 25

An amount of 40 g of n-hexadecyl alcohol was placed in a four necked flask and heated on an oil bath at about 80°C to mel t the alcohol . An amount of 10.0 g of methyl D-gluco¬ saccharoascorbate monohydrate and two drops of concentrated sulfuric acid were added to the melt i th stirring, and the mixture was stirred for 5 hours under stirring on an oi l bath at about 110°C.

After completion of the reaction, the reaction mixture as poured into 200 ml of n-hexane, and the resultant preci- pi tates ere col lected. After washing wi th petroleum ether and drying, the preci i tates ere recrystall ized from eth l acetate/n-hexane to provide 10.1 g of n-hexadecyl D- luco- saccharoascorbate in a yield of 54.1 % . Mel ting point: 111-112°C Elemental analysis ( % ) for C ₂₂ H ₃ β0 ₇ :

Calculated: C, 63.74; H, 9.24

Found: C, 63.72; H, 9.20 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3500-3050 (br) , 1765, 1740, 1710. 'H-NMR (d ₆ -DMS0, δ ) :

1.75-1.95(310 , 2.0-2.7 (2811) , 4.03 ( t , 211) . -4.47 (d , Hi,

J=3Hz) , 4.90(d, 111, J=3Hz) , ca. ll(br, 1H) . Two OH were too broad to determine.

Examp 1 e 26

An amount of 70 g of n-octadecyl alcohol was placed in a four necked flask and heated on an oil bath at about 80°C to melt the alcohol , and to this melt were added 41.6 g of D-glucosaccharoascorbic acid monohydrate with stirring. After fully mixing, two drops of concentrated sulfuric acid were added to the mixture, and the mixture was stiired under reduce pressures of 20-30 mmllg on an oi l bath at about 110°C . As the reaction proceeded, the water generated as distilled off.

After 3 hour reaction, the reaction mixture was cooled to room temperatures to become solids. The solids were

recrystal lized from ethyl ace ta te/n- hexane (1/4) to provide 61.0 g of the first crystals. The mother liquor was concen¬ trated under reduced pressures ,, -aifd the residue was recrysta¬ ll ized from ethyl ace ta te/n-hexane (1/5) to provide 7.5 g of the second crystals. Thus, 68.5 g of n-octadecyl D-gluco¬ saccharoasc rbate were obtained in total. The yield was found 77.4 % . Melting point: 118 °C (recrystallized from ethyl acetate/n- he ane) Elemental analysis (%) for C ₂ H ₂ 0 ₇ :

Calculated: C, 65.13; H, 9.56

Found: C, 65.22; H, 9.60 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3500-3100, 1770, 1740, 1715.

0.86(t, 310 , 2.1-2.4(br, 30H) , 2.4-2.7(br, 210 , 4.04(t,

2H) , 4.46(d, 1H, J=3Hz) , 4.90 (d, 1H, J=3Hz) , 8.1-8.5(br,

2H) , 11.06(br, 1H) .

E am le 27

A mixture of 22.2 g of methyl D-glucosaccharoascorbate monohydrate, 54 g of n-octadecyl al ^~ cτϋhol and two drops of concentrated sulfuric acid was stirred under reduced pressures of 20-30 mmHg on an oil bath at about 110°C. As the reaction proceeded, the water and methanol generated were distilled off.

After five hour reaction, the reaction mixture was added to 600 ml of n-hexane with stirring to become solids. The solid materials were collected by filtration, and washed with hot n-hexane. After drying, the solids were dissolved in a least amount of ethyl acetate under heating. To this solution as added n-hexane in small portions so that flake like white crystals precipitated. The precipitates were collected by fil tration and dried, to provide 29.3 g of n-octadecyl D- glucosaccharoascorbate in a yield of 66.2 %.

Example 28

To a mixture of 19.0 g of stearyl iodide, 10.4 g of D- glucosaccharoascorbic acid monohydrate and 200 ml of dimethyl formamide were added under s tirring 7.60 g of potassium carbonate, and the reaction was carried out at room tempera¬ ture for 20 hours.

