Schiff bases of aromatic amines and β-diketones including those containing Ph end-groups have been shown to exist as the keto-amine tautomer using NMR spectroscopy. The Schiff bases derived from aromatic amines and 2-hydroxyl-1-naphthaldehyde were concluded to be an equilibrium mixture of the ketoenamine and enolimine forms. The influence of electronic effects in the aromatic amines on the hydrogen-bond strength was also ...