Selective oxidation of cyclopentene with H_2O_2 by using H_3PW_(12)O_(40) and TBAB as a phase transfer catalyst

The selective oxidation of cyclopentene by aqueous H₂O₂ using H₃PW₁₂O₄₀ and tetrabutyl ammonium bromide (TBAB) as a phase transfer catalyst has been investigated. The results show that the presence of TBAB significantly improved the oxidation selectivity of cyclopentene. The effects of the reaction conditions on the conversion of cyclopentene were investigated in detail. The optimal reaction conditions are as follows:the H₃PW₁₂O₄₀ to TBAB molar ratio, 1:1-1:3; H₃PW₁₂O₄₀ to cyclopentene molar ratio, 0.54:100-0.64:100; and molar ratio of H₂O₂ to cyclopentene, 1.6:1. The conversion reached to 59.8% in 4 h at 35.0℃, while the selectivity of glutaraldehyde was 38.0% and the selectivity of 1,2-cyclopentanediol was 55.6%. In addition, a route for oxidation of cyclopentene by aqueous H₂O₂ using a heteropoly acid and quaternary ammonium salt as a phase transfer catalyst was proposed.