Process for the preparation of thiocarboxylate silane

A process for the preparation of an aqueous solution of a salt of a thiocarboxylic acid which comprises reacting an aqueous solution of a sulfide and/or hydrosulfide with an acid halide and/or acid anhydride in the presence of a phase transfer catalyst to provide the aqueous solution of thiocarboxylic acid salt, wherein the structures of the sulfide, hydrosulfide, acid halide and acid anhydride are represented by the formulae:

• M2S (6)
• MSH (7)
• GI(-Y-L)a (8)
• wherein
• each occurrence of M is an alkali metal;
• ammonium;
• or a mono-, di-, or tri-substituted ammonium;
• each occurrence of L is a halogen atom, sulfonate group, sulfinate group, or carboxylate group;
• Y is carbonyl, C(═O);
• each occurrence of R is chosen independently from the set of groups comprising hydrogen, alkyl groups, alkenyl groups, alkynyl groups, aryl groups and aralkyl groups with each R containing from 0 to about 30 carbon atoms;
• each occurrence of G1 is independently R or a polyvalent group derived from an alkyl, alkenyl, aryl or aralkyl group, containing from 1 to about 40 carbon atoms,
• each occurrence of the subscript a is independently an integer from 1 to 6 and wherein the phase transfer catalyst is represented by the formula:
• (R1R2R3R4Q+)nA−n (9)
• wherein
• each separate occurrence of R1, R2, R3 and R4, is, independently, an R, wherein R is a hydrogen, an alkyl, an alkenyl, an alkynyl, an aryl or an aralkyl containing from 0 to about 30 carbon atoms;
• Q is nitrogen or phosphorus;
• and A−n is a monovalent or polyvalent anion where the minus sign denotes that the species is an anion, and n denotes the number of negative charges on the anion;
• and, wherein the subscript n is a positive integer of from 1 to about 6.