Absolute and Site-Specific Abstraction Rate Coefficients for Reactions of Cl with CH3CH2OH, CH3CD2OH, and CD3CH2OH between 295 and 600 K

Abstract

Absolute rate coefficients for reactions of Cl atoms with selectively deuterated ethanols have been measured between 295 and 600 K by a laser-photolysis/CW infrared absorption method. Yields of HCl are determined by comparison with the Cl + ethane or Cl + propane reaction, permitting site-specific branching fractions to be derived. Smog chamber experiments with Fourier transform infrared (FTIR) detection are performed to determine products of the room-temperature Cl + C{sub 2}H{sub 5}OH reaction. The rate coefficients for all ethanols display only a slight temperature dependence and can be parameterized by simple Arrhenius expressions: k{sub CH{sub 3}CH{sub 2}OH} = (9.4 {+-} 1.4) x 10{sup {minus}11}e{sup (45 {+-} 32)/T}, k{sub CD{sub 3}CH{sub 2}OH} = (6.6 {+-} 0.9) x 10{sup {minus}11}e{sup (90 {+-} 40)/T}, and k{sub CH{sub 3}CD{sub 2}OH} = (6.9 {+-} 0.7) x 10{sup {minus}11}e{sup ({minus}76 {+-} 40)/T} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1} (error bars {+-}2{sigma}). Combining the results from the present work with literature data, the authors recommend k{sub CH{sub 3}CH{sub 2}OH} = (9.5 {+-} 1.9) x 10{sup {minus}11} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1} at 298 K. The room-temperature contribution of abstraction at the methyl site is found to be 0.07 & 0.02 from FTIR product analysis of themore » Cl + CH{sub 3}CH{sub 2}OH reaction and 0.08 {+-} 0.02 from laser photolysis/CW infrared absorption measurements (error bars {+-}2{sigma}). Abstraction of the hydroxyl hydrogen is negligible. A small but significant amount of HCl ({nu} = 1) is produced in the Cl + CD{sub 3}CH{sub 2}OH and Cl + CH{sub 3}CH{sub 2}OH reactions at room temperature.« less