Relative Strength of Benzoic and Salicylic Acids in Alcohol—Water Solutions

Abstract

Data on the influence of phosphates, sulfates and arsenates on the dissolution of aged colloidal aluminum hydroxide in 0.2 N hydrochloric acid, have been presented.2. Within certain limits, the amount of the hydroxide dissolved is a logarithmic function of the concentration of the electrolyte yielding bivalent and trivalent anions. The equations take the form = K log a + C.3. The influence of the anion of higher valence is attributed to adsorption at the solid-liquid interface which produces a reduction in the electrical potential difference.4. The findings are not in accord with the diffusion theory of reactions in heterogeneous systems.

Ionizable P1 Residues in Serine Proteinase Inhibitors Undergo Large pK Shifts on Complex Formation

“…Ionization of uncharged acids yields charged products. Therefore the large upward pK shift, seen upon addition of organic cosolvents to such acids, is expected (35)(36)(37). On the other hand, ionization of cationic acids involves a transfer of charge from the cationic reactant to the hydronium ion, which is one of the products.…”

“…On the other hand, ionization of cationic acids involves a transfer of charge from the cationic reactant to the hydronium ion, which is one of the products. Therefore, cosolvent effects on pK are anticipated to be, and are, small and erratic (35)(36)(37). Burial in a protein differs from transfer to an organic solvent, as the hydronium ion resides in an aqueous solution; only the side chain is buried.…”

Indicator Studies of Acids and Bases in Benzene.

“…On the other hand, the strengths of the cationic acids represented by the indicators and substituted ammonium ions have increased to a very considerable amount over their strengths in water relative to the uncharged acids. It remains an interesting problem to determine whether these changes can be accounted for quantitatively on the basis of the electrical work of transfer, or whether it will be necessary to invoke further hypotheses dependent upon the molecular structure (10,11). The answer to this question must await an independent determination of the charge type before definite conclusions can be drawn.…”

Ionization constants of substituted benzoic acids in ethanol-water

“…The earlier values given in the literature [15,16] were not used since it was either impossible to calculate the exact weight percentage of ethanol or not enough data were available to calculate the thermodynamic ionization constants. Up to about 44 weight percent ethanol, the thermodynamic pK values of the different investigators are seen to be in quite good agreement despite the fact that in this work and that of Grunwald, glass electrodes were used , whereas Tabagua and Bright and Briscoe employed hydrogen -\ Agel and hydrogen -c alomel electrodes, res pec tively.…”