Fourier transform infrared studies of the reaction of Cl atoms with PAN, PPN, CH₃OOH, HCOOH, CH₃COCH₃ and CH₃COC₂H₅ at 295±2 K

The relative rate technique has been used to measure rate constants for the reaction of chlorine atoms with peroxyacetylnitrate (PAN), peroxypropionylnitrate (PPN), methylhydroperoxide, formic acid, acetone and butanone. Decay rates of these organic species were measured relative to one or more of the following reference compounds; ethene, ethane, chloroethane, chloromethane, and methane. Using rate constants of 9.29×10^-11, 5.7×10^-11, 8.04×10^-12, 4.9×10^-13, and 1.0×10^-13 cm³ molecule^-1 sec^-1 for the reaction of Cl atoms with ethene, ethane, chloroethane, chloromethane, and methane respectively, the following rate constants were derived, in units of cm³ molecule^-1 s^-1: PAN, <7×10^-15; PPN, (1.14±0.12)×10^-12; HCOOH, (2.00±0.25)×10^-13; CH₃OOH, (5.70±0.23)×10^-11; CH₃COCH₃, (2.37±0.12)×10^-12; and CH₃COC₂H₅, (4.13±0.57)×10^-11. Quoted errors represent 2σ and do not include possible systematic errors due to errors in the reference rate constants. Experiments were performed at 295±2 K and 700 torr total pressure of nitrogen or synthetic air. The results are discussed with respect to the previous literature data and to the modelling of nonmethane hydrocarbon oxidation in the atmosphere. In recent discussions with Dr. R. A. Cox of Harwell Laboratory, UKAEA, we learnt of a preliminary value for the rate constant of the reaction of Cl with acetone of (2.5±1.0)×10^-12 cm³ molecule^-1 sec^-1 measured by R. A. Cox, M. E. Jenkin, and G. D. Hayman using molecular modulation techniques. This value is in good agreement with our results.