Sodium-23 nuclear magnetic resonance of resins and mixed solvent systems

Abstract

The sodium-23 spin–lattice relaxation time (T1) was determined at 10 MHz on Dowex 50W-X2 ion exchanger resin as a function of the dielectric constant of the solvent. The relaxation time varied from 24.8 msec in distilled water (D=78.5) to values too short to determine in water–ethanol mixtures below a dielectric constant of 35. Similar studies were conducted on 250 mm sodium bisulfite (NaHSO3) in a series of aqueous–nonaqueous mixtures. The results indicate that T1 may be expressed as a function of the macroscopic dielectric constant for any binary solvent system. For systems with a dielectric constant greater than 65 the relationship is given by T1=a exp(bD), where a and b are constants for a particular solvent system.