Ultrasonic relaxation in methyl salicylate and salicylaldehyde

Abstract

Ultrasonic relaxation behaviour in methyl salicylate and salicylaldehyde has been studied using two independent ultrasonic methods, namely ultrasonic absorption and sound velocity dispersion. Ultrasonic absorption was determined in the frequency range 0.5–13.0 MHz employing the acoustic streaming and pulse techniques. The velocity dispersion was studied by using an ultrasonic interferometer in the frequency range 0.5–5 MHz. The activation energy of the backward reaction, ΔH_a, has been found to be 23.0 ± 4.0 and 23.0 ± 4.0 kJ mol^–1 and the internal energy, ΔH₀, is 11.9 ± 3.0 and 9.6 ± 3.0 kJ mol^–1 for methyl salicylate and salicylaldehyde, respectively.