Web Release Date: March 21,
Dicarbonyl Products of the OH Radical-Initiated Reactions of Naphthalene and the C1- and C2-Alkylnaphthalenes
and
Environmental Toxicology Graduate Program, Department of Environmental Sciences, Department of Chemistry, and Air Pollution Research Center, University of California, Riverside, California 92521
Received for review November 27, 2006
Revised manuscript received January 30, 2007
Accepted February 5, 2007
Abstract:
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 
-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.
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