作者:Na Song、David M. Stanbury
DOI:10.1021/ic201897m
日期:2011.12.19
that includes the rate of oxidation of phenol as well as the rates of these overoxidation steps show that the degree of overoxidation is rather limited at high pH but quite extensive at low pH. This pH-dependent overoxidation leads to a pH-dependent stoichiometric factor in the rate law for oxidation of phenol and causes some minor deviations in the rate law for oxidation of phenol. Empirically, these
先前已经确定,由于[IrCl 6 ] 2–的缺乏,苯酚的水氧化过程通过[IrCl 6 ] 3–和苯氧基的产生而进行。苯氧基自由基的偶联主要产生4,4'-联苯酚,2,2'-联苯酚,2,4'-联苯酚和4-苯氧基苯酚。这些偶联产物的进一步氧化会导致过氧化,从而导致最终产物的混合物非常复杂。[IrCl 6 ] 2–对四种偶联产物的氧化速率定律与苯酚本身的氧化速率定律具有相同的形式:-d [Ir IV ] / d t = (k ArOH + kArO – K a / [H + ])/(1 + K a / [H + ])} [ArOH] tot [Ir IV ]。已在25°C下确定了四种底物的k ArOH和k ArO –值,并将其分配给H 2O-PCET和电子转移机制分别。包括苯酚的氧化速率以及这些过氧化步骤的速率在内的组合机理的动力学模拟表明,过氧化的程度在高pH值下相当有限,而在低pH值下则相当