78-77-3Relevant articles and documents
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Noller,Dinsmore
, p. 1025,1028, 1030 (1932)
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PROCESSES FOR MAKING ALKYL HALIDES
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Page/Page column 8, (2010/09/18)
The invention is directed to processes for producing an alkyl halide, preferably isobutyl bromide. In one embodiment, the process comprises the steps of: (a) contacting an alcohol with a hydrogen halide in a reactor at elevated temperature under conditions effective to form an initial product mixture comprising the alkyl halide, the alcohol, the hydrogen halide and water; (b) cooling the initial product mixture to form a cooled organic phase positioned above a cooled aqueous phase; (c) separating the cooled organic phase from the cooled aqueous phase. The process preferably further comprises a step of: (d) heating at least a portion of the cooled aqueous phase under conditions effective to form additional alkyl halide.
Kinetics and thermochemistry of the R + HBr ? RH + Br (R = n-C3H7, isoC3H7, n-C4H9, isoC4H9, sec-C4H9 or tert-C4H9) equilibrium
Seetula, Jorma A.,Slagle, Irene R.
, p. 1709 - 1719 (2007/10/03)
The kinetics of the reactions of n-C3H7, isoC3H7, n-C4H9, isoC4H9, sec-C4H9 and tert-C4H9 radicals, R, with HBr have been investigated in a beatable tubular reactor coupled to a photoionization mass spectrometer. The reactions were studied by a time-resolved technique under pseudo-first-order conditions, where the rate constants of R + HBr reactions were obtained by monitoring the decay of the radical as a function of time. The radical was photogenerated in situ in the flow reactor by pulsed 248 nm exciplex laser radiation. All six reactions were studied separately over a wide range of temperatures and, in these temperature ranges, the rate constants determined were fitted to an Arrhenius expression (error limits stated are 1σ + Students t values, units cm3 molecule-1 s-1): k(n-C3H7) = (1.6 ± 0.2) × 10-12 exp[+(5.4 ± 0.2) kJ mol-1/RT], k(isoC3H7) = (1.4 ± 0.2) × 10-12 exp[+(6.9 ± 0.2) kJ mol-1/RT], k(n-C4H9) = (1.3 ± 0.2) × 10-12 exp[+(6.4 ± 0.4) kJ mol-1/RT], k(isoC4H9) = (1.4 ± 0.2) × 10-12 exp[+(6.1 ± 0.2) kJ mol-1/RT], k(sec-C4H9) = (1.4 ± 0.3) × 10-12 exp[+(7.5 ± 0.3) kJ mol-1/RT] and k(tert-C4H9) = (1.2 ± 0.3) × 10-12 exp[+(8.3 ± 0.3) kJ mol-1/RT]. The kinetic information was combined with the kinetics of the Br + RH reactions to calculate the entropy and the heat of formation values for the radicals studied. The thermodynamic values were obtained at 298 K using a second-law procedure. The entropy values and enthalpies of formation are (entropy in J K-1 mol-1 and enthalpy in kJ mol-1): 284 ± 5, 100.8 ± 2.1 (n-C3H7); 281 ± 5, 86.6 ± 2.0 (isoC3H7); 329 ± 5, 80.9 ± 2.2 (n-C4H9); 316 ± 5, 72.7 ± 2.2 (isoC4H9); 330 ± 5, 66.7 ± 2.1 (sec-C4H9) and 315 ± 4, 51.8 ± 1.3 (tert-C4H9). The C-H bond strength of analogous saturated hydrocarbons derived from the enthalpy of reaction values are (in kJ mol-1): 423.3 ± 2.1 (primary C-H bond in propane), 409.1 ± 2.0 (secondary C-H bond in propane), 425.4 ± 2.1 (primary C-H bond in n-butane), 425.2 ± 2.1 (primary C-H bond in isobutane), 411.2 ± 2.0 (secondary C-H bond in n-butane) and 404.3 ± 1.3 (tertiary C-H bond in isobutane). The enthalpy of formation values are used in group additivity calculations to estimate Δf H298○ values of six pentyl and four hexyl free radical isomers.
