Premium
Rates and equilibria in the reaction system Br + i ‐C 4 H 10 ⇌ HBr + t ‐C 4 H 9 . The heat of formation of the t ‐butyl radical
Author(s) -
Islam Tajmeri S. A.,
Benson Sidney W.
Publication year - 1984
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.550160806
Subject(s) - chemistry , reaction rate constant , bond dissociation energy , atmospheric temperature range , dissociation (chemistry) , equilibrium constant , thermodynamics , enthalpy , entropy of activation , standard enthalpy of formation , standard enthalpy of reaction , medicinal chemistry , analytical chemistry (journal) , kinetics , organic chemistry , physics , quantum mechanics
The very low pressure reactor (VLPR) technique has been used to measure the bimolecular rate constant of the title reaction at 300 K. The rate constant is given by log k 1 (1/mol s) = (11.6 ± 0.4) − (5.9 ± 0.6)/θ the equilibrium constant has also been measured at the same temperature and is given by K 1 = (5.6 ± 1) × 10 −3 and hence log k −1 (1/mol s) = 9.5 ± 0.1. The results show that the reaction Br + t C 4 H 9 → HBr + i C 4 H 8 is unimportant under the present experimental conditions. Assigning the entropy of t ‐butyl radical to be 74 ± 2 eu which is in the possible range, the value of K 1 gives ΔH ° f( t ‐butyl) = 9.1 ± 0.6 kcal/mol −1 . This yields for the bond dissociation, DH° ( t ‐butyl‐H) = 93.4 ± 0.6 kcal/mol. Both of these values are found to be in good agreement with recent VLPP studies.