摘要
通过密度泛函理论计算,研究锰氧咔咯催化环己烷氧化成己二醛的反应,讨论该催化过程的多态反应活性.计算表明,该反应经历两步羟基化和一步C—C键断裂过程.两步羟基化都是由氢转移开始,形成碳自由基中间体,接着迅速发生的自由基反应形成二醇的中间体.C—C键断裂过程由氢转移开始,先形成氧自由基中间体,氧自由基单电子和邻近环C—C键存在强烈的相互作用,导致该C—C键活化断裂和第二个氢的协同转移.反应的速控步是第二步羟基化过程,因此碳自由基中间体的稳定性决定该反应的难易,这也解释了实验上观察到叔碳的活性大于仲碳的活性顺序.
Mn-corrole catalyzed oxidation of cyclohexane to adipaldehyde has been investigated by density functional calculations.Calculations show that the catalytic reaction comprises three processes,i.e.two hydroxylation steps and one C—C bond cleavage step.The consecutive hydroxylations are initiated by the hydrogen-atom transfer（HAT）from substrate to the（oxo）manganese（V）corrole,coupled with a rapid rebound reaction of the Mn-bound OH group to the carbon radical.Similarly,the C—C bond cleavage was initiated by the hydrogen-atom transfer（HAT）from one of the intermediate with two OH groups to the（oxo）manganese（V）corrole,leading to the oxygen radical.The strong interactions between the oxygen radical and the adjacent C—C bond result in the C—C bond activation remarkably and cleavage,coupled with the HAT from the remaining OH group to the（oxo）manganese（V）corrole.The second hydroxylation is the rate-determining step for the overall reaction,and the stability of the carbon radical intermediate may dominate the reactivity accordingly.
出处
《分子科学学报》
CAS
CSCD
北大核心
2014年第4期265-272,共8页
Journal of Molecular Science
基金
国家重点基础研究发展计划(973)项目(2011CB808504
2012CB214900)
国家自然科学基金资助项目(21133007
21373164)
贵州省科学基金资助项目([2012]2151)
关键词
锰氧咔咯
环己烷氧化
催化反应机理
密度泛函理论
（Oxo）manganese corrole
oxidation of cyclohexane
mechanism of catalyzed oxidation
density functional theory
