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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Role of carbon-carbon phenyl migration in the pyrolysis mechanism of β-O-4 lignin model compounds: Phenethyl phenyl ether and α-hydroxy phenethyl phenyl ether
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Role of carbon-carbon phenyl migration in the pyrolysis mechanism of β-O-4 lignin model compounds: Phenethyl phenyl ether and α-hydroxy phenethyl phenyl ether

机译：碳-碳苯基迁移在β-O-4木质素模型化合物热解机理中的作用：苯乙基苯基醚和α-羟基苯乙基苯基醚

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摘要

We investigate phenyl shift and subsequent β-scission reactions for PhCHXCH·OPh [X = H, OH], which are part of the pyrolysis mechanism of phenethyl phenyl ether (PPE) and α-hydroxy PPE. PPE and its derivatives are model compounds for the most common linkage in lignin, the β-O-4 linkage. We use density functional theory to locate transition states and equilibrium structures and kinetic Monte Carlo in combination with transition-state theory for kinetic simulations. Oxygen-carbon and carbon-carbon phenyl shift reactions proceed through cyclic intermediates with similar barriers. However, while subsequent β-scission of the oxygen-carbon shift products proceeds with virtually no barrier, the activation energy for β-scission of the carbon-carbon shift products exceeds 15 kcal/mol. We found that about 15% of β-radical conversion can be attributed to carbon-carbon shift for PPE and α-hydroxy PPE at 618 K. Whereas the oxygen-carbon shift reaction has been established as an integral part of the pyrolysis mechanism of PPE and its derivatives, participation of the carbon-carbon shift reaction has not been shown previously.
机译：我们研究了PhCHXCH·OPh [X = H，OH]的苯位移和随后的β断裂反应，这是苯乙基苯基醚（PPE）和α-羟基PPE热解机理的一部分。 PPE及其衍生物是木质素中最常见的连接（β-O-4连接）的模型化合物。我们使用密度泛函理论来定位过渡态和平衡结构以及动力学蒙特卡洛，并结合过渡态理论进行动力学模拟。氧-碳和碳-碳苯基转移反应通过具有类似壁垒的环状中间体进行。然而，尽管随后的氧-碳转变产物的β-断裂实际上没有障碍地进行，但是碳-碳转变产物的β-断裂的活化能超过15kcal / mol。我们发现，在618 K时，PPE和α-羟基PPE的大约15％的β-自由基转化可归因于PPE和α-羟基PPE的碳-碳转移。而氧-碳转移反应已被确定为PPE热解机理的组成部分以及它的衍生物，碳-碳变换反应的参与以前没有显示出来。

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