We consider a quantitative framework that joins together a series of key energy parameters of chemical compounds: enthalpy of formation, atomization enthalpy, bond dissociation energy, mean thermochem-ical bond energies, and radical reorganization energy (i.e., the energy associated with reorganization of molecular fragments into corresponding radicals). The results of these calculations for more than 70 radicals are provided. A double difference technique is proposed for calculations of enthalpies of formation of radicals. The radical reorganization energies obtained here and in other studies are compared.

Standard vaporization enthalpies of 4-nitrobiphenyl and 1, 1′- biphenyl are obtained on an isothermal heat conducting Calvet microcalorimeter with an estimated accuracy of ≤ 1 per cent for the first time. Standard formation enthalpies of some biphenyl derivatives in state of gas are determined. The calculation scheme by a method by “a double difference” of formation enthalpies of aromatic radicals and bond dissociation energies is offered. Using fundamental equations of the chemical physics, the new calculation method is offered to determine the energies of reorganization of molecules fragments into radicals. Formation enthalpies of radicals, namely biphenyl-4-yl and 3-methylfurazan-4-yl, are determined. Reorganization energies of radicals and bond chemical energies have been calculated.

Enthalpies of vaporization, \( \Delta _{\text{vap}} H^{\circ }_{298} \), were determined for perfluorooctyl-1-bromide (PFOB) at the temperature 298.15 K. Measurements were performed on an adiabatic vaporization calorimeter for the first time. Saturated vapor pressures are determined for PFOB by an ebulliometry method in the temperature range from 329 to 414 K. A second-order group additivity method has been applied to predict the vaporization enthalpies of some perfluorocompounds. The contributions of methyl, isopropyl, octyl and bromo group to the vaporization enthalpies of the perfluorocarbons derivatives are estimated and aimed at either prediction of properties of fluids.

The enthalpies of formation of some biphenyl derivatives were determined. A "double difference" method for calculating the enthalpies of formation of aromatic radicals and the bond dissociation energies was proposed. The enthalpies of formation of the radicals biphenyl, diphenyl oxide, and phenyl oxide were determined. The energies of reorganization of these radicals as well as phenyl and 4-, 3-, and 2- pyridyls were calculated. The sums of the energies of the chemical bonds in the molecular moieties transformed into radicals upon the decomposition of chemical compounds were found to be constant for different compounds. The energies of the chemical bonds in arenes were determined.

The standard molar enthalpies of combustion for three methyl and dimethyl nitrooxazolidine derivatives in the liquid and crystalline states were determined using a high-precision static bomb combustion calorimeter. The resulting values were used to derive the standard molar enthalpies of formation of the azidomethyl-N-nitrooxazolidines. The standard molar enthalpies of vaporization for these compounds were measured using a Calvet microcalorimeter. The enthalpies of formation of some nitrooxazolidine-derived radicals and biradicals were calculated.

Enthalpies of vaporization, \( \Delta_{\text{l}}^{\text{g}} H_{\text{m}}^{\circ}, \) were determined for 3-isopropylbiphenyl in the temperature range from 323 to 373 K. Measurements were performed on an isothermal heat conducting Calvet microcalorimeter according to the standard procedure with an estimated accuracy of 0.7 per cent. The average values of the standard enthalpies of vaporization were adjusted to 298.15 K. The latter has been used to calculate the standard formation enthalpy for 3-isopropylbiphenyl in the gaseous state. A second-order group additivity method has been applied to predict the vaporization enthalpies of some cyclic compounds. The contributions of tert-butyl, methyl, and isopropyl group to the vaporization enthalpies of the aromatic hydrocarbon derivatives are estimated.

The energies of combustion of 4-methylbiphenyl and 4,4′-dimethylbiphenyl in the crystal state were measured in a precision calorimeter equipped with a self-sealing bomb at 298.15 K. The enthalpies of vaporization of these substances were measured in an isothermal heat-conducting Calvet microcalorimeter. Standard enthalpies of formation were calculated for 4-methylbiphenyl and 4,4′-dimethylbiphenyl in the crystal, liquid, and gas states.

Vapour pressure of 2-methyl-biphenyl, 3-methyl-biphenyl, 4,4'-di-methyl-biphenyl, 3-iso-propyl-biphenyl, 3-tert-butyl-biphenyl and 4,4'-di-tert-butyl-biphenyl were measured by the transpiration method. Vapour pressure of 3-iso-propyl-biphenyl, 3-tert-butyl-biphenyl and 4-tert-butyl-biphenyl measured by ebulliometry. Equations for temperature dependences of the saturated vapour pressures were derived. Molar standard enthalpies of vaporization at the reference temperature were calculated from temperature dependences of vapour pressures. Additionally, enthalpies of vaporization of 3-iso-propyl-biphenyl were directly measured in the temperature range from 323 to 373 K using an isothermal heat conducting Calvet microcalorimeter. The enthalpy of vaporization at the reference temperature 298 K of 3-iso-propyl-biphenyl was calculated from the experimental temperature dependence of vaporization enthalpy. The Ambrose-Walton equation was applied for correlation and prediction of vapour pressures and vaporization enthalpies of alkyl-substituted biphenyls. (C) 2012 Elsevier B.V. All rights reserved.

The standard massic energies of compounds of 4-tert-butylbiphenyl and 4,4′-di-tert-butylbiphenyl were measured at T=298.15K by static-bomb combustion calorimetry. The standard enthalpies of vaporization, fusion and sublimation were measured in a Calvet microcalorimeter, or by differential scanning calorimetry. The standard molar enthalpies of formation in the condensed and gaseous states were obtained from these data. The tert-butyl group increments for the substitution of one hydrogen atom in a position “4” in biphenyl molecule were calculated.

The enthalpies of vaporization of four compounds with three-membered rings (bicyclopropyl, 1,2-bicyclopropylacetylene, 1-cyclopropylpentadiine-1,3, and 1,2,2-trimethylcyclopropene) were determined calorimetrically. The temperature dependence of saturated vapor pressure of 1,2,2-trimethylcyclopropene was studied by ebulliometry, and the results were approximated by the equation ln p = A + B/T. The enthalpy of vaporization, normal boiling temperature, critical parameter, and similarity criterion according to the law of corresponding states in the variant suggested by Filippov were calculated. The calculated corrections to the enthalpy of vaporization (kJ/mol) for the cyclopropene ring containing methyl substituents are discussed in comparison with the data on related compounds.

The boiling temperatures of ethyl tert-butyl ether (ETBE), isobutyl tert-butyl ether (IBTBE), and di-isopropyl ether (DIPE) have been measured by comparative ebulliometry over the moderate pressure range 10.8⩽(P/kPa)⩽101.7. The equations of the temperature dependences of the saturated vapour pressures and enthalpies of vaporization have been derived. The normal boiling temperatures of the ethers were computed to be 345.84K, 386.06K, and 341.64K, respectively. The experimental data on the vapour pressure of the ethers under study were extended to the whole range of the liquid phases between critical and triple points by means of corresponding states law and combined treatment of the pT-parameters and low-temperature differences of the heat capacities of ideal gas and liquid, ΔCp=Cp∘(g)-Cp∘(l), respectively.