Procedure for estimating the heats of formation of aromatic compounds: chlorinated benzenes, phenols and dioxins

Shaub, Walter M.

doi:10.1016/0040-6031(82)87008-1

Cited by 50 publications

(39 citation statements)

References 11 publications

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“…The results of our measurements and derived quantities estimated by Shaub. (1) This rather large disagreement is really not surprising. First of all, it was assumed (1) that the energy of replacement of a hydrogen atom with chlorine in dibenzo-p-dioxin was roughly equivalent to the energy of the same replacement in benzene.…”

Section: Resultsmentioning

confidence: 87%

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The standard molar enthalpy of formation of 2-chlorodibenzo-p-dioxin

Papina

Kolesov

Vorobieva

et al. 1996

The Journal of Chemical Thermodynamics

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Section: Resultsmentioning

confidence: 87%

“…In particular, D f H°m(g) values of all 75 PCDDs were estimated in 1982 by Shaub. (1) There is no doubt that all estimates will be more accurate if reliable experimental values of D f H°m for several model compounds are available.…”

Section: Introductionmentioning

confidence: 98%

The standard molar enthalpy of formation of 2-chlorodibenzo-p-dioxin

Papina

Kolesov

Vorobieva

et al. 1996

The Journal of Chemical Thermodynamics

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“…19) The thermodynamic data for Dioxins 17) and precursors 24) were the same as that of Yazawa et al, in which the species having the same molecular formula and the same toxic equivalent factor were summated. The carbon deposition was neglected in the thermodynamic evaluations of Dioxins, because Dioxins were not formed under low CO/CO 2 ratio with the carbon coexisted.…”

Section: Thermodynamic Evaluations On the Formation Of Dioxinsmentioning

confidence: 92%

Mechanism of Dioxins/Furans Formation at High Temperature in Combustion Processes.

et al. 2003

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To understand the mechanism of toxic dioxins/furans (Dioxins) formation in incineration processes, the combustion experiments were carried out with an electric furnace in laboratory scale at 1 073 K using mainly the powder of regent grade polyvinyl chloride (PVC powder) as a combustion material under a complete and an incomplete combustion conditions. In addition, the thermodynamic evaluations have been done on the formation and decomposition of Dioxins.Dioxins are formed even at the combustion temperature of 1 073 K under the conditions in which the fly carbonaceous matters exist. It is supposed that Dioxins are mainly formed on the surface of the fly carbonaceous matters where high CO/CO 2 ratio is established. Dioxins' concentration is correlated with the number of the fly carbonaceous matters in an exhaust gas. The formation/suppression of Dioxins is dependent upon the amount of the fly carbonaceous matters remained in the exhaust gas from the combustion furnaces.

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“…Therefore, theoretical studies can be relevant for understanding the mechanisms of PCDD formation in combustion processes. Most of the theoretical studies have focused on the determination of thermodynamic properties, [4,35,[40][41][42][43][44][45][46][47][48] while the remainder have analyzed the molecular geometry, [49][50][51] vibrational frequencies, [50] mechanisms of formation [35,[52][53][54][55] and decomposition, [56] and reactivity with OH radicals. [57] The mechanisms of formation of PCDDs involving anionic species have been studied less than those involving radicals and focusing only on the closure step of the central ring for PCDD formation.…”

Section: Introductionmentioning

confidence: 99%

Formation of Trichlorinated Dibenzo‐p‐dioxins from 2,4‐Dichlorophenol and 2,4,5‐Trichlorophenolate: A Theoretical Study

Suárez

Menéndez

et al. 2006

ChemPhysChem

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The reaction of the 2,4,5-trichlorophenolate anion with 2,4-dichlorophenol to afford trichlorinated dibenzo-p-dioxins (T3CDDs) is investigated at the B3LYP/6-31+G(d) and B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d)+ZPVE(B3LYP/6-31+G(d)) levels of theory. The first stage of the process corresponds to the formation of a predioxin, which can evolve through four different routes. Two of them lead directly to the products 2,3,7-T3CDD and 1,3,8-T3CDD, and the other two afford different predioxin-type intermediates, which in turn can evolve through all or some of the four routes to give new predioxins or T3CDD. Consequently, the theoretical results obtained show plainly the complex chemistry implied in the formation of dioxins from chlorophenols via anionic mechanisms by disclosing all the critical structures through which the system evolves, thus allowing assessment of the viability of the different mechanistic routes and the accessible products. The statistical thermodynamics treatment at 1 atm and 298.15, 600, 900, and 1200 K indicates that at higher temperatures, the Gibbs energy barrier for the formation of the initial predioxin is clearly the rate-determining step for the whole process, but at lower temperatures the Gibbs energy barrier for this step is similar to those for its evolution into 2,3,7-T3CDD. This result is in contrast with previous proposals that the closure of the central ring is the rate-limiting step. Finally, according to our results the rate constant for the formation of polychlorinated dibenzo-p-dioxins increases with the temperature, in agreement with the experimental observation that the conversion of trichlorophenols increases when going from 600 to 900 K in the gas phase in the absence of catalysts, and with DFT molecular dynamics results.

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Procedure for estimating the heats of formation of aromatic compounds: chlorinated benzenes, phenols and dioxins

Cited by 50 publications

References 11 publications

The standard molar enthalpy of formation of 2-chlorodibenzo-p-dioxin

The standard molar enthalpy of formation of 2-chlorodibenzo-p-dioxin

Mechanism of Dioxins/Furans Formation at High Temperature in Combustion Processes.

Formation of Trichlorinated Dibenzo‐p‐dioxins from 2,4‐Dichlorophenol and 2,4,5‐Trichlorophenolate: A Theoretical Study

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