GB818269A - Improvements in or relating to the preparation of phenthiazine derivatives - Google Patents

Abstract

10 - (N - Lower alkyl - piperidyl - 31 - methyl)-phenthiazines (the term "lower alkyl" denoting alkyl groups of 1-4 carbon atoms) are prepared by alkylating phenthiazine with (pyridyl-3)-methyl chloride or bromide or an acid addition salt thereof in the presence of an inert organic solvent (e.g. benzene, toluene, xylene or tetrahydronaphthalene) and an alkali metal condensation agent (e.g. an alkali metal or a hydride, amide or oxide thereof, particularly lithium hydride, sodamide or sodium oxide), quaternizing the 10-(pyridyl-31-methyl)-phenthiazine obtained with a lower alkyl halide, and then catalytically hydrogenating the resulting lower alkyl pyridinium halide derivative in the presence of a metal sulphide hydrogenation catalyst resistant to inactivation by sulphur present in heterocyclic combination (e.g. a sulphide of a metal of Group VIa or VIII of the Periodic system, particularly molybdenum, cobalt or nickel sulphide). In examples, the quaternization step is effected with methyl chloride or methyl, ethyl, n- or iso-propyl or n-butyl bromide. Reference is made to the hydrochloride and sulphate of the intermediate 10 - (pyridyl - 31 - methyl) - phenthiazine and the following salts of the final products: hydrochloride (monohydrate), lactate and oxalate of the N-methyl compound, hydrochloride of the N-ethyl compound, and hydrobromide and hydrochloride of the N-n-propyl compound. Specification 772,179 is referred to.