GB722541A - Dipropionic acids of the heterocyclic series, and derivatives thereof - Google Patents

Abstract

N,N-Dipropionic compounds of the heterocyclic series are manufactured by a process wherein a heterocyclic compound which contains two NH- groups and at least one >C=O or >C=S group in the same ring is heated with acrylic acid or a substituted acrylic acid in which the substituent is a hydrocarbon radical or with amides, esters or nitriles of said acrylic acids, in a solvent together with caustic soda. The invention also comprises dipropionic acids of the heterocyclic series containing two propionic acid groups attached by means of their b -carbon atoms to 2 nitrogen atoms of heterocyclic rings containing two -N=atoms and at least one >C=O or >C=S group. N-Substitution products obtained where a functional derivative of acrylic acid is employed as starting material are converted to the corresponding N,N1-dipropionic acids by saponification. In examples: N,N1-di-b -cyanethyl ethylene urea is obtained by adding acrylonitrile to a warmed suspension of ethylene urea and sodium hydroxide in dioxane and recovering the product after acidifying the mixture which may be hydrolysed under acid or alkaline conditions to ethylene urea N,N1-dipropionic acid. An N,N1-di-b -cyanethyl compound which may be converted to ethylene thiourea N,N1-dipropionic acid by hydrolysis is similarly obtained when ethylene-thiourea is employed as starting material and similar products are obtained when an ester of methacrylic acid is employed as starting material (1); N,N1-di-b -cyanethyl-2,5-diketopiperazine, which may be hydrolysed, e.g. with barium hydroxide solution to 2,5-diketopiperazine-N,N1-dipropionic acid, is obtained by adding acrylonitrile to a warmed suspension of 2,5-diketopiperazine and sodium hydroxide in dioxane. The isomeric N,N1-di-b -cyanomethyl compound and the corresponding N,N1-dipropionic acid are obtained when 2,6-diketopiperazine is employed as starting material (2); N,N1-di-b -cyan-methyl-o-phenylene-urea is prepared by dropping acrylonitrile into a suspension of o-phenylene urea and sodium hydroxide in dioxane at elevated temperature. The product may be hydrolysed to o-phenylene urea-N,N1-dipropionic acid by hydrolysis with barium hydroxide. Analogous compounds are obtained when o-phenylene-urea is replaced by o-phenylene-thiourea. Acrylic acid or, e.g., the ethyl ester of acrylic acid may be employed instead of acrylonitrile.