Phase-Transfer-Catalyzed Azo Coupling Reactions in Two-Phase Systems

The azo coupling reaction of p-methoxybenzenediazonium tetrafluoroborate with N,N-dimethylaniline has been investigated in a water-1,2-dichloroethane system. It has been found that, among the several additives examined, the phenolate ion, generated from picric acid or 2,4-dinitro-1-naphthol, acted as an effective phase-transfer catalyst. Further, the reaction of p-diethylaminobenzenediazonium tetrafluoroborate with dimedone, an active methylene compound, has also been investigated in the same two-phase system; a remarkable acceleration in the rate was observed in the presence of tetraalkyl onium salts, and even in their absence.