title: Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters.
abstract: The specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous organic mixtures with wide ranging nucleophilicity and ionizing power. For 1, we also report the first-order rate constants determined at different temperatures in pure ethanol (EtOH), methanol (MeOH), 80% EtOH, and in both 97% and 70% 2,2,2-trifluoroethanol (TFE). The enthalpy (ΔH(≠)) and entropy (ΔS(≠)) of activation values obtained from Arrhenius plots for 1 in these five solvents are reported. The specific rates of solvolysis were analyzed using the extended Grunwald-Winstein equation. Results obtained from correlation analysis using this linear free energy relationship (LFER) reinforce our previous suggestion that side-by-side addition-elimination and ionization mechanisms operate, and the relative importance is dependent on the type of chloro- or chlorothioformate substrate and the solvent.
authors.affiliation: Department of Chemistry, Wesley College, 120 N. State Street, Dover, DE 19901-3875, USA.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: D'Souza
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: McAneny
authors.forename: Dennis N
authors.initials: DN
authors.lastname: Kevill
authors.forename: Jin Burm
authors.initials: JB
authors.lastname: Kyong
authors.forename: Song Hee
authors.initials: SH
authors.lastname: Choi