Kinetic and product studies of Cl atoms reactions with a series of branched Ketones

Abstract

The rate constants for the Cl atom reaction with three branched ketones have been measured at 298±2K and 760Torr using the relative rate method in the absence of NO. The rate constants values obtained (in units of 10−10cm3/(molecule·sec)) are: k(2-methyl-3-pentanone)=1.07±0.26, k(3-methyl-2-pentanone)=1.21±0.26, and k(4-methyl-2-pentanone)=1.35±0.27. Combining the chemical kinetic data obtained by this study with those reported for other ketones, a revised Structure Activity Relationship (SAR) parameter and R group reactivity (kR) of R(O)R′ and CHx (x=1, 2, 3) group reactivity (kCHx) toward Cl atoms were proposed. In addition, the products from the three reactions in the presence of NO were also identified and quantified by using PTR-ToF-MS and GC-FID, and the yields of the identified products are: acetone (39%±8%)+ethanal (78%±12%), 2-butanone (22%±2%)+ethanal (75%±10%)+propanal (14%±1%) and acetone (26%±3%)+2-methylpropanal (24%±2%), for Cl atoms reaction with 2-methyl-3-pentanone, 3-methyl-2-pentanone and 4-methyl-2-pentanone, respectively. Based on the obtained results, the reaction mechanisms of Cl atoms with these three ketones are proposed.