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

Article abstract of DOI:10.1021/j100048a013

A pulse radiolysis technique was used to study the UV absorption spectrum of CF3CF2CFHO2 radicals (at 250 nm ? = (175 +/- 36) x 10^-20 cm² molecule^-1).The observed bimolecular rate constant for the self reaction of CF3CF2CFHO2 radicals was k_13obs = (5.2 +/- 1.4) x 10^-12 cm³ molecule^-1 s^-1.Rate constants for reactions of CF3CF2CFHO2 radicals with NO and NO2 were k₃ > 8 x 10^-12 and k₄ = (6.3 +/- 0.7) x 10^-12 cm³ molecule^-1 s^-1, respectively.Using a FTIR spectrometer/smog chamber technique it was shown that, under atmospheric conditions, reaction with O2 and decomposition via C-C bond scission are competing loss mechanisms for CF3CF2CFHO radicals.A lower limit of 10⁵ s^-1 was deduced for the rate of decomposition of CF3CF2CFHO radicals via C-C bond scission at 296K in 1 bar of SF6 diluent.It is estimated that in the atmosphere approximately 98percent of CF3CF2CFHO radicals will undergo decomposition into C2F5 radicals and HC(O)F and 2percent will react with O2 to give C2F5C(O)F.As part of this work relative rate methods were used to measure rate constants of (1.3 +/- 0.3) x 10^-12 and (1.5 +/- 0.3) x 10^-15 cm³ molecule^-1 s^-1 for the reactions of CF3CF2CFH2 with F and Cl atoms, respectively.