Gas‐phase hydrogen abstraction from asymmetrically halogenated ethanes by chlorine atoms

Abstract

The hydrogen abstraction from asymmetrically fluorinated and chlorofluorinated ethanes by chlorine atoms has been investigated in the gas phase between 264 and 333OK using the competition method. Arrhenius parameters for the reaction on both sites of the molecules are discussed.

Competitive photochlorination and kinetic isotope effects for hydrogen/deuterium abstraction from the methyl group in C2H6, C2D6, CH3CHCl2, CD3CHCl2, CH3CCl3, and CD3CCl3

“…The highest activation energy and the slowest rate are observed for CH,CC13 where there are only primary hydrogens. Similar trends have also been found in the case of fluoroethanes (13,16,17). A plausible qualitative explanation of these observations may be sought in terms of repulsive and electron withdrawal effects by the bound chlorine atom(s).…”

Pyrolysis of 1,1-dichloro-1-fluoroethane in the absence and presence of added propene or CCl4: A computer-aided kinetic study

“…The steps are the molecular reactions (1) and (Ϫ1), the radical chain initiation (2), 1 the chain propagations (3) and (4) and their reverses, the radical transfer reactions (5) and (6) and their back reactions, and the chain terminations (Ϫ2), (7), and (8), the last one being heterogeneous. When CCl 4 is added, the chain initiation (2) is replaced by the faster step (9) followed by the transfer steps (10) to (12) and their reverses, and the chain terminations become the radical recombinations (Ϫ9), (13), and (14).…”

“…Cl ϩ CF ϭ CH : CClF CH D 2 2 2 2 g Estimated from Arrhenius parameters for similar reactions. h Experimental value from [12]. i Value determined in [5] for the reactor used in this work.…”

“…As also can be seen, this autoacceleration is well described by the optimization model. Analyses of the rates of the elementary reaction steps show that (i) the acceleration is due to the supplementary production of Cl atoms by the fast chain initiation step (9), and (ii) the autoacceleration results from reactions (11) and (12), which convert unreactive CCl 3 D radicals into reactive CCl 2 FCH 2 D and Cl chain carriers, respectively. Figure 8 shows that the concentration of the CCl 3 D radicals remains almost constant in the course of reaction, while the concentrations of the chain carriers increase.…”