Ultrasonic absorption properties of solutions. Part 6.—Tetra-alkylammonium salts in water and tetra-n-butylammonium bromide in formamide, methylformamide and dimethylformamide

Abstract

The ultrasonic absorption properties over the range 1.5–230 MHz are reported for aqueous solutions containing tetra-methylammonium, tetra-ethylammonium, tetra-n-propylammonium and tetra-n-butylammonium bromides and tetra-n-butylammonium chloride. Solutions of tetra-n-butylammonium bromide in formamide, methylformamide and dimethylformamide have also been studied in this range. The relaxation curves for solutions containing tetra-n-butylammonium bromide have been analyzed using two relaxation frequencies. The marked similarities in the ultrasonic absorption properties of aqueous and non-aqueous solutions together with the detection of an absorption in this region for tetra-ethylmethane lead to the conclusion that the relaxations are basically a result of some form of rotational isomerism within the alkylammonium ion.