GB585666A - Improvements in and relating to the manufacture of thioketones - Google Patents

Abstract

A thioketone is prepared by condensing a quaternary salt of a heterocyclic nitrogen base of the general formula <FORM:0585666/IV/1> wherein R is alkyl or substituted alkyl, R2 is H or alkyl, X is an anion, and either (1) a is O and Z the non-metallic atoms to complete a 5- or 6-membered ring containing the group <FORM:0585666/IV/2> wherein A and B are monovalent substituents or H, or together form a fused-on ring, or (2) a is 1 and Z is <FORM:0585666/IV/3> with an ester of a dithiocarboxylic acid. The reaction may be effected in presence of a basic condensing agent, and the group attached to the heterocyclic nitrogen atom may be an alkyl or substituted alkyl group (e.g. b -ethoxyethyl, allyl, or benzyl). Examples illustrate the production of 1-ethyl-2-thioacetylmethylene-1 : 2-dihydroquinoline from quinaldine etho-p-toluenesulphonate and methyl dithioacetate, of 3 - ethyl - 2 - thioacetylmethylene - benzthiazoline from 2 - methylbenzthiazoline etho-p-toluenesulphonate and methyl dithioacetate, of 5 - chloro - 3 - methyl - 2 - thiopropionyl - methylenebenzthiazoline from 5-chloro-2-methylbenzthiazole metho - p - toluenesulphonate and methyl dithiopropionate, of 1-ethyl-2-thioacetylmethylene-b -naphthathiazoline from 2-methyl-b -naphthathiazole etho-p-toluenesulphonate and methyl dithioacetate, of 3-ethyl-4-phenyl-2-thioacetylmethylene - 4 - thiazoline from 2 - methyl - 4 - phenylthiazole ethiodide and methyl dithioacetate, of 3 - (n - propyl) - 2 - thioacetylmethylenebenzthiazoline from 2-methylbenzthiazole n-propiodide and methyl dithioacetate, of 1-ethyl-4-thioacetylmethylene - 1 : 4 - dihydroquinoline from lepidine ethiodide and methyl dithioacetate, of 3-ethyl-2-thioacetylmethylene-a -naphthathiazoline from 2 - methyl - a - naphthathiazole etho - p - toluenesulphonate and methyl dithioacetate, of 3-ethyl-2-(a -(thioacetyl)-ethylidene)-benzthiazoline from 2-ethylbenzthiazole ethiodide and methyl dithioacetate, of 2 - cyclohexylthioformylmethy - lene - 3 - ethylbenzthiazoline from 2 - methylbenzthiazole etho - p - toluenesulphonate and the methyl ester of dithiocyclohexanecarboxylic acid, and of 1-phenyl-2-thioacetylmethylenebenzthiazoline from 2-methylbenzthiazole pheniodide and methyl dithioacetate. n-Butyl dithioacetate is prepared by reacting sodium dithioacetate with n-butyl bromide. According to the Provisional Specification, the thioketone may be prepared from a quaternary salt of a heterocyclic nitrogen base containing a R2-CH2- group (wherein R2 is H or alkyl) in the a - or g -position to the quaternary nitrogen atom. Specifications 533,425, 546,705, 551,331 and 566,010 are referred to.