Time-resolved observation of the formation of carbonic difluoride and carbonic chloride fluoride in the chlorodifluoromethyl + oxygen and dichlorofluoromethyl + oxygen reactions: the unimolecular elimination of chlorine atoms from chlorodifluoromethoxy and dichlorofluoromethoxy radicals
摘要:
The unimolecular elimination of chlorine atoms from CF2ClO and CFCl2O radicals has been observed at 238 and 298 K, and at 4-20 Torr total pressure by measurement of the rate of formation of the carbonyl halide product in real time. The fragment ion (CFO)+ was found to be specific for the detection of CF2O and CFClO and was monitored by time-resolved mass spectrometry in flash photolysis of mixtures of CF2ClBr or CFCl3 with O2 and NO. These two Cl atom elimination reactions were verified to be very facile, even at low temperatures. The rate constants were estimated by regression analysis of experimentally measured formation curves of CF2O and CFClO, and decay curves of CF2ClO2 and CFCl2O2 were determined in the same experiments. The estimated 298 K rate constants are (6.4 +/- 1.4) x 10(4) s-1 for CF2ClO and (1.2 +/- 0.4) x 10(5) s-1 for CFCl2O.
Rate constants for the reaction of halogenated alkylperoxyl radicals with iodide: influence of substituents, solvent polarity, and proton concentration
polarity of solvent mixtures and electronegativity of the substituents at the α-C atom of the peroxyl radicals. They strongly depend on all these variables, with the actual numbers covering a range from 3 × 105 to 7.0 × 108 M−1 s−1. A good linear relationship is obtained between logk and the dielectric constant of the solvent mixture. Within a particular solvent mixture the rateconstants depend strongly
Time-resolved observation of the formation of carbonic difluoride and carbonic chloride fluoride in the chlorodifluoromethyl + oxygen and dichlorofluoromethyl + oxygen reactions: the unimolecular elimination of chlorine atoms from chlorodifluoromethoxy and dichlorofluoromethoxy radicals
作者:Fuxiang Wu、Robert W. Carr
DOI:10.1021/j100183a046
日期:1992.2
The unimolecular elimination of chlorine atoms from CF2ClO and CFCl2O radicals has been observed at 238 and 298 K, and at 4-20 Torr total pressure by measurement of the rate of formation of the carbonyl halide product in real time. The fragment ion (CFO)+ was found to be specific for the detection of CF2O and CFClO and was monitored by time-resolved mass spectrometry in flash photolysis of mixtures of CF2ClBr or CFCl3 with O2 and NO. These two Cl atom elimination reactions were verified to be very facile, even at low temperatures. The rate constants were estimated by regression analysis of experimentally measured formation curves of CF2O and CFClO, and decay curves of CF2ClO2 and CFCl2O2 were determined in the same experiments. The estimated 298 K rate constants are (6.4 +/- 1.4) x 10(4) s-1 for CF2ClO and (1.2 +/- 0.4) x 10(5) s-1 for CFCl2O.