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首页> 外文期刊>Chemistry: A European journal >Highly selective, recyclable epoxidation of allylic alcohols with hydrogen peroxide in water catalyzed by dinuclear peroxotungstate
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Highly selective, recyclable epoxidation of allylic alcohols with hydrogen peroxide in water catalyzed by dinuclear peroxotungstate

机译：双核过氧钨酸盐催化水中的过氧化氢对烯丙醇进行高度选择性的可循环环氧化

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摘要

The highly chemo-, regio-, and diastereoselective and stereospecific epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide in water can be efficiently catalyzed by the dinuclear peroxotungstate, K-2[{W(=O)(O-2)(2)(H2O)}(2)(mu-O)].2H(2)O (I). The catalyst is easily recycled while maintaining its catalytic performance. The catalytic reaction mechanism including the exchange of the water ligand to form the tungsten-alco-holate species followed by the insertion of oxygen to the carbon-carbon double bond, and the regeneration of the dinuclear peroxotungstate with hydrogen peroxide is proposed. The reaction rate shows first-order dependence on the concentrations of allylic alcohol and di-nuclear peroxotungstate and zero-order dependence on the concentration of hydrogen peroxide. These results, the kinetic data, the comparison of the catalytic rates with those for the stoichiometric reactions, and kinetic isotope effects indicate that the oxygen transfer from a dinuclear peroxotungstate to the double bond is the rate-limiting step for terminal allylic alcohols such as 2-propen-1-ol (1a).
机译：双核过氧钨酸钾K-2 [{W（= O）（O-2） （2）（H 2 O）}（2）（mu-O）]。2H（2）O（I）。该催化剂易于回收，同时保持其催化性能。提出了一种催化反应机理，包括交换水配体以形成钨-醇-钨酸盐物种，然后将氧插入碳-碳双键中，并用过氧化氢再生双核过氧钨酸盐。反应速率显示出对烯丙基醇和双核过氧钨酸盐浓度的一阶依赖性，以及对过氧化氢浓度的零阶依赖性。这些结果，动力学数据，催化速率与化学计量反应的比较以及动力学同位素效应表明，从双核过氧钨酸盐到双键的氧转移是末端烯丙基醇（如2）的限速步骤-丙烯-1-醇（1a）。

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