Reactivity and aromaticity of polyaromatics in radical cyclization reactions

Theoretical ab initio calculations are presented on cyclization. reactions of polyaromatics that occur by a radical mechanism. Such processes are one of the elementary steps for polyaromatic hydrocarbon formation in thermal cracking units and during soot formation. Ring closure can take place at various sites of the polyaromatic surface. It is the aim of this study to obtain insight into the influence of the local structure on the reactivity of the polyaromatics. Aromaticity is a determining factor for the reactivity and can be probed by various magnetic properties such as the diamagnetic susceptibilities, proton chemical shifts, and nucear-independent chemical shifts. A correlation is established between the magnetic properties and activation energy of the studied reactions. (C) 2003 Wiley Periodicals, Inc.