Tautomerism of anthraquinones: III. Tautomerization and rotational isomerization as processes responsible for the appearance of several π1,π*-bands in the absorption spectra of hydroxy-substituted quinones

Hydroxy-substituted anthraquinones, naphthoquinones, and naphthacenequinones exist as equilibrium mixtures of different tautomers and rotational isomers which give rise to several π1,π*bands in their electronic absorption spectra. Each π1,π*band can be assigned to a particular tautomer and conformer on the basis of the substituent constants σA. © 2006 Nauka/Interperiodica.