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

1999 ◽  
Vol 44 (4) ◽  
pp. 678-683 ◽  
Author(s):  
Hassan A. Azab ◽  
Kholoud M. Aboul Nour
Keyword(s):  
Organic Solvent ◽  
Dissociation Constants ◽  
Medium Effect ◽  
Solvent Mixtures ◽  
Second Stage ◽  
Physiological Research

Mathematical representation of apparent dissociation constants in aqueous–organic solvent mixtures

2002 ◽  
Vol 246 (1-2) ◽  
pp. 135-142 ◽  
Author(s):  
Abolghasem Jouyban ◽  
Hak-Kim Chan ◽  
Brian J. Clark ◽  
William E. Acree
Keyword(s):  
Organic Solvent ◽  
Dissociation Constants ◽  
Mathematical Representation ◽  
Solvent Mixtures

Solvent effects on dissociation of substituted benzenesulphonamides in acetone, 1,2-dichloroethane, tetramethylene sulphone, pyridine and some aqueous organic solvent mixtures

1986 ◽  
Vol 51 (9) ◽  
pp. 1948-1957 ◽  
Author(s):  
Miroslav Ludwig ◽  
Oldřich Pytela ◽  
Miroslav Večeřa
Keyword(s):  
Organic Solvent ◽  
General Formula ◽  
Potentiometric Titration ◽  
Solvent Effects ◽  
Dissociation Constants ◽  
Dimethyl Sulphoxide ◽  
Organic Component ◽  
Solvent Mixtures

The potentiometric titration has been used to measure dissociation constants of fifteen substituted arenesulphonamides of general formula XC6H4SO2NH2 (or X2C6H3SO2NH2) in acetone, 1,2-dichloroethane, tetramethylene sulphone, pyridine, and mixtures water-ethanol (25, 50, 75, 90% by vol. of the organic component), water-dimethylformamide (25, 50, 75% by vol.), water-acetone (25% by vol.), and water-2-methoxyethanol (80% by wt.). The results are compared with those published earlier for water, methanol, ethanol, dimethylformamide, dimethyl sulphoxide, and acetonitrile.

Further studies an the extended Hammett equation comprising the hydrophobic constant: Reactivity data for benzoic acids, arylacetic acids, β-arylpropionic acids, trans- and cis-cinnamic acids, methyl benzoates; dissociation constants, DDM reaction and alkaline hydrolysis in various water-organic solvent mixtures

1990 ◽  
Vol 55 (1) ◽  
pp. 119-135 ◽  
Author(s):  
Anthonius J. Hoefnagel ◽  
Bartholomeus M. Wepster
Keyword(s):  
Organic Solvent ◽  
Alkaline Hydrolysis ◽  
Dissociation Constants ◽  
Solvent Mixtures ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
Cinnamic Acids ◽  
Tert Butanol ◽  
Arylacetic Acids

The extended Hammett eguaition Δ = ρs + hπ comprising the hydrophobic constant π is found to be effective in the title compounds and reactivities in various solvent mixtures. In 32 vol.% tert-butanol-water hmdecreases in the order ArCOOMe (-0.25), cis-ArCH=CHCOOH (-0.18), ArCOOH and ArCH2COOH (-0.16), ArCH2CH2COOH and trans-ArCH=CHCOOH (-0.07). For ArCOOH, mixtures like 40-60% methanol, 50% ethanol, 50% acetone and 50% dioxane give similar hm values of circa -0.05. For ArCH2COOH the effects of 3-iodo and 4-iodo substituents are acid-weakening in 32% tert-butanol. The consequences of the hπ term for ρ, σ, and the averaging of σ values, are discussed.

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