Chlorine‐photosensitized reactions in the Cl₂ + O₂ + 1,1,1,2‐C₂H₂Cl₄ system

Abstract

The gas-phase photochlorination (A = 436 nm) of the 1 , l , l ,2-C2H2C1( has been studied in the absence and the presence of oxygen at temperatures between 360 and 420°K. Activation energies have been estimated for the following reaction steps:The dissociation energy D(CC13CHCl-02) f (24.8 =t 1.5) kcal/mole has also been estimated from the difference in activation energy of the direct and reverse reactionsThe mechanism is discussed and the rate parameters are compared to those obtained for a series of other chlorinated ethanes.

Review of Rate Constants and Exploration of Correlations of the Halogen Transfer Reaction of Trisubstituted Carbon-Centered Radicals with Molecular Halogens

“…The kinetic database is most extensive for chlorine transfer. Experimental gas-phase data for k Cl (R • ) are collected in Table . − Structures labeled with simple numerals result from single reported measurements or from fits to multiple measurements (see text); such multiple measurements are indicated by the same numeral but with an alphabetic suffix added. Only the numerals without letter suffixes indicate the values of k Cl,298 (R • ) used for regression analyses.…”

“…Only the numerals without letter suffixes indicate the values of k Cl,298 (R • ) used for regression analyses. The majority have been obtained from the PLP/PIMS method, − ,− ,,, along with several from the k Cl / k O 2 – k O 2 method ,,− ,,,− , and from the rotating sector method. ,− Note that the substituents on the radical center are heavily weighted toward alkyl groups and halogen atoms, with limited representation from other heteroatoms (a few O and S but no N) or carbon-centered substituents such as carbonyl. To obtain even these few, more indirect methods and kinetic assumptions were often necessary.…”