GB414952A - Manufacture of halogenated phenylthioglycollic acids - Google Patents

Abstract

Halogenated phenylthioglycollic acids are prepared by chlorinating or brominating a phenylthioglycollic acid of the general formula <FORM:0414952/IV/1> wherein the two letters x in o-position to the thioglycollic acid grouping do not represent carboxyl groups or any groups capable of being converted into carboxyl groups by saponification and wherein at least one of the four letters x represents halogen, alkyl, an alkoxy-group or an alkylmercapto-group. Such phenylthioglycollic acids include o- and m-chloro- or bromphenyl-1-thioglycollic acid, and o- and m-alkylsuch as methyl and ethylphenyl-1-thioglycollic acids; dichloro-, dibromo-, dialkyl-, dialkoxy-, dialkylmercaptophenyl - 1 - thiogly - collic acids such as the 2 : 5 - dimethyl and 2 : 5- and 2 : 6-dichloro phenyl-1-thioglycollic acid; trihalogenphenyl-1-thioglycollic acid; monohalogen monoalkyl-, monohalogen di-alkyl-dihalogenmonoalkylphenyl-1-thioglycollic acids such as 2-methyl-3 : 5-dichlorophenyl-1-thioglycollic acid; halogenalkyloxy- and halogenalkylmercaptophenyl - 1 - thioglycollic acids such as 2-chloro-5-ethoxylphenyl-1-thioglycollic acid. Suitable chlorinating or brominating agents include chlorine or bromine and substances yielding them such as sulphuryl chloride in the presence or absence of halogen carriers such as iodine, antimony pentachloride or iron and its salts and in the presence or absence of a diluent such as benzene, chlorobenzene, glacial acetic acid, nitrobenzene, chloroform, tetrachlorethene, dioxane and sulphuric acid. In examples of a solution of 2 : 5-dimethylphenol - 1 - thiogylcollic acid in chlorobenzene is treated with antimony penta chloride and sulphuryl chloride to yield the 4-chloro compound; (2) A solution of 2-chloro-5-ethoxyphenyl-1-thioglycollic acid in tetrachlorethane is mixed with antimony chloride and treated with a solution of sulphuryl chloride in tetrachlorethane to yield the 2-4-dichloro compound; (3) a solution of 2 : 5-dimethylphenyl-1-thioglycollic acid in chlorobenzene containing iodine is treated with a solution of bromine in chlorobenzene to yield the 4-bromo compound. 2 : 5 - Dimethylphenyl - 1 - thioglycollic acid is prepared by treating p-xylene with chlorsulphonic acid to yield 2 : 5-dimethyl-1-benzene sulphochloride, reducing this by means of zinc dust and hydrochloric acid to the thiophenol and condensing with chloracetic acid.