Studies on the Tautomerism of 2-Anilinopyridine and Related Heterocycles. II. 2-Anilino-5-nitropyridine and 2-Anilinopyrimidine

Abstract The tautomeric behavior of 5-nitro-2-anilinopyridine and 2-anilinopyrimidine was studied. 2-(N-Methylanilino) and l-methyl-2-(phenylimino)-1,2-dihydro derivatives were prepared as models for the amino and imino tautomers, respectively, and their spectra were compared. The results and the assumed tautomeric equilibrium constants strongly suggest the equilibria to be favorable to the amino tautomers, the Kt values being considerably smaller than that of the parent 2-anilinopyridine.