558-38-3Relevant articles and documents
Dehydrochlorination of 2-chloroethanol, 2-chloro-1-propanol, 1-chloro-2-propanol, 2-chloro-2-methyl-1-propanol and 1-chloro-2-methyl-2- propanol
Pihlaja, Kalevi,Kiuru, Marja-Leena,Sippola, Anne
, p. 120 - 133 (2013/09/24)
The reactions between a few 1,2-chlorohydrins and sodium hydroxide have been studied and shown to involve a two-step nucleophilic elimination of hydrogen chloride. The data are given for the slow rate-determining step of 2-chloroethanol 1, 2-chloro-1-propanol 2, 1-chloro-2- propanol 3, 2-chloro-2-methyl-1-propanol 4 and 1-chloro-2-methyl-2-propanol 5. Compounds 4 and 5 gave 2-methyl-1,2-propanediol as the final product instead of oxiranes given by compounds 13. In contrast to some earlier reports the mere water reaction was shown to be almost negligible. In constant ionic strength the base concentration had no effect on the rates whereas at different base concentrations (0.0500.250 mol dm-3) alone the rate of alkaline dehydrochlorination of 1 clearly decreased (103k2, dm 3 mol-1 s-1: 10.0-8.7, respectively). The rate of 2 at constant base concentration (0.010 mol dm-3) and at different ionic strengths (dm3 mol-1: 0.010-0.500) decreased also (103k2, dm3 mol-1 s-1: 76-65, respectively) indicating that the decrease is mainly due to the change in the ionic strength also in the former case. ARKAT-USA, Inc.
C-H bond activation by metal oxo species: Chromyl chloride oxidations of cyclooctane, isobutane, and toluene
Cook, Gerald K.,Mayer, James M.
, p. 7139 - 7156 (2007/10/02)
Chromyl chloride, CrO2Cl2, oxidizes cyclooctane, isobutane, and toluene under mild conditions (25-60 °C). The reactions give chlorinated products (chlorocyclooctane, tert-butyl chloride, and benzyl chloride) and a dark chromium-containing precipitate. Hydrolysis of the precipitate yields oxygenated products, such as ketones, aldehydes, chloro ketones, epoxides, and alcohols. Kinetic data show that all of the reactions are first order in CrO2Cl2 and first order in substrate, with no sign of an induction period. Primary isotope effects have been observed for t-d1-isobutane and d8-toluene. The kinetic and mechanistic data indicate that the reactions proceed by initial hydrogen atom transfer from the substrate to CrO2Cl2 The rates of hydrogen atom abstraction by CrO2Cl2 vary in the order cyclohexane ? and ΔS?, indicating a common mechanism for the four substrates. The pathways leading from the initially formed alkyl radicals to the observed products are described. The ability of CrO2Cl2 to abstract a hydrogen atom from alkanes is remarkable, as it is a closed-shell, diamagnetic species, not a radical. It is proposed that the hydrogen atom abstracting ability derives from the strong O-H bond formed on hydrogen atom transfer, in [Cl2(O)Cr(OH)]. The rates of the CrO2Cl2 reactions correlate with rates of hydrogen atom abstraction by oxygen radicals, assuming a CrO-H bond strength of 83 kcal/mol (similar to that in HMnO4-). The implications of this perspective for transition metal mediated hydrogen atom transfer reactions are discussed.
