GB735899A - Manufacture of hydrazine compounds - Google Patents

Abstract

A process for the manufacture of compounds which contain a pyridazine ring and also contain a hydrazino group in at least one of the two ortho-positions relative to the ring nitrogen atoms comprises reacting hydrazine with a compound which contains a pyridazine ring and also contains an unsubstituted mercapto group in at least one of the two ortho-positions relative to the ring nitrogen atoms, or with a corresponding disulphide. The reactant containing the pyridazine ring may be used in the form of a salt. The reaction is advantageously carried out in the presence of an inert diluent, and in the presence of a condensing agent, and preferably at an elevated temperature. Suitable reactants are mercapto-phthalazines especially 1-mercapto- and 1 : 4-dimercapto-phthalazine, and mercapto-pyridazines especially 3-mercapto - 6 - aryl - and 3 - mercapto - 6 - alkylpyridazine, particularly 3-mercapto-6-phenylpyridazine, and the corresponding disulphides such as 1 : 11-dithio-bis-(4-phenyl-phthalazine). In the examples the following compounds are prepared: 1-hydrazino-, 1,4-dihydrazino- and 1-hydrazino-4-methyl-phthalazine. 1 - Hydrazino - 4 - mercapto - phthalazine is prepared by reacting 1-hydrazino-4-chlorophthalazine with alcoholic potassium hydrosulphide. Bis - phthalazyl - (1) - disulphide is prepared by reacting 1-mercapto-phthalazine with bromine in glacial acetic acid and treating the resulting dihydrobromide salt with caustic soda. Specifications 629,177 and 654,821 are referred to.