Abstract: Process for the preparation of aliphatic or aromatic mono- or dicarboxylic acids of 4 to 22 carbon atoms by oxidation of the corresponding aldehydes having the same number of carbon atoms in a carboxylic acid from the group consisting of formic acid, acetic acid, and propionic acid or in a carboxylic acid/water mixture at a temperature of 50.degree.-130.degree. C. and at 1 to 25 bar and in the presence of an oxidizing agent.

Abstract: Process for the preparation of an N-substituted glycine ester or an N-substituted glycine acid by reaction of a glyoxylic acid ester half-acetal (hemiacetal) or glyoxylic acid half-acetal (hemiacetal) 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.

Abstract: Process for preparing primary amines from aldehydes by mixing an aldehyde with a diluent, where in the case of an alcohol or of water as diluent the mixing temperature is at most 5.degree. C. to prevent the formation of the hemiacetal or the aldehyde hydrate, and bringing the mixture into contact with a mixture of ammonia, hydrogen and hydrogenation catalyst, whereby the formation of an imine is prevented, at temperatures of from 60.degree. to 180.degree. C. and pressures of from 20 to 60 bar, at least 15 mol of ammonia being used per mol of aldehyde group, and also an apparatus for carrying out the process.