AMINO ACID SALTS

FIELD OF THE INVENTION

The present invention relates to the chemical synthesis of amido acids, and their conversion to amido acid phenyl ester sulfonates for use as bleach activators This conversion can be direct by reaction of the amido acids with phenol sulfonic acid derivatives; or by the conversion of the amido acids to their phenyl ester form and then the conversion of said amido phenyl esters into their sulfonated form, or by the conversion of the amido acids to their anhydride and then reaction with sodium phenol sulfonate to form the amido acid phenyl ester sulfonates BACKGROUND OF THE INVENTION

The synthesis of ingredients for use in low unit cost consumer goods such as laundry detergents, fabric softeners, hard surface cleansers, and the like, is of considerable interest to manufacturers. Indeed, while formularies and patents are filled with listings of prospective ingredients for use in such products, the reality is that many such ingredients are simply too expensive for day-to-day use. This expense is often due either to the cost of the raw materials used to make such ingredients, or to the complex reaction and processing chemistry which is required in their manufacture. Accordingly, manufacturers have conducted a continuing search for both inexpensive raw materials and simple reaction sequences which can produce high performance, high value ingredients at the lowest possible cost.

The amido acids comprise one class of chemicals whose amido and carboxylate functional groups suggest their use as surfactants (i.e., sarcosinates), fabric softeners, antistatic agents and the like. Moreover, the amido acids constitute a basic raw material for the amido phenyl ester sulfonate class of chemicals which can serve as bleach activators in laundry detergents and other types of bleach-containing cleaning compositions. Such activators have several desirable attributes such as excellent bleaching performance with minimal color damage on fabric dyes, good washing machine compatibility and a good odor profile in the wash. On the positive side, the amido acids and their aforementioned derivatives are potentially obtainable from inexpensive raw materials. Unfortunately, the synthesis of certain amido acids is somewhat complicated and can involve the use of solvents, with additional problems associated with recycle streams and the like. Problems can also arise with the formation of undesirable colored by-products. Moreover, the conversion of the

amido acids to their phenyl ester sulfonate form is not straightforward and can be surprisingly problematic.

The present invention provides a simple method for the synthesis of amido acids. It also provides four methods for converting amido acids into amido acid phenyl ester sulfonates which are suitable for use as bleach activators in laundry detergents, and the like. The first method is a simple, one-step esterification of amido acid with phenol to provide an amido acid phenyl ester which can subsequently be reacted with SO3 and neutralized in conventional fashion to give amido acid phenyl ester sulfonates. The second prepares the amido acid phenyl ester by transesterification of ester derivatives of phenol followed by the conversion to the amido acid ester sulfonates as described for the first method. The third method involves transesterification of ester derivatives of phenol sulfonic acid or salt (typically sodium or potassium) with amido acid to provide amido acid phenyl ester sulfonates directly. The fourth method involves making the anhydride of the amido acid and reacting this anhydride with sodium phenolsulfonate to also produce amido acid phenyl ester sulfonates directly.

The individual reaction sequences herein proceed in acceptable yields (typically 60%, and higher) and, importantly, result in products with minimal discoloration In some cases, the reactions may be conducted without added solvents, i.e., the reactants act as solvents. Hence, for many purposes the reaction products need not be extensively purified which further improves the overall economics of the processes.

BACKGROUND ART

The boric acid-catalyzed esterification of certain phenols is described by W Lowrance, Jr., in Tetrahedron Letters No. 37 pp. 3453-3454 (1971 ). See Surfactant Science Series. Vol. 7, Part III. p581-617, for general syntheses of amido acids A process for preparing certain benzenesulfonate salts appears in U.S. 5, 153,541 , Amini and Dumas, October 6, 1992.

SUMMARY OF THE INVENTION

The present invention encompasses a method for preparing amido acids and salts thereof of the formulae O

R--C - -N--R1 -C OM

R ₂ O

(IA) and

O

(IB)

2 1 wherein R and R are independently a C. or higher hydrocarbyl substituents, R is

C, -C _{1 0} hydrocarbylene substituent, and M is a cationic moiety selected from alkali metal salts and hydrogen, by the steps of

(a) reacting a carboxylic acid ester of the formula

O

R-C-OR3 Carboxylic Acid Ester with an amino acid salt of the structure

O

HN- -R-i C OM

R2

Ammo Acid Salt or

O

R-C --N-(CH2) ₂ Sθ ₃ M

R2 , respectively, wherein R, R*, and R^ are as described before, and M is an alkali metal salt, and

(b) optionally, neutralizing the amido acid salt formed by step (a) to form the amido acid, whereby M is hydrogen in formulae IA and IB

The preferred method for preparing said amido acids is conducted at a temperature from about 80°C to about 200°C, especially from about 120°C to about 180°C

In one preferred embodiment the method herein employs an amino acid salt selected from the salts of 6-aminocaproic acid, sarcosine, glycine, tauπne, N-methyl taurine, serine, isoserine, methionine, and proline In a preferred aspect, the carboxylic acid ester is a methyl or ethyl ester (R ^J = methyl or ethyl) having substituent R as Cό-Ci

In order to facilitate mixing of the reactants and minimize reaction time, it is preferred to conduct the reaction in an alcohol solvent which has a boiling point of at least 100°C The presence of a basic catalyst such as sodium methoxide also accelerates the reaction The reaction proceeds in greater than 90% vield with a molar ratio of fatty methyl ester reactant to amino acid salt reactant to basic catalyst of about 1 1 0 2

The invention also encompasses a method for preparing amido acid phenyl esters of the formula

O

R C IM- -Rt C OPh

R ₂ O

(ID wherein R, Rl and R- are as described herein before, comprising reacting an amido acid having Formula (IA) above with phenol in the presence of a strong catalyst and boric acid to produce the amido acid phenyl esters of Formula (II).

