Patent ID: 6689907
Filing Date: 2004-02-10
Classification: C07C

Abstract:
Process for the manufacture of a mercaptocarboxylic acid of formula (I): in which:R1 represents hydrogen or â€ƒand R2 represents hydrogen or methyl; comprising the steps of reacting in a reaction medium (a) an unsaturated carboxylic acid of formula (II): in whichR1 and R2 are as defined above, and (b) a hydrosulphide of formula ASH, A being an alkali metal cation or a cation NR3R4R5R6+, R3 to R6 each representing H or a hydrocarbon radical, or of formula Q(SH)2, Q being an alkaline-earth metal cation; wherein the reaction medium is selected from the group consisting of an aqueous medium, an aqueous-alcoholic medium and an alcoholic medium, introducing a supply H2S into the reaction medium, wherein the H2S is introduced into the medium by a direct external supply or is produced in situ by reacting the hydrosulphide with at least one acid introduced into the medium; and acidifying the reaction medium to obtain the desired compound (I); wherein the reaction is carried out in the reaction medium without CS2, further wherein the reaction medium has a pH of from 6.5 to 8.