MR spectra and azo-quinonehydrazone tautomerism in 4-arylazo-1-naphthol derivatives,without intramolecular proton transfer

Conclusions Using¹³C-NMR spectroscopy conditions have been elucidated under which 4-R-azo-1-naphthol derivatives containing carbo- and heterocyclic functional groups R exist in solution predominantly in azo- or quinonehydrazone tautomeric forms, respectively. A mechanism has been proposed to account for azo-quinonehydrazone tautomerism; this mechanism would be expected to be valid in aprotic meida for hydroxyazo compounds which do not contain intramolecular hydrogen bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1292–1298, June, 1988.The authors wish to thank S. I. Dvoskin for submitting samples of compounds (Ia) and (Ic).