Tautomeric pyridines. Part XIV. The tautomerism of 2-benzyl-, 2-benzhydryl-, and 2-anilino-pyridine

Abstract

U.v. spectra of the pyridinoid title compounds and of models for the corresponding pyridonoid tautomers show that the pyridinoid tautomeric forms are greatly preferred in aqueous solutions. pK_a Measurements allow quantitative determinations of tautomeric equilibrium constants which are compared with data for various other systems; the latter data include new results for some enamine–imine equilibria. The aromatic character of the pyridonoid forms of the title compounds is discussed.