Solvent Effects in Diazo-coupling Reactions

Abstract The kinetics of the diazo-coupling reactions of benzenediazonium fluoroborates with 1,3,5-trimethoxybenzene and 2-naphthol have been studied in non-aqueous media including both protic and dipolar aprotic solvents. In the case of the reaction with 1,3,5-trimethoxybenzene, no significant solvent effect on the reaction rate was observed. However, in the case of the reaction with 2-naphthol, the reaction rate was affected markedly by the solvent; in dipolar aprotic solvents, the reaction proceeded much faster than in protic solvents. The observed results are interpreted in terms of the difference in solvation toward the naphtholate ion.