GB314542A - Process for the manufacture of tri-substituted thioureas - Google Patents

Abstract

314,542. I. G.. Farbenindustrie Akt.- Ges. June 30, 1928, [Convention date]. Trisubstituted thioureas are prepared by splitting off hydrogen sulphide from a secondary amine salt of a dithiocarbamic acid derived from a primary amine. According to the examples, (1) sodium methyldithiocarbamate is first prepared from carbon disulphide, methylamine and sodium hydroxide in known manner and boiled with dimethylamine hydrochloride in alcoholic or aqueous solution to give trimethylthiourea; when the solution is alcoholic, the sodium chloride which separates is first filtered off; (2) an aqueous solution of dimethylamine hydrochloride is heated with sodium phenyldithiocarbamate, obtained by interaction of aniline with carbon disulphide in presence of sodium hydroxide, until N-phenyl-N<1>- dimethylthiourea separates out. The Specification as open to inspection under Sect. 91 (3) (a) also describes the preparation of trisubstituted thioureas by treating a salt of a dithiocarbamic acid monosubstituted on the nitrogen atom, the salt being one with a light metal or organic, cation, with a secondary amine salt of an acid other than dithiocarbamic acid, and then splitting off hydrogen sulphide. It also includes examples according to which carbon disulphide is run into a mixture of dimethylamine and butylamine in water, or of aniline and dibutylamine in water, or of methylamine and dimethylamine in ether; on boiling until hydrogen sulphide is no longer evolved, dimethylbutylthiourea, dibutylphenylthiourea or trimethylthiourea respectively is obtained. This subjectmatter does not appear in the Specification as accepted.