Carboxylic acids in dimethylsulfoxide. A calorimetric study

Benoit, R. L.; Louis, C.; Fréchette, Monique

doi:10.1016/0040-6031(90)87012-2

Cited by 5 publications

(3 citation statements)

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“…Accordingly, the difference between the free energies of protonation in the two media [(Δ(Δ G HAc o )] is strongly negative (Scheme and Table ). [Data in Table are taken from refs , , and − .] This is due: i), mainly, to the highly unfavorable free energy of transfer of acetate from water to DMSO (+50 kJ mol –1 ) and ii ), in part, to the favorable energy of transfer of acetic acid from water to DMSO (−14.2 kJ mol –1 ). , The former contribution is due to the poor solvation of acetate in DMSO and essentially determined by the unfavorable transfer enthalpy which is a consequence of the large energy (Δ H Ac tr = 65.4 kJ mol –1 , Table ) required to break the water hydrogen-bonding-network when acetate is transferred from water to DMSO …”

Section: Resultsmentioning

confidence: 99%

“… a From log K = 12.6 in ref . b Reference . c Reference , μ = 0.0 mol dm –3 . d Δ(Δ G HAc o ) = Δ G HAc,DMSO o –Δ G HAc,water o = Δ G HAc tr – Δ G H + tr – Δ G Ac – tr ; −44.8 = Δ G HAc tr – (−19.4) – (50 ± 4) = −14.2 ± 4. e Reference . f Reference . g This value has a large uncertainty (±4 kJ mol –1 ) as it is a weighed average of three measurements which span from 53.7 to 46.4 kJ mol –1 . h Δ G , Δ H , and T Δ S in kJ mol –1 . Δ(Δ X HAc o ) = Δ X HAc, DMSO o – Δ X HAc, water o = Δ X HAc tr – Δ X H + tr – Δ X Ac – tr . …”

Section: Resultsmentioning

confidence: 99%

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Energetics and Structure of Uranium(VI)–Acetate Complexes in Dimethyl Sulfoxide

et al. 2012

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The thermodynamics of the complexation between uranium(VI) and acetate in dimethyl sulfoxide (DMSO) was studied at 298 K in an ionic medium of 0.1 mol dm(-3) tetrabutyl ammonium perchlorate. The results show that the uranyl ion forms three strong successive mononuclear complexes with acetate. The complexes, both enthalpically and entropically stabilized, are significantly more stable in DMSO than in water. This feature can be ascribed to the weak solvation of acetate in DMSO. The thermodynamic parameters for the formation of the uranium(VI) complexes with acetate in DMSO are compared with those with ethylenediamine in the same solvent. The difference between the two ligand systems reveals that, for the complexation reactions involving charge neutralization, the reorganization of the solvent gives a very important contribution to the overall complexation energetics. The coordination mode of acetate in the uranyl complexes and the changes of the solvation sphere of UO(2)(2+) upon complexation were investigated by FT-IR spectroscopy in DMSO and in acetonitrile/DMSO mixtures. In addition, DFT calculations were performed to provide an accurate description of the complexation at the molecular level. The experimental and calculated results suggest that acetate is solely bidentate to UO(2)(2+) in the 1:1 and 1:3 complexes but mono- and bidentate in the 1:2 complexes. The DFT calculations also indicate that the medium effects must always be taken into account in order to gain accurate information on the complex formation in solution. In fact, the relative stability of the reaction products changes markedly when the DFT calculations are carried out in vacuum or in DMSO solution.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Energetics and Structure of Uranium(VI)–Acetate Complexes in Dimethyl Sulfoxide

et al. 2012

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“…More information is obtained from the discussion of the thermodynamic data of the association process and especially from those characterizing its non-Coulombic contributions, and derived from the relation = ; see eq 2. The tendency to form covalent bonds between the Li + ion and the acetate anion in the ion pair would result in a large negative value of about −45 kJ/mollike that obtained for acetic acid in DMSOwhich is not observed; see section 3.3.3. Upon fluorination of the acetate anion, enthalpies should be shifted more strongly toward less negative values than those quoted for chloroacetic acids in ref , −32 kJ mol -1 ( y = 1), −18 kJ mol -1 ( y = 2), and −1.8 kJ mol -1 ( y = 3), because fluorine is a more electronegative substituent.…”

Section: Resultsmentioning

confidence: 88%

Effects of Electronegative Substituents of Anions on Ion-Pair Formation. 1. Temperature Dependence of the Conductivity of Lithium Fluoroacetate and Alkali-Metal Acetate Solutions in Dimethyl Sulfoxide

1996

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The effect of electron-withdrawing substituents on ion−ion interactions is exemplified by conductivity studies on dimethyl sulfoxide solutions of lithium acetate and fluoroacetates. Association constants decrease upon increasing fluorine substitution by a factor of 50. They are correlated with mean oxygen charges calculated with the help of semiempirical quantum mechanical methods. The distance parameters from such calculations prove to be good estimates for the liquid state. Non-Coulombic contributions of the CH3COO- ion to the ion−ion interactions show stronger competition with solvent molecules in the solvation shell of the Li+ ion than the CF3COO- ion, which is a weak ligand in comparison to the dimethyl sulfoxide molecule.

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