科研之友
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摘要
Selective oxyfunctionalization of monoterpenes is an interesting route to utilize these inexpensive natural products for a number of applications, such as pharmaceutical, flavor and perfumery industry as well as useful synthetic intermediates. The use of solid materials in catalytic oxidations in the liquid-phase has recently been extensively investigated because of their easy recovery and the possibility of regeneration which results in a reduction of the environmental impact. In this work, a new heterogeneous catalyst Co(acac)(2)/Silm was prepared with supporting Co ( acac)(2) on silica gel modified with 3-chloropropyltrimethoxysilane and imidazole, and the structure of catalyst was characterized by IR, UV-Vis and ICP-AES. Oxidation reactions of limonene, alpha-pinene and beta-pinene with dioxygen in acetonitrile solutions containing catalytic amounts of Co( acac)(2)/SiIm were studied. The results show that the higher conversion and products chemoselectivities were obtained. Limonene and a-pirtene gave epoxides as predominant products with chemoselectivities 62% and 79% at 58% and 72% conversion, respectively. On the other hand, P-pinene gave allylic oxides as major products with chemoselectivity 85% at a 55% conversion rate. In addition, the reaction mechanism and competition were simply discussed.
- 出版日期2009-9-10
- 单位中南大学
