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Kinetics of the reactions of halogenated methyl radicals (CF 3 , CF 2 Cl, CFCl 2 , and CCl 3 ) with molecular chlorine
Author(s) -
Timonen Raimo S.,
Russell John J.,
Gutman David
Publication year - 1986
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550181008
Subject(s) - chemistry , radical , reaction rate constant , arrhenius equation , kinetics , chlorine , photoionization , bromine , chemical kinetics , photodissociation , halogen , chlorine atom , mass spectrometry , analytical chemistry (journal) , photochemistry , activation energy , medicinal chemistry , alkyl , organic chemistry , ionization , ion , physics , quantum mechanics , chromatography
The kinetics of four gas‐phase reactions involving halogenated methyl radicals (R CF 3 , CF 2 Cl, CFCI 2 , and CCI 3 ) with molecular chlorine have been studied using a tubular reactor coupled to a photoionization mass spectrometer. The radicals were homogeneously generated by the pulsed photolysis of precursor molecules at 193 nm. The subsequent decays of the radical concentration were monitored in real‐time experiments as a function of Cl 2 concentration to obtain the rate constants of these R + Cl 2 reactions. Where possible, the rate constants were measured as a function of temperature to determine Arrhenius parameters. Apparent discrepancies between these measured rate constants for CF 3 and CCl 3 with Cl 2 and ones obtained in prior indirect studies are explained. The higher activation energies for these R + Cl 2 reactions compared to that of the CH 3 + Cl 2 reaction are attributed in part to the different polarities of the transition states formed.