MCM-41固载主族金属Schiff碱配合物催化环己基过氧化氢为氧源的环己酮Baeyer-Villiger氧化

According to the shortcomings such as high explosivity of peroxo acid as oxidant in the preparation of ε-caprolactone, the foundational research on the cyclohexanone Baeyer-Villiger oxidation based on the cooxidation principles will be developped in this project. Firstly, the active metal componets will be selected to synthesis the schiff base complex with the activity of carrying oxygen. Then, the immobilization of the complex on the zeolite carrier modified by the aminosilane reaction after synthesised by the method of hydrothermal will be realized, which can solve the easily deactivation problem of the Schiff base complex due to the formation of dimmers between the moleculers. The influence factors such as structure of carrier, type of complex, modificated conditions on immobilization effect will be emphatically investigated, many kinds of physical and chemical means will be used to characterize the structure of immobilized catalyst applied in the Baeyer-Villiger oxidation of cyclohexanone used cyclohexyl peroxide as oxidant. The mechanism of Baeyer-Villiger catalytic oxidation reaction will be studied and the structure-activity relationship of catalyst will be explored. The influence of the reaction temperature, pressure and catalyst concentration will also be investigated. The selectivity of ε-caprolactone is expected to reach 90% and the catalyst is hoped with higher activity and stability. This project aimed at establishing the structure activity relationship between the schiff base complex and activated performace for oxidant and keto carbonyl group, laying a theoretical fundation for the cyclohexanone Baeyer-Villiger oxidation used cyclohexyl peroxide as oxidant.

针对传统的过氧酸为氧化剂的ε-己内酯制备带来的高爆炸性等缺点，开展基于共氧化原理的环己酮Baeyer-Villiger氧化的基础研究。首先遴选活性金属组分，合成具有载氧活性的金属Schiff碱配合物。以水热合成法制备的MCM-41分子筛为载体，在氨基硅烷化修饰的基础上实现配合物的固载，以期解决金属席夫碱配合物分子之间易于聚合失活的问题。重点考察载体结构、配合物种类及修饰条件等对固载效果的影响，并采用多种物化手段对固载催化剂进行结构表征。将固载催化剂应用于环己基过氧化氢为氧化剂的环己酮B-V氧化，研究其催化反应历程，探索催化剂结构与活性之间的关系，考察温度、压力和催化剂浓度等对B-V氧化反应的影响，期望己内酯选择性达到90%，且催化剂具备较高活性和稳定性。项目旨在建立金属Schiff碱配合物结构与其对酮羰基和氧化剂活化性能之间的构效关系，为烷基过氧化氢做氧化剂的环己酮B-V氧化奠定理论基础。

Baeyer-Villiger氧化是制备重要化学中间体ε-己内酯最行之有效的方法，建立B-V绿色氧化反应体系的关键在于经济安全的氧化剂和高效催化剂的设计。采用环己烷无催化氧化产物环己基过氧化氢(CHHP)为氧源，构筑氨基功能化介孔分子筛MCM-41固载的主族金属配合物Sn(salen)为催化剂的环己酮B-V氧化反应，但Sn(salen)未表现出B-V氧化进攻酮羰基所需的Lewis酸性，对于烷基过氧化氢的活化不明显，反应效率低下。因而改用化学气相沉积（CVD）、直接水热合成、离子交换和浸渍四种方法合成Sn掺杂的Sn-MCM-41介孔分子筛。结果表明通过CVD制备出的Sn-MCM-41，经过液相硅烷化疏水修饰改性后，催化CHHP和环己酮的B-V氧化反应，CHHP的转化率为50.5%，环己酮转化率为19.8%，己内酯的选择性为8.5%，该体系首次实现了烷基过氧化氢与环己酮通过共氧化制备己内酯。进一步选用水热预处理的无定型SiO2为载体，通过CVD法掺杂Sn，Sn/SiO2催化双氧水为氧化剂的环己酮B-V氧化反应，环己酮转化率为41％，己内酯选择性可达96％。以水热脱铝后的NaY分子筛为载体通过液相同晶取代法制备含Sn催化剂Sn-NaY(DeAl)应用于环己酮B-V氧化反应，在n(H2O2):n(酮)= 1.5:1，乙腈为溶剂，70℃下反应24h的工艺条件下，环己酮的转化率可达44%，己内酯的选择性为62%，制备过程和性能均优于Sn-β分子筛。通过气相同晶取代法制备的Sn/NaY(DeAl)对环己酮的B-V氧化反应表现出更好的催化活性，在双氧水过量的情况下，对环己酮的转化率为48%，己内酯的选择性为66%，TON数高达248。两种同晶取代方法的对比说明四配位的骨架Sn物种接受电子对形成的Lewis酸是催化环己酮B-V氧化反应中的活性中心。