2-Amino-5-chloro-4-methylbenzenesulfonic acid is a colorless to slightly reddish crystalline powder. The compound is obtained by chlorination of p-toluenesulfonic acid to form 3- chloro-4-methylbenzenesulfonic acid, subsequent nitration of this acid to a mixture of nitro isomers, precipitation of the 2-chloro-4-methyl-6-nitrobenzenesulfonic acid with sodium chloride solution, and, finally, Bechamp reduction of the nitro group with iron and acetic acid. The compound is used as Lake Red C and CLT Acid as a diazo component for azo dyes and azo pigments.
