The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressures

Citation:	Orlando, J.J., and G.S. Tyndall, 2010: The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressures. International Journal of Chemical Kinetics, 42, DOI: 10.1002/kin.20493.
UCAR/NCAR/UCP Authors:	Orlando, J.J. , NCAR Earth System Laboratory (NESL), Atmospheric Chemistry Division (ACD) Tyndall, G.S. , NCAR Earth System Laboratory (NESL), Atmospheric Chemistry Division (ACD)
UCAR Affiliations:	Atmospheric Chemistry Division (ACD), NCAR Earth System Laboratory (NESL)
Full Text:	Download osgc-000-000-000-218.pdf Preprint size: 217 KB
Abstract:	The Cl-atom-initiated oxidation of two esters, ethyl formate [HC(O)OCH₂CH₃] and ethyl acetate [CH₃C(O)OCH₂CH₃], has been studied at pressures close to 1 atm as a function of temperature (249–325 K) and O₂ partial pressure (50–700 Torr), using an environmental chamber technique. In both cases, Cl-atom attack at the CH₂ group is most important, leading in part to the formation of radicals of the type RC(O)OCH(O•)CH₃ [R = H, CH₃]. The atmospheric fate of these radicals involves competition between reaction with O2 to produce an anhydride compound, RC(O)OC(O)CH3, and the so-called α-ester rearrangement that produces an organic acid, RC(O)OH, and an acetyl radical, CH₃C(O). For both species studied, the α-ester rearrangement is found to dominate in air at 1 atm and 298 K. Barriers to the rearrangement of 7.7 ± 1.5 and 8.4 ± 1.5 kcal/mole are estimated for CH₃C(O)OCH(O•)CH₃ and HC(O)OCH(O•)CH₃, respectively, leading to increased occurrence of the O₂ reaction at reduced temperature. The data are combined with those obtained from similar studies of other simple esters to provide a correlation between the rate of occurrence of the α-ester rearrangement and the structure of the reacting radical.
Classification:	Refereed
Resource Type:	Article
Date Published	2010-07-01
Relations:	http://onlinelibrary.wiley.com/doi/10.1002/kin.20493/abstract
Published Version:	10.1002/kin.20493
Copyright Notice:	Copyright 2010 Wiley Periodicals, Inc.
Citable URL:	http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-000-218