In this method the strong acid (non-boric acid) catalyst is a member selected from the group consisting of sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid, phosphonic acid and mixtures thereof. Preferably, the mole ratio of boric acid to the strong acid catalyst is at least about 1 : 1, more preferably at least about 1 :3.6. Preferably, the mole ratio of amido acid to strong acid catalyst is at least about 1 :0.05 and more preferably about 1 :0.25. This esterification reaction is preferably conducted at a temperature in the range from about 180°C to about 210°C, and is most preferably conducted without added solvent.

The esterification herein is preferably conducted at a temperature of about 180- 190°C in the absence of solvent, with 98% sulfuric acid as the acidic catalyst, and at a mole ratio of boric acid to sulfuric acid of at least about 1 :3.6. Preferably, an excess of phenol is used, typically a phenol:amido acid mole ratio of about 5: 1 to about 20:1.

The invention also encompasses a method for preparing amido acid phenyl esters of the Formula (II) comprising reacting an amido acid having Formula (IA) above with a phenyl ester of a lower molecular weight carboxylic acid moiety, preferably phenyl acetate, in the presence of a basic catalyst. The basic catalyst can be selected from the group consisting of carboxylate salts, carbonates, imidazole and mixtures thereof. Preferably, the mole ratio of basic catalyst to amido acid is at least about 0.001 : 1, more preferably at least about 0.01 : 1. Preferably, the mole ratio of amido acid to phenyl ester is at least about 1 : 1 and more preferably about 3: 1. This transesterification reaction is preferably conducted at a temperature in the range from about 160°C to about 210°C, and is most preferably conducted without added solvent.

As an overall proposition, the invention herein also provides a method for preparing bleach activators comprising sulfonating and neutralizing an amido acid phenyl ester of Formula (II) prepared according to the foregoing processes to produce amido acid phenyl ester sulfonates of the formula:

(HI)

wherein R, R^ and R- are as described hereinbefore, the amido acid phenyl ester sulfonate is predominantly para-substituted (as pictured) although ortho- substitution is acceptable, and M is a cationic moiety, preferably a mono- or divalent metal salt (e.g., potassium, sodium) or hydrogen, which for use of these compounds as bleach activators should be sutstantially free of transition metal ions (known to cause instability of peroxy compounds).

The invention also encompasses a method for preparing amido acid phenyl ester sulfonates of the Formula (III) above by reacting an amido acid of Formula (I A) above with an ester derivative of phenol sulfonic acid or salt of the formula.

wherein M is a cationic moiety as described herein before, and R ^J is an acid moiety, preferably a lower (C2-C5) molecular weight carboxylic acid moiety such as the most preferred acetic acid moiety. When M is hydrogen, the addition of catalyst is not required; when M is a metal salt, this transesterification reaction can utilize an acid or base catalyst.

Reaction temperatures for this transesterification reaction are at least about 150°C, preferably from about 180°C to about 220°C, for reactions with acetoxy benzene sulfonic acid sodium salt. Lower reaction temperatures, from about 140°C to about 180°C, are preferred for reactions with acetoxy benzene sulfonic acid.

The invention also provides a method for preparing amido acid phenyl ester sulfonates of the Formula (III) above by reacting an amido acid of Formula (IA) above with a lower (C4-C10) molecular weight carboxylic acid anhydride (e.g., (R^CO^O, wherein each R^ is the same or different C ]-C4 hydrocarbyl substituents), preferably acetic anhydride, to form the amido acid anhydride. The amido acid anhydride is then reacted with phenolsulfonate salt (preferably the sodium salt) to form the desired amido acid phenyl ester sulfonates.

The amido acid anhydride is prepared by reacting amido acid with the lower molecular weight carboxylic acid anhydride in a molar ratio ranging from about 1 :3 to about 5: 1. Reaction temperatures are from about 70- 1 10°C with reaction times of about 1-18 hr. Catalysts such as sodium acetate, sodium carbonate, sodium bicarbonate, imidazole, or methanesulfonic acid can be used. At the end of the

reaction, carboxylic acid and/or excess carboxylic acid anhydride, such as acetic acid and/or excess acetic anhydride, are removed by distillation

The crude amido acid anhydride mixture is then reacted with anhydrous sodium phenolsulfonate in a molar ratio of about 1 : 1. Reaction temperatures are from about 100-200°C with reaction times of about 1-6 hr. Basic catalysts such as sodium acetate or imidazole can be used. If the crude amido acid anhydride contains excess amido acid, then solvent is not needed. If excess amido acid is not present in the amido acid anhydride, solvents such as dimethylformamide, toluene, or xylenes can be used.

All percentages, ratios and proportions herein are on a mole basis, unless otherwise specified. All documents cited are incorporated herein by reference DETAILED DESCRIPTION OF THE INVENTION

The reaction sequence ( 1 ) for the synthesis of the amido acids and reaction sequence (2a) and (2b) for their conversion to the phenyl ester form are shown below. Sequence (3) illustrates the conventional sulfonation step, which typically includes base neutralization to prepare the salt form of the amido phenyl ester sulfonate class of bleach activators. Sequences (4a), (4b), and 5 show alternative methods for preparing the amido phenyl ester sulfonate directly from the amido acid prepared by Sequence (1). The reaction sequences as illustrated employ octanoic acid methyl ester and 6-aminocaproic acid sodium salt, but this is only by way of illustration and not limitation, as will be seen hereinafter.

Acid Catalyst Amido Acid Phenyl Ester

+

O Carboxylic Acid Phenyl Ester

H O

^■ ' . ^/ -^N-~- .'-- ^■ . ^■ ''-. -OPh o H O

Diamido Acid Phenyl Ester

Sequence 2b

Sequence 3

Amido Acid Phenyl Ester Amido Acid Phenylestersulfonate

Sequence 4a

Sodium Acetoxybenzenesulfonate Amido Acid Phenylestersulfonate

Sθ3 a

^■ 6 Ac ₂ 0

OH

Sequence 4b

Amido Acid Acetoxybenzenesulfonate Amido Acid Phenylestersulfonate

Phenolsulfonic Acid Phenylacetate Phenol

Sequence 5

Amido Acid Anhydride

The following is by way of illustration, and not limitation, of conditions, equipment and the like, useful in Sequences 1, 2, 3, 4, and 5 of the instant process.

