Rate coefficients for the reactions of chlorine atoms with methanol and acetaldehyde

Rate coefficients have been measured for the reactions of Ci atoms with met hanol (k(1)) and acetaldehyde (k(2)) using both absolute (laser photolysis with resonance fluorescence) and relative rate methods at 295 +/- 2 K. The measured rate coefficients were (units of 10(-11) cm(3) molecule(-1) s(-1)) : absolute method, k(1) = (5.1 +/- 0.4), k(2) = (7.3 +/- 0.7); relative met hod k(1) = (5.6 +/- 0.6) k(2) = (8.4 +/- 1.0), Based on a critical evaluati on of the literature data, the following rate coefficients are recommended: k(1) = (5.4 +/- 0.9) x 10(-11) and k(2) = (7.8 +/- 1.3) x 10(-11) cm(3) mo lecule(-1) s(-1) (95% confidence limits). The results significantly improve the confidence in the database for reactions of Cl atoms with these oxygen ated organics. Rate coefficients were also measured for the reactions of Cl -2 with CH2OH, k(5) = (2.9 +/- 0.6) x 10(-11) and CH3CO, k(6) = (4.3 +/- 1. 5) x 10(-11) cm(3) molecule(-1) s(-1), by observing the regeneration of Cl atoms in the absence of O-2. Based on these results and those from a previo us relative rate study, the rate coefficient For CH3CO + O-2 at the high pr essure limit is estimated to be (5.7 +/- 1.9) x 10(-12) cm(3) molecule(-1) s(-1). (C) 1999 John Wiley & Sons, inc.