Kinetics and Thermodynamics of Atmospherically Relevant Aqueous Phase Reactions of α-Pinene Oxide

Abstract

Recent work has demonstrated that isoprene-derived epoxide intermediates are responsible for a wide variety of chemical species found in ambient secondary organic aerosol (SOA). Since the second most abundant biogenic hydrocarbon, α-pinene, is also known to form an epoxide intermediate, nuclear magnetic resonance techniques were used to study products, kinetics, and equilibria of the aqueous phase reactions of that epoxide, α-pinene oxide. The present results indicate that α-pinene oxide will react very quickly with aqueous atmospheric particles, even under low acidity conditions. Depending on the acid concentration of the aqueous solutions, a number of new products are observed from the reaction of α-pinene oxide, some of which are expected to partition back to the gas phase. In contrast to some previous results, no long-lived organosulfate or organonitrate species are observed, and no species which retain the α-pinene bicyclic carbon backbone are observed. Rather, the overall product distribution can be explained by various rearrangements of the initial carbocation intermediate formed in the ring opening of α-pinene oxide, all of which can be rationalized by the thermodynamically driven relief of the bicyclic ring strain in the α-pinene carbon backbone.

Publisher

American Chemical Society

Publication Date

1-1-2013

Publication Title

Journal of Physical Chemistry

Department

Chemistry and Biochemistry

Document Type

Article

DOI

https://dx.doi.org/10.1021/jp402093x

Keywords

Secondary organic aerosol, Isoprene, Epoxides, Photooxidation, Hydrolysis, Organosulfates, Isomerization

Language

English

Format

text

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