Studies of the Absorption Spectra of Azo Dyes and their Metalcomplexes.I. The Absorption Spectra of Phenylazoacetoacetanilide and its Related Compounds

Phenylazoacetoacetanilide and its related compounds have the hydrazone structure. The phenylazoacetoacetic acid ethylester, for example, forms an intramolecular hydrogen bond between a ketone group and a hydrazone group in the solid state and in non-polar solvents. The electronic absorption spectra exhibit three groups of bands—A,B and C—D. The effects upon the spectra of the intramolecular hydrogen bond and of the π-p conjugation at the carboxylic acid amide group have been discussed.