Kinetic and equilibrium aspects of the effects of salts and nonelectrolytes upon the ionization equilibrium of tris-p-methoxyphenylmethanol in aqueous solution at 25°

Publisher Website
Google Scholar
Abstract
The rates of formation and disappearance of the R3C+ ion in aqueous solution at 25° are measured in the presence of several electrolytes and nonelectrolytes, the effects of which upon HR, also reported, can therefore be interpreted in terms of these two opposing reactions. (It is first verified that the rate of disappearance of the ion is not complicated by general base catalysis.) Additives generally influence the forward and reverse reaction rates in opposite ways and thus produce still more marked effects upon the equilibrium [R3C+]/[R3COH] ratio and HR. Electrolytes and nonelectrolytes also have large and varied effects upon the solubility of R3COH, but although these resemble the effects of the additives upon the rate of formation of the ion, no simple correlation with the latter emerges. Instead a good correlation is found between the rate of formation of R3C+ and the Hammett function H0, implying that the reasons for the peculiarities in the HR scale are to be sought in effects upon the reverse reaction. Perchlorates [which like (CH3)4NCl behave similarly to the nonelectrolytes in their effects upon the solubility of R3COH] have a very marked effect upon the reverse reaction even at quite low concentrations and this behaviour (interpreted tentatively in terms of a ‘structure enforced association’ between R3C+ and ClO4 –) is believed to hold the key to the absence of a simple correlation between HR and water activity for strong acids.

This publication has 0 references indexed in Scilit: