双核烷基咪唑过氧磷钨酸盐相转移催化剂合成及催化烯烃环氧化性能

合成并表征了一类双核长链烷基咪唑阳离子修饰的过氧磷钨杂多酸盐催化剂Dnmin]1.5PW4O24,考察了催化剂在过氧化氢为氧源的烯烃环氧化反应中的催化活性.研究表明,这类催化剂在反应过程中表现出相转移催化现象,并具有较高的催化活性和选择性.其中,双核十二烷基咪唑杂多酸盐催化剂D12min]1.5PW4O24的活性最佳,其环己烯转化率和环氧环己烷选择性分别达到97.7%和96.3%.催化剂在经过简单离心分离后可重复使用,重复使用4次后环己烯转化率和环氧环己烷选择性仍可分别达到72.4%和97.2%.催化剂D12min]1.5PW4O24在其它几种烯烃的环氧化反应中均表现出相转移催化特性,且具有较高的催化活性.

Synthesis of dicationic alkyl imidazolium peroxopolyoxotungsten-based phase transfer catalyst and its catalytic activity for olefin epoxidation

Peroxopolyoxotungsten-based hybrid catalysts modified by dicationic long-chain alkyl imidazolium cations have been synthesized and characterized. The catalytic activity of the catalysts was measured for the epoxidation of olefins with H₂O₂. These catalysts proved to be high catalytic activity phase transfer catalysts. In particular, for the catalyst D₁₂min]_1.5PW₄O₂₄ modified by the dodecyl dicationic imidazolium cation, the conversion of cyclohexene and selectivity for epoxycyclohexane were 97.7% and 96.3%, respectively. After the reaction, the catalyst could be recovered simply by filtration and reused four times. The conversion of cyclohexene and selectivity for epoxycyclohexane were still 72.4% and 97.2%, respectively, after recycling the catalyst four times. In addition, this phase transfer catalyst can be applied to the epoxidation of a wide range of olefins.