J . Phys. Chem. 1993,97, 1 1696-1 1698
11696
Long Path Fourier Transform Infrared Spectroscopic Study of the Reactions of CF300 and CF3O Radicals with NO2 J. Chen, V. Young, T. Zhu, and H.Niki' Centre for Atmospheric Chemistry and Department of Chemistry, York University, 4700 Keele Street, North York, Ontario, Canada M3J lP3 Received: June 2, 1993: In Final Form: August 31, 1993'
Mechanisms of the reactions of C F 3 0 0 and CFjO radicals with NO2 have been studied using the long path FTIR method in the visible (A 1 400 nm) photolysis of CF3NO in the presence of excess NO2 (in mTorr range) in 700 Torr of air at 297 & 2 K. In the early stage of the photolysis, the predominant F-containing product detected was CF3OON02 formed via the addition reaction CF@O + NO2 (+M) CF300N02 (+M). Addition of excess N O to the above irradiated mixture in the dark led to the loss of CF300N02 and concomitant production of CFsON02, FN02, and CF20, consistent with the Occurrence of CF300 N O CF3O NO2 followed by the addition reaction C F 3 0 NO2 (+M) CF3ON02 (+M) (290%) and the F-transfer reaction CF,O NO2 CF2O FNO2 (I 10%). An alternative decomposition channel of CF300N02 to yield CF20 and FNO2 as reported in the literature was not observed in the present study.
-
-
+
+
-
+
+
+ NO2
-
CF20
+ FN02
+ NO
-
CF20
+ FNO
and
Introduction
The oxidation of the trifluoromethoxy radical (CF30) is one of the major uncertainties in the mechanism of tropospheric degradation of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) containing a CF3 group.' Recently, we have carried out a series of long path FTIR-based studies of the reactions of CF30 radicals with NO,2 alkanes? and alkene^,^ using the visible photolysis of CF3NO as the source of CF30 radicals, i.e.
-
+ hv(A 1 400 nm) CF, + N O CF, + 0, (+M) CF,OO (+M) CF,OO + N O CF,O + NO2
CF,NO
-
(1)
(2) (3)
The present study is an extension of the above studies to the reactions of C F 3 0 0 and CF30 radicals with N02. To our knowledge, no kinetic or mechanistic studies of these reactions under tropospheric conditions have been reported previously. Similar to the other CX300(X = H or halogen atoms) radicals, C F 3 0 0is expected to undergo an addition reaction with NO2 to form CF300N02which is thermally unstable and redissociates to C F 3 0 0 and N02:5,6 CF,OO
+ NO, (+M)
-
CF,OONO, (+M)
(4,-4)
Previously, Hohorst and DesMarteau' prepared pure CFp00N02 in a variety of low temperature (
