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

Abstract

Abstract 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 ) × 1 0 - 12 exp [ - ( 359 ± 70 ) / T ] ; k 2 = ( 4.35 ± 0.65 ) × 1 0 - 12 exp [ ( 342 ± 92 ) / T ] ; k 3 = ( 2.22 ± 0.20 ) × 1 0 - 11 exp [ ( 217 ± 58 ) / T ] and k 4 = ( 5.41 ± 1.51 ) × 1 0 - 11 exp [ ( 245 ± 168 ) / T ] (in units of cm3 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 cm3 molecule−1 s−1). The results are discussed in terms of structure-reactivity relationships and the atmospherics implications are also analyzed.