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The dark reactions F 2 + CF 3 I, C 2 F 5 I, and n ‐C 3 F 7 I
Author(s) -
Johnson D. E.,
Walters E. A.,
Dorko E. A.
Publication year - 1996
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/(sici)1097-4601(1996)28:1<43::aid-kin6>3.0.co;2-m
Subject(s) - chemistry , arrhenius equation , iodide , kinetic energy , radical , kinetics , activation energy , induction period , alkyl , methyl iodide , medicinal chemistry , photochemistry , organic chemistry , catalysis , physics , quantum mechanics
The reactions between F 2 and the lowest members of the homologous series of perfluoroalkyl iodides (CF 3 I, C 2 F 5 I, and n ‐C 3 F 7 I) have been studied. For these compounds, an exponential decrease in the alkyl iodide concentration over time following an induction period is observed for certain experimental conditions. Other conditions lead to chaotic‐like kinetic behavior where the rate of alkyl iodide consumption continually changes. Kinetic rate data with CF 3 I show that the disappearance rate depends upon both the type of surface and surface preparation. For all three compounds, Arrhenius plots reveal activation energies on the order of 10 kcal/mol, consistent with effective initiation steps of F 2 + RI → RIF + F, where R represents the CF 3 , C 2 F 5 , or n ‐C 3 F 7 radical respectively. The end products of the F 2 + RI reactions are RF, R 2 , and IF 5 , suggesting that the R radicals play an important kinetic role. Introducing O 2 into the F 2 + RI reaction systems results in successive oxidation of R by O 2 , leading to the formation of CF 2 O as an additional end product. IF(B → X) emission is observed from the RI‐rich F 2 + RI reactions, confirming the existence of IF as an intermediate. © 1996 John Wiley & Sons, Inc.