Matrix isolation study of the ozonolysis of cis-2-butene

CHED 1001

Mary Clay, aurora0458@yahoo.com1, Bruce A. Ault2, and Michael Hoops2. (1) Department of Chemistry, Austin Peay State University, 601 College Street, Box 4547, Clarksville, TN 37044, (2) Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221
Ozonolysis of volatile organic compounds play a significant role in the chemistry of the troposphere. Extensive studies of these reactions have lead to an understanding of parts of the mechanism, but the Criegee intermediate remains a mystery. We have worked to isolate and characterize the Criegee intermediate arising from the ozonolysis of cis-2-butene using merged and twin jet deposition matrix isolation, infrared spectroscopy, theoretical calculations,and 18O labeling. Gaussian 03W was used to generate theoretical vibrational spectra for each of the intermediates proposed in the Criegee mechanism using DFT B3LYP/6-311G++d2p. These spectra served as the foundation for identification of product bands observed in merged and twin jet experiments. Product bands observed at 1349cm-1 and 997cm-1 were accompanied by -16cm-1 and -19cm-1 shifts to lower energy in 18O labeled merged jet experiments, supporting the successful isolation of the Criegee intermediate. Characterization of all but four of the remaining products bands supported the rearrangement/ fragmentation of the Criegee intermediate to form formaldehyde, ketene, methane, and carbon dioxide, in addition to the primary and secondary ozonides.