title: Mechanistic insights into ozone-initiated oxidative degradation of saturated hydrocarbons and polymers.
abstract: Accurate quantum chemical calculations were employed to investigate the mechanism of ozone-initiated oxidation of C-H bonds of saturated hydrocarbons and polymers. Step wise hydrogen atom abstraction generates the first resting state the trihydroxide -COOOH, which undergoes decomposition to produce the free radical species alkoxyl -CO˙ and peroxyl ˙OOH thereby setting off a complex chain of radical processes. The H transfer from peroxyl radical to alkoxyl allows formation of inactive alcohol and the singlet excited dioxygen. Other competitive processes include the self fragmentation or β-scission of the alkoxyl -CO˙ to give rise to a carbonyl (ketone or aldehyde) and a C-centred free radical species. Tertiary C-H bonds are most susceptible to O3 oxidation followed by secondary and primary. Among the polymers studied, poly(styrene) is the least resistant to C-H bond ozonation, followed by poly(propylene), poly(methacrylate), poly(methyl methacrylate) and poly(vinyl chloride). Calculations also reveal catalytic effects of water in promoting the C-H bond oxidation process in polymer systems without competing H-bond donor groups.
authors.affiliation: ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra ACT 2601, Australia. michelle.coote@anu.edu.au.
authors.forename: Richmond
authors.initials: R
authors.lastname: Lee
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Coote