557-91-5Relevant academic research and scientific papers
Synthesis of hydroxylated hydrocarbons
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Page/Page column 5, (2008/06/13)
Ethylene glycol, other diols, triols, and polyols are made in an efficient manner by reacting dibromides with water in the presence of a metal oxide. An integrated process of dibromide formation, alcohol synthesis, metal oxide regeneration, and bromine recycling is also provided.
Reaction of atomic bromine with ethyl bromide. The heat of formation of the CH3CHBr radical and the α-carbon-hydrogen bond dissociation energy
Tschuikow-Roux,Salomon,Paddison
, p. 3037 - 3040 (2007/10/02)
The gas-phase bromination of C2H5Br in the presence of C2H5Cl as competitor has been studied between 40 and 100°C at total reactant pressures of ～37 Torr and haloethane/Br2 ratios of ～7. Below 90°C hydrogen abstraction by bromine atoms from C2H5Br occurs only from the bromomethyl group, the sole bromination product being CH3CHBr2. At higher temperatures the onset of bromine atom attack on the β-hydrogens is also observed, giving rise to trace amounts of CH2BrCH2Br and somewhat larger yields of C2H4 resulting from the decomposition of the CH2CH2Br radical. Over the temperature range of this investigation the rate constant ratio for the abstraction of secondary hydrogen in CH3CH2Cl and CH3CH2Br obeys an Arrhenius law, which, combined with the known rate parameters for CH3CH2Cl, yields for CH3CH2Br k3/cm3 mol-1 s-1 = 1012.645±0.099 exp[-(10583 ± 158)/RT]. From an assessment of thermochemical and kinetic data the following heat of formation of the CH3CHBr radical and the C-H bond dissociation energy in ethyl bromide have been obtained: ΔHf°(CH3CHBr) = 29.6 ± 1.1 kcal/mol and D°(CH3CHBr-H) = 96.4 ± 1.1 kcal/mol. The results are discussed in comparison with the bromination data of other monohaloethanes and the corresponding methyl halides. Bond-energy-bond-order (BEBO) calculations for bromine atom attack on CH3CH2X (X = H, F, Cl, Br) show that this empirical model predicts correctly both the trend and magnitude of the observed activation energies. As anticipated from the Hammond postulate, "late" transition states with bond orders of n(R...H) = 0.15 to 0.18 are predicted for these endothermic processes.
Photodecomposition of Gaseous Bromoethane at 163.4 nm
Jung, Kyung-Hoon,Choi, Young Sik,Yoo, Hee Soo,Tschuikow-Roux, E.
, p. 1816 - 1822 (2007/10/02)
The 163.4-nm photolysis of gaseous C2H5Br has been investigated at 298 K over the pressure range 2-100 torr, using a bromine lamp.The effects of additives, N2,CF4, and NO, were also studied.In the pure system the observed reaction products and their respective quantum yields are C2H4 (ca.0.36), C2H6 (0.42-0.79), C2H3Br(0.1-0.24), CH3CHBr2 (0.24-0.32) and n-C4H10 (0.01), most yields increasing with substrate pressure.An opposite trend is observed with increasing pressure of inert gases.The addition of NO as a radical scavenger completely supresses the formation of C2H6, C2H3Br, CH3CHBr2, and n-C4H10, and partially reduces the yield of C2H4.The results are interpreted in terms of the initial formation of two electronically excited states which are linked by way of a pressure dependence, one of which yields C2H4 by molecular elimination of HBr, while the second decomposes by carbon-halogen bond fission.The kinetics of the secondary process are discussed in some detail.
Photolysis of 3-Bromo-3-methyldiazirine
Crespo, Maria T.,Figuera, Juan M.,Rodriguez, Juan C.,Utrilla, Roberto Martinez
, p. 5790 - 5796 (2007/10/02)
The photolysis at 354 nm of 3-bromo-3-methyldiazirine in gas phase has been studied.After a careful search of the various possibilities we have found that all available evidence points toward the intermediary formation of hot vinyl bromide, presumably via isomerization of the corresponding carbene.Its unimolecular decomposition can take place by two different paths: one is the molecular detachment of HBr and the other the radical scission of the C-Br bond.This last way of radical formation is responsible for the apparently confusing experimental data.According to our result the activation energy for the radical decomposition is closer to that of the molecular detachment than previously thought.
Two channel competitive photodecomposition reaction of gaseous bromoethane at 193.1 nm
Jung, Kyung-Hoon,Lee, Chong Mok,Yoo, Hee Soo
, p. 2486 - 2489 (2007/10/02)
The vacuum ultraviolet photolysis of gas phase bromoethane at 193.1 nm (6.42 eV) was studied over the pressure range of 1.1-303.2 Torr at room temperature using a carbon atom lamp.The pressure effect with and without inert gas, i.e., He or N2, was investigated.A scavenger effect of the reaction was also observed by adding NO as a radical scavenger.The principal reaction products were C2H6, C2H4, 1,1-C2H4Br2, and N-C4H10.The quantum yields of C2H4 and C2H6 were found to increase slightly with the reactant pressure.When the pressure of He or N2 was varied at a constant pressure of C2H5Br, however, the quantum yields of C2H4 and C2H6 were found to be pressure independent.Addition of NO completely suppressed the formation of C2H6, C2H4Br2, and C4H10, and partially reduced that of C2H4.These results were interpreted in terms of two channel competition between the molecular elimination and the formation of radicals.Two different decomposition modes were 82percent radical reaction and 18percent molecular elimination.
Thermocatalytic Reactions of 1,1-Bromochloroethane
Bushneva, L. I.,Levanova, S. V.,Rodova, R. M.,Rozhnov, A. M.
, p. 1403 - 1404 (2007/10/02)
The thermocatalytic reactions of 1,1-bromochloroethane have been investigated and the thermodynamic characteristics (ΔH0T and ΔS0T) of the disproportionation and dehydrohalogenation reactions have been obtained.The thermodynamic functions (ΔH0f and S0) of 1,1-bromochloroethane have been estimated and the deviation of the enthalpy of formation from additivity owing to the Cl-Br mutual influence in the gem-positions has been determined.
