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首页> 外文期刊>Catalysis science & technology >Homogeneous catalytic oxidation of styrene and styrene derivatives with hydrogen peroxide in the presence of transition metal-substituted polyoxotungstates
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Homogeneous catalytic oxidation of styrene and styrene derivatives with hydrogen peroxide in the presence of transition metal-substituted polyoxotungstates

机译：在存在过渡金属取代的聚氧化盐的情况下，苯乙烯和苯乙烯衍生物的均质催化氧化

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摘要

The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates with general formula [XW11M(H2O)O-39]((n-m)-), where X = P, B or Si and M = Mn, Fe or Co, were evaluated as catalysts in the oxidation of styrene, alpha-methylstyrene, p-methylstyrene, alpha,p-dimethylstyrene, p-chlorostyrene, p-nitrostyrene, and p-methoxystyrene under mild conditions, using aqueous H2O2 as an eco-sustainable oxidant. In this study, the influence of the catalysts and of the different styrene substituents on the oxidation reaction profile was evaluated in terms of conversion and selectivity. For all the performed catalytic studies, the main product results from the oxidative cleavage of the vinyl double bond, except in the case of the oxidation of p-methoxystyrene catalysed by BW11Mn, for which p-methoxyphenol is the main product. The catalysts BW11Mn and SiW11Co give rise to 100% conversion for almost all of the substrates, excluding p-methoxystyrene and p-nitrostyrene for both catalysts and alpha,p-dimethylstyrene only in the case of BW11Mn. The selectivity for C=C cleavage products resulting from the oxidative cleavage of the vinyl double bond can be as high as 98%, reaching 98% conversion for p-nitrostyrene when SiW11Co was used as a catalyst. Possible pathways are discussed and the oxidation of a few presumed intermediates was carried out. The systematic study of several substituted styrene derivatives suggests a possible reactivity order for these compounds in the catalytic system considered.
机译：Keggin型多氧酮的四丁基铵（TBA）盐，具有一般公式[XW11M（H2O）O-39]（（N-M） - ），其中X = P，B或Si和M = M = M = M = M = M = M = M = M = MN，Fe或Co，在苯乙烯，α-甲基苯乙烯，P-甲基苯乙烯，α，P-二甲基苯乙烯，P-氯苯乙烯，P-硝基苯乙烯和P-甲氧基苯乙烯的催化剂中，在使用H2O2的情况下，使用H2O2作为环保氧化剂。在这项研究中，根据转化和选择性评估了催化剂和不同苯乙烯取代基对氧化反应曲线的影响。对于所有进行的催化研究，主要产物是由乙烯基双键的氧化裂解引起的，除非由BW11MN催化的P-甲氧基苯乙烯的氧化，而P-甲氧基酚是主要产物。催化剂BW11MN和SIW11CO对几乎所有底物产生100％的转化率，仅在BW11MN的情况下，催化剂和α-甲氧基于P-甲氧基苯乙烯和P-硝基苯乙烯。由乙烯基双键氧化裂解产生的C = C裂解产物的选择性高达98％，当使用SiW11CO用作催化剂时，P-硝基苯乙烯的转化率达到98％。讨论了可能的途径，并进行了一些假定的中间体的氧化。对几种取代苯乙烯衍生物的系统研究表明，考虑到催化系统中这些化合物的可能反应性顺序。

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