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Author(s):   Zhang, D.; Zhang, R.Y.; Allen, D.T.
Title:   C-C bond fission pathways of chloroalkenyl alkoxy radicals
Journal:   J. Chem. Phys.
Volume:   118
Page(s):   1794 - 1801
Year:   2003
Reference type:   Journal article
Squib:   2003ZHA/ZHA1794-1801

Reaction:   CH2=CHC(CH3)(O·)CH2Cl → CH2=CHCOCH3 + ·CH2Cl
Reaction order:   1
Temperature:   300 K
Rate expression:   8.8x103 [s-1]
Category:  Theory
Data type:   Transition state theory
Pressure dependence:   Rate constant is high pressure limit
Comments:   The authors calculate the reaction to be 2.5 kcal/mol endothermic and the acitivation energy (zero point energies included) is given as 12.5 kcal/mol. It is unclear, however, if these values pertain to 0 K or 300 K.

The authors caried out density-functional theory and ab initio molecular orbital calculations todetermine the structures and energetics of the chloroalkenyl alkoxy radicals arising from Cl-initiatedreactions of isoprene. The transition states and products of their decomposition reactions were determined and transition state theory was used to calculate high-pressure limit decomposition rates.

Geometry optimizations of the various species were performed at the Becke three parameter Lee?Yang?arr ~B3LYP!/6-31G(d,p) level, and single-point energies were computed usingsecond-order M?er?lesset and coupled-cluster theory with single and double excitationsincluding perturbative corrections for the triple excitations.

The results indicate that C? bond decomposition of the chloroalkenyl alkoxy radicals is relatively slow and likely plays a minor role in the Cl-isoprene reactions. The authors discuss the Implications of their results on the formation yields of methyl vinyl ketone, methacrolein, and 1-chloro-3-methyl-3-buten-2-one.

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