Homolytic bond dissociation energies for C-H bonds adjacent to sulfur and aromatic moieties: The effects of substituents of C-H bond strengths of the benzylic positions in coal model compounds.

摘要

Sulfur-containing compounds are precursors for thiyl radicals at coal liquefaction temperatures due to the weakness of The and S-S bonds. Thiyl radicals play important roles in hydrogen atom shuttling between benzylic positions and catalyze the cleavage and the formation of strong C-C bonds. Although many reactions of thiyl and other sulfur-containing radicals are qualitatively understood, the homolytic bond dissociation energies (EDE's) and the thermochemistry associated with many key high molecular weight hydrocarbon and sulfur-containing organic structures important to coal is lacking because they are inappropriate for gas-phase techniques. The measurement of BDE's has been proven to be difficult even in the simplest of molecules.