In homopolar solvents α-keto acids form a stable proton chelate between the carboxyl and α- carbonyl groups. This chelate causes a major bathochrome shift of the n-π*-bands of the α- carbonyl group as compared to the spectrum of the non-chelated molecule, and moreover it shows a remarkable vibrational band structure. The UV spectra of α-keto acid amides also suggest an intramolecular-NH⋯ O C interaction. A study of the action of the alkyl group ...
