长链烷基冠醚在烯烃环氧化反应中的相转移催化作用

Application of Long Chain Alkyl Crown Ethers to Epoxidation of Olefins

为了实现温和条件下烯烃的环氧化,近年来模拟细胞色素P-450单加氧酶催化烃类氧化的研究十分活跃,其中以金属卟啉/NaOCl（CH2Cl2/H2O）模拟体系研究最多.从近年文献看,在Meunier等建立的该两相催化反应体系中,通过改变催化剂的结构、各种助剂及氧源浓度等可达到较好的催化效果,其相转移剂一般选用季铵盐类化合物.有文献报导以聚乙二醇取代季铵盐,结果证明聚乙二醇的相转移作用也很明显.

Long chain alkoxymethyl crown ethers were used as phase transfer catalyst to two phase system of olefin epoxidation catalyzed by metalloporphyrins. The yield of epoxide is more than 90% and selectivity is about 100%, which are more satisfactory as compared with those of quaternary ammonium salts. This result might be attributed to the complexation of crown ether with metals resulting in more effective concentration of OC1- to act as oxidant.