GB575145A - Improvements in or relating to the preparation of amidine salts - Google Patents

Abstract

Amidine salts are obtained by the reaction of an iminothio-ether base with a salt of ammonium or of a primary or secondary amine. In particular, from the appropriate di-iminothioether bases are obtained salts of aromatic diamidines of the general formula Am.B.X.B.Am, wherein Am represents the amidine or N-substituted amidine group, B represents an aromatic residue and X represents: (a) a direct linkage, or (b) an alkane chain (CH2)n, wherein n is an integer from 1 to 12 and in which one or more of the -CH2- groups may be replaced by an oxygen or sulphur atom or by an -NH-group, or (c) A-CR1=CR2- group, wherein R1 and R2 represent hydrogen atoms or alkyl, aralkyl or aryl groups and may be the same or different. Advantageously, the treatment is at an elevated temperature, but below that at which any substantial quantity of ammonia is evolved, and the proportions of the reactants are adjusted so that when the ammonium or amine salt is in aqueous solution and the imino thio-ether is in alcoholic solution both reactants remain in solution when such solutions are mixed at 50-80 DEG C. In examples: (1) a -e -diphenoxy pentane-4 : 41-bis-(carbonim inothiobenzyl-ether) is heated with ammonium chloride in aqueous ethyl alcohol at 60-70 DEG C. for 26 hours, the solution is decanted into acetone and the precipitated 4 : 41 - diamidino - a ,e - diphenoxy-pentane dihydrochloride is recrystallised from dilute hydrochloric acid; (2) a - - diphenoxy-propane-4 : 41-bis-(carboniminothiobenzyl-ether) in alcoholic solution is mixed with an aqueous solution of ammonium chloride and the mixture is heated at 60-70 DEG C. for 48 hours; the filtered reaction solution is poured into acetone and the a -g -diphenoxy-propane-4 : 41-bis-(carbonamidine) dihydrochloride is precipitated; (3) trans-stilbene-4 : 41-bis-(carboniminothiobenzyl-ether) in alcoholic solution is mixed with an aqueous solution of ammonium b -hydroxyethanesulphonate, the mixture is heated at 40-50 DEG C. for 30 hours and thereafter at 70 DEG C. for 4 hours to obtain trans-stilbene-4 : 41-bis-(carbonamidine)-di-b -hydroxyethanesulphonate; (4) diphenyl ether - 4 : 41 - bis - carbon - iminothiobenzyl - ether) in alcoholic solution is mixed with an aqueous solution of ammonium b -hydroxyethane sulphonate and the mixture is heated at 70 DEG C. to obtain 4 : 41-bis - (carbonamidine) - di - b - hydroxyethanesulphonate, and the solution may be treated with caustic soda to obtain the free base. Specification 549,639 also is referred to. Di-benzylthio-imino ethers used in the examples are obtained by the reaction of the corresponding nitriles with benzyl mercaptan.