Study of Relative Association, Apparent Molar Compressibility and Free Length of Entacapone API in alcohols at different Frequencies

  The values of ultrasonic velocity is measured by using ultrasonic interferometer for 0.01M solution of entacapone in methanol, ethanol, 1-propanol and 1-butanol as a solvent at 303.15 K by using frequency 2 MHz, 4 MHz and 6 MHz. This experimental data is used to explore the acoustic properties like intermolecular free length, relative association and apparent molar compressibility. From these thermodynamic and acoustic properties, the molecular interactions like solute-solute and solute-solvent occurring in solution have been interpreted with respect to change in solvent at different frequencies. It was observed that apparent molar compressibility value decreases from 2 MHz to 6 MHz in solvent Methanol to 1-butanol. Decreasing trend in Ultrasonic velocity shows less interaction between solute and solvent molecules. From 2 MHz to 6 MHz intermolecular free length increases which shows weak molecular interaction. Relative association increases from methanol to 1-butanol from increasing frequency i.e. from 2MHz to 6MHz. It shows strong solute solvent interaction.