After completion of the reaction, the reaction mixture was concentrated under reduced pressures. To the residue was added 50 ml of water, and th mix ure w neutral ized wi th di luted hydrochloric acid, and e tracted three times i th ether in amounts of 700 ml . The extract wa washed wi th ater dried over anhydrous sodium sul fa te, and the sol vent as removed by dis ti l lation und r reduced pres ures. The re.sidue was recrystal l ized from eter/n-hexane to provide 2.43 g of n-octadecyl D-glucosaccharoa corbate in a yield of 11.0 % .

Example 29

An amount of 7.75 g of n-octadecyl 2 , 3- d i - 0- benzy 1 - D- glucosaccharoascorbate was dissolved in 50 ml of ethyl actate, and there were added to the solution 500 mg of 5 % Pd/C.

Then the mi ture was s tirred under normal pressures in the presence of hydrogen gas for 4 hours ^' and 20 minutes.

After completion of the reaction, the catalyst was removed from the reaction mixture by fi l tration, washed wi th smal l amounts of ethyl acetate, and the washings were combined wi th the fi l trate. The ethyl acetate was removed by disti lla¬ tion from the fil trate under reduced pressures, and the residu was recrystall ized from ethyl ace ta te/n- hexane, to provide 5.17 g of n-octadecyl D-glucosaccharoascorbate in a yield of 93.9 I.

Example 30

A solution of 1.65 g of sodium ydroxide in 100 ml of met anol as added dropwise to a olution of 18.7 g of n-octadec l D-glucosaccharoascorbate in 100 ml of methanol

hile the mixture was cooled so that the temperatures of he mixture was maintained at not more than 10°C.

The resultant white cry tals ere collected by filtra¬ tion, washed i h methanol and dried to provide 16.5 g of monosodiu salt of n-octadecyl D-glucosaccharoascorbate in a yield of 88.2 % .

Melting point: 170-173°C (decomposi tion) Elemental analysis (%) for C24ll4i0 ₇ a:

Calculated: C, 62.05; H, 8.90

Found: C, 62.08; H, 9.21 IR spectrum (maximum absorptions, cm ^" ', KBr) :

3600-3350(br) , 1760, 1735, 1630.

Example 31 A solution of 1.94 g of 85 1 potassium hydroxide in

100 ml of methanol was added dropwise to a solution of 13.3 g of n-octadecyl D-glucosaccharoascorbate in 200 ml of methanol at temperatures of not more than 10°C.

The resul tant precipi tates were collected by filtration, ashed with methanol and dried to provide 12.0 g of mono- pottasium salt of n-octadecyl D-glucosaccharoascorbate in a yield of 83.0 %.

Melting point: 120-140°C (decomposed, not clear)

Elemental analysis (%) for C ₂ H i0 ₇ K: Calculated: C, 59.97; H, 8.60 Found: C, 60.33; H, 8.82

IR spectrum (maximum absorptions, cm ^" ', KBr) :

3500-3100, 1780, 1760, 1740, 1670, 1640, 1630.

Example 32

A solution of 3.9 g of barium hydroxide octahydrate in 100 ml of methanol was added dro ise to a solution of 13.3 g of n-octadecyl D-gl ucosaccharoascorba te in 200 ml of methanol at temperatures of not more than 10°C. The mixture was stirred to become turbid and finally

pasty. The insoluble materials were col lected by fi l tration, washed wi th methanol and dried to provide 12.0 g of mono- barium sal t of n-octadecyl D-glucosaccharoascorbate.

The yield was found 93.5 % based on the barium hydro id octahydrate used.

Mel ting point: 145- 180°C (decomposed, not clear) Elemental analysis (%) for C ₂₄ H ₄ ι 0 ₇ Ba • 0.5H _z 0 :

Calculated: C, 55.51; H, 8.15

Found: C, 55.28; II, 8.02 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3400-3000, 1765, 1740, 1620.

Example 33

Ammonia was introduced into a solution of 20.0 g of π ^■ octadecyl D-glucosaccharoascorbate in 350 ml of me han l a t temperatures about 10°C. After the introduction of nearl the theoretical amount of ammonia, the insoluble materials formed were collected by fil tration, washed i th me han l , and dried to provide 17.9 g of monoam onium sal t of n- octadecyl D-gluc.osaccharoascorbate in a yield of 80.2 %. Mel ting point: 138- 142°C (decomposed) Elemental analysis (%) for C24H SNO7 ^" : Calculated: C, 62.72; H, 9.87 Found: C, 62.66; H, 9.93 I spectrum (maximum absorptions, cm ^" ' , KBr) :

3500-3000, 2350, 1760, 1730, 1720 (sh) , 1620.

