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Abstract

The rate constants of the reactions between the OH radical and a series of hydrofluoropolyethers (HFPE) have been measured. The reaction of OH with CHF(2)OCF(2)OCH(2), CHF(2)OCF(2)CF(2)OCHF(2), CHF(2)OCF(2)CF(2)OCF(2)OCHF(2) and CH(3)OC(4)F(9) were investigated at 295 K ± 3 K and 740 Torr ± 5 Torr total pressure. The following values of the rate constants were determined for the reaction with the OH radical: K(1) = (2.6 ± 0.5) E-15 cm{3} molecule {-1}s{-1}, K(2) = (4.9 ± 1.5) E-15 cm{3} molecule {-1}s{-1}, K(3) = (4.8 ± 1.0) E-15 cm{3} molecule {-1}s{-1} and K(4) = (7.3 ± 0.8) E-15 cm{3} molecule {-1}s{-1}. Infrared spectra were obtained for all four HFPEs in the range from 600 cm{-1} to 4000 cm{-1} (3 µm to 17 µm), with the following integrated band intesity (IBI) values obtained: IBI(1) = (5.15 ± 0.23) E-16 cm molecule {-1} for the 978 cm{-1} to 1584 cm{-1} band, IBI(2) = (6.04 ± 0.13) E-16 cm molecule {-1} for the 930 cm{-1} to 1501 cm{-1} band, IBI(3) = (8.49 ± 0.34) E-16 cm molecule {-1} for the 963 cm{-1} to 1587 cm{-1} band and IBI(4) = (4.23 ± 0.14) E-16 cm molecule {-1} for the 845 cm{-1} to 1428 cm{-1} band. Carbonyl fluoride, CF(2)O, was the only fluorine-containing degradation product that was found both from the reaction of CHF(2)OCF(2)OCF(2)CF(2)OCHF(2) and from that of CH(3)OC(4)F(9) with measured product yields of between 60% and 97%, and between 20% and 40% (based on carbon atoms), respectively. Due to the high uptake parameter of CF(2)O to liquid water, its lifetime in the atmosphere is very short. It is rapidly incorporated into raindrops/aerosols, where it eventually degrades to HF and CO(2). The global warming potential of CF(2)O is therefore negligible compared to those of chlorofluorocarbon (CFC)-11 and CFC-12.

Additional information

Authors: CAVALLI F, JRC Ispra (IT);GLASIUS M, JRC Ispra (IT);HJORTH J, JRC Ispra (IT);JENSEN N R, JRC Ispra (IT);RINDONE B, University of Milan, Department of Environmental Science (IT)
Bibliographic Reference: Article: Atmospheric Environment (1997)
Record Number: 199711616 / Last updated on: 1997-12-09
Category: PUBLICATION
Original language: en
Available languages: en