Influence of temperature in the kinetics of the gas-phase reactions of a series of acetates with Cl atoms

Absolute rate coefficients have been measured for the first time as a function of temperature for the gas phase reactions of chlorine atoms with a series of aliphatic acetates: methyl acetate (k(1)), ethyl acetate (k(2)), n-propyl acetate (k(3)) and n-butyl acetate (k(4)). The experiments were carried out using the pulsed laser photolysis-resonance fluorescence technique (PLP-RF), over the temperature range 265-383 K. The obtained kinetic data were used to derive the Arrhenius expressions: k(1) = (9.31 +/- 1.02) x 10(-12) exp[-(359 +/- 70)/T]; k(2) = (4.35 +/- 0.65) x 10(-12) exp[(342 +/- 92)/T]; k(3) = (2.22 +/- 0.20) x 10(-11) exp[(217 +/- 58)/T] and k(4) = (5.41 +/- 1.51) x 10(-11) exp[(245 +/- 168)/T] (in units of cm(3) molecule(-1)s(-1)). The rate constants obtained at room temperature were as follows: methyl acetate, 0.279 +/- 0.031; ethyl acetate, 1.37 +/- 0.20; n-propyl acetate, 4.60 +/- 0.41 and n-butyl acetate, 12.3 +/- 3.4 (in units 10(-11) cm(3) molecule(-1)s(-1)). The results are discussed in terms of structure-reactivity relationships and the atmospherics implications are also analyzed. (c) 2005 Elsevier Ltd. All rights reserved.