S−H Bond Dissociation Enthalpies in Thiophenols:  A Time-Resolved Photoacoustic Calorimetry and Quantum Chemistry Study

Santos, Rui M. Borges dos; Muralha, Vânia S. F.; Correia, Catarina F.; Guedes, Rita C.; Cabral, Benedito J. Costa; Simões, José A. Martinho

doi:10.1021/jp025677i

Cited by 77 publications

(73 citation statements)

References 34 publications

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“…Although there are several experimental studies in which the energetics of PhOH‚‚‚S intermolecular bonds were determined, 12 we have found that the so-called ECW method, developed by Drago and co-workers, 13 provides an alternative and direct way of estimating that bond enthalpy in many solvents. 8,14,15 Regarding the enthalpy of solvation of the hydrogen atom, it is usually identified with the enthalpy of solvation of H 2 , which is nearly constant for organic solvents (1.2 ( 0.2 kcal mol -1 ). 8 However, it is important to stress that this value becomes redundant when the PhO-H gas-phase bond dissociation enthalpy relies on DH°s ln (PhO-H) obtained from photoacoustic calorimetry (PAC) experiments.…”

Section: Introductionmentioning

confidence: 99%

Solvent Effects on the Energetics of the Phenol O−H Bond: Differential Solvation of Phenol and Phenoxy Radical in Benzene and Acetonitrile

et al. 2003

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Monte Carlo statistical mechanics simulations, density-functional theory calculations, time-resolved photoacoustic calorimetry, and isoperibol reaction-solution calorimetry experiments were carried out to investigate the solvation enthalpies and solvent effects on the energetics of the phenol O-H bond in benzene and acetonitrile. A good agreement between theoretical and experimental results is obtained for the solvation enthalpies of phenol in benzene and acetonitrile. The theoretical calculations also indicate that the differences between the solvation enthalpies of phenol (PhOH) and phenoxy radical (PhO • ) in both benzene and acetonitrile are significantly smaller than previous estimations based on the ECW model. The results for the solvation enthalpies are used to obtain the O-H bond dissociation enthalpies in benzene and acetonitrile. For benzene and acetonitrile, the theoretical results of 89.4 ( 1.2 and 90.5 ( 1.7 kcal mol . A detailed analysis of the solvent contributions to the differential solvation enthalpy is made in terms of the hydrogen bonds and the solute-solvent interactions. Both PhOH and PhO• induce a significant, although equivalent, solvent reorganization enthalpy. Finally, the convergence of the solute-solvent interaction is analyzed as a function of the distance to the solute and illustrates the advantages and limitations of local models such as microsolvation and hydrogen-bond-only models.

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Section: Introductionmentioning

confidence: 99%

Solvent Effects on the Energetics of the Phenol O−H Bond: Differential Solvation of Phenol and Phenoxy Radical in Benzene and Acetonitrile

et al. 2003

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“…Literatures values of the bond enthalpy of dissociation (BDH) of C 6 H 5 S–H bond shows significant disparity in the range of 77.5 kcal/mol–85.9 kcal/mol [27]. Herein, BDH of C 6 H 5 S–H is reevaluated using isodesmic work reactions as:

C_{6} H_{5} SH + X^{‧} \to C_{6} H_{5} S + XH

where X is considered to be one of the sulfur-centered radicals of HS, CH 3 S. This method is shown to provide accurate BDH values by deploying reference species with well-known enthalpies of formation (errors not greater than ±0.50 kcal/mol) while maintaining the same number of radical species on both sides of the reaction [28].…”

Section: Resultsmentioning

confidence: 99%

Theoretical derivation for reaction rate constants of H abstraction from thiophenol by the H/O radical pool

Batiha

Altarawneh

Al-Harahsheh

et al. 2011

Computational and Theoretical Chemistry

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Reaction and activation energy barriers are calculated for the H abstraction reactions (C6H5SH + X• → C6H5S + XH, X = H, OH and HO2) at the BB1K/GTLarge level of theory. The corresponding reactions with H2S and CH3SH are also investigated using the G3B3 and CBS-QB3 methods in order to demonstrate the accuracy of BB1K functional in finding activation barriers for hydrogen atom transfer reactions. Arrhenius parameters for the title reactions are fitted in the temperature range of 300 K–2000 K. The calculated reaction enthalpies are in good agreement with their corresponding experimental reaction enthalpies. It is found that H abstraction by OH radicals from the thiophenol molecule proceed in a much slower rate in reference to the analogous phenol molecule. ΔfH298o of thiophenoxy radical is calculated to be 63.3 kcal/mol. Kinetic parameters presented herein should be useful in describing the decomposition rate of thiophenol; i.e., one of the major aromatic sulfur carriers, at high temperatures.

