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 N2 bath gases at total pressures between 100 and 750 Torr by the relative rate method. The rate constant of the title reaction was found to be a factor 1.07 ± 0.02 (2σ) 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) × 10-11 cm3 molecule-1 s-1. The products of the reaction were detected by FTIR and UV absorption spectroscopy. Analysis of Cl2 and HCl products allowed branching ratios of 0.2 ± 0.1 for HCl + CH2OCl formation and 0.8 ± 0.2 for Cl2 + CH3O formation to be determined. The high rate constant implies that reaction with Cl atoms is an important loss process for CH3OCl in the polar stratosphere.