Sequence 1. The carboxylic acid ester reactant can be selected from alkyl esters (preferably methyl or ethyl) of straight chain aliphatic, branched chain aliphatic, saturated or unsaturated, aromatic, heroaromatic, ethercarboxylic and cycloaliphatic carboxylic acids. Nonlimiting examples include methyl or ethyl esters of the following carboxylic acids: acetic, propionic, butyric, caprylic, caproic, nonanoic. 3,5,5-trimethylhexanoic, decanoic, lauric, myristic, palmitic, stearic. oleic, linoleic. behenic, 2-methyl-undecanoic, 2-butyl-octanoic, 2-ethyl-hexanoic, alkyl- and alkenylsuccinic, adipic, cyclohexyl, C ₈ (EO) ₉ CO ₉ H, benzoic, chloro-benzoic. nitrobenzoic, naphthenic, abietic, nicotinic, 2-pyridine-carboxylic. terephthalic. phthalic, and mixtures thereof.

The amino acid salt reactant in Sequence 1 can be, for example: the sodium salts of amino acids derived from hydrolysis of 5-12 membered ring lactams such as 5-aminovaleric acid and 6-aminocaproic acid or sodium salts of sarcosine. glycine. taurine, N-methyl taurine, serine. isoserine. methionine. and proline. and mixtures

thereof The sodium salts of the amino acids can be generated either by neutralizing the amino acids with a sodium hydroxide solution and then drying or by neutralizing with sodium methoxide (convenient for lab preparations since it does not introduce water).

The reaction conditions in Sequence 1 are as follows Any air in the system during lactam hydrolysis and amidation steps causes darkening of the reaction mixture. Also the presence of water during lactam hydrolysis and amidation drastically reduces the yield of these steps Consequently, an inert gas (nitrogen is convenient) is sparged through the reaction mixture during these steps in Sequence 1 Inert gases such as argon, or the like, can also be used The objective is to provide a nonoxidizing reaction system in order to minimize the formation of colored contaminants.

Lactam hydrolysis is necessary if a lactam is used as the source of the ammo acid salt reactant. An alcohol solvent is used in which dry sodium hydroxide has at least partial solubility. In order to complete the hydrolysis in a 2-8 hr reaction time, the alcohol used must have a boiling point above 100°C. The alcohol will also serve as the solvent for the amide formation step It is preferred that the alcohol boiling point be less than 200°C, since it must be removed from the amido acid prior to Sequence 2 or 4 and for economical reasons be easily recycled. 1-Butanol is an especially preferred solvent.

Lactam hydrolysis requires a molar ratio of sodium hydroxide to lactam of at least 1 1 , preferably 1 05 1 The sodium methoxide catalyst to be used in the amide formation step may be added during lactam hydrolysis, since alcohol solution or suspension of amino acid salt reactant is used directly in the amide formation step The hydrolysis proceeds most readily when the amount of solvent used is the minimum necessary to dissolve the sodium hydroxide.

Amidation requires that the amino acid salt reactant be at least partially miscible in the carboxylic acid ester In the case of the sodium salts of 6-aminocaproic acid, glycine, or taurine, a solvent is necessary to achieve partial miscibility In the case of sarcosine sodium salt, no solvent is necessary if the reaction is performed at 180- 200°C.

Reaction temperatures in the amidation step will typically be above about 80°C and below about 200°C and are preferably in the range from about 1 10°C to about 180°C For low boiling carboxylic acid esters such as ethyl acetate, it may be appropriate to use a pressure vessel in order to achieve the desired reaction temperature Reaction times can vary, of course, depending on the reactant volumes

lϋ being employed. However, as a general rule for reactions in the 100 mis size range, a reaction time in the range from about 0 5 hours to about 4 hours is sufficient

During the amidation step, the alcohol originating from the carboxylic acid ester (typically methanol) is distilled from the reaction In order to accelerate the reaction, some of the alcohol solvent (typically butanol) may also be removed so long as the reaction mixture is still easily stirred.

Reaction stoichiometry in the amidation step employs a molar ratio of amino acid salt reactant to carboxylic acid ester to basic catalyst of about 1 1.05 0 2 The basic catalyst is preferably sodium methoxide

After the amidation step, to form the amido acid the amido acid salt must be neutralized to the amido acid and the alcohol solvent removed A variety of acids (sulfuric, formic acids) can be used to neutralize the alcohol solution of the amido acid salt so long as the salt of the neutralization acid is sparingly soluble in the alcohol solvent. For example, acetic acid is not as preferred as formic acid because sodium acetate is more soluble than sodium formate in methanol/butanol Formic acid is convenient if 1 -butanol is the reaction solvent Sodium formate is sparingly soluble in 1 -butanol and precipitates. Amido acid is soluble in the butanol Typically a molar ratio of acid to amido acid salt of about 1.1 is used Finally, butanol is removed from the amido acid by distillation and can be recycled. Sequence 2a. The preparation of the phenyl esters of carboxylic acids, especially the amido acids, is as follows. Useful carboxylic acid reactants in Sequence 2 include all of the amido acids prepared per Sequence 1. The phenol reactant includes phenol, itself, as well as alkyl substituted phenols such as cresols and phenol derivatives such as phenolsulfonates

The strong acid catalyst used in Sequence 2 can be any of the strong protonic acid catalysts used in Sequence 1 Sulfuric acid (98%) is convenient, inexpensive and preferred. Under the process conditions the sulfuric acid sulfates the phenol in situ. so that the strong acid catalyst is at least partially the phenolsulfonic acid

While not intended to be limiting by theory, it is believed that the mechanism of ester formation involves the formation of a triphenol borate ester by a reaction of a borate material with the phenolic material, followed by exchange of phenol for carboxylic acid to form a carboxylic/boric anhydride species, followed by some manner of phenol displacement of the borate ester from the carboxylic-boric anhydride species; followed by exchange of water to form the borate species and reform the triphenol borate active catalyst agent. Accordingly, any borate or boric acid material, or precursor thereof, which results in the formation of a triphenol borate ester with phenol or substituted phenols can be used herein Typical examples

of such materials include boric acid, boric acid precursors, boric acid esters, for example, materials such as borax, tributylborate, triphenylborate, and the like. A wide variety of borate materials are available from standard, commercial sources. Boric acid is a convenient and inexpensive catalyst for use in Sequence 2.

