席夫碱钼(Ⅵ)配合物的制备及催化大豆油环氧化

Synthesis of cis-Dioxomolybdenum(Ⅵ)-tridentate Schiff Base Complexes and Its Catalytic Activity on the Epoxidation of Soybean Oil

以水杨醛和邻氨基酚为起始原料,合成了N-亚水杨醛基-2-氨基苯酚配体(H2SAP);H2SAP与乙酰丙酮钼的无水乙醇溶液反应,制得席夫碱钼(Ⅵ)配合物MoO2(SAP)(EtOH);采用元素分析、红外光谱、紫外光谱、1H NMR及热重分析对配合物进行了表征.以MoO2(SAP)(EtOH)为催化剂,研究了其催化合成环氧大豆油的催化性能,考察了氧源种类、反应温度、反应时间及溶剂/助剂等因素对环氧化反应的影响.结果表明,以65%(质量分数)叔丁基过氧化氢(65%TBHP)为氧源,在80℃时反应4 h,转化率和选择性分别为43.0%和67.2%,MoO2(SAP)(EtOH)在催化体系中表现出强烈的助剂效应,当加入强给电子配体咪唑时,环氧产率显著降低.同时对该配合物催化环氧化机理进行了初步探讨.

The tridentate Schiff base ligand salicylaldehyde-2-hydroxyanil（H2SAP） was obtained via a Schiff base condensation reaction between salicylaldehyde and o-aminophenol in ethanol medium. cis-Dioxomolybdenum（Ⅵ）-tridentate Schiff base complex MoO2（SAP）（EtOH） was synthesized by mixing H2SAP with a solution of MoO2（acac）2 in ethanol. MoO2（SAP）（EtOH） was characterized and its catalytic activity was examined for epoxidation of soybean oil（SBO）. The effects of types of oxidants, reaction temperature, time, solvent and additives on the epoxidation of SBO were discussed in detail. The conversion and selectivity of epoxidized soybean oil（ESO） reach 43.0% and 67.2%, respectively, at 80℃ for 4 h, with tert-butyl hydroperoxide（65% TBHP, mass fraction） as oxidant. Meanwhile, the epoxide yield was related to the nature of additives. The yield of ESO reduced dramatically by adding strong coordinating ligands such as imidazole. The mechanism of interaction between the catalyst and oxidant was also investigated.