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 β-O-4 linkage in lignin. The input rate constants were obtained with transition state theory based on density functional calculations. Pre- and postcomplexes for hydrogen abstraction and β-scission reactions were included assuming thermal equilibrium. Individual rate constants compare well with experimental estimates. The calculated overall α/β-product selectivity is qualitatively in agreement with experiment. The simulation revealed that the carbon–carbon phenyl shift reaction for the β-PPE radical is part of the pyrolysis mechanism.