Revisiting Alkane Hydroxylation with m‐CPBA (mChloroperbenzoic Acid) Catalyzed by Nickel(II) Complexes
Revisiting Alkane Hydroxylation with m‐CPBA (mChloroperbenzoic Acid) Catalyzed by Nickel(II) Complexes
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重新审视镍 (II) 配合物催化的 m-CPBA（间氯过苯甲酸）烷烃羟基化
DOI：
10.1002/chem.202102532
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Itoh S.
中科院分区：
文献类型：
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作者：
Shinke;T.;Itoh;M.;Wada;T.;Morimoto;Y.;Yanagisawa;S.;Sugimoto;H.;Kubo;M.;Itoh S.
研究了镍（II）配合物NiII(L)催化m - CPBA （m -氯过苯甲酸）对烷烃羟基化反应的机理。在环烷烃的氧化反应中，NiII（TPA）是一种收率高、醇选择性高的高效催化剂。在金刚烷的氧化过程中，叔碳主要被氧化。反应速率与[底物]和[NiII(L)]有一级关系，与[m‐CPBA]无关；vobs=k2[底物][NiII(L)]。该反应表现出较大的动力学氘同位素效应（KIE），为6.7，表明氢原子的抽离参与了催化循环的限速步骤。此外，相关四齿配体负载的NiII(L)表现出明显不同的催化活性，表明NiII(L)在催化循环中的贡献。基于动力学分析和o2和ccl4对产物分布模式的显著影响，(L)NiII−O。并讨论了芳氧基自由基作为活性氧化剂的作用。
Mechanistic studies are performed on the alkane hydroxylation withm‐CPBA (m‐chloroperbenzoic acid) catalyzed by nickel(II) complexes, NiII(L). In the oxidation of cycloalkanes, NiII(TPA) acts as an efficient catalyst with a high yield and a high alcohol selectivity. In the oxidation of adamantane, the tertiary carbon is predominantly oxidized. The reaction rate shows first‐order dependence on [substrate] and [NiII(L)] but is independent on [m‐CPBA];vobs=k2[substrate][NiII(L)]. The reaction exhibited a relatively large kinetic deuterium isotope effect (KIE) of 6.7, demonstrating that the hydrogen atom abstraction is involved in the rate‐limiting step of the catalytic cycle. Furthermore, NiII(L) supported by related tetradentate ligands exhibit apparently different catalytic activity, suggesting contribution of the NiII(L) in the catalytic cycle. Based on the kinetic analysis and the significant effects of O2and CCl4on the product distribution pattern, possible contributions of (L)NiII−O.and the aroyloxyl radical as the reactive oxidants are discussed.