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合成了一类新型八羟基喹啉双核钛配合物,初步考察了这类配合物在催化烯烃与H2O2环氧化反应中的催化性能.结果表明配体的取代基对此类配合物的催化性能有很大的影响,由5,7-二卤代,特别是5-氯取代配体制备的配合物显示高的催化效率:它的催化转化率比普通喹啉配合物的催化转化率提高了44%,这可能与卤素取代基能加强配体与钛原子的配位作用有关.基于紫外技术,提出了此类钛配合物催化烯烃环氧化的机理:在酸性条件下,配合物中一个钛-氧-钛桥断裂,双氧水进攻后形成带氢键作用的过氧化物活性中间体,该中间体进一步生成了低活性的过氧化物.
A series of novel octahydroquinone binuclear titanium complexes were synthesized and the catalytic performance of these complexes in the epoxidation of olefins with H2O2 was investigated. The results showed that the catalytic activity of the ligands on the complexes Has a great impact, the complexes prepared from 5,7-dihalogenated, especially 5-chloro-substituted ligands show high catalytic efficiency: their catalytic conversion rate is increased over the catalytic conversion of common quinoline complexes 44%, which may be related to the halogen substituents can enhance the coordination of the ligand and the role of titanium atoms based on the UV technology, proposed catalytic mechanism of such titanium epoxidation of olefinic mechanism: Under acidic conditions, a complex Titanium - oxygen - titanium bridge fracture, hydrogen peroxide formed after the attack with a hydrogen bond peroxide active intermediates, the intermediate further generated low activity of the peroxide.