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“…The molar enthalpy of the bond dissociation of the enolic hydrogen in the monothio-b-diketones, D m (S-H, HbdikS, enol, g) was considered to be the same as the S-H bond dissociation enthalpy in the thiophenol [43], (349 ± 30) kJ Á mol À1 in order to derive the hD m i (Zn-L) in the zinc(II) monothio-b-diketonate complexes. Table 7 lists the mean bond dissociation enthalpies of Zn(II) to ligand, hD m i (Zn-L), in both the zinc(II) b-diketones and monothio-b-diketones with the values seeming to show some energetic differences on the binding of the Zn(II) to the different ligands.…”

Section: Discussionmentioning

confidence: 99%

Standard molar enthalpies of formation of zinc(II) β-diketonates and monothio-β-diketonates

Silva

Santos

Giera

2008

The Journal of Chemical Thermodynamics

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Keywords: Standard molar enthalpy of formation Enthalpy of dehydration High temperature Calvet microcalorimetry Zinc(II) b-diketonates Zinc(II) monothio-b-diketonates Solution calorimetry Zn(II)-ligand mean molar dissociation enthalpies Bis(dibenzoylmethanate)zinc(II) Bis(thenoyltrifluoroacetonate)zinc(II) Diaquobis (thenoyltrifluoroacetonate) zinc(II) Bis(mono-thiodibenzoylmethanate)zinc(II) Bis[monothiothenoyltrifluoroacetonate] zinc(II) a b s t r a c tThe standard (p = 0.1 MPa) molar enthalpies of formation of crystalline bis(dibenzoylmethanate)zinc(II), Zn(DBM) 2 , diaquobis(thenoyltrifluoroacetonate)zinc(II), Zn(TTFA) 2 (H 2 O) 2 , bis(monothiodibenzoylmethanate)zinc(II), Zn(HDBMS) 2 , and bis(monothio-thenoyltrifluoroacetonate)zinc(II), Zn(HTTFAS) 2 , were determined, at T = 298.15 K, by high precision solution-reaction calorimetry. The standard molar enthalpy of dehydration of the diaquobis(thenoyltrifluoroacetonate)zinc(II), Zn(TTFA) 2 (H 2 O) 2 , complex was measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar dissociation enthalpies zinc(II)-ligand, hD m i(Zn-L), were derived.kJÁmol À1 Bis(dibenzoylmethanate)zinc(II), Zn(DBM) 2 À546.9 ± 4.0 Diaquobis(thenoyltrifluoroacetonate)zinc(II), Zn(TTFA) 2 (H 2 O) 2 À2556.2 ± 8.4 Bis(monothiodibenzoylmethanate)zinc(II), Zn(DBMS) 2À107.0 ± 5.9 Bis(monothiothenoyltrifluoroacetonate)zinc(II), Zn(TTFAS) 2 À1563.6 ± 8.0

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S−H Bond Dissociation Enthalpies in Thiophenols: A Time-Resolved Photoacoustic Calorimetry and Quantum Chemistry Study

Cited by 77 publications

References 34 publications

Solvent Effects on the Energetics of the Phenol O−H Bond: Differential Solvation of Phenol and Phenoxy Radical in Benzene and Acetonitrile

Solvent Effects on the Energetics of the Phenol O−H Bond: Differential Solvation of Phenol and Phenoxy Radical in Benzene and Acetonitrile

Theoretical derivation for reaction rate constants of H abstraction from thiophenol by the H/O radical pool

Standard molar enthalpies of formation of zinc(II) β-diketonates and monothio-β-diketonates

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