J. Cubillos, Santiago Vásquez, C. Correa
Jan 31, 2010
Citations
2
Influential Citations
27
Citations
Journal
Applied Catalysis A-general
Abstract
Abstract The epoxidation of R-(+)-limonene using in situ generated dimethyldioxirane (DMD) as the oxidizing agent and four Jacobsen-type catalysts ((R,R)-Jacobsen, (S,S)-Jacobsen, racemic Jacobsen and achiral Jacobsen) was examined. The effect of the amount of KHSO 5 and acetone in the catalyzed and un-catalyzed reaction was also assessed. The main reaction products were diepoxide and endocyclic monoepoxide. In the absence of catalyst, the amount of KHSO 5 did not significantly influence conversion and selectivity. The catalyst can be segregated to a different phase and separated from the reaction media when the amount of KHSO 5 is above the stoichiometric ratio, R-(+)-limonene/KHSO 5 = 0.5 mmol/mmol, and acetone/mmol R-(+)-limonene = 2 mL/mmol. However, when the amount of KHSO 5 is below the stoichiometric ratio (R-(+)-limonene/KHSO 5 = 1.5 mmol/mmol) the catalyst is difficult to separate. Under the reaction conditions of this study, when the catalyst is segregated, no effect of the catalyst chiral center, (R,R)-Jacobsen or (S,S)-Jacobsen, was found on conversion and selectivity. Additionally, the (R,R)-Jacobsen's catalyst proved to be very stable to oxidative degradation.