title: Border reactivity of polycyclic aromatic hydrocarbons and soot platelets toward ozone. A theoretical study.
abstract: PAH-based models, with an even or odd number of unsaturated carbon atoms and π electrons (even and odd PAHs for short), are selected to investigate, by molecular and periodic methods, their electron distribution and border reactivity toward ozone, and also to represent local features and edge reactivity of even or odd soot platelets. These results will contrast those previously collected for the internal positions of similar even (J. Phys. Chem. A 2005, 109, 10929.) or odd systems (J. Phys. Chem. A 2008, 112, 973.). Topologically different peripheral positions, representative of armchair and zigzag borders, exhibit different reactivity right from the beginning. Ozone attacks start off either to give primary ozonides by concerted addition or, nonconcertedly, to first produce trioxyl intermediates. Then, a variety of pathways are described, whose viability depends on both model and position. They can open the way to the possible formation of epoxide, aldehyde, and phenol groups (all entailing O(2) production) or ether (+CO(2)), lactone (+H(2)CO), and ketone functionalities. To sum up, functionalization, regardless of how achieved, can give a number of groups, most of which actually observed in PAH ozonization experimental studies. This picture can be matched up to the results on internal sites of our preceding papers, for which epoxidation was the only outcome. Most interestingly, formation of a ketone group may turn an even system into an odd one (and conversely) while involving production of HOO(•).
authors.affiliation: Dipartimento di Chimica Generale e Chimica Organica, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Giordana
authors.forename: Andrea
authors.initials: A
authors.lastname: Maranzana
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ghigo
authors.forename: Mauro
authors.initials: M
authors.lastname: Causà
authors.forename: Glauco
authors.initials: G
authors.lastname: Tonachini
mesh_terms: D006108:Graphite / Q000737:chemistry*; D008956:Models, Chemical; D010126:Ozone / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D053260:Soot / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D053260:Soot; D010126:Ozone; D006108:Graphite