Ultrasonic and spectroscopic investigations of hydrogen bonded complexes of aromatic aldehydes with aniline in n-Hexane at 303.15 K

Abstract

Acoustical properties are computed for three ternary systems of aniline (ANI) and structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde (SA) in n-hexane medium from the measured ultrasonic velocity, density and dynamic viscosity at 303.15K and at atmospheric pressure. The trend in the acoustical parameters in the concentration range investigated confirmed complex formation through intermolecular hydrogen bonding between aldehyde and aniline. The formation constants (K) of the hydrogen bonded complexes are determined by ultrasonic method. The existence of strong aldehyde–amine interaction is also confirmed through electronic absorption spectra and the formation constants of these complexes are determined using Benesi–Hildebrand method at 303.15K. The values of K determined by ultrasonic and optical methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlated with computed molecular properties.