Thermal Decomposition of CF3C(O)O2NO2, CClF2C(O)O2NO2, CCl2FC(O)O2NO2, and CCl3C(O)O2NO2

✍ Scribed by F. Zabel; F. Kirchner; K. H. Becker

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 1017 KB
• Volume: 26
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550260805

✦ Synopsis

Haloacetyl peroxynitrates are intermediates in the atmospheric degradation of a number of haloethanes. In this work, thermal decomposition rate constants of CF3C(0)02N02, CClFzC(0)02N02, CC12FC(0)02N02, and CC13C(0)02N02 have been determined in a temperature controlled 420 1 reaction chamber. Peroxynitrates (R02N02) were prepared in situ by photolysis of RH/C12/02/N02/N2 mixtures (R = CF3C0, CClFzCO, CC12FC0, and CCLCO). Thermal decomposition was initiated by addition of NO, and relative ROzN02 concentrations were measured as a function of time by long-path IR absorption using an FTIR spectrometer. First-order decomposition rate constants were determined a t atmospheric pressure (M = Nz) as a function of temperature and, in the case of CF3C(0)02N02 and CC13C(0)02N02, also as a function of total pressure. Extrapolation of the measured rate constants to the temperatures and pressures of the upper troposphere yields thermal lifetimes of several thousands of years for all of these peroxynitrates. Thus, the chloro(fluoro)acetyl peroxynitrates may play a role as temporary reservoirs of C1, their lifetimes in the upper troposphere being limited by their (unknown) photolysis rates. Results on the thermal decomposition of CClFzCHzOzNOz and CC12FCHzOzN02 are also reported, showing that the atmospheric lifetimes of these peroxynitrates are very short in the lower troposphere and increase to a maximum of several days close to the tropopause. The ratio of the rate constants for the reactions of CF3C(0)02 radicals with NO2 and NO was determined to be 0.64 2 0.13 ( 2 ~) at 315 K and a total pressure of 1000 mbar (M = N2).