Azocoupling Reaction of 1-Naphthol in Various Nonaqueous Solvents

Abstract

The solvent effect on the ratio of 2and 4-azo dye in the coupling products of 1-naphthol with p-nitrobenzenediazonium tetrafluoroborate has been studied in various nonaqueous solvents at 20°C In polar protic solvents(I) such as methanol, ethanol, 1-propanol and acetic acid, the selectivities of 2-azo dye formation were 5, 4, 3 and 3%, respectively, which were less than the value (7%) in water. In the nonpolar aprotic solvents(II) such as benzene, toluene, cyclohexane, dichloromethane and carbon tetrachloride, the selectivities of 2-azo dye increased to some extent and were 15, 20, 21, 30 and 22%, respectively. The solvent effect was discussed and the reaction was interpreted in SEAr mechanism, along with the base catalysis in deprotonation from the a-complex.