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

[Display omitted] ► Pyrolysis of phenethyl phenyl ether, a β-O-4 model compound for lignin. ► Kinetic Monte Carlo based on DFT rate and equilibrium constants. ► α/β-Product selectivity agrees qualitatively with experiment. ► New carbon–carbon phenyl shift reaction identified as part of the mechanism. 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.