Thermochemistry of Dihalogen-Substituted Benzenes: Data Evaluation Using Experimental and Quantum Chemical Methods

Abstract

Temperature dependence of vapor pressures for 12 dihalogen-substituted benzenes (halogen = F, Cl, Br, I) was studied by the transpiration method, and molar vaporization or sublimation enthalpies were derived. These data together with results available in the literature were collected and checked for internal consistency using structure-property correlations. Gas-phase enthalpies of formation of dihalogen-substituted benzenes were calculated by using quantum-chemical methods. Evaluated vaporization enthalpies in combination with gas-phase enthalpies of formation were used for estimation liquid-phase enthalpies of formation of dihalogen-substituted benzenes. Pairwise interactions of halogens on the benzene ring were derived and used for development of simple group additivity procedures for estimation of vaporization enthalpies, gas-phase, and liquid-phase enthalpies of formation of dihalogen-substituted benzenes.

Benzoic acid derivatives: Evaluation of thermochemical properties with complementary experimental and computational methods

“…Main requirements for the reference materials are stability, easy way for purification and purity attestation, non-hygroscopicity and possibly low cost. The methyl and methoxy substituted benzoic acids are good candidates to fulfill these requirements and to be used as the reference materials, provided that their thermochemical This contribution complements our previous work on thermochemistry of substituted benzenes [7][8]. The experimental and computational study of the methyl-and methoxy substituted benzoic acids presented in Fig.…”

“…It should be also mentioned, that similar disagreement between the theoretical and the experimental enthalpy of formation was observed for another 1,2-di-substituted benzene, namely 1,2-difluorobenzene [8]. In the frame of the current study we decided to prefer the experimental enthalpy of formation of 2-methoxybenzoic acid, but we shall pay attention to this disagreement in our future work.…”

Thermochemistry of Substituted Benzamides and Substituted Benzoic Acids: Like Tree, Like Fruit?

“…To reveal general tendencies, we collected the (g, 298.15 K) values for a wide range of substituted benzamides and benzoic acids (see Table ), as well as substituted benzenes (see Table S8 in the Supporting Information) available from the recent literature. It should be mentioned that the experimental data from each chemical family taken for the analysis of the structure–property relations have been carefully evaluated for the internal consistency in our previous work …”

Enthalpies of Vaporization and Sublimation of the Halogen-Substituted Aromatic Hydrocarbons at 298.15 K: Application of Solution Calorimetry Approach

“…The interaction of chlorine substituents in the 1,2 position is apparently also weak (about 1 kJ·mol −1 ) and could be neglected for the simplicity of calculations. 24 This simplification still keeps true for two (ortho Cl−Cl) contributions within the 1,2,3,5-tetrachlorobenzene, where the experimental and estimated enthalpies of vaporization are in close agreement (see Table 4). However, it could be expected that with increasing of number of ortho substituents on the aromatic rings the accumulation of the neglected interactions decrease the accuracy of estimation.…”