It is further hypothesized that the presence of the strong protic acids probably plays at least three different roles in the esterification mechanism: catalysis of the initial borate ester formation; catalysis of phenol displacement of the borate species; and as a desiccant for water which is produced in the reaction

With regard to reaction conditions, in Sequence 2 any air in the system causes a drastic darkening of the reaction mixture, just as in Sequence 1. Consequently, nitrogen sparging or sparging with another inert gas in order to provide a nonoxidizing condition is preferably used. Again, as in Sequence 1 , it is preferred in Sequence 2 to use an inert reaction vessel such as those made from glass, quartz, stainless steel, or the like.

Reaction temperatures of at least 150°C, preferably from about 180°C to about 200°C, are preferred, and reaction times are similar to those disclosed for Sequence 1, typically 2 to 4 hours. Water (which may be present in the starting materials) is removed during the first 30 minutes of the reaction by azeotropic distillation of phenol/water. The presence of water is detrimental to the overall yield because it can result in the hydrolysis of the amide linkage of the amido acids and/or amido acid phenol esters.

It has been determined that excess phenol or substituted phenol is necessary to drive the reaction to completion. Less excess phenol is viable if azeotropic distillation is carried out for the entire reaction time. Typically, about a 5 mole excess of said phenol or substituted phenol is employed, preferably from about 8 to about 12 mole excess. Based on the amido acid portion of one mole, the strong acid catalyst proportion is at least about 0.01 mole, preferably from about 0.25 mole to about 0.5 mole. The boric acid is used at levels from about 0.01 mole to about 0.07 moles, based on the amido acid reactant.

Following the esterification reaction, excess phenol is removed from the reaction mixture by vacuum distillation or other suitable means, and can be recycled. The remaining reaction product consists of the desired amido acid phenol ester. carboxylic acid phenyl ester and unreacted amido acid. This reaction product can be purified prior to sulfonation, or can be sulfonated without further purification since the contaminants are compatable with many detergent compositions.

Sequence 2b. Transesterification of a phenyl ester of a lower (C -C5) molecular weight carboxylic acid moiety, preferably phenyl acetate, with amido acid

in the presence of a basic catalyst provides amido acid phenyl ester in good yield The basic catalyst can be selected from the group consisting of carboxylate salts, carbonates, imidazole and mixtures thereof Preferably, the mole ratio of basic catalyst to amido acid is at least about 0 001 1, more preferably at least about 0 01 1 Preferably, the mole ratio of amido acid to phenyl ester is at least about 1 1 and more preferably about 3 1 This transesterification reaction is preferably conducted at a temperature in the range from about 160°C to about 210°C, and is most preferabh conducted without added solvent

Sequence 3 Sulfonation of the amido acid phenol ester can be conducted using sulfur trioxide, sulfur trioxide vapor, chlorosulfonic acid, sulfur tπoxide complexes, oleum, sulfamic acid, and the like, plus other typical sulfonating agents Reaction can be carried out without solvent, or, if desired, can be conducted in solvents such as sulfur dioxide, methylene chloride, ethylene dichloride, carbon tetrachloride, fluorotrichloromethane, and the like. It is preferred to run the sulfonation reaction of Sequence 3 without solvent Of course, unsaturated materials should be avoided in the reaction mixture, primarily due to color formation

As in the case of Sequences 1 and 2, the sulfonation reaction of Sequence 3 is highly acidic and inert reaction vessels are again used Reactors can be of the continuous film or continuous cascade types, for example When sulfur trioxide is used as the sulfonating reactant, it is preferably introduced in an inert gas stream (nitrogen or dry air) containing 1-20% by weight sulfur trioxide Reaction temperatures are typically 20°C to 200°C with reaction times of from 5 to 180 minutes (based on 1 mole of amido acid phenyl ester being sulfonated) For a typical run, the amido acid phenyl ester is present at a 1 mole level and this sulfonating agent used at a 0 9- 1 5 mole level Product work-up involves neutralizing the crude reaction mixture to pH 4-6 with base such as sodium bicarbonate, sodium acetate, sodium formate, or the like

Sequence 4 Amido acid phenyl ester sulfonate can also be made by transesterification of acetoxybenzenesulfonic acid or its salt (typically sodium or potassium) with amido acid. If acetoxybenzenesulfonic acid sodium salt is used, then a 3-4 mol equivalent excess of amido acid is necessary to act as solvent If acetoxybenzenesulfonic acid is used, then a 1 2 mol equivalent excess of amido acid is sufficient Either base or acid catalysis promotes the transesterification of acetoxybenzenesulfonic acid sodium salt, sodium acetate or sulfuric acid are typically used Transesterification with acetoxybenzenesulfonic acid does not require a catalyst

A stream of inert gas is passed over the reaction so as remove acetic acid as it is formed and provide a nonoxidizing environment As in Sequence 3. inert reaction vessels are preferred

Reaction temperatures of at least about 150° C, preferably from about 180° C to about 220° C, are necessary for transesterification with acetoxybenzenesulfonic acid sodium salt Lower reaction temperatures (from about 100° C to about 140° C) are preferred when using acetoxybenzenesulfonic acid because less side products are formed Reaction times are 1-4 hours for either transesterification

