Trichloroacetyl chloride, CCl3COCl, as an alternative Cl atom precursor for laboratory use and determination of Cl atom rate coefficients for n-CH2[double bond, length as m-dash]CH(CH2)xCN (x = 3-4).

An investigation of CCl3COCl was conducted with the purpose of using the compound as an alternative Cl atom precursor in laboratory settings. CCl3COCl can be used with or without O2 as a source of Cl atoms and photolysis studies in air and N2 diluent displayed COCl2 and CO as being the major photolysis products. Relative rate studies were performed to determine the Cl atom rate coefficients for reaction with CH3Cl and C2H2 and the results were in agreement with literature values. Cl atom rate coefficients for reaction with n-CH2[double bond, length as m-dash]CH(CH2)3CN and n-CH2[double bond, length as m-dash]CH(CH2)4CN were determined as (2.95 ± 0.58) × 10-10 and (3.73 ± 0.60) × 10-10 cm3 molecule-1 s-1, respectively. CCl3COCl requires UV-C irradiation, so not all molecules are feasible for use in e.g. relative rate studies. Furthermore, it is recommended to perform experiments with O2 present, as this minimizes IR feature disturbance from product formation.

Atmospheric Chemistry of Pentafluorophenol: Kinetics and Mechanism of the Reactions of Cl Atoms and OH Radicals.

Fourier transform infrared smog chamber techniques were used to study the kinetics and mechanisms of the reactions of Cl atoms and OH radicals with pentafluorophenol (C6F5OH) in 700 Torr total pressure of air or N2 diluent at 296 ± 2 K. Rate constants k(OH + C6F5OH) = (6.88 ± 1.37) × 10-12 cm3 molecule-1 s-1 and k(Cl + C6F5OH) = (2.52 ± 0.31) × 10-11 cm3 s-1 molecule-1 in 700 Torr air diluent were determined. In 700 Torr N2, the rate constant for the reaction of C6F5OH with Cl atoms is linearly dependent on the Cl atom concentration. Product studies on this reaction in both 700 Torr air and 700 Torr N2 diluent show the formation of nonconjugated products. The photolysis constant of C6F5OH was determined by 254 nm UV irradiation of a C6F5OH and CH3CHO mixture in 700 Torr air or N2 at 296 ± 2 K and yielded a photolysis rate constant of J(C6F5OH) = (2.83 ± 0.25) × 10-3 s-1. Results are discussed with respect to the atmospheric chemistry of other halogenated aromatic species.

Atmospheric Chemistry of n-CH2═CH(CH2) xCN ( x = 0-4): Kinetics and Mechanisms.

Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure the kinetics of the reaction of n-CH2═CH(CH2) xCN ( x = 0-4) with Cl atoms, OH radicals, and O3: k(CH2═CHCN + Cl) = (1.03 ± 0.13) × 10-10, k(CH2═CHCH2CN + Cl) = (2.02 ± 0.35) × 10-10, k(CH2═CH(CH2)2CN + Cl) = (2.75 ± 0.45) × 10-10, k(CH2═CHCN + OH) = (4.21 ± 0.95) × 10-12, k(CH2═CHCH2CN + OH) = (1.55 ± 0.34) × 10-11, k(CH2═CH(CH2)2CN + OH) = (2.98 ± 0.64) × 10-11, k(CH2═CH(CH2)3CN + OH) = (3.34 ± 0.64) × 10-11, k(CH2═CH(CH2)4CN + OH) = (3.61 ± 0.85) × 10-11, k(CH2═CHCN + O3) = (2.55 ± 0.28) × 10-20, k(CH2═CHCH2CN + O3) = (1.17 ± 0.24) × 10-18, k(CH2═CH(CH2)2CN + O3) = (3.35 ± 0.69) × 10-18, k(CH2═CH(CH2)3CN + O3) = (4.07 ± 0.82) × 10-18, and k(CH2═CH(CH2)4CN + O3) = (7.13 ± 1.49) × 10-18 cm3 molecule-1 s-1 at a total pressure of 700 Torr of air or N2 diluents at 296 ± 2 K. CH2ClC(O)CN, HC(O)CN, HC(O)Cl, HCN, NCC(O)OONO2, and ClC(O)OONO2 were identified as products from the Cl initiated oxidation of CH2═CHCN. The product spectra were compared to experimental and theoretically calculated IR spectra. No products could be determined from the oxidation of n-CH2═CH(CH2) xCN ( x = 1-4). With the determined OH rate constants, the atmospheric lifetimes for n-CH2═CH(CH2) xCN ( x = 0-4) were estimated to be 66, 18, 9.3, 8.3, and 7.7 h, respectively. It was found that these unsaturated nitriles have no significant atmospheric environmental impact.