Kinetic Studies of the Base Catalysis and the Primary Salt Effect on the Coupling Reaction of 1-Naphthol

Abstract

The general base catalysis and the primary salt effect on the coupling reaction of 1-naphthol with p-methoxy or p-methyldiazobenzene have been studied kinetically.The rate of the coupling at 4-positiQn of 1ewnaphthol was found to be given by k, (base) (diazonium ion) (naphtholate ion), where base denotes monohydric phosphate ion, acetate ion, dihydric phosphate ion, water and pyridine (Fig.1). A linear relationship between the logarithms of k. and the disso iatien constant of the base was also found when monohydric phosphate ion, acetate ion, or dihydric phosphate ion was used as a base. The catalytic effect ef water was much smaller than that expected by the abeve relationship, while that ef pyridine was larger (Fig.2).The rate of the reaction at 2-position of 1-naphthol was, on the other hand, almost independent of the concentration of a base except water (Fig.1).The salt e ect suggested that the reaction took place between two ionic species, i. e., diazonium ion and naphtholate ion (Fig.3)i