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The absolute rate constant for the metathesis t ‐C 4 H 9 • + DI → C 4 H 9 D + I• and the heat of formation of the t ‐butyl radical
Author(s) -
Rossi Michel,
Golden David M.
Publication year - 1979
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.550110904
Subject(s) - chemistry , bond dissociation energy , arrhenius equation , isobutane , activation energy , atmospheric temperature range , reaction rate constant , kinetic energy , analytical chemistry (journal) , metathesis , dissociation (chemistry) , thermodynamics , medicinal chemistry , kinetics , organic chemistry , polymerization , catalysis , physics , polymer , quantum mechanics
The Arrhenius parameters for the title reaction have been measured in a very‐low‐pressure pyrolysis apparatus in the temperature range 644–722 K and are given by log k 2 ( M −1 · sec −1 ) = 9.68 ‐ 2.12/θ, where θ = 2.303 RT in kcal/mol. Together with the published Arrhenius parameters for the reverse reaction from iodination studies, they result in a standard heat of formation of the t ‐butyl radical of 8.4 kcal/mol, accepting S 0 (C 4 H 9 ·) = 72.2 e.u. at 300 K from other kinetic data, and thus confirm the accepted value for Δ H f 0 ( t ‐C 4 H 9 ·), at variance with recent investigations which yielded significantly higher values. This value for Δ H f 0 ( t ‐C 4 H 9 ·) results in a bond‐dissociation energy (BDE) for isobutane of 92.7 kcal/mol.