Proton nuclear magnetic resonance study of diamagnetic cation association with hydroxylic substates. Interpretation of ionic molal shifts in methanol and water

Stockton, Gerald W.; Martin, John S.

doi:10.1021/ja00775a010

Cited by 30 publications

(9 citation statements)

References 5 publications

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“…for isodielectric solvent systems, but further consideration of the electrostatic terms necessary in the discussion of other systems is required. It is hoped that this present work, which coordinates, correlates, and advances progress made by other workers (7,18,19,20,45,46,61,62,66,67,68), will stimulate systematic experimental investigations of suitable systems by both spectroscopic and ther- …”

Section: Discussion and Criticisms Of The Present Approachsupporting

confidence: 58%

Thermodynamics of Preferential Solvation of Electrolytes in Binary Solvent Mixtures

Covington

Newman

1976

Thermodynamic Behavior of Electrolytes in Mixed Solvents

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The solvation changes of an ion, as the composition of a binary solvent is varied, can be treated on the basis of n successive equilibria where n is the solvation number. From a detailed consideration of the thermodynamics of preferential solvation, it is possible to define a free energy of preferential solvation ∆G ps ө and relate it to the more familiar free energy of trans fer, ∆G ps ө determinable for a neutral combination of ions from emf measurements. The treatment can be modified to include a case of change of solvation number and to non-statis tical distribution of the solvated species. When separate sol vent NMR signals from solvation shells can be detected or mixed solvates isolated, a further development enables a satis factory explanation to be given for the observed distribution of solvated species.

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Section: Discussion and Criticisms Of The Present Approachsupporting

confidence: 58%

Thermodynamics of Preferential Solvation of Electrolytes in Binary Solvent Mixtures

Covington

Newman

1976

Thermodynamic Behavior of Electrolytes in Mixed Solvents

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“…What is observed then. is an overali effect on the chemical shift (1,12), as the shift dra~vs contributions from ion-solvent interaction as well as changes in solvent structure (13,14).…”

Section: Methodsmentioning

confidence: 99%

Nuclear magnetic resonance study of electrolytes in 1,3-dimethylethyleneurea

Rosenfarb¹,

Caruso²

1976

Can. J. Chem.

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JOSEPH ROSENFARB and JOSEPH A . CARUSO. Can. J. Chem. 54, 3492 (1976). A series of lithium, sotlium. potassium, and ammonium salts were investigated by proton magnetic resonance spectroscopy in 1,3-di1nethyIethylene~~rea. a relatively new non-aqueous solvent of high polarity and moderately high dielectric constant. The salts were found to shift the solvent proton peaks linearly as a function of salt concentration. Thiosulfate, perchlorate, and iodide salts shifted the solvent peaks downfield while tetraphenylborate salts uniquely shifted the peaks upfield indicating an ~~n u s u a l type of solvation behavior for the tetraphenyiborates in this solvent.JOSEPH ROSENFARB et JOSEPH A. CARUSO. Can. J. Chem. 54, 3192 (1976). On a CtudiC par rmil du proton dans la dimCt11y-1-1.3 ethylkne urke un solvant non aqueux relativement nouveau de haute polarit6 et de constante dieiectrique modCree, une sCrie de sels de lithium, de sodium, de potassium et d'ammonium. On a trouve que les sels dkplacent les signaux des protons du solvant d'une f a~o n lineaire en fonction de la concentration du sel. Les sels du thiosulfate. du perchlorate et de l'iodure deplacent les pics du solvant vers les bas champs alors que les sels du tCtraphinylborate sont les seuk B tiiplacer les pics vers les hauts champs; ces resultats indiquent un type particulier de colnportemene desolvatation des iCtraphenylborates dans ce solvant.[Traduit par le journal]Proton magnetic resonance which has been used to investigate the solvation behavior of ions in aqueous solutions (1-4) has bcen extended t o non-aqueous media as well (5). Recently 1,3-dimethylethyleneiirea (DMEU) has been investigated with regard t o somc of its fundamental properties (0) and to the behavior of electrolytes therein (7,8). It was found that DMEU is a solvent of high polarity (4.09 in dioxane) (9), moderately high dielectric constant (37.6 at 1 MHz) (6). and possesses good dissociative power towards electrolytes, comparable to that of hr-methyl-2-pyrrolidone and methanol. Particularl!~ interesting kvas the property that sodium and potassiu:~~ salts were isoconducting in DMEU (7). Therefore further study into the nature of solvation in DMEU was indicated.cipitates were thoroughly washed with deionized water, dried, and recrystallized from acetone with water portions. All salts were finely ground and dried in the appropriate manner (5, 7, 10).DMEU was freshly prepared as previously described (6) and had a specific conductance of about 5 X ohm-' ~111-1. MeasurenzetztsChemical shift data were obtained using a Varian A-60 nmr spectrometer. Tetramethylsilane ( 5 ' ; ) was used as an internal reference from which peak shifts were calculated. Since an internal reference was used. no bulk diamagnetic correctio~s were applied (11). Shift data were reproducible to t 0.3 Hz or 0.005 ppm.Results and Discussion A number of alkali halides, tetraalkylammonium salts, and multivalent salts have been investigated in aqueous solution (1,12). It was Experimentalobserved that a downfield (negative) shift of...

