Atmospheric Chemistry of HFC-236cb: Spectrokinetic Investigation of the CF3CF2CFHO2 Radical, Its Reaction with NO and NO2, and the Fate of the CF3CF2CFHO Radical

Abstract

A pulse radiolysis technique was used to study the UV absorption spectrum of CF3CF2CFH02 radicals (at 250 nm CT = (175 f 36) x lo-,' cm2 molecule-'). The observed bimolecular rate constant for the self reaction of CF3CF2CFH02 radicals was k130b\ = (5.2 f 1.4) x lo-', cm3 molecule-' s-I. Rate constants for reactions of CF3CF2CFH02 radicals with NO and NO, were k3 > 8 x lo-', and k4 = (6.3 k 0.7) x lo-'? cm3 molecule-' s-l, respectively. Using a FTIR spectrometerkmog chamber technique it was shown that, under atmospheric conditions, reaction with 0 2 and decomposition via C-C bond scission are competing loss mechanisms for CF3CFKFHO radicals. A lower limit of lo5 s-' was deduced for the rate of decomposition of CF3CF2CFHO radicals via C-C bond scission at 296 K in 1 bar of SF6 diluent. It is estimated that in the atmosphere approximately 98% of CF3CF2CFHO radicals will undergo decomposition into C2Fj radicals and HC(0)F and 2% will react with 0 2 to give C,F5C(O)F. As part of this work relative rate methods were used to measure rate constants of (1.3 f 0.3) x lo-'' and (1.5 i 0.3) x cm3 molecule-' s-' for the reactions of C F~C F~C F H Z with F and C1 atoms, respectively.

Atmospheric Chemistry of HFC-236cb: Fate of the Alkoxy Radical CF3CF2CFHO

“…To understand the ultimate products and, hence, the environmental impact of HFC-236cb, data concerning the atmospheric chemistry of the CF 3 CF 2 CFHO radical are needed. A previous study has shown that reactions 7 and 8 compete for CF 3 CF 2 CFHO radicals under atmospheric conditions: At 700 Torr total pressure and 296 K, the rate constant ratio k 8 / k 7 = k d / k O2 was found to be 3 × 10 20 molecule cm -3 …”

Atmospheric chemistry of benzaldehyde: UV absorption spectrum and reaction kinetics and mechanisms of the C6H5C(O)O2 radical

“…Synthetic 12) gives and k 7 \ (1.16 ^0.12) ] 10~15 (1.10 ^0.15) ] 10~15 cm3 molecule~1 s~1. We choose to quote a Ðnal value of that is the average of the two deterk 7 minations together with uncertainties which encompass the extremes of the uncertainty ranges of the individual determinations, hence cm3 molecule~1 s~1.…”

Kinetics and mechanism of the thermal gas‐phase oxidation of perfluorobutene‐2 in presence of trifluoromethyl hypofluorite

“…The decomposition rates of fluorinated alkoxy radicals are very sensitive to change in molecular configuration. The CF 3 CF 2 CFHO • radical decomposes 17 times more rapidly than the CF 3 CFHO • radical 51. CF 3 CF 2 CFHO • can be viewed as CF 3 CFHO • with one fluorine atom substituted by a CF 3 group.…”