Ultrasonic method of determination of stability constants of charge transfer complexes of certain carbonyl compounds and diethylamine in n-hexane

Abstract

The ultrasonic velocities (U), densities (ρ) and viscosities (η) were measured for solutions containing equimolar concentrations of diethylamine (donor), nine aldehydes and nine ketones (acceptors) in n-hexane at 303 K. Acoustical parameters such as adiabatic compressibility (β), free length (L _f), viscous relaxation time (τ), and molecular interaction parameter (χ_U) have been computed. These values indicate the formation of charge transfer complexes between carbonyl compounds and amine. Formation constant (K) values of the complexes have been evaluated using the equation proposed by Kannappan. The constant values of free energy of activation (ΔG ) and relaxation time indicate the formation of similar charge transfer complexes in these systems. However, the variation in free energy of formation (ΔG°_F) values suggests that their thermodynamic stability depends on the structure of donor and acceptor.

Keywords:

• charge transfer complexes
• carbonyl compounds
• diethylamine
• stability constant
• ultrasonic method

Acknowledgement

One of the authors (IG) is grateful to UGC, New Delhi for the award of Teacher Fellowship under Faculty Improvement Programme.