V. A. Khrustalev

Synthesis and ring-chain tautomerism of salts of alkylidene(arylidene) derivatives of amidrazones

A number of salts of alkylidene (arylidene) derivatives of amidrazones was obtained by the reaction of S-methylthioamidium iodides with hydrazones of monocarbonyl compounds. According to the 1H and 13C NMR data, these compounds in solutions are capable of ring-chain tautomerism of the 1-alkylideneamidrazone-1,2,4-triazoline type. The position of the equilibrium is determined chiefly by steric interactions of the substituents attached to the C-N2 bond.

Ring-chain tautomerism of diacetyl and benzil thioacylhydrazones

The products of condensation of thiobenzohydrazide with diacetyl and benzil have the structures of the corresponding 1,3,4-thiadiazol-2-ines; the same diketones and phenylthioacetylhydrazine were used to synthesize derivatives that display in solutions the ability to undergo thioacylhydrazone-1,3,4-thiadiazoline tautomerism. A bis derivative, viz., 5-(2′-phenyl-5′-methyl-1,3,4-thiadiazolin-2-yl)-5-methyl-2-phenyl-1,3,4-thiadiazol-2-ine, was obtained in the condensation of excess thiobenzohydrazide with diacetyl.