Examp 1 e 34

An amount of 140 g of n-octadecyl alcohol and 0.1 ml of concentrated sulfuric acid were added to 83.2 g of L- gulosaccharoascorbic acid, and the mixture was heated 100- 120°C for 6 hours with stirring hile the ater generated by the esterification reaction was removed by disti llation under reduced pressures. After compeltion of the reaction, 2 l i ters of e hyl

acetate and 1 liter of water were added to the reaction mixture, and funnel separation was conducted to remove the unreacted raw materials which transferred to an aqueous layer. An amount of 5 liters of n-hexane was added to the ethyl acetate layer, and the resultant precipitates were collected by filtration and dried, to provide 84 g of n-oc adecyl L-gulosaccharoascorbate in a yield of 46.5 % . Melting point: 94-96°C Elemental analysis (%) for C2 H4 zOγ • 0.5H ₂ 0 :

Calculated: C, 63.83; H, 9.60

Found: C, 64.07; H, 9.61 IR spectrum (maximum absorptions, cm ^" ', KBr) :

3500, 3400-3200, 2920, 2850, 1770, 1740, 1705, 1680,

1660, 1640. 'H-NMR (d ₆ -DMS0, δ ) :

0.85(s, 310, 1.23(s, 3210 , 4.11(t, 210 , 4.4(d, Hi,

J=3Hz) , 4.95(d, 1H, J=3Hz) . The OH was too broad to determine.

Example 35

A mixture of 10.0 g of D-glucosaccharoascorbic acid monohydrate, 16 ml of isostearyl alcohol , one drop of concentrated sulfuric acid, and 30 ml of te trahydrofuran was refluxed under heating for 7 hours. After completion of the reaction, the reaction mixture was dissolved in 400 ml of ethyll acetate, washed with water, dried and then concentrated under reduced pressurers. The residue was subjected to silica gel chromatography using n-hexane/ether as a solvent to provide 9.69 g of isostearyl D-glucosaccharoascorbate 0.3 hydrate as an oily material in a yield of 45.0 % .

Elemental analysis (%) for C ₂₄ H ₄ ∑OT • 0.3H ₂ 0 : Calculated: C, 64.35; H, 9.58 Found: C, 64.28; H, 9.35 IR spectrum (maximum absorptions, cm ^" ', liquid film) :

3600-3000, 1760, 1740, 1690. 'H-NMR (d ₆ -DMS0, δ ) :

1.7-2. Kbr, 610, 2.1-2.45 (br, 2811), 2.45-2.8(br, 1H), 4.05 (d, 2H), 4.55 (d, 111, J=3!lz), 4.97(d, 1H, J=3Hz) . The OH was too broad to determine.

Example 36

A mixture of 20.8 g of D-glucosaccharoascorbic acid monohydrate, 48.6 ml of 65 % oleyl alcohol and two drops of concentrated sulfuric aci w s he ted on an oil bath at about 110°C for 2hours under reduced r ssures of 20-30 mmHg.

After completion of t e re ction, the reaction mixture was dissolved in 500 ml of ethyl acetate, washed with water, dried and then concentrated under reduced pressurers. An amount of about 300 ml of n-hexane was added to the residue, and the resultant precipitat s ere collected by filtration, and dried to provide 29.8 g of oleyl D-glucosaccharoascorbate in a yield of 67.6 %.

Melting point: 84-85°C (recrystallized from n-hexane) Elemental analysis (%) for C _{z 4} II<ι o0 ₇ :

Calculated: C, 65.43; II, 9.15

Found: C, 65.41; II, 9.23 IR spectrum (maximum absorptions, cm ^{" 1} , KBr) :

3600-3000, 1780, 1765, 1740, 1715 _: 1700(sh), 1695(sh) 'H-NMR (CDCl a, δ ) :

0.8-1.0U, 3H), 1.1-2.2 (br, 28H) , 4.23 (t, 2H) , 4.79

(d, 1H, J=3Hz), 5.12 (d , 1H, J=3Hz) , 5.15-5.50 (br, 2H)

The OH was too broad to determine.

