The ratios of the zwitterion form to the uncharged form of glycine, KD=[NH3+CH2COO−]/[NH2CH2COOH], were determined in mixtures of water with methanol, ethanol, t-butyl alcohol, dimethyl sulfoxide, acetonitrile, 1,4-dioxane, N,N-dimethylformamide, and tetrahydrofuran. The value of In KD decreases and, therefore, ΔG298° increases, with the increase in the mole fractions of the organic solvents. The plots of ΔG°  vs. reciprocal of the dielectric constants of the alcoholic mixtures are simply linear indifferent to the kind of alcohols, indicating that this relation obeys the Scatchard equation and that the free energy change of the process of the intramolecular protonation in glycine is controlled mainly by electrostatic interaction, especially by the entropy change associated with the preferential solvation around the charged amino and carboxyl groups.

The effects of various kinds of alcohol on the temperature of the maximum density of water were observed. The results revealed are as follows : 1) The change in the temperature of the maximum density due to alcohols, ΔT, is not proportional to the solute concentration, disobeying Despretz’s rule and in contrast with ordinary electrolytes. 2) The ΔT for univalent aliphatic alcohols at low concentrations is generally positive; that for tert-butyl alcohol is the largest. The ΔT is likely to become high as the number of carbon atoms and the degree of branching in alkyl radicals increase. 3) The elevation of the temperature of the maximum density due to the interaction of alcohol and water, ΔT′, depends upon the weakness of the cohesion of alcohol and the strength of the hydration of the hydrophilic molecules. 4) As the concentration of alcohol increases, there occurs a lowering of ΔT as a result of interaction between the solute molecules themselves. Similar interactions are seen between different alcohol molecules in ternary systems, but can not be seen between alcohol and electrolytic ions, where the solutes behave independently of each other. In the last case, the additivity of ΔT is realized fairly well.

The temperature of the maximum density (T. M. D.) of aqueous solutions of various organic polar substances at various concentrations were measured dilatometrically, and the degrees of elevating the T. M. D., ΔT, were estimated. The information derived from the experimental results includes: 1) At any concentration, the values of ΔT for all substances used in the present study are inevitably negative, in contrast with the cases of alkyl monovalent alcohols, reported on in the preceding paper. 2)ΔT′, defined as the difference between the actual elevation of T. M. D. and that when the solution is assumed to be an ideal mixture, is given by an empirical formula, ΔT′=ax+bx2, where a is a characteristic constant of the solute, indicating the degree of the interaction between the solute and water; it generally has a more negative value as the substance is more polar. 3) Benzene does not interact with water; therefore, ΔT′=0 and a=b=0 in so far as it is soluble in water. 4) An additivity correlation concerning a is realized from the composing radicals, and the a values assigned to respective radicals show a simple parallelism with their own polarities. 5) The b parameter is negative for all substances ; the absolute value of this is greater as the molar volume becomes larger.

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