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Item Thermal Decomposition of Manganese(II) Oxalate in Vacuum and in Oxygen(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (07), 1974) Brown, Michael E.; Dollimore, David; Galwey, Andrew K.Comparative studies of the kinetics of thermal decomposition of anhydrous manganese(ll) oxalate in vacuum and in oxygen are reported. Reaction rates were appreciably influenced by the conditions of salt dehydration : both decompositions were more rapid for vacuum-dehydrated react ant than for salt dehydrated in air. The shapes of product yield against time curves were not detect- ably changed by the presence of oxygen. The solid product from the oxidation reaction was largely Mn;O3 and the activation energy was significantly lower than previously reported values for the vacuum decomposition which yields MnO. Mechanistic interpretation of the kinetic data was supplemented where appropriate by observations from electron micrographs. Product gas analyses, during the course of decomposition reactions, indicated the initial formation of products containing Mn3+, though this was subsequently reduced. Reaction mechanisms involving the participation of Mn3+ in both decomposition and oxidation of manganese(II) oxalate arc proposed.Item Catalyzed Thermal Decomposition of Organic Acids: Part 2.—Catalyzed Decomposition of Cyclopentane- and Cycloheptane-carboxylic Acids by Hydrogen Bromide(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (1), 1973) Ahonkhai, S. I.; Emovon, E. U.Cyclopcntanc- and cycloheptane-carboxylic acids decompose by a molecular mechanism into carbon monoxide, water and the corresponding alkene on catalysis by HBr in a seasoned Pyrex vessel. The decomposition is homogeneous and first order in acid and catalyst, HBr. The second order rate constants, expressed by the Arrhenius equations are: k2 = 1012.17e-29 550/RTcm3mol-1 s-1 for cycloheptanecarboxylic acid and k2 = 1013.49e-34 590/RTcm3mol-1 S-1 for cyclopentanecarboxylic acid over the temperature range 369.0-434.0°C (R in cal mol"1).Item Thermal Decomposition of Ethyl, Isopropyl and t-Butyl Fluorides in the Gas Phase(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (11), 1972) Dastoor, P. N.; Emovon, E. U.Ethyl, isopropyl and t-butyl fluorides decompose in a flow system into hydrogen fluoride and the corresponding olefin by a predominantly molecular mechanism. The first order rate constants are given by the Arrhenius equations: ethyl fluoride (520–600°C) : k/s–1= 1012.16±0.04exp–59 200±2000/RT, isopropyl fluoride(445–522°C) : k/s–1= 1011.83±0.02 exp–53 900±800/RT, t-butyl fluoride (329–370°C) : k/s–1= 1013.96±0.01 exp–50 400±900/RT.Item Microcalorimetric Studies: Thermal Decomposition and Iodination of Metal Carbonyls(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (9), 1972) Connor, J. A.; Skinner, H. A.; Virmani, Y.The Calvet high temperature microcalorimeter was used to measure the enthalpies of thermal decomposition and the enthalpies of reaction with iodine vapour, of carbonyls of Mo, Mn, and Cr. ΔH°f(c) values for Mo(CO)6, Mn2(CO)10, Cr(CO)6, Mn(CO)5Cl and Mn(CO)5Br were obtained. These studies have confirmed the literature value for ΔH°f(Mn2(CO)10, c), but disagree with the currently accepted value for ΔH°f(Cr(CO)6, c). The bond dissociation energies D[(CO)5Mn—Cl] and D[(CO)5Mn—Br] were evaluated at 73 and 61 kcal mol–1 respectively: these values are ca. 20 kcal mol–1 less than the mean bond dissociation energies, D(Mn—Cl) and D(Mn—Br), in MnCl2(g) and MnBr2(g), and ca. 15 kcal mol–1 less than the dissociation energies in the diatomic molecules MnCl, MnBr.