title: Gas Phase Oxidation of Campholenic Aldehyde and Solution Phase Reactivity of its Epoxide Derivative.
abstract: The rate constant for the OH reaction with campholenic aldehyde (CA) was measured using the flow tube-chemical ionization mass spectrometry method with a relative rate kinetics technique and was found to be (6.54 ± 0.52) × 10-11cm3molecule-1s-1at 100 Torr pressure and 298 K. A mechanism for the formation of the observed products was developed for both NO-free and NO-present conditions. On the basis of measurements of the pressure dependent yields of the products, between 5 and 20% of the CA oxidation at atmospheric pressure is predicted to lead to campholenic aldehyde epoxide (CAE). The aqueous solution reaction rate constants for CAE were determined via NMR spectroscopy and were found to be (2.241 ± 0.036) × 10-5s-1for neutral conditions and 0.0989 ± 0.0053 M-1s-1for acid-catalyzed conditions at 298 K. The products of the CAE aqueous solution reaction were identified as an isomer of CAE and the aldehyde group hydrated form of this isomer. Unlike the isoprene-derived epoxide, IEPOX, a nucleophilic addition mechanism was not observed. On the basis of the rate constants determined for CA and CAE, it is likely that these species are reactive on atmospherically relevant time scales in the gas and aerosol phases, respectively. The results of the present study largely support a previous supposition that α-pinene-derived secondary organic aerosol may be influenced by the multiphase processing of various intermediate species, including those with epoxide functionality.
authors.affiliation: Department of Chemistry and Biochemistry, Oberlin College , Oberlin, Ohio 44074, United States.
authors.forename: William C
authors.initials: WC
authors.lastname: Thomas
authors.affiliation: Department of Chemistry and Biochemistry, Oberlin College , Oberlin, Ohio 44074, United States.
authors.forename: William D
authors.initials: WD
authors.lastname: Dresser
authors.affiliation: Department of Chemistry and Biochemistry, Oberlin College , Oberlin, Ohio 44074, United States.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Cortés
authors.affiliation: Department of Chemistry and Biochemistry, Oberlin College , Oberlin, Ohio 44074, United States.
authors.forename: Matthew J
authors.identifier: http://orcid.org/0000-0002-1656-8261
authors.initials: MJ
authors.lastname: Elrod