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

摘要

Disclosed is a method for production of N-substituted glycine ester or N-substituted glycine acid by reaction of glyoxyl acid semi-acetal ester, eventually glyoxyl acid semi-acetal with amine and by hydrogenation of arisen intermediate, as well as use of the method for production of indoxyl derivatives and indigo by closing the circle of N-arylglycine ester, made according to the said method, in molten carbonate of alkaline metal or carbonate of alkaline earths metal with addition of alkaline metal amide or without it and eventually by oxidation of arisen indoxyl derivative to the corresponding indigo derivative.