Multistep Bond Breaking and Making Processes of Relevance to Thermal Coal Chemistry. Final Report February 1982 - February 1985

摘要

The objective of the research program is to determine chemical reaction mechanisms leading to bond formation, aromatization, and char formation during the pyrolysis of polyaromatic materials. Experimental studies determined rates and mechanisms of reactions in high temperature, polyaromatic fluids while theoretical work developed predictive methods for these reactions. Rate constant determinations have led to a broad increae in our predictive ability for free radical reactions of polyaromatic species. Advances were made in the following areas; (a) bond homolysis, (b) molecular disproportionation, (c) radical H-abstraction, (d) radical disproportionation, and recombination, (e)beta-H transfer, (f) hydroaromatic equilibria, and (g) separation of steric and resonance energy effects. Mechanisms of hydrogen transfer and bond formation were determined in another series of studies involving polyaromatic. H-transfer is entirely a free radical process, generally involving chain reactions. A new route was found for polyaromatic polymerization in anthracene systems. Finally, the authors have developed a new theoretical approach for treating very larg polyaromatic molecules and graphite edges. A variety of theoretical tools have been developed, some of which allow the examination of molecules containing as many as 12,000 carbon atoms. All techniques show a profound effect on reactivity of edges type, even for very large molecules. This provides a chemical basis for discussing reactions at 'active sites'.