Ultrasonic relaxation study in methyl acetate by using the high-Q ultrasonic resonator method

Ultrasonic absorption measurements in methyl acetate have been carried out over the frequency range 0.1 similar to 10 MHz at temperatures of 5 similar to 30 degreesC using a high-Q ultrasonic resonator method which is useful for ultrasonic relaxation studies around 1 MHz. The results show the typica l spectrum of a single relaxation process, from which the relaxation freque ncy and strength could be determined. The temperature dependence of these p arameters give the activation enthalpy (DeltaH(*)) and enthalpy difference (DeltaH) between cis and trans isomers of methyl acetate of DeltaH(*) = 6.6 kcal/mol and DeltaH = 3.4 kcal/mol.