J. Kelemen
Apr 1, 1981
Citations
0
Influential Citations
51
Citations
Journal
Dyes and Pigments
Abstract
Derivatives of 1-phenylazo-2-naphthol have been the subject of research for nearly a century, and their tautomeric behaviour is now well understood. This contrasts with sparse and controversial reports on the structure of naphthylamine analogues. To remedy this situation, a comparative study, involving compounds from both phenylazo-naphthol and naphthylamine series with OMe, CN and NO2 substituents in the 4′ position has been started. HMO calculations indicated that the azo form of 1-phenylazo-2-naphthylamine is significantly more stable than the hydrazone, whereas the π bonding energies of the corresponding naphthol tautomers are of comparable magnitude. The validity of the Huckel calculations was checked on a greater set of phenylazo dyes with different coupling components. Results from electronic absorption spectroscopy show a frozen equilibrium with naphthylamine derivatives. From a McRae type analysis of the solvent-induced frequency shifts in various media an argument for the azo structure of all investigated 1-phenylazo-2-naphthylamines could be obtained. PPP calculations of spectral properties support this assignment.