REACTION OF CHLORINE ATOMS WITH METHYLPEROXY AND ETHYLPEROXY RADICALS

Flash photolysis combined with time-resolved UV spectroscopy and trans ient IR absorption measurements shows that chlorine atoms react rapidl y with CH3O2 and C2H5O2, producing ClO and CO among other products. Th e room temperature rate constants are k(2) = (1.5 +/- 0.2) X 10(-10) c m(3) s(-1) for both reactions. The distribution of products is interpr eted to indicate that the reaction with methylperoxy radicals proceeds via two channels to yield CH3O + ClO with a branching ratio of 0.51 /- 0.05 and CH2O2 + HCl with a branching ratio of 0.49 +/- 0.05. The C riegee intermediate, CH2O2, has a lifetime of 15 +/- 5 mu s and subseq uently decomposes via three channels, with 61 +/- 7% producing CO + H2 O. The ethylperoxy reaction proceeds analogously with a branching frac tion of 0.49 +/- 0.05 for the C2H5O + ClO channel, but with a CO yield similar to 1/6 of the yield from the methylperoxy reaction.