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“…The relatively small influence of NEt4C104 on p~~0 brings some justification in the use of perchlorate and tetraethylammonium salts to study hydration of small cations and anions respectively as was done by other workers. [6][7][8] Some vapor pressure measurements were made on the systems H2O-salt-DMSO with 0.7 M Et4NC1, Et4NC104, LiC104, KC104, and Ca(C104)2, but the total pressures were comparable to the vapor pressure of pure DMSO, so that no accurate water partial pressures could be calculated by difference. The K 1 and K2 values for C1-and Li+ obtained from measurements on the systems H20-0.5 M NEt4CI (and LiC104)-TMS are included in Table 11.…”

Section: Tmsmentioning

confidence: 99%

Hydration of ions in dipolar aprotic solvents

Benoit¹,

Lam²

1974

J. Am. Chem. Soc.

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Interactions between water at low concentrations and 1:l electrolytes have been studied in four dipolar aprotic solvents of increasing basicity: sulfolane (TMS) < acetonitrile (AN) < propylene carbonate (PC) << dimethyl sulfoxide (DMSO). The experimental methods used involved solubility, proton nmr, vapor pressure, and calorimetric determinations. Results are interpreted in terms of hydration constants K1 and enthalpies Ail1 for the 1:l complexes with CI-, NO3-, H+, Li+, Na+, and Ag+ ions in most of the cited solvents. The K1 values are somewhat insensitive to the nature of the ion, except for H+, but sensitive to the nature of the solvent. For DMSO all Kl values are particularly low, thus accounting for this solvent retaining its dipolar aprotic character in the presence of some water. The values of K1 (CI-) are directly proportional to Henry's law constants for water in each solvent. The enthalpy changes AH1 are low and nearly equal for the replacement of one AN or PC molecule by one water molecule in the solvation shells of CI-and Li+. It follows that the strong solvation of CI-by bulk water is due to cooperative effects. Comparison of the AH1 values with gas-phase ionic hydration enthalpies shows contrasting behavior for negative and positive ions. The calculated values of the solvation enthalpies of the hydrated ions are discussed. Some comments are made regarding the acidity of H@+ in solvents. The comparison of rates or equilibrium constants of ionic reactions in water with those in dipolar aprotic (DPA) solvents has received a great deal of attention.] The observed solvent effects have been discussed in terms of changes in ionic solvation energies. Relatedly, the behavior of binary mixtures of water-DPA solvents offers further interest; a first step in understanding ionic solvation in these complex media is to study water-poor binary mixtures. A knowledge of ionic hydration in such aqueous media also throws light on the role of water as a solvent, since the self-association of water in DPA solvents may be reduced or eliminated according to its concentration and the basicity of the ~o l v e n t .~ It can then be advanced that ionic hydration in aqueous DPA solvents bears some relation to the now well-documented hydration of ions in the gas phase.4The present work was undertaken to study the interactions between water at low concentrations and 1:l electrolytes, mainly perchlorates and tetraethylammonium salts, in four DPA solvents, in order to provide thermodynamic data for a comparison of the hydration of C1-, NO3-, H+, Li+, Na+, and Ag+ in these aqueous media. The ions NO3-, Li+, Na+, and Ag+ were selected to afford an eventual comparison with hydration in molten nitrates and concentrated nitrate aqueous solutions. The DPA solvents chosen, sulfolane (TMS), acetonitrile (AN), propylene carbonate (PC), and dimethyl sulfoxide (DMSO) have different donor groups and increasing basicities in the order T M S < AN < PC << DMSO. The experimental methods used to obtain the 1:l ionic hydration constants or to redete...

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Proton nuclear magnetic resonance study of diamagnetic cation association with hydroxylic substates. Interpretation of ionic molal shifts in methanol and water

Cited by 30 publications

References 5 publications

Thermodynamics of Preferential Solvation of Electrolytes in Binary Solvent Mixtures

Thermodynamics of Preferential Solvation of Electrolytes in Binary Solvent Mixtures

Nuclear magnetic resonance study of electrolytes in 1,3-dimethylethyleneurea

Hydration of ions in dipolar aprotic solvents

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