Atmospheric chemistry of isopropyl formate and tert‐butyl formate |
| |
| Authors: | Andre Silva Pimentel Geoffrey S. Tyndall John J. Orlando Michale D. Hurley Timothy J. Wallington Mads P. Sulbaek Andersen Paul Marshall Theodore S. Dibble |
| |
| Affiliation: | 1. Departamento de Química, Pontificia Universidade Católica do Rio de Janeiro, Gávea 22453‐900, Rio de Janeiro, RJ, Brazil;2. National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307;3. Physical & Environmental Sciences Department, Ford Motor Company, Mail Drop SRL‐3083, Dearborn, MI 48121;4. Department of Chemistry, University of California, Irvine, Irvine, CA 92697;5. Center for Advanced Scientific Computing and Modeling, Department of Chemistry, University of North Texas, 1155 Union Circle, #305070, Denton, TX 76203‐5017;6. Chemistry Department, State University of New York–Environmental Science and Forestry, Syracuse, NY 13210 |
| |
| Abstract: | Formates are produced in the atmosphere as a result of the oxidation of a number of species, notably dialkyl ethers and vinyl ethers. This work describes experiments to define the oxidation mechanisms of isopropyl formate, HC(O)OCH(CH3)2, and tert‐butyl formate, HC(O)OC(CH3)3. Product distributions are reported from both Cl‐ and OH‐initiated oxidation, and reaction mechanisms are proposed to account for the observed products. The proposed mechanisms include examples of the α‐ester rearrangement reaction, novel isomerization pathways, and chemically activated intermediates. The atmospheric oxidation of isopropyl formate by OH radicals gives the following products (molar yields): acetic formic anhydride (43%), acetone (43%), and HCOOH (15–20%). The OH radical initiated oxidation of tert‐butyl formate gives acetone, formaldehyde, and CO2 as major products. IR absorption cross sections were derived for two acylperoxy nitrates derived from the title compounds. Rate coefficients are derived for the kinetics of the reactions of isopropyl formate with OH (2.4 ± 0.6) × 10?12, and with Cl (1.75 ± 0.35) × 10?11, and for tert‐butyl formate with Cl (1.45 ± 0.30) × 10?11 cm3 molecule?1 s?1. Simple group additivity rules fail to explain the observed distribution of sites of H‐atom abstraction for simple formates. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 479–498, 2010 |
| |
| Keywords: | |
|
|
