Alcohol, acidity constants basic properties

For example, comparing ethanol and water as acids in isopropanol solution, Hine and Hine found ethanol to be 0.95 as acidic as water, and Kolthoff found ethanol to be 0.002S as basic as water. Accordingly, considering acidic and basic properties alone, we might expect the autoprotolysis constant of ethanol to be 0.95 x 0.0025 x 10 or 2.4 X 10" . The actual value is smaller, 3 x 10" , evidently in part because the low dielectric constant of 25 causes more association than expected. In addition, the associated structure of water and alcohols in the liquid state complicates estimates of this type. 

Organic solvents influence the ionization constants of weak acids or bases in several ways (note that they influence the analytes and the buffer as well). Concerning ionization equilibria, an important solvent property is the basicity (in comparison to water), which reflects the interaction with the proton. From the most common solvents, the lower alcohols and acetonitrile are less basic than water. Dimethyl sulfoxide is clearly more basic. However, stabilization of all particles involved in the acido-basic equilibrium is decisive for the pKa shift as well. For neutral acids of type HA, the particles are the free, molecular acid, and the anion, A . In the equilibrium of bases, B, stabilization of B and its conjugated acid, HB, takes place. As most solvents have a lower stabilization ability toward anions (compared to water), they shift the pK values of adds of type HA to higher values in general. No such clear direction of the change is found for the pK values of bases however, they undergo less pronounced shifts. 

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