Acetoxybenzenesulfonic acid sodium salt can be prepared from reaction of excess acetic anhydride with dry phenolsulfonic acid sidium salt Acetic anhydride or acetic acid can serve as a solvent Acetoxybenzenesulfonic acid can be made from reaction of acetic anhydride with dry phenolsulfonic acid Alternatively, it can be made from sulfonation of phenyl acetate with sulfur trioxide or chlorosulfonic acid

Following transesterification with acetoxybenzenesulfonic acid sodium salt, the excess amido acid must be removed from product and recycled This can be achieved by grinding the reaction product into small particles and dissolving the amido acid with a solvent The solid amido acid phenyl ester sulfonate is then collected by filtration Several solvents are suitable cold methanol, butanol at 60° C, toluene and xylenes at 100°C, octanoic acid Product workup after transesterification with acetoxybenzenesulfonic acid involves neutralizing the crude reaction mixture as in Sequence 3

Sequence 5 Formation of the amido acid anhydride is accomplished by reacting amido acid with acetic anhydride. Reaction temperatures between 70 and 120°C are favored to avoid acylation of the amide nitrogen The molar ratio of amido acid to acetic anhydride is from 1 3 to 5 1 If the molar ratio is 3 1 and higher, it is not necessary to add a solvent for the reaction with sodium phenolsulfonate After a reaction time of 1-18 hr, acetic acid and/or acetic anhydride are distilled from the reaction mixture to give the crude amido acid anhydride Sodium phenolsulfonate is then added in a 1 1 molar ratio to the amido acid anhydride and the reaction is heated at from 100 - 200°C for 1-18 hr Toluene or xylenes can be used as solvents for this reaction At the end of the reaction, unreacted amido acid can be removed from the amido acid phenyl ester sulfonate by washing with a hot solvent (ie toluene) which melts or dissolves the amido acid, but does not dissolve the amido acid phenyl ester sulfonate

It is to be understood that the overall process herein provide several advantages over other processes For example, with respect to the amido acids, the usual synthesis of amido acids (ie sarcosinate surfactants) employs the reaction of fatty

acid chlorides with an amino acid in an aqueous alkaline medium There ai e substantial cost advantages over the present development, inasmuch as fatty methyl esters are less expensive starting materials than fatty acid chlorides In the usual synthesis, sodium chloride waste is generated, which is not a factor in the present invention. Moreover, the process does not involve large amounts of water, which would have to be removed prior to Sequence 2

With regard to the amido acid phenyl ester synthesis of Sequence 2, esterification of the amido acid can be achieved by forming the acid chloride of the amido acid and subsequently reacting it with phenol or phenolsulfonate The prior art reaction has the same problems as those mentioned above for the amido acid synthesis. While esterification of conventional carboxylic acids with phenols using boric/sulfuric acid has been described in the Lowrance article, cited hereinabove, the reaction conditions described by Lowrance fail to esterify amido acids in any reasonable yields. For example, the present process employs much higher reaction temperatures than those disclosed by Lowrance, said temperatures being achieved by using phenol as the azeotroping agent. Moreover, much higher amounts of sulfuric acid catalyst are used herein, which promotes the desired reaction while reducing side reactions.

In the prior art (e.g., European Patent Application No 105,673, published April 18, 1984) of forming phenyl ester sulfonates, a fatty acid anhydride is formed (from reaction with acetic anhydride) and then reacted with phenolsulfonic acid sodium salt. It should be noted that reaction of amido acid with acetic anhydride under these conditions results not only in formation of amido acid anhydride, but also in formation of imides which is unacceptable. Transesterification with acetoxybenzenesulfonic acid or its salt avoids imide formation

The overall processes herein comprising either Sequences 1, 2a, and 3, Sequences 1, 2b, and 3, Sequences 1 and 4, or Sequences 1 and 5 have several advantages, including one or more of: low cost starting materials; minimum number of reaction steps; good yields for each step; reasonable reaction times; no waste by-products; ability to recycle starting materials; and no solids handling until the last step.

The following Examples further illustrate the invention but are not intended to be limiting thereof.

Analytical GC Analysis Method. This method is applicable to the determination of the relative content of octanoic acid, decanoic acid, octanoic acid phenyl ester, octanoyl caprolactam, 2-pyrrolidinone, octanoyl diamido acid, phenylesters of Cg-C _] o

amidocaproic acid, Cg amidobutyric acid, caprolactam, 6-aminocaproic acid. Cg-C ] Q amidocaproic acid, and phenol, in reaction samples.

The components listed above are separated, after silylation, by temperature programmed GC on a 15m DB 1 column. A hot (300°C) split injector is used and detection is by FID. GC area % is used to estimate content of components in a sample. The materials containing active hydrogens are derivatized with BSTFA containing 1% TMCS. Chemicals: Reagents Pyridine

N,O-bis (trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane Equipment: Equipment Description Source

Hewlett Packard 5890 GC Hewlett Packard

HP7673 split injection flame ionization detector Column: 15m, DB-1, J&W Scientific

0.25mm ID, .25u Procedure:

1. Standard Preparation:

(See sample preparation below to make retention time standard solutions.)

2. Sample Preparation:

Weigh 5-10 mg sample into a GC vial, add 1.0 mL derivatization grade pyridine and 0.6 mL BSTFA (w/1% TMCS), seal vial, and heat at 70°C for 30 minutes

16 i) Oven initial 50°C Decanoyl amidocaproic 25.3. 26.2 temperature acid j) Oven ramp rate 8.0°C/min. Hexanoyl amidocaproic acid 25 7 phenyl ester k) Oven final 325°C Octanoyl amidocaproic acid 27 6 (333)* temperature phenyl ester 1) Oven final hold time 4.63 min. Decanoyl amidocaproic acid 29.6, 30.5 phenyl ester

Octanoyl diamidocaproic 3 1.4, 32.4 (442) acid Molecular weight of GC component. 4. Calculation of Mole% Conversion: The GC relative area % for each component derived from caprolactam is divided by its molecular weight or the molecular weight of its trimethylsilyl derivative to give a relative mol%. The relative mol% for all components derived from caprolactam are summed to give a total relative mol%. Finally, each relative mol% is divided by the total relative mol% to give mol% conversion. An analogous procedure is used to calculate mol% conversion of amido acid to amido acid phenyl ester.

