Ultrasound assisted phase-transfer catalytic epoxidation of 1,7-octadiene - a kinetic study.
An ultrasound assisted phase-transfer catalyzed epoxidation of 1,7-octadiene is greatly enhanced by using a cocatalyst of phosphotungstic acid in the presence of hydrogen peroxide in an organic solvent/aqueous solution two-phase medium. An active intermediate of the catalyst (Q3PW12(O)nO40, where Q = R4N+) produced from the reaction of phosphotungstic acid, hydrogen peroxide, and Aliquat 336. A rational mechanism of epoxidation is proposed to account for the reaction from the experimental evidence. The organic-phase reactions, including two series reactions, are the rate-controlling steps to produce two products, viz., 1,2-epoxy-7-octene and 1,2,7,8-diepoxyoctane. The kinetics of epoxidation, including the characteristics of the catalyst and the effect of the amount of cocatalyst, agitation speed, quaternary ammonium salts, amount of Aliquat 336, amount of hydrogen peroxide, amount of chloroform, pH value, organic solvents, and temperature on the conversion of 1,7-octadiene were investigated in detail. A kinetic model was built, from which a pseudo-first-order rate law is sufficient to describe the behavior of the reaction.
Wang
Maw-Ling
ML
Department of Environmental Engineering, Hung Kuang University, Shalu, Taichung County, 433 Taiwan, ROC. chmmlw@sunrise.hk.edu.tw
Rajendran
Venugopal
V
D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry* / Q000528:radiation effects*; D007700:Kinetics; D013010:Sonication; D013729:Terpenes / Q000737:chemistry* / Q000528:radiation effects*
D004852:Epoxy Compounds; D013729:Terpenes