Example 37

A mixture of 1.04 g of D-glucosaccharoascorbic acid monohydrate, 4.61 g of lignoceryl alcohol and one drop of concentrated sulfuric acid was heated on an oil bath at about 1 0°C for 2hours under reduced pressures of 20-30 m Hg. After completion of t e reaction, the reaction mixture

was cooled. The resultant solids were pulverized and washed with about 100 ml of water. After drying and washing with a small amount of n-hexane, the solids ere recrystallized from ethyl ace ta te/n-hexane, to provide 1.93 g of lϊgnoceryl D-glucosaccharoascorbate 1/2 hydrate in a yield of 72.0 % . Melting point: 118°C Elemental analysis (%) for C ₃ o-Hs ι0 ₇ • 0.5H ₂ 0 :

Calculated: C, 67.26; H, 10.35

Found: C, 67.41; H, 10.32 IR spectrum (maximum absorptions, cm ^" ' , KBr) :

3500-3100, 1760, 1735, 1705. 'H-NMR (CDCls, δ ) :

0.98(t, 3H) , 1.15-1.45 (br, 4210 , 1.45- 1.60 (br, 210 ,

4.1 (t, 3H) , 4.55(d, HI, J=3Hz) , 5.0(d, 111, J=3Hz) . The

OH was too broad to determine.

The followihgs are examples of the electroconductive coating composition of the invention. Parts designate parts by weigh t.

Example 38

An amount of 30 parts of an acrylic resin was mixed and kneaded with 50 parts copper powder and 20 parts of an organic solvent to provide an elec roconducti e coating composition. An amount of 10 g of the composition was kneaded with 0.05 g of a saccharoascorbic acid ester as shown in Table 1, and then was mixed with about 5 ml of ethyl acetate to properly adjust the viscosity of the composition. The composition was coated in an area of 7 cm x 7 cm and in a thickness of about 50 micron meter on sheets of glass, and dried overnight.

The surface resistance was measured by use of a tester. Thereafter the surface was forcibly deteriorated in an hot air oven at 80°C for a predetermined period of time, and then taken out of the oven. After standing to room temperatures, the surface resistance was again measured. The results are

shown in Table 1, in which the resistances are an average of four point measurements at a 2 cm interval of terminals of the tester.

Simi larly to the above, the composition was coated in an area of 7 cm x 7 cm and in a thickness of about 100 micron meter on an ABS resin sheet, and dried overnight.

The surface resistance was measured before and after the forced d terioration in the same manner as above. Th resul ts re sho n in Table 2, in which the resistances are an average of fi e point measurements at a 1.4 cm interval of terminals of the tester.

For com rison, an electroconductive composition was prepared i thout the incorporation of the saccharoascorbic acid ester otherwise in the same manner as above. The surface re i ance of the glass and ABS resin sheets are s own in Tabl 1 and 2, respectively.

Table 1

Surface Resistances (Ω)

Appearances

Add i t i ves I'n i t i a 1 Af ter (hrs . )

150 650 986 1346

Me hyl ester 11 1 1 2 2 3 None Octyl ester 13 5 5 5 5 3 None

Decyl ester 12 2 3 3 3 3 4 None Cetyl ester 12 3 5 5 4 4 - None

Oleyl ester 12 4 2 2 4 4 4 None Stearyl ester 10 3 3 3 4 4 3 None Benzyl ester 10 3 3 3 3 3 3 None

None 13 6 5 500 1 1000000 - **

*) Al l are the esters of D-glucosaccharoascorbic acid. **) The film was found to get dark.

Table 2

Surface Resistances (Ω)

Appearances

Addi ti ves Initial After (hrs. )

360 910 1340

Stearyl ester ^* ' 3 2 2 3 ***

Decyl ester ^* ' 3 3 3 3.5 ***

Benzyl ester ^* ' 2 2 3 3 ***

Stearyl ester ^** ' 3 2 3 3 ***

None 3 10 900 >1KΩ ****

*) The esters of D-glucosaccharoascorbic acid.

**) The esters of L-gu losaccharoascorbic acid.

***) The film was found to get slighly dark.

****) The film was found to get dark.

The composition of the invention forms a durable and stable elec roconductive layer which is not substantially reduced in .el ectroconduct iv i ty wi th time.

