Bond Dissociation Enthalpies of a Dibenzodioxocin Lignin Model Compound

The initial steps in the thermal degradation of dibenzodioxocin, a relatively recently discovered seven-membered-ring linkage in lignin, have been evaluated using density functional calculations. The bond dissociation enthalpy of the various ring-opening reactions is closely related to the delocalization of the unpaired electrons in the products. It also appears as if these are barrierless reactions.