Ultrasonic wave aided selective epoxidation of mixed styrene and α-pinene with air over nanosized Co3O4

Catalytic selective epoxidation of mixed biolefins with air over nanosized Co3O4 catalyst under mild ultrasonic conditions has been first reported. When the styrene/alpha-pinene molar ratio was 1:5, the highest conversions were, respectively, reached 81.8 mol% for styrene and 76.1 mol% for alpha-pinene, with the epoxidation selectivity of 84.1% (styrene oxide) and 94.6% (alpha-pinene oxide), notably higher than those of the conventional reactions under magnetic stirring. An intermolecular electron-transfer phenomenon between conjugated styrene and electron-rich alpha-pinene was revealed by UV-vis spectra, which was considerably important for the enhancement of reactivities of both olefinic molecules observed experimentally. (C) 2009 Elsevier B.V. All rights reserved.