The N- (l-oxoalkyl) amino or N-alkylaminocarbonyl polyhydroxyalkanecarboxylic acids of this invention are not known. Fatty acid-N-alkylpolyhydroxyalkylamides are known as anionic detergents, for instance, from DE 4,443,643. These compounds, however, contain an N- (1-oxoalkyl) aminopolyhydroxyalkane moiety but not a carboxylic acid group. On the other hand, polyhydroxyalkanecarboxylic acids are known, for instance from US 3,607,922, but these derivatives do not contain an N- (1-oxoalkyl) amino moiety. According to this US patent, glucose was oxidized to gluconic acid by oxygen in the presence of a platinum group metal catalyst. No utility of the product was given.

It has now been found that N- (l-oxoalkyl) amino or N-alkylaminocarbonyl poly- hydroxyalkanecarboxylic acid derivatives are very suitable for use as surfactants, especially in washing and cleaning processes. These compounds have improved water solubility while maintaining excellent biodegradability, and are therefore preferred over the known compounds for those uses.

The invention provides an N- (1-oxoalkyl) amino or N-alkylaminocarbonyl polyhydroxyalkanecarboxylic acid derivatives of the formulae R1-CO-N (R2)-CH2-A-COOX and Ri (R2) N-CO-A-COOX wherein: Ri is an alkyl group with 8-22 carbon atoms; R2 is hydrogen or an alkyl group with 1-6 carbon atoms; A is an alkylen group with 3-5 carbon atoms substituted with at least two hydroxy groups; and X is hydrogen, an alkali metal, or an alkaline-earth metal.

When the acid of the invention is in the form of a salt, X is an alkali metal or an alkaline-earth metal (ion). Alkali metals comprise lithium, sodium, and potassium; alkaline-earth metals comprise magnesium and calcium. The preferred counterions are alkali metals, particularly sodium and potassium.

Preferably, each of the carbon atoms of moiety A is substituted with a hydroxy group. These hydroxy-substituted carbon atoms are chiral carbon atoms, which may possess the R or S configuration. Compounds with all-R, all-S, or mixed- R, S configurations are considered to be part of this invention. Optically active, racemic, and meso-isomers are also considered to be encompassed by this invention, as are diastereoisomers. Compounds wherein moiety A is an alkylen group with 4 carbon atoms (butylen) are preferred.

Ri is an alkyl group with 8-22 carbon atoms, which optionally may be unsaturated. Examples are alkyl groups (including alkenyl groups), such as octyl, nonyl, decyl (capryl), undecyl, dodecyl (lauryl), tetradecyl (myristyl), pentadecyl (palmityl), hexadecyl (cetyl), octadecyl (stearyl), eicosanyl (arachdyl), dococanyl, geranyl (C10), palmityl (C16), oleyl (C18), lineoyl (C18), and the like. Preferably Ri has 10-14 carbon atoms.

A most preferred compound according to the invention is the N- (1- oxoalkyl) amino or N-alkylaminocarbonyl polyhydroxyalkanecarboxylic acid and salts thereof, wherein Ri is an alkyl group with 12 carbon atoms. Thus or the sodium or potassium salt is a preferred compound. Other preferred compounds are and its sodium or potassium salt. The dodecyl group in these preferred compounds can be present as a constituent of the

coconut fatty moiety together with minor quantities of smaller and larger alkyl residues.

In practice it is very convenient to use natural fatty acids as the source of group Ri. Consequently, group Ri will then be a mixture of alkyl groups. Thus when the reductive amination is performed with coconut fatty acid, group Ri is mainly a C12 group, but it also contains alkyl groups with C10-18, and even minor quantities of residues from higher and lower fatty acids, such as caproic acid, may be present. The term"R1 is an alkyl group with 8-22 carbon atoms" therefore also covers mixtures of alkyl groups, the mean number of carbon atoms being 8-22.

R2 is a hydrogen or an alkyl group with 1-6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl, isopentyl, hexyl, and the like.

Preferably, R2 is hydrogen or a methyl group.

The invention further pertains to a method for the preparation of the N- (1- oxoalkyl) amino or N-alkylaminocarbonyl polyhydroxyalkanecarboxylic acid derivatives. This method is characterized in that the primary hydroxy group of an alcohol of the formulae R1-CO-N (R2)-CH2-A-CH20H or Ri (R2) N-CO-A- CH20H, wherein Ri, R2, and A have the previously given meanings, is oxidized to give the corresponding N- (1-oxoalkyl) amino or N-alkylaminocarbonyl polyhydroxyalkanecarboxylic acid (formula 1), with oxygen in an aqueous medium with a pH>6 in the presence of a heterogeneous catalyst of group Vill of the periodic system.

Compounds of formula 11 are known in the art. Most conveniently these fatty acid-N-alkylpolyhydroxyalkylamides are derived from reducing sugars, such as glucose or b-gluconolactone, by reductive amination. These methods are well- known, for instance from US 1,985,424, US 2,016,962, US 2,703,798, WO 92/06072, and WO 92/06984.

The oxidation of these alkylamides is performed with oxygen. Pure oxygen can be used, but also oxygen-containing gases such as air. The reaction is performed at pH>6, preferably at pH 6-10, most preferably at pH 7-9, usually in the presence of sodium hydroxide or potassium hydroxide, after which the sodium or potassium salt is directly formed (X = Na or K).

The reaction is further performed in the presence of a heterogeneous catalyst of Group VIII of the periodic system. Preferably, the catalyst is a heterogeneous catalyst on the basis of palladium or platinum. A platinum catalyst is preferred, such as Adam's catalyst, platinum on active carbon, or platinum on aluminum oxide. The catalyst may contain promotors, such as Bi and Pb.

