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研究了钼钒磷杂多化合物过氧化氢体系对环己烷、正己烷和正戊烷羟化的催化性能,环己烷氧化物产率为33.5%,醇的选择性达73%,正戊烷氧化物产率为23.5%,酮的选择性达78.5%.用UV-Vis和IR表征了催化体系中M(O2),M=Mo,V)过氧络合物的生成,证明Mo(O2)稳定存在于体系中,而V(O2)是不稳定的活性中间物种.比较了MeCN和HOAc两种介质中的反应曲线及产物选择性的差异,结果表明CCl4对前者中的反应有阻止作用,而对后者无任何影响.据此,提出了两种介质中V(O2)活性物与烷烃作用的不同机理:MeCN介质中均裂产生Ⅴ(Ⅳ)─O—O·的机制和HOAc介质中的分子氧化机制.
The catalytic performance of the molybdovanadophosphoric complex hydrogen peroxide system for the hydroxylation of cyclohexane, n-hexane and n-pentane was studied. The yield of cyclohexane oxide was 33.5%, the selectivity of alcohol was 73% The alkoxide yield was 23.5% and the ketone selectivity was 78.5%. The formation of peroxo complexes of M (O2), M = Mo, V in the catalytic system was characterized by UV-Vis and IR. It was proved that Mo (O2) was stable in the system and V (O2) Active intermediate species. The differences between the reaction curves and the product selectivity in MeCN and HOAc media were compared. The results showed that CCl4 could prevent the reaction in the former, and had no effect on the latter. Therefore, different mechanisms of the interaction of V (O2) with alkanes in two kinds of media are proposed: the mechanism of homogeneity of Ⅴ (Ⅳ) ─O-O · in MeCN and the mechanism of molecular oxidation in HOAc media.