Lipase has been used for epoxidizing olefins such as monoterpenes for more than two decades. This epoxidation is accomplished by adding hydrogen peroxide (H₂O₂) to a carboxylic acid in the presence of a lipase such as Candida antartica lipase B (CALB) to produce percarboxylic acid, which then epoxidizes monoterpenes according to the Prilezhaev mechanism. One drawback of this process is the need for continuous addition of hydrogen peroxide to maintain maximum productivity. To overcome this hurdle, the industrial anthraquinone autooxidation process for hydrogen peroxide production was scaled down and coupled with lipase-mediated epoxidation in a semi-continuous manner. Palladium on alumina pellets (5% loading) was used as the catalyst for obtaining high yields of high-concentration hydrogen peroxide (50% weight by volume), followed by epoxidation of 3-carene, (+) limonene, and α-pinene. A total reaction time of 5 h was used for hydrogen peroxide production and 2–3 h for the epoxidation reactions. Pure 3-carene epoxide and α-pinene epoxide were obtained in isolated yields of 88.8 ± 2.8% and 83.8 ± 2.6%, respectively. Limonene epoxide was obtained as a mixture of mono- and di-epoxides in a ratio of 70% and 30%, respectively, with an isolated yield of 71.5 ± 3.1%.

中文翻译：

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半连续化学酶萜烯环氧化的发展：蒽醌自氧化和脂肪酶介导的环氧化过程的结合

脂肪酶已经用于环氧化烯烃例如单萜的超过二十年。这种环氧化反应是在脂肪酶（例如念珠菌）存在下，将过氧化氢（H ₂ O ₂）加到羧酸中来完成的。脂酶B（CALB）产生过羧酸，然后根据Prilezhaev机理环氧化单萜。该方法的一个缺点是需要连续添加过氧化氢以保持最大的生产率。为了克服这一障碍，缩小了生产过氧化氢的工业蒽醌自氧化工艺的规模，并以半连续方式与脂肪酶介导的环氧化反应相结合。氧化铝颗粒上的钯（5％负载）用作获得高收率的高浓度过氧化氢（50体积％重量）的催化剂，随后3-烯，（+）li烯和α-pine烯的环氧化。过氧化氢的生产总反应时间为5小时，环氧化反应的总反应时间为2-3小时。以88的分离产率获得了纯净的3-烯基环氧化合物和α-pine烯环氧化合物。分别为8±2.8％和83.8±2.6％。以单环氧化物和二环氧化物的混合物形式分别得到70％和30％的柠檬烯环氧化物，分离产率为71.5±3.1％。