Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
J Org Chem. 2010 Jun 4;75(11):3705-14. doi: 10.1021/jo1004668.
Quantum mechanical calculations (DFT) have provided a mechanism for the oxidative C-H bond cleavage step in Fenton-like hydrocarbon hydroxylation. A transition structure for hydrocarbon oxidation by aqueous solvated cationic iron(III) hydroperoxides ((H(2)O)(n)Fe(III)OOH) is presented that involves a novel rearrangement of the hydroperoxide group (FeO-OH --> FeO...HO) in concert with hydrogen abstraction by the incipient HO* radical with activation barriers ranging from 17 to 18 kcal/mol. In every hydroperoxide examined, the activation barrier for FeO-OH isomerization, in the absence of the hydrocarbon, is significantly greater than the overall concerted activation barrier for C-H bond cleavage in support of the concept of O-O bond isomerization in concert with hydrogen abstraction. The transition structure for the oxidation step in simple anionic iron(III) hydroperoxides has been shown to bear a remarkable resemblance to model porphyrin calculations on cytochrome P450 hydroxylation.
量子力学计算（DFT）为芬顿样烃羟化中氧化 C-H 键断裂步骤提供了一种机制。本文提出了一种通过水合的阳离子铁（III）过氧氢化物（（H(2)O)(n)Fe(III)OOH）氧化烃的过渡态结构，涉及过氧基团（FeO-OH --> FeO...HO）的新颖重排与初始 HO* 自由基的氢提取协同进行，其活化能垒范围为 17 至 18 kcal/mol。在所研究的每一种过氧氢化物中，在没有烃的情况下，FeO-OH 异构化的活化能垒明显大于 C-H 键断裂的总协同活化能垒，这支持了 O-O 键异构化与氢提取协同进行的概念。简单的铁（III）过氧氢阴离子氧化步骤的过渡态结构与细胞色素 P450 羟化的模型卟啉计算具有显著的相似性。
