Studies on the Solubility and Dissociation Constants of Oxalic Acid in Aquo + Ethanolic Mixtures and Determination of Single-Ion Gibbs Energy of Transfer from Aqueous to Aquo + Ethanolic Mixtures

Gumtya, S. K.; Lahiri, S. C.; Aditya, S.

doi:10.1524/zpch.2002.216.8.971

Cited by 9 publications

(8 citation statements)

References 12 publications

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“…This value is lower than the molar conductivity reported by De Lisi et al (1976, 1978 for infinite dilution by a factor of about 2, and it is relevant to the concentration range (10 −3 -10 −2 M) studied in this paper. The molar conductivity of proton in alcoholic solutions (Table 1) and the conductivities of acid solutions measured in the present study are consistent with the dissociation constants of oxalic and phosphoric acid in alcoholic solutions reported by Bhattacharyya et al (1980), Bandyopadhyay and Lahiri (2002), Gumtya et al (2002), and Tossidis (1976). Apparently the ions located in the diffuse part of electric double layer are expected to have lower mobilities than bulk ions.…”

Section: Data-fitting Proceduressupporting

confidence: 91%

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Simple model of surface-induced electrolytic dissociation of weak acids in organic solvents

Kosmulski

2010

Adsorption

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The electric conductivity of solutions of oxalic and phosphoric acid (up to 0.025 M) in ethanol and methanol has been studied in the presence of TiO 2 (1-10% by mass). TiO 2 enhanced the conductivity of solutions of oxalic and phosphoric acid in the both alcohols. The experimentally observed behavior was successfully modeled using a model with two types of surface sites. Sites of the first type bind the acids in molecular form. Sites of the second type bind the acids in form of hydrogen oxalate and dihydrogen phosphate anions, respectively, and protons are released to the solution, and contribute to enhanced conductivity. The adsorption model properly reflects the electrokinetic potential of titania particles in alcoholic solutions of oxalic and phosphoric acid.

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Section: Data-fitting Proceduressupporting

confidence: 91%

“…3 The effect of TiO 2 on the conductivity of phosphoric acid in 94% ethanol. The model parameters are summarized in Table 2 oxalic acid in alcoholic solutions reported by Gumtya et al (2002). Probably the present model is not suitable for electrolyte solutions.…”

Section: Conductivitymentioning

confidence: 97%

Simple model of surface-induced electrolytic dissociation of weak acids in organic solvents

Kosmulski

2010

Adsorption

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“…Many solutes that are weak electrolytes in water become even weaker electrolytes in organic solvents. For example, p K a1 and p K a2 of oxalic acid are 4.2 and 8.2 in anhydrous ethanol, while in water the corresponding values are 1.3 and 4.3. The solubility of oxalic acid in anhydrous ethanol is 2.07 M, that is, almost two times higher than the solubility in water.…”

Section: Introductionmentioning

confidence: 99%

Surface-Induced Electrolytic Dissociation of Oxalic Acid in Polar Organic Solvents

Kosmulski¹,

Próchniak²,

Rosenholm³

2009

Langmuir

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The presence of titania powder (chiefly anatase) enhanced electrolytic dissociation of oxalic acid in lower aliphatic alcohols (but not in water). The surface-induced dissociation was manifested in enhanced electric conductance of a dispersion containing solvent, oxalic acid, and titania, which was substantially higher than the conductance of dispersion containing only solvent and titania and of solution of oxalic acid in that solvent. This phenomenon can be applied to control the electrokinetic potential of particles in polar organic solvents.

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“…Figure 11, for example, shows a comparison the solvent dependences of oxalic acid and acetic acid in EtOH−water mixtures. 25 An exception to this general behaviour is exhibited by maleic acid, which shows a greater contrast between the first and second pK a values. This is illustrated in Figure 12, which shows a comparison of the behaviours of maleic acid, fumaric acid, and acetic acid in MeOH−water mixtures.…”

Section: Solventsmentioning

confidence: 96%

“…The second dissociation constants behave in a qualitatively similar way but are normally slightly more sensitive to solvent variation, as are the second and third p K a values of citric acid. Figure , for example, shows a comparison the solvent dependences of oxalic acid and acetic acid in EtOH–water mixtures …”

Section: Dissociation Constants In Aqueous/solvent Mixturesmentioning

confidence: 99%

Acids, Bases, and Salts in Mixed-Aqueous Solvents

Cox

2015

Org. Process Res. Dev.

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The dependence of the dissociation constants of acids and bases and their tendency to form salts upon solvent composition in mixed-aqueous solvents are reviewed, along with the activities of the solvent components. The acid−base equilibria are dominated by preferential solvation of the ions by water molecules in the mixtures, compounded by the very high water activities across most of the solvent composition range; the neutral components are normally preferentially solvated by the organic component of the solvent mixture. Neutral acids, such as carboxylic acids and phenols, show only modest increases in pK a (1−2 pK units) in solvent mixtures containing up to 60−70 wt % organic component; thereafter is a much steeper, solventdependent increase to the value in the pure organic solvent. Cationic acids, such as protonated amines, anilines, and pyridines, display a universal decrease in pK a (∼1 pK unit) up until around 80 wt % organic solvent, almost independent of the nature of the base or the solvent; beyond this, there is a relatively strong increase in pK a to the value in the pure solvent. The protonation of amines by carboxylic acids becomes progressively more difficult as the organic content of the solvent mixtures increases, with equilibrium constants for protonation in 60 wt % solvent being typically reduced by 3 orders of magnitude relative to those in water. The solubilities of salts formed between simple carboxylic acids and amines with a strong difference in aqueous pK a values will show a monotonic decrease with added organic component of the solvent; where one of the acid or base species has a high "organic" (hydrophobic) component, the solubility will typically pass through a maximum as the organic content of the solvent mixture increases. In cases where salt formation is strongly limited in aqueous solution (acids and bases with similar pK a values), the solubilities of the salts will increase continuously with added organic component of the solvent.

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Studies on the Solubility and Dissociation Constants of Oxalic Acid in Aquo + Ethanolic Mixtures and Determination of Single-Ion Gibbs Energy of Transfer from Aqueous to Aquo + Ethanolic Mixtures

Cited by 9 publications

References 12 publications

Simple model of surface-induced electrolytic dissociation of weak acids in organic solvents

Simple model of surface-induced electrolytic dissociation of weak acids in organic solvents

Surface-Induced Electrolytic Dissociation of Oxalic Acid in Polar Organic Solvents

Acids, Bases, and Salts in Mixed-Aqueous Solvents

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