THE HYDRATION OF AROMATIC QUATERNARY AMMONIUM SALTS DEDUCED FROM THE MEASUREMENTS OF DENSITY AND NMR

Abstract

The densities of aqueous solutions of aromatic quaternary ammonium salts have been measured at 6°, 15°, 25°, 35° and 45°C. The infinite dilution molal expansibility _??_, has been calculated from the partial molal volume _??_, at various temperatures. The ∂_??_/∂t values are found to be positive for all of the salts. The ∂²_??_/∂t² values are found to be zero for all of the salts except TMPA⁺ with the negative one. This negative value suggests that the TMPA⁺ is a structure breaker.
The experimental Sv values for all of the salts do not agree with that predicted by the Debye-Hückel theory. This deviation of Sv is interpreted by the influence of the salts on the water structure on the basis of the correlation with the water proton chemical shifts of the salt solutions.