Surinder K. Kapoor

Reaction of gem-dibromocyclopropanes with zinc in dimethylformamide

Dehalogenation of five assorted gem-dibromocyclopropanes with zinc in dimethylformamide is described. Monobromocyclopropanes, allenes are fully saturated cyclopropanes are obtained. The method is of preparative value only in certain cases.

A convenient dehalogenation of organic halides via organozinc compounds

A simple, nonreductive procedure for the dehalogenation of organic halides to hydrocarbons is described, involving treatment with zinc in dimethylformamide followed by hydrolysis.

Kinetics and mechanism of oxidations by peroxodiphosphate ions. Part 3. Oxidation of hypophosphite in aquous perchloric acid by the hydrolytic product peroxomonophosphate in a consecutive reaction

Oxidation of hypophosphite by peroxodiphosphate in perchloric acid solution is a consecutive reaction, (i) and (ii), H4P2O8+ H2O [graphic omitted] H3PO5+ H3PO4(i), H3PO5+ H3PO2 [graphic omitted] H3PO4+ H3PO3(ii) and a plot of [H3PO5] against time for the reaction exhibits a maximum. In a separate study, the rate law for reaction (ii) has been found to be (iii), where K1 and K2 are the acid-ionization constants of H3PO2 and H3PO5–d[H3PO5]/dt=k2[H3PO5]T[H3PO2]T[H+]2/([H+]+K1)([H+]+K2)(iii) respectively; k2 was (1.2 ± 0.08)× 10–2 dm3 mol–1 s–1 at [H+]= 0.50 mol dm–3, I= 1.0 mol dm–3, and 45 °C. An estimated value of K2 is 0.15 mol dm–3 at 35 °C and I= 1.0 mol dm–3. Maximum concentrations of H3PO5 and the times at which they are built up have been calculated using the values of kh and k2, and these are in good agreement with the observed values.

Kinetics and mechanism of oxidations by peroxodiphosphate ions. Part I. Oxidation of arsenic(III) in aqueous perchloric acid

Peroxodiphosphate, [P2O8]4–, oxidises arsenious acid in perchloric acid medium according to equation (i). H4P2O8+ H3AsO3+ H2O → 2H3PO4+ H3AsO4(i) The mechanism essentially involves hydrolysis of the species [H2P2O8]2–, [H3P2O8]–, and H4P2O8, and the rate of the redox reaction is independent of the arsenic (III) concentration. The rate law when 2.5 > [HClO4] > 0.1 mol dm–3 is as in (ii), and the values of k2 and k3 are (2.7 ± 0.2)× 10–4 and (8.65 ± 0.3)× 10–3 s–1 respectively at 45 °C. –d[P2O8]/dt=k2[H3P2O8–]+k3[H4P2O8](ii) The rate of reaction is independent of the ionic strength. Acrylamide, F–, Cu2+, Mn2+, Fe2+, and phosphate have no effect on the reaction, but Ag+ catalyzes the reaction.