Cl Atom Initiated Photo-oxidation of Mono-chlorinated Propanes To Form Carbonyl Compounds: A Kinetic and Mechanistic Approach

Cl atom initiated photo-oxidation of mono-chlorinated propanes to form the carbonyl compounds was investigated. Propionaldehyde and acetone were identified to be major products in the oxidation of 1-chloropropane and 2-chloropropane, respectively. The complete product analyses were carried out using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools, and an appropriate oxidation mechanism was proposed on the basis of the product analyses. The temperature dependent rate coefficients for the reactions of Cl atoms with 1-chloropropane (1-CP) and 2-chloropropane (2-CP) were measured experimentally in the gas phase, using the relative rate method in the temperature range 268-363 K and at 1 atm pressure. Ethane, ethylene, and ethyl acetate were used as reference compounds. The obtained rate coefficients for the reactions of Cl atoms with 1-CP and 2-CP at room temperature (298 K) and at 1 atm pressure were (4.64 +/- 0.70) X 10(-11) and (2.57 +/- 0.44) x 10(-11) cm(3) molecule(-1) s(-1), respectively. Furthermore, to complement our experimentally obtained results, computational calculations were performed for these reactions using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) in combination with the CCSD/cc-pVDZ//MP2/6-31+G(d,p) level of theory. Detailed discussion on feasibility of the reactions, branching ratios, degradation mechanism, and atmospheric implications are discussed in this manuscript.