The azinyl–azinylidene tautomerism of azinylmethanes and general problems of the tautomerism of azines

The results of studies on the tautomerism of azinylmethanes are surveyed. The terminology, the structure of the tautomeric forms, the thermodynamics and mechanisms of their interconversion, the dependence of the equilibrium on structure factors and the character of the medium, and certain general characteristic features of tautomeric equilibria of the azinyl–azinylidene type are discussed. The bibliography includes 127 references.