Hydrogen abstraction from chlorinated ethanes by chlorine atoms

Abstract

Tk« hyûrogca abatraetion froa tha chlarinatad athaaaa hj ohloriaa ataaa hac baan iavaatigatad in tha gaa phaaa batvaaa 323 aad 423*X. Akaaluta Taluaa of tha rata eonatanta hara baan obtainad uaing a compatition nathod with ehlorefona ar aathjl ehlarida aa eospetltor. Tha aetiratian anargiaa aad tha pra->azponaatial faetora ara diaenaaad.

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

“…Although these data show a high degree of scatter when plotted according to the Arrhenius rate law, an approximate temperature dependence is given by In (kl/kl) = 0.53 + 137/T, in satisfactory agreement with our value of In (k,/kz) = 0.545 + 151/T based on the data in Table I. Table 4 and compared with CH3CH2C1 and with the internal competition data for CH,CHCl, of Cillien et al (15) over the temperature range 303-353 K. It should be noted that since no external competitor is involved, the uncertainties associated with the latter do not enter into this direct comparison. The agreement in the activation energy difference between tertiary and primary hydrogens in CH3CHC12 is excellent, while the ratio of pre-exponential factors differs by about 30%.…”

“…Since the activation energy increases significantly in going from CH3CH2Cl to CH3CHC12 to CH3CC13 (Table 3) while the KIE shows a strong opposite trend (Table 6), either the generalization of Lewis breaks down in this case, or the thermochemical data are inadequate. Our results, taken in conjunction with those of Cillien et al (15) and Wine et al (7,8) strongly suggest that the C-H bond energies in chloroethanes and the estimated heats of formation of chlorinated ethyl radicals are in need of revision.…”

“…In the light of the Arrhenius parameters for the primary and tertiary hydrogen abstraction presented in Table 3, the activation energy for the "mixed" processes reported by Wine and Semmes seems to be too low. The reaction of chlorine atoms with 1,1,1-trichloroethane has also been investigated competitively by Cillien et al (15) and directly by Wine, Semmes, and Ravishankara (7). In this case only one type of hydrogen is available and the results of This work "Stated uncertainties represent f l u .…”

Competitive chlorination reactions with ICl. II. CH4, C2H6, C3H8, and C2H5Cl

“…co-workers, kA/kB = 0.20 (9). Comparisons with the rate of abstraction from ethane (see Table 2) are not so good but, nevertheless, quite reasonable.…”

Liquid phase hydrogen abstraction from asymmetrically chlorinated ethanes by chlorine atoms

“…Since careful results were available on the gas phase hydrogen abstraction from chloroethanes by chlorine atoms [5] we have extended that work by the study of the liquid phase chlorinations of ethyl chloride, 1,l -dichloroethane and 1,l ,2-trichloroethane in order to measure the ratio of the rates of attack of the chlorine atom on both sides of these molecules. As long as dichlorination products are kept negligible, this ratio is given by G , * / k k = CR,ClI/CRSC11…”