Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part V. The halogen acids in 10, 20, 40, and 60%(<scp>W/W</scp>) acetic acid–water mixtures at 25°

Bennetto, H. P.; Feakins, D.; Turner, D. J.

doi:10.1039/j19660001211

Cited by 21 publications

(7 citation statements)

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“…(b) The second is the greater stabilization of the proton in methanol + water mixtures relative to that in pure water through ion-solvent interaction (Bennetto et al 1966;Tomkins, 1966). This effect will generate a low activity coefficient of the proton, therefore causing a slight decrease in pK a2 * values.…”

Section: Resultsmentioning

confidence: 99%

Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

and

Nour

1999

J. Chem. Eng. Data

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The apparent second stage dissociation constants of piperazine-N,N-bis[2-hydroxypropanesulfonicacid] (POPSO), N-[2-hydroxyethy1]piperazine-N′-3-propane sulfonic acid (HEPPS), 2-[N-cyclohexylamino]ethanesulfonic acid (CHES) and mono[tris(hydroxymethyl)aminomethane] phosphate (Trizma) were determined at (25.0 ( 0.1) °C and I ) 0.1 mol dm -3 (KNO 3 ) by potentiometric pH titration in pure water and different hydroorganic solvent media. The organic solvents used were methanol and ethanol as amphiprotic hydrogen bond acceptor-donor (HBA-D) solvents, N,N-dimethylformamide (DMF), dimethy1 sulfoxide, acetone, and dioxane as hydrogen bond acceptor solvents, and acetonitrile as an HBA-HBD solvent. The ESAB2M computer program was used to refine the initial estimates of the apparent secondstage dissociation constants of the four zwitterionic buffers studied. pk a2 * values change with increasing organic content of the solvent mixture. The results obtained are discussed in terms of average macroscopic properties of the mixed solvents. The implications of the results with regard to specific solute-solvent interacions, particularly stabilization of zwitterionic species, are discussed. The effects of coorganic solvents on the acid dissociation equilibria have been interpreted using solvatochromic quantitative values of Kamlet-Taft hydrogen bond acidity and basicity (R, β) and dipolarity-polarizability π* of the solvent.

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Section: Resultsmentioning

confidence: 99%

Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

and

Nour

1999

J. Chem. Eng. Data

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“…2. The greater stabilization of the proton in methanolwater or ethanol-water mixtures relative to that in pure water through ion-solvent interaction (15,16). This effect will generate a low activity coefficient of the proton in alcoholCan.…”

Section: Resultsmentioning

confidence: 99%

Medium effect on the second-stage dissociation constant of N-(2-acetamido)imino diacetic acid (H₂ADA)

Hassan¹,

Azab²,

Gyar³

et al. 1992

Can. J. Chem.

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The second-stage dissociation constant values of N-(2-acetamido)imino diacetic acid (H2ADA) were determined at 25 ± 0.1 °C by potentiometric titration in different mixed-solvent mixtures (methanol, ethanol, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, and dioxane). It was observed that the pKa value is slightly influenced as the solvent is enriched in methanol and ethanol, and remains practically constant in the presence of different amounts of DMF and DMSO. A prounounced change in the pKa value was observed as the solvent is enriched in acetone or dioxane. These results are discussed in terms of various solvent characteristics. It is concluded that the electrostatic effect has only a relatively small influence on the dissociation equilibrium of the imino group [Formula: see text]. Other solvent effects such as solvent basicity, different stabilization of the free base of the conjugate acid by hydrogen bonding interactions in aquoorganic solvent media relative to pure aqueous media, as well as proton–solvent interaction play an important role in the acid dissociation equilibrium.

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“…(b) The greater stabilization of the proton in methanol + water mixtures relative to that in pure water through ion-solvent interaction (Bennetto et al, 1966;Tomkins, 1966).…”

Section: Mops Ampso and Heppso Possess The Following Zwitterionic Str...mentioning

confidence: 99%

Apparent Second-Stage Dissociation Constants of Some Zwitterionic Buffers for Biochemical and Physiological Research in Various Hydroorganic Media

1998

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The apparent second-stage dissociation constants of 3-(N-morpholino)propanesulfonic acid, 3-[(1,1dimethyl-2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid, and N-(2-hydroxyethyl)piperazine-N′-(2-hydroxypropanesulfonic acid) were determined at (25.0 ( 0.1) °C and I ) 0.1 mol dm -3 (KNO 3 ) by potentiometric pH titration in pure water and different hydroorganic solvent media. The organic solvents used were methanol, ethanol as amphiprotic hydrogen bond acceptor-donor (HBA-D) solvents, N,Ndimethylformamide, dimethyl sulfoxide, acetone, dioxane as hydrogen bond acceptor solvents, and acetonitrile as (HBA-HBD) solvent. The ESAB2M computer program was used to refine the initial estimates of the apparent second-stage dissociation constants of the three zwitterionic buffers studied. pK a2 * values change with increasing organic content of the solvent mixture. The results obtained are discussed in terms of average macroscopic properties of the mixed solvents. The implications of the results with regard to specific solute-solvent interactions, particularly stabilization of zwitterionic species, are discussed. The effects of coorganic solvents on the acid dissociation equilibria have been interpreted using solvatochromic quantitative values of Kamlet-Taft hydrogen bond acidity and basicity (R, β) and dipolarity-polarizability π * of the solvent.

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Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part V. The halogen acids in 10, 20, 40, and 60%(W/W) acetic acid–water mixtures at 25°

Cited by 21 publications

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Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

Medium effect on the second-stage dissociation constant of N-(2-acetamido)imino diacetic acid (H₂ADA)

Apparent Second-Stage Dissociation Constants of Some Zwitterionic Buffers for Biochemical and Physiological Research in Various Hydroorganic Media

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Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part V. The halogen acids in 10, 20, 40, and 60%(W/W) acetic acid–water mixtures at 25°

Cited by 21 publications

References 0 publications

Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

Medium Effect on the Apparent Second Stage Dissociation Constants of Some Zwitterionic Buffers for Physiological Research in Various Water + Organic Solvent Mixtures

Medium effect on the second-stage dissociation constant of N-(2-acetamido)imino diacetic acid (H2ADA)

Apparent Second-Stage Dissociation Constants of Some Zwitterionic Buffers for Biochemical and Physiological Research in Various Hydroorganic Media

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Medium effect on the second-stage dissociation constant of N-(2-acetamido)imino diacetic acid (H₂ADA)