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Laser‐induced kinetics: Arrhenius parameters for t ‐C 4 H 9 + XI → i ‐C 4 H 9 X + I (X = H,D) and the Heat of Formation of the t ‐butyl radical
Author(s) -
Rossi M. J.,
Golden D. M.
Publication year - 1983
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.550151204
Subject(s) - arrhenius equation , chemistry , kinetics , thermal decomposition , activation energy , atmospheric temperature range , analytical chemistry (journal) , chemical kinetics , decomposition , flash photolysis , reaction rate constant , thermodynamics , organic chemistry , physics , quantum mechanics
The metathesis reaction of DI with t ‐C 4 H 9 generated by 351‐nm photolysis of 2,2′‐azoisopropane was studied in a low‐pressure reactor (VLPϕ Knudsen cell) in the temperature range of 302–411 K. The data obeyed the following Arrhenius relation when combined with recent data by Rossi and Golden gathered by the same technique ( t ‐C 4 H 9 by thermal decomposition of 2,2′‐azoisobutane): log k 2 D ( M −1 s −1 ) = 9.60 – 1.90/θ, where θ = 2.303 RT kcal/mol for 302 K < T > 722 K. The metathesis reaction of HI with t ‐C 4 H 9 was studied at 301 K and resulted in k 2 H ( M −1 ·s −1 ) = (3.20 ± 0.62) × 10 8 . An analogous Arrhenius relation was calculated for the protiated system if the small primary isotope effect k 2 H / k 2 D was assumed to be √2 at 700 K. It was of the following form: log k 2 H ( M −1 ·s −1 ) = 9.73 – 1.68/θ. Preliminary data of Bracey and Walsh indicate that earlier Arrhenius parameters determined for the reverse reaction are somewhat in error. Their value of log k 1 ( M −1 ·s −1 ) = 11.5 – 23.8/θ yields 7delta; H f ,300 0 ( t ‐butyl) = 9.2 kcal/mol and S 300 0 ( t ‐butyl) = 74.2 cal/mol7°K when taken in conjuction with this study.