1-Diazo-2-または2-Diazo-1-naphtholおよびその4-Sulfonic Acid誘導体の構造について

抄録

Structural form of the -⁺N₂ group in 1-diazo-2-naphthol (V) and 2-diazo-1-naphthol (VI), and their 4-sulfonic acids (III and IV) in solid and in water-perchloric acid solution was studied from their infrared and ultraviolet absorption spectra. In the solid state, V and VI took the quinonoid form, and their perchlorate took the diazonium form, while III and IV were in the diazonium form and their metal salts, the quinonoid form. Ultraviolet absorption of the solid form also showed difference of quinonoid and diazonium types.
Ultraviolet absorption spectra of these compounds were measured in water-perchloric acid solution and acidity of their phenolic hydroxyls was compared from the ratio of the quinonoid and diazonium forms and its relation to the concentration of perchloric acid. It was thereby found that their acidity is much stronger than that of known p-diazophenol (pKa=3.40), their pKa being less than 1. The acidity of these hydroxyls increased in the order of V, III, VI, and IV.