4-ALKYL-3-CHLORO-BENZENESULFONIC AND 4-ALKYL-3-CHLORO-BENZENESULFONYLCARBOXYLIC ACIDS AND 4-ALKYL-3-CHLORO-ALKYLSULFONYLBENZENES AND PROCESS FOR PREPARING THEREOF

摘要

Process for the preparation of 4-alkyl-3-chloroalkylsulphonylbenzenes of the formula (1) IMAGE in which R1 and R2 are identical or different and denote (C1-C4)-alkyl, by chlorinating p-alkylbenzenesulphonyl chloride of the formula (2) IMAGE in which R1 has the abovementioned meaning, with at least one mole of chlorine in the presence of a chlorine donor at temperatures of approximately 50 to approximately 100@C to give a compound of the general formula (3) IMAGE in which R1 has the abovementioned meaning, and this compound is subsequently reduced using sodium hydrogen sulphite or sodium sulphite in an aqueous medium at temperatures of approximately 40 to approximately 90@C to give a compound of the general formula (4) IMAGE in which R1 has the abovementioned meaning, and this compound is subjected to a condensation reaction with an alpha -halocarboxylic acid of the general formula (5) IMAGE in which R is hydrogen or (C1-C3)-alkyl and X is bromine or chlorine, or one of its salts, to give a 4-alkyl-3-chlorobenzenesulphonylcarboxylic acid of the general formula (6) in which R1 and R have the abovementioned meaning, or one of its salts, IMAGE and this compound is subsequently decarboxylated by heating. The invention furthermore relates to compounds of the formula (1) in which R1 is (C1-C4)-alkyl and R2 is (C2-C4)-alkyl or R1 is (C2-C4)-alkyl and R2 is (C1-C4)-alkyl, and to compounds of the formula (4) in which R1 is (C1-C4)-alkyl, and to compounds of the formula (6) in which R is hydrogen or (C1-C3)-alkyl and R1 is (C1-C4)-alkyl, and to the corresponding alkali metal salts.