Atmospheric Chemistry of 4:2 Fluorotelomer Alcohol (CF₃(CF₂)₃CH₂CH₂OH):  Products and Mechanism of Cl Atom Initiated Oxidation

Smog chamber/FTIR techniques were used to study the products and mechanism of the Cl atom initiated oxidation of 4:2 fluorotelomer alcohol (CF 3 (CF 2 ) 3 CH 2 CH 2 OH) in 700 Torr of N 2 /O 2 diluent at 296 K. CF 3 (CF 2 ) 3 CH 2 CHO is the sole primary oxidation product. CF 3 (CF 2 ) 3 CHO, CF 3 (CF 2 ) 3 CH 2 COOH, and CF 3 (CF 2 ) 3 CH 2 C(O)OOH are secondary oxidation products. Further irradiation results in the formation of CF 3 (CF 2 ) 3 COOH, COF 2, and CF 3 OH. CF 3 (CF 2 ) 3 CHO, CF 3 (CF 2 ) 3 CH 2 COOH, and CF 3 (CF 2 ) 3 CH 2 C(O)OOH are formed from CF 3 (CF 2 ) 3 CH 2 CHO oxidation in yields of 46%, 27%, and ≤27%, respectively. Using relative rate techniques, a value of k (Cl + CF 3 (CF 2 ) 3 CH 2 CHO) = (1.84 ± 0.30) × 10 -11 cm 3 molecule -1 s -1 was determined. The yield of the perfluorinated acid, CF 3 (CF 2 ) 3 COOH, from the 4:2 fluorotelomer alcohol increased with the diluent gas oxygen concentration. For the experimental conditions used herein and employing >98% consumption of 4:2 fluorotelomer alcohol, the molar yields of CF 3 (CF 2 ) 3 COOH were <0.011, 0.031, 0.042, and 0.056 in experiments conducted with 10, 140, 400, and 700 Torr O 2, respectively. These results suggest that the atmospheric oxidation of fluorotelomer alcohols may be a significant source of the perfluorinated carboxylic acids that are observed in remote areas.