Dicarbonyl Products of the OH Radical-Initiated Reactions of Naphthalene and the C1- and C2-Alkylnaphthalenes

• Published in: Environmental science & technology Vol. 41; no. 8; pp. 2803 - 2810
• Main Authors: Wang, Lin, Atkinson, Roger, Arey, Janet
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.04.2007
• Subjects: Applied sciences; Atmospheric pollution; Exact sciences and technology; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Substituent effect; Hydrocarbon; Pollutant behavior; Reaction initiator; Reaction product; Troposphere; Urban area; Polycyclic aromatic compound; Naphthalene derivatives; Free radical reaction; Gas chromatography; Naphthalene; Hydroxyl radicals; Air pollution; Property structure relationship; Gaseous phase reaction; Mass spectrometry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0628102

Naphthalene and the C1- and C2-alkylnaphthalenes are the most abundant polycyclic aromatic hydrocarbons (PAHs) in urban atmospheres. Their major atmospheric loss process is by gas-phase reaction with hydroxyl (OH) radicals. In this study, we have used in situ direct air sampling atmospheric pressure ionization mass spectrometry (API-MS) as well as gas chromatography−mass spectrometry (GC/MS) techniques to investigate the products of the gas-phase reactions of OH radicals with naphthalene, naphthalene-d8, 1- and 2-methylnaphthalene (MN), 1- and 2-MN-d10, 1- and 2-ethylnaphthalene (EN), and the 10 isomeric dimethylnaphthalenes (DMNs). The major reaction products are ring-opened dicarbonyls that are 32 mass units higher in molecular weight than the parent compound, one or more ring-opened dicarbonyls of lower molecular weight resulting from loss of two β-carbons and associated alkyl groups, and ring-containing compounds that may be epoxides. Phthalic anhydride and alkyl-substituted phthalic anhydrides were observed as second generation products. The position of alkyl-substitution on the naphthalene ring is a key factor determining the ring cleavage site and the isomeric product distribution.