Cumene oxidation by cis-[RuIV(bPY)2(py)(O)]2+, revisited
Cumene oxidation by cis-[RuIV(bPY)2(py)(O)]2+, revisited
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DOI：
10.1021/ic035298j
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发表时间：
2004-02-23
影响因子：
4.6
通讯作者：
Mayer, JM
中科院分区：
文献类型：
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作者：
Bryant, JR;Matsuo, T;Mayer, JM
cis-[Ru-IV(bpy)(2)(py)(O)](2+) 在乙腈溶液中主要将枯烯（2-苯基丙烷）氧化为枯醇（2-苯基-2-丙醇）、α-甲基苯乙烯和苯乙酮。与之前的报道相反，添加亲核试剂不会加速反应速率。因此没有证据证明最初提出的氢化物转移机制。相反，结果与初始氢原子从枯烯转移到钌氧基的机制一致。这由速率与 C-H 键强度的相关性以及观察到的各种产物表明。苯乙酮的形成比枯烯少一个碳，建议通过涉及 2-苯基丙醛的酰基脱羰的多步骤途径发生。由于在厌氧条件下难以生成烷氧基自由基，并且顺式-[Ru-IV(bpy)(2)(py)(O)](2+)氧化三苯甲烷时缺乏重排产物，因此认为涉及枯氧基自由基β-断裂的替代机制不太可能。
cis-[Ru-IV(bpy)(2)(py)(O)](2+) oxidizes cumene (2-phenylpropane) in acetonitrile solution primarily to cumyl alcohol (2-phenyl-2-propanol), alpha-methylstyrene, and acetophenone. Contrary to a prior report, the rate of the reaction is not accelerated by added nucleophiles. There is thus no evidence for the hydride transfer mechanism originally proposed. Instead, the results are consistent with a mechanism of initial hydrogen atom transfer from cumene to the ruthenium oxo group. This is indicated by the correlation of rate with C-H bond strength and by the various products observed. The formation of acetophenone, with one carbon less than cumene, is suggested to occur via a multistep pathway involving decarbonylation of the acyl radical from 2-phenylpropanal. An alternative mechanism involving beta-scission of cumyloxyl radical is deemed unlikely because of the difficulty of generating alkoxyl radicals under anaerobic conditions and the lack of rearranged products in the oxidation of triphenylmethane by cis-[Ru-IV(bpy)(2)(py)(O)](2+).