GB319075A - The manufacture of ortho-carboxyamido arylthioglycollic acids - Google Patents

Abstract

319,075. Carpmael, A., (I. G. Farbenindustrie Akt.-Ges.). June 19, 1928. o-Carboryamidoaryl-mercaptans and thioglycollic acids; o-carboxyarylthioglycollic acids.-A substituted o-cyanarylsulphochloride is treated, in the presence of an organic solvent, with a metal or a metal salt having a reducing action, together with a strong mineral or organic acid having a hydrolizing action, the reaction being regulated so that no nitrogen of the cyanic group is split off, and the resulting o-carboxyamidoarylmercaptan is condensed with chloracetic acid in alkaline solution to give o-carboxyamidoarylthioglycollic acids. According to examples, 1-methyl-2-cyano-5-chlorbenzene-3-sulphochloride, 1-methoxy- and 1-ethoxy-4-cyanobenzene-3-sulphochlorides and 1-chlor-4-cyanobenzene-3-sulphochloride are reduced and hydrolized, in the presence of benzene or chlorbenzene, by means of zinc dust and hydrochloric acid to the corresponding o-carboxyamidomercaptans which are then coupled with chloracetic acid to give 1-methyl-2- carboxyamido-5-chlorbenzene-, 1-methoxy- and 1- ethoxy-4-carboxyamidobenzene- and 1-chlor-4- carboxyamidobenzene-3-thioglycollic acids. In a further example, 1-methyl-2-cyano-5- and G- chlorbenzene-3-sulphochlorides are reduced and hydrolized by means of zinc dust and glacial acetic acid, in the presence of benzene or chlorbenzene, and the resulting o-carboxyamidomercaptans coupled with chloracetic acid. Finely powdered iron and stannous chloride are mentioned as reducing agents, and formic acid and the sulphonation products of naphthalene may be used for effecting hydrolysis. The removal of ammonia from the o-carboxyamidoarylthioglycollic acids by heating with dilute caustic soda to give the corresponding o-carboxyarylthioglycollic. acids is referred to. o-Cyanarylsulphochlorides are prepared from the corresponding o-aminoarylsulphonic acids by converting the amino group into the cyano group bv Sandmeyer's reaction, and treating with phosphorus pentachloride or an excess of chlorsulphonic acid. Thus, 1-methyl-5-chlor- and 1- methyl-6-chlor-2-aminobenzene-3-sulphonic acids, 1-methoxy- and l-ethoxv-4-aminobeuzene-3-sulphonic acids and 1-chlor-4-aminobenzene-3- sulphonic acid are converted first into the corresponding o-cyanoarylsulphonic acids and then into the o-cyanoarylsulphochlorides.