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CoTPP电化学催化还原溴代环己烷的机理
Mechanism Study on Electrochemical Reduction of Co(Ⅱ)TPP/Cyclohexyl Bromide system
【摘要】 以电化学循环伏安、现场ESR电化学以及现场薄层电化学方法研究了电生Co(Ⅰ)TPP与溴代环己烷的反应机制。在DMF中,Co(Ⅱ)/Co(Ⅰ)的氧化还原有明显的催化溴代环己烷还原的特征,反应现场有自由基生成。反应产物之一是Co—C键化合物,可以在-1.30V(SCE)一电子还原。当存在CH_2=CHCN时,生成另一种Co—C键化合物,该化合物在—1.10V(SCE)处一电子还原。证明溴代环己烷与Co(Ⅰ)TPP反应主要是经过形成烷基自由基的机制进行的。
【Abstract】 The mechanism of electrochemical reactions of electrogenerated Co(Ⅰ)TPP andcyclohexyl bromide was investigated with cyclic voltammetry,in-situ ESR-spectroelec-trpchemistry and in-situ micro-electrode-CV thin-layer electrochemistry in DMF solution.The redox reaction of Co(Ⅱ)/Co(Ⅰ) parallelly catalyzed the reduction of cyclohexylbromide,and generated both the cyclohexyl radicals and Co-C bond compoundC6H11 Co(Ⅲ)TPP. Further reduction of the Co-C bond compound at-1.30V (SCE ) im-plied an EC mechanism,namely electrochemical reduction followed by Co-C bond splittingreaction which regenerated the cyclohexyl radicals with rate constant of 0. 73s ̄(-1). The pres-ence of additional CH2=CHCN led to the generation of a new Co-C bond compound whichgave rise to a reduction peak at-1. 10V (SCE).A mechanism for the Co(Ⅱ)TPP/cyclo-hexyl bromide system, suggesting that the cyclohexyl bromide primarily reacts with electro-generated Co(Ⅰ)TPP via the production of the cyclohexyl radicals,has been proposed.
【Key words】 cobalt tetraphenylporphyrn; electrochemical redox reaction; cyclohexyl bromide; in-situ ESR;
- 【文献出处】 应用化学 ,CHINESE JOURNAL OF APPLIED CHEMISTRY , 编辑部邮箱 ,1995年06期
- 【分类号】TQ231.14
- 【下载频次】76