Process for the preparation on 3-(N,N-Dimethylamino)benzoic acid

摘要

The invention provides a process for the preparation of 3-(N,N-dimethylamino) benzoic acid which comprises subjecting an aqueous solution of an alkali metal salt or ammonium salt of 3-aminobenzoic acid to reductive methylation in the presence of a supported transition metal catalyst, by the controlled and continuous addition of a solution of formaldehyde over a period of 0.5 to 20 hours with a hydrogen pressure between 1 bar and 40 bar and with the temperature of the reaction mass gradually raised during the reduction, the reaction being carried out within the temperature range of 20 DEG C to 120 DEG C, and wherein a buffering agent is added such that the pH of the reaction mass after reductive methylation is from 6.5 to 9.5.