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Theoretical and experimental studies of the diketene system: Product branching decomposition rate constants and energetics of isomers
Author(s) -
Bui Binh,
Tsay Ti Jo,
Lin M. C.,
Melius C. F.
Publication year - 2007
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.20263
Subject(s) - diketene , ketene , chemistry , reaction rate constant , thermal decomposition , decomposition , branching (polymer chemistry) , standard enthalpy of formation , conformational isomerism , branching fraction , kinetics , computational chemistry , medicinal chemistry , organic chemistry , molecule , physics , atomic physics , quantum mechanics
The kinetics and mechanism for the thermal decomposition of diketene have been studied in the temperature range 510–603 K using highly diluted mixtures with Ar as a diluent. The concentrations of diketene, ketene, and CO 2 were measured by FTIR spectrometry using calibrated standard mixtures. Two reaction channels were identified. The rate constants for the formation of ketene ( k 1 ) and CO 2 ( k 2 ) have been determined and compared with the values predicted by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory for the branching reaction. The first‐order rate constants, k 1 (s −1 ) = 10 15.74 ± 0.72 exp(−49.29 (kcal mol −1 ) (±1.84)/RT) and k 2 (s −1 ) = 10 14.65 ± 0.87 exp(−49.01 (kcal mol −1 ) (±2.22)/RT); the bulk of experimental data agree well with predicted results. The heats of formation of ketene, diketene, cyclobuta‐1,3‐dione, and cyclobuta‐1,2‐dione at 298 K computed from the G2M scheme are −11.1, −45.3, −43.6, and −40.3 kcal mol −1 , respectively. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 580–590, 2007