PROCESS FOR PREPARING N-SUBSTITUTED GLYCINIC ACIDS OR GLYCINE ESTERS AND USE OF SAID PROCESS IN INDIGO SYNTHESIS

摘要

Process for the preparation of an N-substituted glycine ester or an Nsubstituted glycine acid by reaction of a glyoxylic acid ester half-acetal or glyoxylic acid half-acetal with an amine and hydrogenation of the intermediate product formed by this reaction, and the use of the process in a process for the preparation of indoxyl and indigo derivatives by cyclization of an N-arylglycine ester, prepared by the above process, in a molten alkali metal carbonate or alkaline earth metal carbonate with or without addition of an alkali metal amide, and if appropriate oxidation of the indoxyl derivative formed by this reaction to give the corresponding indigo derivative.