Thermochemical Properties, ΔfH°(298.15 K), S°(298.15 K), and Cp°(T), of 1,4-Dioxin, 2,3-Benzodioxin, Furan, 2,3-Benzofuran, and Twelve Monochloro and Dichloro Dibenzo-p-dioxins and Dibenzofurans

Abstract

Values for ΔfH°(298.15 K), S°(298.15 K), and Cp°(T) (5⩽T/K⩽6000) are computed by density functional B3LYP/6-31G(d,p) and B3LYP/6-311+G(3df,2p) calculation methods for 12 monochloro and dichloro dibenzo-p-dioxins and dibenzofurans: 1-chloro dibenzo-p-dioxin, 2-chloro dibenzo-p-dioxin, 1,6-dichloro dibenzo-p-dioxin, 1,8-dichloro dibenzo-p-dioxin, 1,9-dichloro dibenzo-p-dioxin, 2,8-dichloro dibenzo-p-dioxin, 3-chloro dibenzofuran, 4-chloro dibenzofuran, 1,6-dichloro dibenzofuran, 3,6-dichloro dibenzofuran, 3,7-dichloro dibenzofuran, and 4,6-dichloro dibenzofuran. Molecular structures and vibration frequencies are determined at the B3LYP/6-31G(d,p) level of theory. Isodesmic reactions are utilized at each calculation level to determine the enthalpy of formation of each species. Contributions to the entropy and the heat capacity from translation, vibration, and external rotations are calculated using the rigid-rotor-harmonic-oscillator approximation based on the B3LYP/6-31G(d,p) structures. The enthalpies of formation for 1,4-dioxin, furan, 2,3-benzodioxin, 2,3-benzofuran, dibenzo-p-dioxin, and dibenzofuran are also calculated. Thermochemical properties of two composite central atom groups and four interaction groups are derived for use in a group additivity scheme to calculate these thermochemical properties of polychlorinated dibenzo-p-dioxins and dibenzofurans.

Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

“…Each ortho-or meta-Cl/Cl interaction is assumed to reduce the enthalpy of formation by 1.8 kcal/mol and 0.60 kcal/mol respectively. These GA rules of Dorofeeva et al [218] were reviewed by Zhu and Bozzelli [221]. They recommended adding 2.6 and 3.6 kcal/mol for each ortho-and meta-chlorine interaction in dibenzo-p-dioxin, respectively.…”

“…These comparisons were carried out by adjustments of vibrational frequencies, moments of inertia and other properties through transformation of the force constants from polycyclic hydrocarbons including dibenzofuran and dibenzo-p-dioxin. Isodesmic reactions were used by Zhu and Bozzelli [221] to determine the enthalpies of formation of various dioxin congeners using DFT (at the B3LYP/6-311 þ G(3df,2p)// B3LYP/6-31G(d) level). Their estimates for the enthalpies of formation of DF and DD were 13.9 and À14.4 and kcal/mol, respectively, in excellent agreement with experimental values.…”

Thermodynamic Parameters Including Acid Dissociation Constants for Bromochlorophenols (BCPs)

“…These isodesmic reactions utilize experimental values of Δ f H ° 298 for phenol (−96.3 ± 0.59 kJ mol –1 ), o -chlorophenol (−131 kJ mol –1 ), o -bromophenol (−78 ± 1.9 kJ mol –1 ), p -chlorophenol (−145.5 ± 8.4 kJ mol –1 ), p -bromophenol (−69.3 ± 2.1 kJ mol –1 ), benzene (82.9 ± 0.9 kJ mol –1 ), bromobenzene (105.4 ± 4.20 kJ mol –1 ), and chlorobenzene (52.4 ± 0.42 kJ mol –1 ) Table provides calculated reaction enthalpies for R1 (Δ R1 H ° 298 ) and R2 (Δ R2 H ° 298 ) and Δ f H ° 298 of the target species.…”

Formation of persistent organic pollutants from 2,4,5-trichlorothiophenol combustion: a density functional theory investigation

“…The accuracy of the B3LYP functional in the study of high temperature combustion reactions has also been widely demonstrated [24][25][26]. This is also the case regarding PCDD/F heats of formation [27]. The Gaussian09 [28] program was used to perform all structural and energy calculations.…”