16156-36-8Relevant articles and documents
Atmospheric Chemistry of HFC-134a: Kinetic and Mechanistic Study of the CF3CFHO2 + HO2 Reaction
Maricq, M. Matti,Szente, Joseph J.,Hurley, Michael D.,Wallington, Timothy J.
, p. 8962 - 8970 (2007/10/02)
Rate constant measurements for the title reaction and for F + CF3CFH2 are reported over the 210-363 K temperature range.Reacting mixtures of CF3CFHO2 and HO2 radicals are created by the flash photolysis of F2 in the presence of HFC-134a (CF3CFH2), H2, and O2 and are probed by time-resolved UV absorption spectroscopy.The deconvolution of spectra taken at various delay times provides concentration versus time profiles for the respective radical species.A comparison of the initial CF3CFHO2 and HO2 concentrations yields a relative rate determination of k1 = (9.8+9-5) * 10-11e(-1130+/-190)/T cm3s-1 for the F + CF3CFH2 rate constant.A simultaneous fit of the radical decay curves to a mechanism containing the known HO2 self-reaction kinetics, the previously determined CF3CFHO2 self-reaction mechanism, and a cross reaction between these species yields a rate constant of k7 = (1.8+2.4-1.0) * 10-13e(910+/-220)/T cm3s-1 for the HO2 + CF3CFHO2 reaction.A product stucy at 296 K by Fourier transform infrared spectroscopy reveals that less than 5percent of the product appears as CF3C(O)F.By inference, >95percent of the reaction gives the hydroperoxide CF3CFHOOH.Implications of these results are discussed with respect to the atmospheric degradation of HFC-134a (CF3CFH2).
Rate Constants for Reduction of substituted Methylperoxyl Radicals by Ascorbate Ions and N,N,N',N'-tetramethyl-p-phenylenediamine
Neta, P.,Huie, R. E.,Mosseri, S.,Shastri, L. V.,Mittal, J. P.,et al.
, p. 4099 - 4104 (2007/10/02)
Absolute rate constants (k) for reduction of substituted methylperoxyl radicals by ascorbate ions and by TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) in aqueous solutions have been determined by pulse radiolysis.The rate constants vary from 1E6 to 1E9 M-1 s-1, increasing as the electron-withdraving capacity of the substituent on the peroxyl group increases.Linear correlations are observed between log k and the Taft substituents ?* for a wide variety of substituents, but not all substituents fit the same line.In the case of ascorbate as reductant, the points for peroxyl radicals that contain halogens on the α-carbon lie on a different line (ρ*=0.41) than that for the other substituents (ρ*=1.25).In the case of TMPD there are alsotwo families of peroxyl radicals: Those comprimising the electron-donating groups Me through t-Bu (ρ=5.6) and those containing electron-withdrawing substituents (ρ*=0.64).
