Kinetic simulation of the thermal degradation of phenethyl phenyl ether, a model compound for the β-O-4 linkage in lignin

Employing kinetic Monte Carlo, we simulated the radical chain propagation of the pyrolysis of phenethyl phenyl ether (PPE), which serves as a model compound for the beta-O-4 linkage in lignin. The input rate constants were obtained with transition state theory based on density functional calculations. Pre- and post-complexes for hydrogen abstraction and beta-scission reactions were included assuming thermal equilibrium. Individual rate constants compare well with experimental estimates. The calculated overall alpha/beta-product selectivity is qualitatively in agreement with experiment. The simulation revealed that the carbon-carbon phenyl shift reaction for the beta-PPE radical is part of the pyrolysis mechanism. (c) 2012 Elsevier B.V. All rights reserved.