title: Hydrogen Isotope Exchange of Chlorinated Ethylenes in Aqueous Solution: Possibly a Termolecular Liquid Phase Reaction.
abstract: This work reports an experimental study of the hydrogen/deuterium exchange in the basic aqueous solutions of trichloroethylene, trans-1,2-dichloroethylene, and cis-1,2-dichloroethylene using (1)H NMR as a monitoring method. 1,1-Dichlorethylene was also investigated but found not to exchange hydrogen isotopes with water. The kinetics of isotope exchange features two different pathways, the first is first order with respect to hydroxide ion, whereas the second is second order. The first pathway is interpreted as a straightforward bimolecular reaction between chloroethylene and hydroxide ion, which leads to the deprotonation of chloroethylene. The second pathway involves a transition state with the association of one molecule of the chloroethylene and two hydroxide ions. It is shown that the second pathway could involve the formation of a precursor complex composed of one chloroethylene molecule and one hydroxide ion, but a direct termolecular elementary reaction is also feasible, which is shown by deriving a theoretical highest limit for the rate constants of termolecular reactions in solution.
authors.affiliation: Faculty of Pharmacy and Biochemistry, University of Zagreb , A. Kovačića 1, 10000 Zagreb, Croatia.
authors.forename: Mario
authors.initials: M
authors.lastname: Gabričević
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Debrecen , 4010 Debrecen, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Lente
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Debrecen , 4010 Debrecen, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Fábián
mesh_terms: D041961:Deuterium Exchange Measurement; D004000:Dichloroethylenes / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007700:Kinetics; D066244:Proton Magnetic Resonance Spectroscopy; D012996:Solutions; D013237:Stereoisomerism; D014241:Trichloroethylene / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004000:Dichloroethylenes; D006878:Hydroxides; D012996:Solutions; D014867:Water; D014241:Trichloroethylene; C031356:hydroxide ion; C035384:1,2-dichloroethylene