| Title: | "Synthesis, Electronic Spectroscopy, and Photochemistry of Methacrolein Oxide: A Four-Carbon Unsaturated Criegee Intermediate from Isoprene Ozonolysis" |
| Author(s): | Vansco MF; Marchetti B; Trongsiriwat N; Bhagde T; Wang G; Walsh PJ; Klippenstein SJ; Lester MI; |
| Address: | "Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States. Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States" |
| ISSN/ISBN: | 1520-5126 (Electronic) 0002-7863 (Linking) |
| Abstract: | "Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the earth's atmosphere, generates the four-carbon unsaturated methacrolein oxide (MACR-oxide) Criegee intermediate. The first laboratory synthesis and direct detection of MACR-oxide is achieved through reaction of photolytically generated, resonance-stabilized iodoalkene radicals with oxygen. MACR-oxide is characterized on its first pi* <-- pi electronic transition using a ground-state depletion method. MACR-oxide exhibits a broad UV-visible spectrum peaked at 380 nm with weak oscillatory structure at long wavelengths ascribed to vibrational resonances. Complementary theory predicts two strong pi* <-- pi transitions arising from extended conjugation across MACR-oxide with overlapping contributions from its four conformers. Electronic promotion to the 1(1)pipi* state agrees well with experiment, and results in nonadiabatic coupling and prompt release of O (1)D products observed as anisotropic velocity-map images. This UV-visible detection scheme will enable study of its unimolecular and bimolecular reactions under thermal conditions of relevance to the atmosphere" |
| Notes: | "PubMed-not-MEDLINEVansco, Michael F Marchetti, Barbara Trongsiriwat, Nisalak Bhagde, Trisha Wang, Guanghan Walsh, Patrick J Klippenstein, Stephen J Lester, Marsha I eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2019/08/27 J Am Chem Soc. 2019 Sep 25; 141(38):15058-15069. doi: 10.1021/jacs.9b05193. Epub 2019 Sep 11" |
