GB577478A - Improvements relating to the manufacture of amidines - Google Patents

Abstract

Amidines of the general formula <FORM:0577478/IV/1> wherein R represents hydrogen or an alkyl or aryl radical, R1 represents an alkyl or aryl radical and R2 and R3 either represent alkyl or aryl radicals or one represents an alkyl or aryl radical and the other a hydrogen atom, are produced by reaction of an amine of the general formula <FORM:0577478/IV/2> with a sulphonic ester having the general formula <FORM:0577478/IV/3> R, R1, R2 and R3 having the significance above and X being a hydrocarbon radical. The requisite sulphonic esters may be prepared (a) in general, by reaction of an N-substituted carboxylic amide with an aromatic sulphonyl halide, or (b) when R and R1 represent alkyl or aryl radicals, by reaction of a sulphonyl halide with a ketoxime having the general formula R.C(=N.OH)R1. In examples: (1) benzenesulphonyl chloride is added with stirring, to formanilide in dry pyridine at -10 DEG C., the product is heated with aniline to produce N.N1-diphenylformamidine hydrochloride and the free amidine is obtained by adding dilute caustic soda; (2) acetanilide is stirred with chloroform and benzenesulphonyl chloride in dry pyridine prior to introducing aniline in chloroform dropwise and, after standing, precipitating N.N1-diphenylacetamidine from the washed aqueous extract by basifying with ammonia; (3) benzanilide and benzenesulphonyl chloride are heated together in pyridine, aniline is added and heating continued, producing N.N1-diphenylbenzamidine hydrochloride from which the free amidine is obtained as in (1); (4) toluene-p-sulphonyl chloride is heated with N-methylbenzamide in dry pyridine prior to introducing aniline, further heating, dissolving in alcohol and isolating the corresponding amidine by adding 4N. sodium hydroxide; (5) diphenylketoxime benzenesulphonate and diethylamine are refluxed together in dry benzene and the corresponding amidine is isolated by extraction with dilute hydrochloric acid, and precipitation with ammonia; (6) toluene-p-sulphonyl chloride in acetone is added, with stirring, to methyl phenyl ketoxime in N. sodium hydroxide cooled below 0 DEG C. and the product is benzene-extracted, washed and evaporated to dryness in vacuo at room temperature and the residue, in benzene, is treated with aniline, warmed to initiate reaction and then boiled, the oil which separates being dissolved in aqueous alcohol and N.N1-diphenylacetamidine liberated therefrom by adding ammonia.