Role of Carbon鈥揅arbon Phenyl Migration in the Pyrolysis Mechanism of 尾-O-4 Lignin Model Compounds: Phenethyl Phenyl Ether and 伪-Hydroxy Phenethyl Phenyl Ether

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• 作者：Ariana Beste ; A. C. Buchanan ; III
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：December 20, 2012
• 年：2012
• 卷：116
• 期：50
• 页码：12242-12248
• 全文大小：411K
• 年卷期：v.116,no.50(December 20, 2012)
• ISSN：1520-5215

文摘

We investigate phenyl shift and subsequent 尾-scission reactions for PhCHXCH路OPh [X = H, OH], which are part of the pyrolysis mechanism of phenethyl phenyl ether (PPE) and 伪-hydroxy PPE. PPE and its derivatives are model compounds for the most common linkage in lignin, the 尾-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鈥揷arbon and carbon鈥揷arbon phenyl shift reactions proceed through cyclic intermediates with similar barriers. However, while subsequent 尾-scission of the oxygen鈥揷arbon shift products proceeds with virtually no barrier, the activation energy for 尾-scission of the carbon鈥揷arbon shift products exceeds 15 kcal/mol. We found that about 15% of 尾-radical conversion can be attributed to carbon鈥揷arbon shift for PPE and 伪-hydroxy PPE at 618 K. Whereas the oxygen鈥揷arbon shift reaction has been established as an integral part of the pyrolysis mechanism of PPE and its derivatives, participation of the carbon鈥揷arbon shift reaction has not been shown previously.