Empirical correlations of partial molar volumes at infinite dilution of organic solutes and transition states for SN2 hydrolysis and ethanolysis of n-alkyl bromides

Abstract

Pseudo-first-order rate constants under pressures ⩽98.1 MPa have been measured for the hydrolysis of ethyl, n-propyl, and n-butyl bromides in water at 298.15 K and for the ethanolysis of methyl, n-propyl, and n-butyl bromides in ethanol at 333.15 K. Activation volumes (cm³ mol^–1) were ca. –11 for the hydrolysis and about –25 for the ethanolysis. Partial molar volumes at infinite dilution were measured for n-butyl bromide in water at 298.15 K and for 66 organic solutes in ethanol at 333.15 K. Partial molar volumes of the transition states are shown to be adaptable to volumetric behaviour for, common solutes, in which the partial molar volume of each solute is compared with that of the n-alkane having the same van der Waals volume.