Kinetics of the hydrolysis of atmospherically relevant isoprene-derived hydroxy epoxides

Title:
Kinetics of the hydrolysis of atmospherically relevant isoprene-derived hydroxy epoxides
Authors:
Cole-Filipiak, Neil C.; O'Connor, Alison E.; Elrod, Matthew J.
Abstract:
Isoprene (the most abundant nonmethane hydrocarbon emitted into the atmosphere) is known to undergo oxidation to 2-methyl-1,2,3,4-butanetetraol, a hydrophilic compound present in secondary organic aerosol (SOA) in the atmosphere. Recent laboratory work has shown that gas phase hydroxy epoxides are produced in the low NOx photooxidation of isoprene and that these epoxides are likely to undergo efficient acid-catalyzed hydrolysis on SOA to 2-methyl-1,2,3,4-butanetetraol at typical SOA acidities. In order to confirm this hypothesis, the specific hydroxy epoxides observed in the isoprene photooxidation experiment (as well as several other related species) were synthesized, and the hydrolysis kinetics of all species were studied via nuclear magnetic resonance (NMR) techniques. It was determined that the isoprene-derived hydroxy epoxides should undergo efficient hydrolysis under atmospheric conditions, particular on lower pH SOA. An empirical structure−reactivity model was constructed that parametrized the hydrolysis rate constants according to the carbon substitution pattern on the epoxide ring and number of neighboring hydroxy functional groups. Compared to the previously studied similar nonfunctionalized epoxides, the presence of a hydroxy group at the α position to the epoxy group was found to reduce the hydrolysis rate constant by a factor of 20, and the presence of a hydroxy group at the beta position to the epoxy group was found to reduce the hydrolysis rate constant by a factor of 6.
Citation:
Cole-Filipiak, N.C., A.E. O Connor, and M.J. Elrod. 2010. "Kinetics of the Hydrolysis of Atmospherically Relevant Isoprene-Derived Hydroxy Epoxides." Environmental Science and Technology 44(17): 6718-6723.
Publisher:
American Chemical Society
DATE ISSUED:
2010-08-02
Department:
Chemistry
Type:
article
PUBLISHED VERSION:
10.1021/es1019228
PERMANENT LINK:
http://hdl.handle.net/11282/309888

Full metadata record

DC FieldValue Language
dc.contributor.authorCole-Filipiak, Neil C.en_US
dc.contributor.authorO'Connor, Alison E.en_US
dc.contributor.authorElrod, Matthew J.en_US
dc.date.accessioned2013-12-23T16:20:21Zen
dc.date.available2013-12-23T16:20:21Zen
dc.date.issued2010-08-02en
dc.identifier.citationCole-Filipiak, N.C., A.E. O Connor, and M.J. Elrod. 2010. "Kinetics of the Hydrolysis of Atmospherically Relevant Isoprene-Derived Hydroxy Epoxides." Environmental Science and Technology 44(17): 6718-6723.en_US
dc.identifier.issn0013-936Xen_US
dc.identifier.urihttp://hdl.handle.net/11282/309888en
dc.description.abstractIsoprene (the most abundant nonmethane hydrocarbon emitted into the atmosphere) is known to undergo oxidation to 2-methyl-1,2,3,4-butanetetraol, a hydrophilic compound present in secondary organic aerosol (SOA) in the atmosphere. Recent laboratory work has shown that gas phase hydroxy epoxides are produced in the low NOx photooxidation of isoprene and that these epoxides are likely to undergo efficient acid-catalyzed hydrolysis on SOA to 2-methyl-1,2,3,4-butanetetraol at typical SOA acidities. In order to confirm this hypothesis, the specific hydroxy epoxides observed in the isoprene photooxidation experiment (as well as several other related species) were synthesized, and the hydrolysis kinetics of all species were studied via nuclear magnetic resonance (NMR) techniques. It was determined that the isoprene-derived hydroxy epoxides should undergo efficient hydrolysis under atmospheric conditions, particular on lower pH SOA. An empirical structure−reactivity model was constructed that parametrized the hydrolysis rate constants according to the carbon substitution pattern on the epoxide ring and number of neighboring hydroxy functional groups. Compared to the previously studied similar nonfunctionalized epoxides, the presence of a hydroxy group at the α position to the epoxy group was found to reduce the hydrolysis rate constant by a factor of 20, and the presence of a hydroxy group at the beta position to the epoxy group was found to reduce the hydrolysis rate constant by a factor of 6.en_US
dc.language.isoen_USen_US
dc.publisherAmerican Chemical Societyen_US
dc.identifier.doi10.1021/es1019228en
dc.subject.departmentChemistryen_US
dc.titleKinetics of the hydrolysis of atmospherically relevant isoprene-derived hydroxy epoxidesen_US
dc.typearticleen_US
dc.identifier.journalEnvironmental Science and Technologyen_US
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