Ideal gas thermodynamic properties of selected bromoethanes and iodoethane

Abstract

The available molecular parameters, fundamental frequencies, potential barrier heights, torsional frequencies, and standard enthalpies of formation at 298.15 K for selected bromoethanes and iodoethane containing one symmetric-top group have been critically evaluated and recommended values selected. The chemical thermodynamic properties in the ideal gas state at one atmosphere pressure using the rigid-iotor harmonic-oscillator approximation have been calculated for CH3CH 2Br, CH3CHBr2, CH3CBr3, C2Br6, and CH3CH2I. The internal rotational c.ontributions have been obtained from the partition function formed by the summation of internal rotation energy levels.

Self-Consistent Heats of Formation for the Ethyl Cation, Ethyl Bromide, and Ethyl Iodide from Threshold Photoelectron Photoion Coincidence Spectroscopy

“…The recommended value of the ethyl bromide heat of formation of −42.63 kJ mol −1 from the PFI-PEPICO paper yields a heat of formation for ethyl iodide of Δ f H 0K ° [EtI] = 4.4 kJ mol −1 or Δ f H 298K ° [EtI] = −11.6 kJ mol −1 . This value is 4.4 kJ mol −1 lower than the latest calorimetry value, and 3.2 kJ mol −1 lower than an older literature number, , clearly outside of their confidence intervals. If we chose the Pedley et al value for the ethyl bromide heat of formation of Δ f H 0K ° [EtBr] = −39.8 ± 1.7 kJ mol −1 , the EtI 0 K heat of formation is 7.2 ± 2.0 kJ mol −1 , which agrees nicely with both literature values.…”

“…The value of the C 2 H 5 Br heat of formation is not well established, with 298 K literature values ranging from −67.8 to −61.9 kJ mol −1 . , Current thermochemical compilations list a value by Wagman et al of −64.52 kJ mol −1 (most likely a typo based on the work by Lane et al) and a higher value −61.9 ± 1.7 kJ mol −1 by Pedley et al A heat of formation of −63.6 ± 2.1 kJ mol −1 used by Kudchadker et al in a critical evaluation of the thermodynamic properties of bromo- and iodoethanes comes from Cox and Pilcher and falls between the extremes of the numbers above. On the basis of arguments that consider the heat of formation of the ethyl radical and cation, it has been concluded recently that the lower (Wagman) value is more likely.…”

Generalized Prediction of Enthalpies of Formation Using DLPNO‐CCSD(T) Ab Initio Calculations for Molecules Containing the Elements H, C, N, O, F, S, Cl, Br

“…Thus the final fitting set includes 45 species for the elements hydrogen, carbon nitrogen, and oxygen. A further 48 species include for the inclusion of fluorine and chlorine and 13 bromine compounds . Sulfur is included in 54 species .…”

Calculated One- and Two-Electron Reduction Potentials and Related Molecular Descriptors for Reduction of Alkyl and Vinyl Halides in Water

“…For these species, carefully reviewed ∆H f° values from the Journal of Physical and Chemical Reference Data (JPCRD) were generally utilized (Chao et al 1973Rodgers et al, 1974;Chen et al, 1975Chen et al, , 1976Kudchadker and Kudchadker, 1975, 1978, 1979. The one exception to this rule was the choice of the more recent values of Kolesov and Papina (Papina et al, 1982;Kolesov and Papina, 1983;Papina and Kolesov, 1987) over earlier values provided in the JPCRD.…”