The reaction temperature and pressure are not very critical. Convenient temperatures are room temperature and higher. Usually the reaction is performed at 40-100°C, and more preferably at 50-80°C. Pressures can be from atmospheric to 10 MPa, and higher. Preferably, the reaction is performed at atmospheric pressure.

The invention is further illustrated by the examples.

Example 1 In a reaction flask 9.65 g of compound I with the formula and 3.5 g of a Pt/C catalyst (10% Pt on active carbon) were dispersed in 270 ml of water by gentle stirring. After flushing with oxygen, the flask was heated to 70°C and the reaction was started after intensive stirring. From a gas burette oxygen was added to supply the reacted oxygen and to maintain the atmospheric pressure. During the reaction the pH was maintained at 8 by the addition of 1N aqueous sodium hydroxide.

After 1 h, 25 mmoles of sodium hydroxide had been used and the reaction was stopped. The catalyst was filtered off and the water-soluble product (sodium salt 0 OH o Coco-C-N-H--f-H--C Na+ Ot CH3 2 was isolated by freeze drying in a

yield of 10. 2 g with a purity of 96%.

(*The cocoyl group mainly consists of dodecyloxo and tridecyloxo moieties).

Example 2 The reaction of Example 1 was repeated with 19.3 g of compound I and 3.5 g of a Pt/C catalyst (10% Pt on active carbon) in 270 ml of water. The pH was maintained at 9 by the addition of 1N aqueous sodium hydroxide. After the uptake of 50 mmoles of sodium hydroxide the reaction was stopped and 20. 1 g of the same product as in Example 1 were obtained.

Example 3 The reaction of Example 1 was repeated with 11.6 g of compound I and 1.75 g of a Pt/C catalyst (10% Pt on active carbon) in 270 ml of water. The pH was maintained at 8 by the addition of 1N aqueous sodium hydroxide. After a reaction time of 6.5 h, 12.6 g of the same product as in Example 1 were obtained.

Example 4 The reaction of Example 1 was repeated with 9.3 g of compound 11 with formula and 3.5 g of a Pt/C catalyst (10% Pt on active carbon) in 250 ml of water. The pH was maintained at 7 by the addition of 1N aqueous sodium hydroxide. After a reaction time of 3 h, 25 mmoles of sodium hydroxide had been used, after which 9.8 g of Oc Cz CocoClHC+HiC\ Na q were obtained in the same manner as in

Example 1 in a purity of 95%.

Example 5 In the manner as described in Example 1,27.9 g of compound 11 and 7 g of a Pt/C catalyst (10% Pt on active carbon) were dispersed in 450 mi of water, At a reaction temperature of 70°C, the pH was maintained at 8 by the addition of 1 N aqueous sodium hydroxide. After a reaction time of 4.5 h, 75 mmoles of sodium hydroxide had been used, after which the reaction was stopped. The bulk of the reaction mixture was removed from the flask through a filtering candle. The catalyst together with a minor quantity of reaction product remained in the flask.

Fresh compound 11 (27.9 g) dispersed in 420 ml of water was added to the flask and the mixture was brought to reaction with oxygen again. The reaction temperature was brought to 70°C and the pH was adjusted to 8. After nearly 5 h, 75 mmoles of sodium hydroxide had been used and the reaction was stopped. The aqueous solution was filtered from the catalyst and combined with the previously removed solution and dried, after which 59.2 g of 0 OH () O OH Coco-C-N-H-H--C ; Na+ were obtained. Example 6 The reaction of Example 1 was repeated with 11.5 g of 0 OH OOH Stearyl-C-N-H--f-H--H-OH CH3 H 4H2 and 3.5 g of a Pt/C catalyst (10% Pt on active carbon) in 270 ml of water. The pH was maintained at 7 by the addition of 1 N aqueous sodium hydroxide and the reaction temperature was kept at 80°C.

After a reaction time of 1.75 h, 25 mmoles of sodium hydroxide had been used, after which 12.5 g of 0 OH o 11 1 C3 2 were obtained in

the same manner as in Example 1.

Example 7 19 g of O OH Coco-N-C+C-H-OH Z (made by reaction of 8-gluconolactone and cocoamine) and 7 g of a Pt/C catalyst (10% Pt on active carbon) were dispersed in 540 ml of water. The flask was flushed with oxygen and subsequently heated to 70°C, after which the reaction was started by increasing the speed of the stirrer in such a way that gaseous oxygen was introduced into the reaction suspension. Oxygen was added from a gas burette to supply the reacted oxygen and to maintain the atmospheric pressure.

The pH of the reaction mixture was maintained at 8 by the addition of 1 N aqueous sodium hydroxide solution. After 6 h, 48 mmoles of sodium hydroxide had been used and the reaction was stopped. The catalyst was filtered off and the recovered solution was freeze-dried, giving 19.6 g of O OH O Coco-N-C-C--C-0 Na HH 4 The purity of the product was 90 % according to 13C-NMR analysis.

Example 8 The following tests show the properties of the claimed products as a surfactant in washing and cleaning products. Test Product of Example Product of Example 14 Surface tension (1 g/t) a 33 mN/m 32mN/m Foam height (0.1 g/I, 20°C, 0° 55 10 dH)' Foam stability (after 5 min) C 50 10 Critical micelle volume (CMC) 0. 05 gli 0.17 g/l

a. according to the method of DeNouy b. according to the method of Ross-Miles ; dH = deutsche Harte c. according to the method of Ross-Miles d. concentration of a surfactant in g/ at complete formation of the micelles (20°C,0° dH) The products were found to be completely biodegradable.