Absolute and Site-Specific Abstraction Rate Coefficients for Reactions of Cl with CH 3 CH 2 OH, CH 3 CD 2 OH, and CD 3 CH 2 OH between 295 and 600 K

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 2 H 5 OH reaction. The rate coefficients for all ethanols display only a slight temperature dependence and can be parametrized by simple Arrhenius expressions: k CH 3 CH 2 OH = (9.4 ± 1.4) × 10 -11 e (45 ± 32)/ T, k CD 3 CH 2 OH = (6.6 ± 0.9) × 10 -11 e (90 ± 40)/ T, and k CH 3 CD 2 OH = (6.9 ± 0.7) × 10 -11 e (-76 ± 40)/ T cm 3 molecule -1 s -1 (error bars ±2σ). Combining the results from the present work with literature data, we recommend k CH 3 CH 2 OH = (9.5 ± 1.9) × 10 -11 cm 3 molecule -1 s -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 the Cl + CH 3 CH 2 OH reaction and 0.08 ± 0.02 from laser photolysis/CW infrared absorption measurements (error bars ±2σ). Abstraction of the hydroxyl hydrogen is negligible. A small but significant amount of HCl ( v = 1) is produced in the Cl + CD 3 CH 2 OH and Cl + CH 3 CH 2 OH reactions at room temperature.