The standard molar enthalpy of formation of 2,3-dichlorodibenzo-p-dioxin

Papina, T. S.; Kolesov, V.P.; Lukyanova, V.A.; Golovkov, V. F.; Chernov, C.A.; Vorobieva, V.P.

doi:10.1006/jcht.1997.0308

Cited by 12 publications

(20 citation statements)

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“…The ∆G f values for Bz and DD were 31.0 kcal/mol 25 10 Isodesmic reactions other than reaction 1 could also be used for the evaluation of thermodynamic properties. For example, Leon et al 19 employed isodesmic reaction 6 that used poly-chlorinated benzenes (PCBs) as references to obtain calculated ∆H f values of PCDDs.…”

Section: Methodsmentioning

confidence: 99%

“…3 The thermodynamic data are also important in the studies of dioxin dechlorination and destruction processes. [4][5][6][7] However, experimental values of ∆H f are available for only three of 75 PCDD congeners (1-monochlorodibenzo-p-dioxin, 8 2-monochlorodibenzo-p-dioxin 9 and 2,3-dichlorodibenzo-p-dioxin 10 ), mainly because of experimental difficulties. In addition, experimental ∆H f values for chlorinated organic compounds may have significant uncertainties, because their combustion reactions in calorimetric measurements are often incomplete.…”

Section: Introductionmentioning

confidence: 99%

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DFT Calculation on the Thermodynamic Properties of Polychlorinated Dibenzo-p-dioxins: Intramolecular Cl−Cl Repulsion Effects and Their Thermochemical Implications

2003

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Polychlorinated dibenzo-p-dioxins (PCDDs) are one of the most intensively studied chemical pollutants. However, the absence of reliable thermodynamic data on PCDDs seriously limits quantitative understanding of their formation and distribution at combustion sources. By carrying out a DFT calculation (B3LYP/6-31G**) for thermodynamic properties of 75 PCDD congeners, we find that previous thermodynamic estimations on the gas-phase enthalpies of formation (∆H f ) and Gibbs free energy of PCDDs were seriously misestimated, particularly for highly chlorinated congeners, largely as a result of underestimating the intramolecular Cl-Cl repulsion energy. The disagreement between the DFT calculation and other methods becomes progressively larger with increasing chlorine substitution. Octachlorodibenzo-p-dioxin (OCDD) that has been considered as the most thermodynamically stable congener in previous calculations turns out to be much less stable. The differences in calculated ∆H f values between OCDD and the most toxic congener, 2,3,7,8-tetrachlorodibenzop-dioxin, or other laterally chlorinated (2,3,7,8-substituted) toxic congeners are within 1 kcal/mol. Most ∆H f values for congeners with five to eight chlorines differ by only 1-2 kcal/mol, since the decreasing electronic energies with increasing the number of chlorines in PCDDs are counterbalanced by increasing Cl-Cl repulsion energy. The intramolecular chlorine repulsion effects in PCDDs are systematically analyzed by using isodesmic reactions.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

DFT Calculation on the Thermodynamic Properties of Polychlorinated Dibenzo-p-dioxins: Intramolecular Cl−Cl Repulsion Effects and Their Thermochemical Implications

2003

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“…The corresponding values in DF are 0.5 and 2.15 kcal/mol. Enthalpies of formation and entropies derived by the GA rules of Zhu and Bozzelli were tested against the experimental values for 2,3-DCDD and 2,3,7,8-TCDD [225] where excellent agreement was obtained. As shown in Table 5, GA and semi-empirical methods have predicted a linear decrease in the enthalpies of formation, and hence more stabilization, with successive chlorination of dioxin moieties.…”

Section: Thermochemical Parameters and Their Influence On Pcdd/f Formmentioning

confidence: 98%

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

Altarawneh

Dlugogorski

Kennedy

et al. 2009

Progress in Energy and Combustion Science

429

279

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“…The value of = −74.1 ± 3.3 kJ/mol determined from calorimetric measurements 4 is in excellent agreement with calculated value of −76 ± 4 kJ/mol. As for 2,3-DCDD, the experimental value, −111.9 ± 6.9 kJ/mol, is substantially more negative than calculated one, −95 ± 5 kJ/mol. Note the uncertainty of the experimental value is rather large.…”

Section: Resultsmentioning

confidence: 51%

“…Because of the large number of PCDD congeners and the high toxicity of some isomers, experimental data on their thermodynamic properties are difficult to obtain. Only for dibenzo- p -dioxin (DD), 1-chlorodibenzo- p -dioxin (1-CDD), 2-chlorodibenzo- p -dioxin (2-CDD), and 2,3-dichlorodibenzo- p -dioxin (2,3-DCDD) were the enthalpies of formation determined from calorimetric studies. − As a result, the group contribution methods − and semiempirical calculations , were used to estimate the values for PCDDs. Quite recently the enthalpies of formation of the 10 most toxic PCDDs were computed by density functional B3LYP method using different types of isodesmic reactions .…”

Section: Introductionmentioning

confidence: 99%

Enthalpies of Formation of Dibenzo-p-dioxin and Polychlorinated Dibenzo-p-dioxins Calculated by Density Functional Theory

Дорофеева

Yungman

2003

J. Phys. Chem. A

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The enthalpies of formation for gaseous dibenzo-p-dioxin and 75 polychlorinated dibenzo-p-dioxin congeners were calculated at the B3LYP density functional theory level using isodesmic reactions. Calculated values are compared with experimental data for dibenzo-p-dioxin, 1-chlorodibenzo-p-dioxin, 2-chlorodibenzo-pdioxin, and 2,3-dichlorodibenzo-p-dioxin as well as with previous results from group additivity estimations and theoretical calculations. The calculated enthalpy of formation of dibenzo-p-dioxin, -52.8 ( 3.0 kJ/mol, is in good agreement with the recent experimental value of -50.1 ( 2.2 kJ/mol, whereas the discrepancies from experimental data for chlorinated dibenzo-p-dioxins range from 2 to 20 kJ/mol. The uncertainties of calculated enthalpies of formation are estimated to be from 3 to 30 kJ/mol.

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The standard molar enthalpy of formation of 2,3-dichlorodibenzo-p-dioxin

Cited by 12 publications

References 1 publication

DFT Calculation on the Thermodynamic Properties of Polychlorinated Dibenzo-p-dioxins: Intramolecular Cl−Cl Repulsion Effects and Their Thermochemical Implications

DFT Calculation on the Thermodynamic Properties of Polychlorinated Dibenzo-p-dioxins: Intramolecular Cl−Cl Repulsion Effects and Their Thermochemical Implications

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

Enthalpies of Formation of Dibenzo-p-dioxin and Polychlorinated Dibenzo-p-dioxins Calculated by Density Functional Theory

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