AMIDATION EXAMPLES I-IV EXAMPLE I Synthesis of C8-Amidocaproic Acid

Step A. Hydrolysis of Caprolactam - A three-neck, 2 L round bottom flask is fitted with mechanical stirrer and condenser and heated with an oil bath. Throughout all reactions, stirring and a static pressure of nitrogen is maintained. Sodium hydroxide pellets 98.5% (34.76 g, 0.856 mol), 25% sodium methoxide in methanol (33.7 g, 0.156 mol), methanol (100 mL), and 1-butanol (210 mL) are added to the flask. The mixture is heated to reflux for about 20 min to dissolve the sodium hydroxide and then concentrated by distilling away 130 mL of solvent. Caprolactam 99%o (88.06 g, 0.78 mol) is added and the mixture refluxed for 3.5 hr. After 15 min, the mixture becomes cloudy and foamy. After 1.5 hr, the reaction is clear. After 2.5 hr, the reaction becomes solid. After 3.5 hr, 1-butanol (60 mL) is added to solubilize the reaction mixture. HNMR and TLC indicate >90% yield of 6-aminocaproic acid sodium salt.

Step B. Amidation of fatty methyl ester - The clear solution of 6- aminocaproic acid sodium salt from Step A is allowed to cool until it starts to solidify and then methyl caprylate 99% (130.91 g , 0.819 mol) is added. The mixture is heated to reflux and it becomes clear after 2 min. After 9 min. the reaction mixture

becomes solid. The reaction is kept at reflux for a total of 1 hr Then methanol (250 mL) / 1 -butanol (500 mL) is added and the reaction mixture refluxed until most of the solid is dispersed (about 10 min). HNMR and TLC indicate ~ 90% yield of amido acid salt.

Step C. Neutralization of amido acid sodium salt - Formic acid 96% (50.35 g, 1.05 mol) is added to the slightly cooled dispersion of amido acid sodium salt from above. The mixture is refluxed for about 10 min until only a fine white precipitate (sodium formate) remains. The reaction mixture is allowed to cool to room temperature and then suction filtered to remove sodium formate. The sodium formate precipitate is washed with 1 -butanol (200 mL). HNMR indicates that the sodium formate contains a trace of amido acid. Butanol and methanol are removed from the amido acid by vacuum distillation to give C8 amidocaproic acid ( 172 4 g, 77% yield based on caprolactam).

EXAMPLE II

Synthesis of Oleyl Amide of Glycine Sodium Salt - A 500 mL, 3-neck, round bottom flask is fitted with thermometer, Dean-Stark trap with condenser, mechanical stirring, and a purge tube through which nitrogen is passed through the reaction mixture. The reaction vessel is charged with glycine (7.28 g, 0.097 mol), sodium methoxide 25% in methanol (25.2 g, 0.1 16 mol), methanol (50 mL), and propylene glycol (24 g). The reaction is refluxed 15 min to neutralize the glycine and then methanol is distilled off using the Dean-Stark trap. The reaction mixture is then heated to 160°C and methyl oleate 70% (43.2 g, 0. 102 mol) is added. Reaction is kept at 160°C for 1.5 hr during which methanol (7 mL) is collected in the Dean-Stark trap. The reaction is allowed to cool, acetone (300 mL) is added, and the mixture cooled to 10°C. The precipitate is collected by filtration, washed with cold acetone (200 mL), and dried in oven at 60°C to give the desired product as a light yellow solid (35.9 g).

EXAMPLE HI

Synthesis of Oleyl Amide of Sarcosine Sodium Salt - A 500 mL, 3-neck. round bottom flask is fitted with thermometer, Dean-Stark trap with condenser. mechanical stirring, and a purge tube through which nitrogen is passed through the reaction mixture. The reaction vessel is charged with sarcosine (8.0 g, 0.09 mol). sodium methoxide 25% in methanol (23.3 g, 0. 108 mol), and methanol (80 mL) The reaction is refluxed 15 min to neutralize the sarcosine and then methanol is distilled off using the Dean-Stark trap. The reaction mixture is then heated to 160°C and methyl oleate 70% (40.0 g, 0.094 mol) is added. Reaction is kept at 18U C for I υ hi

during which methanol is collected in the Dean-Stark trap The reaction is allowed to cool and the desired product clear solid (49 8 g) is obtained

EXAMPLE IV

Synthesis of Myristyl Amide of Taurine Sodium Salt - A 500 mL. 3-neck. round bottom flask is fitted with thermometer, Dean-Stark trap with condenser mechanical stirring, and a purge tube through which nitrogen is passed through the reaction mixture The reaction vessel is charged with taurine ( 12 0 g, 0 096 mol), sodium methoxide 25% in methanol (24 9 g, 0 1 15 mol), methanol ( 150 mL), and propylene glycol (34 g). The reaction is refluxed 15 min to neutralize the taurine and then methanol is distilled off using the Dean-Stark trap The reaction mixture is then heated to 160°C and methyl myristate (24.7 g, 0.10 mol) is added Reaction is kept at 160°C for 1.0 hr during which methanol (7 mL) is collected in the Dean-Stark trap. The reaction is allowed to cool, acetone (300 mL) is added, and the mixture cooled to 10°C. The precipitate is collected by filtration, washed with cold acetone (200 mL), and dried in oven at 60°C to give the desired product as a white solid (33.0 g).

