RATE-CONSTANT AND MECHANISM OF THE REACTION BETWEEN CL AND CH3OCL AT 295 K

The reaction between Cl atoms and CH3OCl was investigated at 295 K in both air and N-2 bath gases at total pressures between 100 and 750 Tor r by the relative rate method. The rate constant of the title reaction was found to be a factor 1.07 +/- 0.02 (2 sigma) greater than that of Cl + C2H6 at room temperature and independent of pressure between 100 and 750 Torr, This yields a rate constant of (6.1 +/- 0.6) x 10(-11) cm(3) molecule(-1) s(-1). The products of the reaction were detected b y FTIR and UV absorption spectroscopy. Analysis of Cl-2 s and HCl prod ucts allowed branching ratios of 0.2 +/- 0.1 for HCl + CH2OCl formatio n and 0.8 +/- 0.2 for Cl-2 + CH3O formation to be determined. The high rate constant implies that reaction with Cl atoms is an important los s process for CH3OCl in the polar stratosphere.