Relative rate techniques were used to measure k(OH+n-C3F7OCH3) = (1.2 ± 0.3) × 10-14, k(Cl+n-C3F7OCH3) = (9.1 ± 1.3) × 10-14, and k(Cl+n-C3F7OC(O)H) = (8.2 ± 2.2) × 10-15 cm3 molecule-1 s-1 at 295 K. From the value of k(OH+n-C3F7OCH3) an estimate of 4.7 years for the atmospheric lifetime of n-C3F7OCH3 is obtained. It was determined that the sole atmospheric fate of n-C3F7OCH2O(•) radicals is reaction with O2 to give n-C3F7OC(O)H (perfluoro-propyl formate). The results are discussed with respect to the atmospheric chemistry and environmental impact of n-C3F7OCH3.

Cavity ring-down (CRD) techniques were used to study the kinetics of the reaction of Br atoms with ozone in 1-205 Torr of either N 2 or O 2 , diluent at 298 K. By monitoring the rate of formation of BrO radicals, a value of k(Br ϩ O 3 ) ϭ (1.2 Ϯ 0.1) ϫ 10 Ϫ12 cm 3 molecule Ϫ1 s Ϫ1 was established that was independent of the nature and pressure of diluent gas. The rate of relaxation of vibrationally excited BrO radicals by collisions with N 2 and O 2 was measured;The increased efficiency of O 2 compared with N 2 as a relaxing agent for vibrationally excited BrO radicals is ascribed to the formation of a transient BrO-O 2 complex.

Cavity ring-down absorption spectroscopy was used to measure k(HCO + O2) = (5.9 ± 0.5) × 10-12, k(HCO + NO) = (1.9 ± 0.2) × 10-11, and k(HCO + Cl2) = (7.6 ± 0.7) × 10-12 cm3 molecule-1 s-1 in 4−10 Torr of N2 diluent at 295 K. FTIR/smog-chamber techniques were used to measure the following rate constant ratios in 15−750 Torr of N2 diluent at 295K:  k(HCO + O2)/k(HCO + Cl2) = 0.85 ± 0.02, k(HCO + NO)/k(HCO + Cl2) = 2.80 ± 0.10, and k(HCO + NO2)/k(HCO +Cl2) = 8.45 ± 0.38. Consistent results were obtained from the two different techniques. In 15−700 Torr of N2 diluent at 295 K the reaction of HCO with Cl2 proceeds via a single channel giving HC(O)Cl + Cl, reaction of HCO with NO gives CO in a yield indistinguishable from 100%, and reaction of HCO with NO2 gives a 70% yield of CO and a 30% yield of CO2. Ab initio calculations show that the reaction of HCO radicals with Cl2 proceeds via the formation of the HC(O)Cl2 complex, which decomposes, rapidly to HC(O)Cl and a Cl atom.

Flash photolysis-resonance fluorescence techniques were used to measure the rate constant for the reaction of OH radicals with methyl pivalate, (CH 3 ) 3 CC(O)OCH 3 over the temperature range 250-370 K. The rate constant exhibited a weak temperature dependence, increasing at both low and high temperature from a minimum value of approximately 1.2 × 10 -12 cm 3 molecule -1 s -1 near room temperature. The UV absorption spectrum of methyl pivalate was measured between 160 and 500 nm at room temperature. Smog chamber/ FTIR techniques were used to study the Cl atom and OH radical initiated oxidation of (CH 3 ) 3 CC(O)OCH 3 in the presence of NO x in 700 Torr of N 2 /O 2 diluent at 296 K. Relative rate techniques were used to measure k(Cl+(CH 3 ) 3 CC(O)OCH 3 ) ) (4.1 ( 0.5) × 10 -11 , k(Cl+(CH 3 ) 3 CC(O)OCH 2 Cl) ) (1.8 ( 0.3) × 10 -11 , and k(Cl+(CH 3 ) 3 CC(O)OC(O)OH) ) (1.7 ( 0.2) × 10 -11 cm 3 molecule -1 s -1 . The reaction of Cl atoms with (CH 3 ) 3 CC(O)OCH 3 was found to proceed (11 ( 3) % via H-abstraction at the -OCH 3 site. The Cl atom initiated oxidation of (CH 3 ) 3 CC(O)OCH 3 in the presence of 15-600 Torr of O 2 and 10-30 mTorr of NO x in 700 Torr total pressure of N 2 diluent at 296 K gives HCHO, CO, acetone, CO 2 , and CH 3 OC(O)O 2 NO 2 products. OH radical initiated oxidation of (CH 3 ) 3 CC(O)OCH 3 in air produces acetone in a yield of 51 ( 6%. Environmental chamber experiments were performed to quantify the effect of methyl pivalate on ozone formation under simulated atmospheric conditions. An expression representing the atmospheric oxidation mechanism of methyl pivalate in computer models of atmospheric chemistry is recommended.

Cavity ring‐down UV absorption spectroscopy was used to study the kinetics of the recombination reaction of FCO radicals and the reactions with O2 and NO in 4.0–15.5 Torr total pressure of N2 diluent at 295 K. k(FCO + FCO) is (1.8 ± 0.3) × 10−11 cm3 molecule−1 s−1. The pressure dependence of the reactions with O2 and NO in air at 295 K is described using a broadening factor of Fc = 0.6 and the following low (k0) and high (k∞) pressure limit rate constants: k0(FCO + O2) = (8.6 ± 0.4) × 10−31 cm6 molecule−1 s−1, k∞(FCO + O2) = (1.2 ± 0.2) × 10−12 cm3 molecule−1 s−1, k0(FCO + NO) = (2.4 ± 0.2) × 10−30 cm6 molecule−1 s−1, and k∞ (FCO + NO) = (1.0 ± 0.2) × 10−12 cm3 molecule−1 s−1. The uncertainties are two standard deviations. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 130–135, 2001