ESTERIFICATION EXAMPLES V-VIII

Synthesis of C8 Amidocaproic Acid Phenyl Ester - A 100 mL, 3-neck. round bottom flask is fitted with thermometer, Dean-Stark trap with condenser, magnetic stir bar, and a purge tube through which nitrogen is passed through the reaction mixture The reaction vessel is charged with C8 amido acid - made from CS acid chloride and aminocaproic acid - (10 g, 0.037 mol, 1 mol equivalent), phenol, sulfuric acid 98%, and boric acid The reaction is kept at 180- 195°C for 4 hours using a high temperature oil bath held at 205-210°C, continuously sparging with nitrogen Some of the phenol is optionally removed with a Dean- Stark trap After 4 hours reaction time, the reaction mixture is analyzed by GC (see GC Analysis Method) to determine % conversion of C8 amidocaproic acid to C8 amidocaproic acid phenyl ester (see Table 6) Other products formed are caprolactam, octanoic acid, octanoic acid phenyl ester, 6-aminocaproic acid Reaction mixture color after 4 hours is noted

Table 1 Esterification Results with C8 Amidocaproic Acid Example #

Phenol (mol equivalent) Sulfuric acid (mol equivalent) Boric acid (mol equivalent) % phenol removed

Reaction color after 4 hr

GC Relative Area % for

Components

Caprolactam

Octanoic acid

6-aminocaproic acid

Octanoic acid phenyl ester

Octanoylcaprolactam

Octanoyl amido acid

Octanoyl amido acid phenyl ester

Octanoyl diamido acid

Octanoyl diamido acid phenyl ester

Mole % Conversion of Amido

Acid to Components

Caprolactam

6-aminocaproic acid

Octanoic acid phenyl ester

Octanoylcaprolactam

Octanoyl amido acid

Octanoyl amido acid phenyl este

Octanoyl diamido acid

Octanoic acid

Octanoyl diamido acid phenyl es

Example #

Phenol (mol equivalent) Sulfuric acid (mol equivalent) Boric acid (mol equivalent) % phenol removed

Reaction color after 4 hr GC Relative Area % for Components Caprolactam Octanoic acid 6-aminocaproic acid

Scale-up Synthesis of C8 Amidocaproic Acid Phenyl Ester - A 250 mL, 3- neck, round bottom flask is fitted with thermometer, condenser, magnetic stir bar, and a sparge tube through which nitrogen is passed through the reaction mixture. The reaction vessel is charged with C8 amidocaproic acid - product of Example 17 - (20.8 g, 0.081 mol), phenol (152.3 g, 1.62 mol), sulfuric acid 98% (2.03 g, 0 02 mol), and boric acid (0.35 g, 0.0057 mol). The reaction is kept at 200° C for 4 hours using a high temperature oil bath, continuously purging with nitrogen During the first hour, of reaction time, 50 mL of phenol is removed via the Dean-Stark trap. After 4 hours reaction time, the reaction mixture is analyzed by GC to determine % conversion of C8 amidocaproic acid to C8 amidocaproic acid phenyl ester (see Table 5). Reaction mixture is brown after 4 hours. Phenol is removed by vacuum distillation (90-100°C, 4.3 mm) to give the desired C8 amido acid phenyl ester as a brown solution (31.6 g) with the analysis shown in Table 7.

Table 2. Esterification Results of Scale-up Reaction GC Relative Area % for Components

Caprolactam Octanoic acid 6-aminocaproic acid Octanoic acid phenyl ester Octanoylcaprolactam

C8

Amidocaprcάc acid phenyl ester (22.00 g, 0.0634 mol) is placed in 100 mL 2-neck round-bottom fitted with a glass tube reaching the bottom of the flask and a condenser connected to a bubbler. The flask is heated to 50°C in an oil bath to melt the phenyl ester. Sulfur trioxide (5.0 g, 2.6 mL, 0.0634 mol) vapor diluted with nitrogen is added to the reaction over 1 hour through the glass tube. [The glass tube is connected via Teflon tubing to another flask heated at 65°C in which liquid sulfur trioxide is placed. Nitrogen is bubbled through the liquid sulfur trioxide to obtain the gas mixture.] The reaction is then heated at 50°C for an additional 30 minutes after the sulfur trioxide addition. The reaction is allowed to cool to room temperature and then poured into saturated aqueous sodium bicarbonate. The product precipitated as a white solid and is collected by vacuum filtration. After drying, the product ( 17.7 g) is obtained in 65% yield.

TRANSESTERIFICATION EXAMPLE XI Synthesis of C 10 Amidocaproic Acid Phenyl Ester - Amido acid ( 1.00 g, 0.0039 mol), phenyl acetate (1.59 g, 0.012 mol), and sodium acetate (0.032 g, 0.00039 mol) are placed in a 100 mL round-bottom flask fitted with condenser The solution is heated at 210° C for 0.5 hr under nitrogen. Then acetic acid and excess phenyl acetate are removed by vacuum distillation with a Kugelrohr apparatus. The product (1.10 g) is obtained as a white solid which contains unreacted amido acid and excess phenyl acetate. HNMR of crude reaction mixture indicates -75% yield

(by integration ratio of the 2 58 ppm resonance - CH2C(=O)OPh - to the 3 1 resonance - C(=O)NHCH2)

TRANSESTERIFICATION EXAMPLE XII

Synthesis of CIO Amidocaproic Acid Phenyl Ester Sulfonate - Into a 100 mL, 3 neck round bottom flask fitted with a nitrogen sparge tube, magnetic stirrer, Dean- Stark trap with condenser, and thermometer, is added C 10 amido acid (48 5 g, 0 17 mol), sodium acetoxybenzenesulfonate (15 g, 0.057 mol), and sodium acetate (0 94 g, 0.114 mol). The reaction is kept at 200 C for 3 hr using a high temperature oil bath held at 205-210° C, continuously sparging with nitrogen Distillate (7 mL) is collected in the Dean-Stark trap. The reaction is poured hot into a mortar and after cooling is ground into a powder HNMR of crude reaction mixture indicates -90% yield (by integration ratio of the 2.58 ppm resonance - CH2C(=O)OPhSO-**Na - to the 3.16 resonance - C(=O)NHCH2) The reaction mixture is recrystallized from methanol (370 mL) to obtain a first crop (15.1 g) and a second crop (4 7 g) of desired product (75% recrystallized yield based on sodium acetoxybenzenesulfonate)

