Structure of Aqueous Solutions of Tetramethylammonium Chloride Investigated by Positron Annihilation and Ultrasonic Methods

The structure of aqueous solutions of tetramethylammonium chloride was investigated using sound velocity and positron annihilation methods. The results are different than those obtained earlier for systems where hydrophobic hydration occurs, although some evidences for formation of clathrate-like hydrates in liquid phase were observed. The results are interpreted, among others, in terms of competition of different hydrates of tetraalkylammonium cations, hydration of chloride anions, and formation of ionic pairs.