Example 39

An amount of 55 parts of an epoxy resin (Epicoat 828) was mixed and kneaded overnight with 100 parts of copper powder and 100 parts of an organic solvent composed of an equal weight of ethyl acetate and toluene by use of a ball mill, to provide a liquid A. An amount of 5.5 parts of triethylene tetramine was dissolved in 20 parts of a solvent composed of an equal weight of ethyl acetate and toluene, to provide a liquid B.

Then the liquid A was mixed with 0.15 parts of stearyl L-gulosaccharoascorbate, and further with 2.5 parts of the liquid B and 0.1 part of resorcinol, to provide an electro¬ conductive coating composition of the invention.

The composition was coated on an ABS resin sheet In an area of 7 cm x 7 cm and in a thickness of about 100 micron meter with a brush, and dried for 3 days.

The surface resistance was measured by use of a tester. Thereafter the urface was forcibly deteriorated in an hot air oven at 80 °C for a predetermined period of time, and then taken out of the oven. After standing to room temperatures, the surface resistance was again measured. The resistances were taken as an average of five point measurements at a 1.4 cm interval of terminals of the tester. The surface resistances were ini tial ly 3Ω , and 2Ω and 4Ω , after 455 hours and 960 hours, respectively. No change in the appearances of the coating was observed over the period.

For comparison, an electroconductive coating compo i tion was prepared i thout the incorporation of the stearyl L- gulosaccharoascorbate otherwise in the same manner as above. In the same experiment s above, the surface resistances were 3Ω ,

6Ω and 700Ω , ini tial ly, after 455 hours and 960 hours, respectively. The coating was .found to get dark after the experi ent.

T e composi tion of the invention forms a durable and stable electroconductive layer which is not substantially ^• reduced in electroconductivi ty with time.

Example 40

An electroconductive coating composition was prepared using benzyl D-glucosaccharoascorbate and otherwise in the same manner as in Example 1. The composition was coated on an ABS resin sheet, dried, and then surface resistance was measured at intervals of time.

The resistances taken as an average of five point measurements at a 1.4 cm interval of terminals were initially 3Ω , and 2Ω ei ther after 470 hours and 984 hours, respectively. The coating was found to remain unchanged in the appearances.

For comparison, an electroconductive coating composition was prepared using anthranilic acid and urushiol, respectivel ,

and otherwise in the same manner as above. In the same experiment as above, the surface resistances of the coating containing anthrani lic acid were initially 4Ω , and 5Ω after 470 hours, but 20Ω after 984 hours. The coating was found unchanged in the appearances.

On the other hand, the surface resistances of the coatin containing urushiol were ini tially 3Ω, and 7Ω after 470 hours, but 15Ω after 984 hours. The coating was found to slightly smel 1 bad.

Examp I e 41

An amount of 112 parts of an acryl ic resin (Acrydick A-801 by Dainippon Ink Kagaku Kogyo K.K.) was kneaded with 130 parts of silver powder and 1.5 parts of isobutyl D- g lucosaccharoascorba te by use of a ball mill overnight. An amount of 24 parts of the resultant mixture was then admixed with 3.-3 parts of an urethane resin (Takenate D-160N by Takeda Chemical Industries, Ltd.) to provide an electroconductive coating composition of the invention. The composi tion was coated on an unsaturated polyester resin sheet in an area of 7 cm x 7 cm and in a thickness of about 100 micron meter, dried and aged for 3 days, and the surface resistance was measured wi th a tester. Thereafter the surface was forcibly deteriorated in an hot air oven at 80°C for a predetermined period of time, and then taken out of the oven. After standing to room temperatures, the surface resistance was again measured.

The resistances taken as an average of five point measurements at a 1.4 cm interval of terminals substantially remained the same over 1500 hours, namely, 1Ω, 1Ω, 2Ω and 1Ω, initially, after 470 hours, 984 hours, and 1500 hours, respectively. Further, no change in the appearances of the coating was observed over the period.

For comparison, an electroconductive coating composition was prepared without the incorporation of the isobutyl D-

g 1 ucosaccharoascorba te and otherwise in the same manner as above. In the sa e experiment as above, the surface resistances were initially 3Ω , 12Ω after 470 hours, 600Ω after 984 hours, and more than 1 kΩ after 1500 hours. Th coating was observed to get dark during the experiment.

The composition of the invention forms a durable and stable electroconductive layer which is not substantial ly reduced in e1ec troconducti vi ty with time.