Kinetics of the reactions of isoprene-derived epoxides in model tropospheric aerosol solutions

Title:
Kinetics of the reactions of isoprene-derived epoxides in model tropospheric aerosol solutions
Authors:
Minerath, Emily C.; Schultz, Madeline P.; Elrod, Matthew J.
Abstract:
Polyols and organic sulfates have recently been identified in the secondary organic aerosol (SOA) formed in the photooxidation of isoprene in both the laboratory and under ambient atmospheric conditions. Nuclear magnetic resonance methods were used to monitor the bulk reaction kinetics of acid-catalyzed hydrolysis reactions for isoprene- and 1,3-butadiene-derived epoxides in order to determine the rates for such reactions in aerosols under the previously studied laboratory conditions and under ambient atmospheric conditions. The measured rate constants were found to vary over 7 orders of magnitude. For the fast case of the hydrolysis of 1,2-epoxyisoprene, the lifetime at neutral pH was found to be only 3 min. On the other hand, for the relatively slow reaction of 1,2-epoxy-3,4-hydroxybutane, the lifetime at the most acidic conditions commonly observed in tropospheric aerosols (pH 1.5) was found to be 7.7 h, a value that is still less than the several day lifetime of tropospheric aerosols. Therefore, the present results suggest that, despite a wide range in reactivities, several possible reactions of isoprene-derived epoxides should be kinetically efficient on atmospheric SOA. The reactions were also studied with the elevated sulfate concentrations that are often characteristic of tropospheric aerosols, and sulfate products were identified for all species except 1,2-epoxyisoprene. Other nucleophiles that may be present in aerosols (nitrate, chloride, bromide, and iodide) were also investigated, and it was found that nitrate and sulfate have similar nucleophilic strength, while the halides are much stronger nucleophiles in their reactions with epoxides. Therefore, aerosols which contain significant concentrations of these species may be expected to readily form species similar to those already identified for the reactions of epoxides with sulfate.
Citation:
Minerath, E.C., M.P. Schultz, and M.J. Elrod. 2009. "Kinetics of the Reactions of Isoprene- Derived Epoxides in Model Tropospheric Aerosol Solutions." Environmental Science and Technology 43(21): 8133-8139.
Publisher:
American Chemical Society
DATE ISSUED:
2009-11
Department:
Chemistry
Type:
article
PUBLISHED VERSION:
10.1021/es902304p
PERMANENT LINK:
http://hdl.handle.net/11282/309335

Full metadata record

DC FieldValue Language
dc.contributor.authorMinerath, Emily C.en_US
dc.contributor.authorSchultz, Madeline P.en_US
dc.contributor.authorElrod, Matthew J.en_US
dc.date.accessioned2013-12-23T16:07:27Zen
dc.date.available2013-12-23T16:07:27Zen
dc.date.issued2009-11en
dc.identifier.citationMinerath, E.C., M.P. Schultz, and M.J. Elrod. 2009. "Kinetics of the Reactions of Isoprene- Derived Epoxides in Model Tropospheric Aerosol Solutions." Environmental Science and Technology 43(21): 8133-8139.en_US
dc.identifier.issn0013936Xen_US
dc.identifier.urihttp://hdl.handle.net/11282/309335en
dc.description.abstractPolyols and organic sulfates have recently been identified in the secondary organic aerosol (SOA) formed in the photooxidation of isoprene in both the laboratory and under ambient atmospheric conditions. Nuclear magnetic resonance methods were used to monitor the bulk reaction kinetics of acid-catalyzed hydrolysis reactions for isoprene- and 1,3-butadiene-derived epoxides in order to determine the rates for such reactions in aerosols under the previously studied laboratory conditions and under ambient atmospheric conditions. The measured rate constants were found to vary over 7 orders of magnitude. For the fast case of the hydrolysis of 1,2-epoxyisoprene, the lifetime at neutral pH was found to be only 3 min. On the other hand, for the relatively slow reaction of 1,2-epoxy-3,4-hydroxybutane, the lifetime at the most acidic conditions commonly observed in tropospheric aerosols (pH 1.5) was found to be 7.7 h, a value that is still less than the several day lifetime of tropospheric aerosols. Therefore, the present results suggest that, despite a wide range in reactivities, several possible reactions of isoprene-derived epoxides should be kinetically efficient on atmospheric SOA. The reactions were also studied with the elevated sulfate concentrations that are often characteristic of tropospheric aerosols, and sulfate products were identified for all species except 1,2-epoxyisoprene. Other nucleophiles that may be present in aerosols (nitrate, chloride, bromide, and iodide) were also investigated, and it was found that nitrate and sulfate have similar nucleophilic strength, while the halides are much stronger nucleophiles in their reactions with epoxides. Therefore, aerosols which contain significant concentrations of these species may be expected to readily form species similar to those already identified for the reactions of epoxides with sulfate.en_US
dc.language.isoen_USen_US
dc.publisherAmerican Chemical Societyen_US
dc.identifier.doi10.1021/es902304pen
dc.subject.departmentChemistryen_US
dc.titleKinetics of the reactions of isoprene-derived epoxides in model tropospheric aerosol solutionsen_US
dc.typearticleen_US
dc.identifier.journalEnvironmental Science and Technologyen_US
dc.subject.keywordEpoxy compoundsen_US
dc.subject.keywordChemical kineticsen_US
dc.subject.keywordResearch methodologyen_US
dc.subject.keywordNuclear magnetic resonanceen_US
dc.subject.keywordPhotochemical oxidantsen_US
dc.subject.keywordTropospheric aerosolsen_US
dc.identifier.volume43en_US
dc.identifier.issue21en_US
dc.identifier.startpage8133en_US
All Items in The Five Colleges of Ohio Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.