Premium
Gas‐phase ozonolysis of cis ‐ and trans ‐dichloroethylene
Author(s) -
Blume Cary W.,
Hisatsune I. C.,
Heicklen Julian
Publication year - 1976
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.550080207
Subject(s) - chemistry , isomerization , ozonolysis , stoichiometry , rate equation , kinetics , reaction rate constant , torr , reaction rate , absorption (acoustics) , chemical kinetics , analytical chemistry (journal) , photochemistry , organic chemistry , thermodynamics , catalysis , physics , quantum mechanics , acoustics
Dichloroethylene (DCE), either cis or trans , was reacted with O 3 at 23°C in both N 2 and O 2 buffered mixtures. Both reactant consumption and product formation were monitored by infrared spectroscopy and, in some cases, O 3 consumption was monitored by ultraviolet absorption. For thoroughly dried mixtures, the initial products were only HCClO and O 2 , but geometrical isomerization also occurred. The stoichiometry of the overall reaction always wasThe HCClO was unstable and disappeared slowly in a first‐order reaction which was, at least in part, heterogeneous. The products were CO and HCl so that the stoichiometric reaction wasThe rate law was complex. The rate was always faster in N 2 than in O 2 . In the N 2 buffered reaction, inhibition occurred as the reaction progressed and O 2 was produced. From the reactant and product decay curves, the following rate behavior was established:where high and low concentrations are relative terms for the initial pressure ranges covered ([DCE] 0 = 0.21−78.4 torr, [O 3 ] 0 = 0.30−6.76 torr). The rate coefficients k 2 , k 3 , and k 4 were larger for the trans ‐DCE than the cis ‐DCE, and for each isomer they were larger in N 2 than in O 2 buffered reactions. The ozonolysis can be explained in terms of the mechanismwhere R 2 is DCE, RO is HCClO, and RO 2 is HCClO 2 . Rate ceofficients are computed. The isomerization is first order in [O 3 ] and approximately first order in [DCE] for the limited kinetic data we were able to obtain. The isomerization does not appear to be explained by the reverse reactions of reactions (6), (7), and (9). Presumably isomerization occurs through some other route.