Patent GB-483224-A (GB)
Title: Improvements in the manufacture and production of n-substituted aspartic acids and their derivatives
Filed: 1936-07-13
Abstract: N-substituted aspartic acids and their derivatives are prepared by treating maleic acid or its anhydride, for a long time at an elevated temperature and in the presence of water, with at least twice the equimolecular amount of an organic compound containing at least one primary amino group, and saponifying the imides intermediately formed.  Further solvents or diluents, such as alcohols or ketones, may be added to the water; the imides need not be isolated.  As examples of organic compounds containing one primary amino group are mentioned aniline, naphthylamines, aminoanthracenes, aminoanthraquinones, toluidines, xylidines, C-ethylanilines, C-phenylanilines, C-cyclohexylanilines, C-phenyl naphthylamines, aminobenzylnaphthalenes and chloro- or bromo-anilines; cyclohexylamine; methyl-, ethyl-, hexyl-, octyl-, dodecyl-, octodecyl- and oleyl-amines; benzylamine; aminocarboxylic acids and chloroalkylamines.  Specified compounds containing more than one primary amino group are o-, m- and p-phenylenediamines, benzidines, naphthylenediamines and diaminoanthracenes.  In the case of the treatment of maleic acid with diamines, only one of the amino groups reacts, so that the products still contain a primary amino group and are therefore useful in the manufacture of azo dyes.  The products in general may be employed in the preparation of tanning agents, dyestuffs and assistants for the textile and related industries. According to two of the examples: (1) maleic acid is heated with over two molecular proportions of aniline at a temperature of 90 DEG  C. for 15 hours in the presence of water and the N-phenylaspartic acid anil which separates out then saponified with caustic soda to give phenyl-aspartic acid; (2) maleic anhydride and p-phenylenediamine in the molecular proportions of 1 : 2 are heated with water for 15 hours at 90-100 DEG  C. and the product saponified with caustic soda, giving p-aminophenyl-aspartic acid.  The remaining examples describe the preparation of similar products by interaction of maleic anhydride with the following substances: o-, m- and p-toluidines, o-, m- and p-chloranilines, 2 - methoxy - 5 - methylaniline, benzidine, aminoacetic acid, methyl-, ethyl-, butyl-, dodecyl-, octodecyl- and oleyl-amines, cyclohexylamine, a - and b -naphthylamines, 2 : 7-aminonaphthol, m-aminophenol, o-, m-and p-nitranilines, 4- and 6-nitro-o-toluidines, nitronaphthylamines, b -aminoanthraquinone, p-aminosalicylic acid, metanilic acid, and the primary amines obtainable by the process described in Specification 421,718 from the fatty acids of palm kernel oil or partly hardened train oil.  The latter compounds have a good washing, wetting and dispersing power and are softening agents for artificial silk, whilst the product from b -aminoanthraquinone is a dyestuff having a good affinity for wool. Specification 465,513 also is referred to.  The Provisional Specification further describes the use of other solvents than water, e.g. alcohols or ketones, and of at least one molecular proportion of an organic compound containing two primary amino groups or the corresponding amounts of compounds containing one or more secondary amino groups substituted by alkylol groups. Specified compounds of the latter class are diethanolamine, dipropanolamine, N-monohydroxyethylaniline, -toluidines, -chloranilines, -naphthylamines, -aminoanthracenes, -butylamine and -laurylamine.  In the case of such compounds, it is advantageous to use about three molecular proportions for each molecular proportion of maleic acid. Primary aromatic amines containing hydroxyalkyl substituents on carbon atoms are also referred to, as well as monoethanolamine and monopropanolamine. Examples are also included of the interaction of maleic anhydride with monoethanolamine, monopropanolamine, aminodihydroxypropane, monohydroxyethylaniline, N - monohydroxy-ethyl-m-toluidine and N-monohydroxyethyl-p-cresidine to give specified products.