Modeling coal chemistry: One electron catalytic reactions

The complexity of the coal structure, in general, and of its organic part, in particular, prevents a rigorous study of coal chemistry. The use of model compounds with less complicated chemical structures to model specific reactions relevant to coal transformation into useful products is necessary and helpful. This is true, however, only if the modeling is properly applied and especially if the results are not excessively extrapolated to all aspects of coal reactivity. The emphasis on all catalytic routes in coal liquefaction has enhanced the interest in the study of the chemistry involved in heterogeneous catalytic reactions relevant to the first stage, solubilization, of coal. One of the important reactions associated with this first stage is the cleavage of carbon-carbon bonds linking aromatic rings with aliphatic moieties. In previous publications (1,2,3) we have used a model compound 4-(l-naphthylmethyl)bibenzyl (1) in which the bond linking the naphthalene ring to a methylene carbon can be selectively cleaved by specific catalysts (i.e. carbon materials, some iron catalysts) at temperatures at which thermal, free radical-initiated reactions, do not take place. Our data suggest that the above-mentioned catalytic cleavage is initiated by the ion radical of 1, with the unpaired electron localized in the naphthalenemore » ring.« less