ESTERIFICATION EXAMPLE XIII

Synthesis of CIO Amidocaproic Acid Phenyl Ester Sulfonate - Into a 100 mL, 3 neck round bottom flask fitted with a nitrogen sparge tube, magnetic stirrer, Dean-Stark trap with condenser, and thermometer, is added C IO amido acid (3 5 g, 0.0123 mol), acetic anhydride (0.46 g, 0.0045 mol), and methanesulfonic acid (0 002 g, 0.00002 mol). The reaction mixture is heated at 100°C for 2 hr. to form the amido acid anhydride. Then anhydrous sodium phenolsulfonate (0 80 g, 0 0041 mol) and sodium acetate (0.017 g, 0.0002 mol) is added and the reaction heated at I 80°C for 1.5 hr. At the beginning the reaction is fluid, but at the end it is a thick paste HNMR of crude reaction mixture indicates -70% yield (by integration ratio of the 2.58 ppm resonance - CH2C(=O)OPh - to the 3.16 resonance - C(=O)NHCH2)

ESTERIFICATION EXAMPLE XIV Synthesis of C8 Amidocaproic Acid Phenyl Ester Sulfonate - Into a 250 mL, 3 neck round bottom flask fitted with a nitrogen sparge tube, magnetic stirrer, Dean-Stark trap with condenser, and thermometer, is added C8 amidocaproic acid ( 10 0 g, 0 039 mol), acetic anhydride (17.9 g, 0.175 mol), sodium acetate (0 16 g, 0 002 mol), and imidazole (0.13 g, 0.002 mol). The reaction mixture is heated at 1 10°C for 3 hr with a nitrogen sparge; 10 mL of distillate is collected in the Dean-Stark trap Then acetic acid and excess acetic anhydride is removed by vacuum distillation to obtain amido acid anhydride. The crude amido acid anhydride is dispersed in ether (60 mL), filtered, and dried to obtain nearly pure amido acid anhydride (indicated bv HNMR) as a white solid (8.6 g).

Into a 100 mL, 3 neck round bottom flask fitted with a nitrogen sparge tube. magnetic stirrer, condenser, and thermometer, is added a portion of the pure amido acid anhydride (3.5 g, 0.0071 mol), anhydrous sodium phenolsulfonate ( 1. 1 1 g, 0.0056 mol), sodium acetate (0.029 g, 0.0004 mol), and toluene ( 12 mL). The reaction is refluxed 3 hr 180 C. A small, homogeneous aliquot of the reaction mixture is taken and evaporated for HNMR analysis. HNMR indicates 75% yield based on sodium phenolsulfonate (by integration ratio of the 2 58 ppm resonance - CH2C(=O)OPh - to the 3.16 resonance - C(=O)NHCH2). Then additional toluene (50 mL) is added, the reaction mixture filtered hot, and the precipitate dried to obtain the desired product as a white solid (2.6 g) which is 54% pure by HNMR (by integration ratio of the 2.58 ppm resonance - CH2C(=O)OPh - to the 3.16 resonance - C(=O)NHCH2) . The remainder of the material is amido acid, sodium phenol sulfonate, and acetoxybenzenesulfonate.

The following illustrates the use of the amido acids and bleach activators of this invention in otherwise conventional consumer goods, but is not intended to be limiting thereof.

EXAMPLE XV

A mild lubricious soap bar composition is prepared in conventional extrusion apparatus, as follows. The bar resists dry cracking and wet smear.

Ingredient Percent (wt )

C 16- 18 f ^att y ^ac ^ soap* 78.0

Amido acid** 6.0

NaCl/KCl (l :l wt.) 0 5 12 ^H 33C(O)N-methylglucamide 8.0

Water and minors Balance

* 1 : 1 (wt.) mixture of Na and K soaps

**Per Example I, above.

EXAMPLE XVI A laundry bleaching system suitable for use alone or in admixture with a conventional granular laundry detergent is as follows.

Ingredient Percent (wt )

Sodium percarbonate 90.0

Bleach activator* 10.0

*Per Example XXVII, above.

The foregoing composition can be added to water at levels of 100 ppm, and above, to provide a fabric bleaching action.

What is Claimed is:

1. A method for preparing amido acids and salts thereof of the formulae O

R-C-N-Rr-C-OM

I !l

R2 O (IA) and

(B)

7 wherein R and R are independently a C, or higher hydrocarbyl substituents,

1 . . . . .

R is C, -C- _{| 0} hydrocarbylene substituent, and M is a cationic moiety selected from alkali metal salts and hydrogen, by the steps of:

(a) reacting a carboxylic acid ester of the formula

O 11 R -C- OR3

Carboxylic Acid Ester with an amino acid salt of the structure p H -R-rC-OM

R2

Amino Acid Salt or

O

R-C-N-(CH ₂ ) ₂ Sθ ₃ M

R2 , respectively, wherein R, R^ and R^ are as described before, and M is an alkali metal salt; and

(b) optionally, neutralizing the amido acid salt formed by step (a) to form the amido acid, whereby M is hydrogen in formulae I A and IB.

2. A method for preparing amido acid phenyl esters of the formula

O

R-C ^~ N-RfC-OPh

R2 O

(ID comprising

(a) preparing, according to the method of Claim 1, an amido acid of the formula O

R-C -N -Rt-C-OM

I il

R2 O

(IA)