Ultrasonic studies on the stability constants of certain charge transfer complexes in solution (original) (raw)
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The ultrasonic velocity (U), density (ρ) and coefficient of viscosity (η) of solutions containing equimolar concentration of two ketones (cyclohexanone and Ethyl methyl ketone) and Pyridine in n-hexane solvent have been measured at 293K, 298K and 303K. Acoustical parameters such as adiabatic compressibility (β), Intermolecular free length (L f), internal pressure (π i) and cohesive energy (CE) values are calculated from the experimental values of U, ρ and η. These investigations indicate the formation of weak charge transfer complexes between various ketones and pyridine in n-hexane solvent. Stability constant (K) values of the charge transfer complexes in solution have been evaluated using Marwein and Bhatt equation. The free energy of activation (ΔG#) for the formation of these complexes is also computed from K values. The free energy of formation (ΔG 0 F) and viscous relaxation time () are found to be almost constant for these complexes indicating the formation of similar charge ...
Archives of Applied Science Research, 2014
The density, speed of the sound and viscosity were measured for solutions containing equimolar concentrations of the ternary mixtures consists of Pyridine as donor with Cyclohexanone, Acetone, Acetophenone and Ethyl methyl ketone as an acceptors separately in n-hexane solvent including pure liquids at 303K. Acoustical and thermodynamic parameters like acoustical impedance (Z), sound velocity (U), internal pressure (πi), Intermolecular free length (Lf) and adiabatic compressibility (s), Formation Constant (K) have been evaluated. The constant values of free energy of formation (ΔG#) and relaxation time () indicates that the formation of similar type of complexes in these systems. The variation in free energy of formation (ΔG0F) values suggests that their thermodynamic stability depends on the structure of donor and acceptor.
Physics and Chemistry of Liquids, 2002
The ultrasonic velocities (U), densities (ρ), and viscosities (η) were measured for solutions containing equimolar concentrations of eight aldehydes namely, benzaldehyde, o-chlorobenzaldehyde, anisaldehyde, p-tolualdehyde, cinnamaldehyde, crotonaldehyde, propionaldehyde, and valeraldehyde as acceptors, benzylamine and cyclohexylamine as donors in n-hexane at 303K. Acoustical parameters such as adiabatic compressibility (β), free length (L f ), viscous relaxation time (ґ), molecular interaction parameter (χ u ) have been computed. These values indicate the formation of charge transfer complexes between aldehydes and amines. Formation constant (K) values of the complexes have been evaluated using a modified Bhat equation proposed by Kannappan. The constant values of free energy of activation (∆G # ) and relaxation time indicate the formation of similar type of complexes in these systems. However, the variation in free energy of formation (∆G) values suggests that their thermodynamic stability depends on the structure of donor and acceptor.
Acoustical and thermodynamical properties of amides with benzonitrile at 303 , 308 and 313
Ultrasonic investigations find extensive applications in characterizing aspects of physicochemical behaviour of binary liquid mixtures 1,2. Ultrasonic velocity measurement provides an important tool to study the liquid state. Such studies have been used to understand the intra and intermolecular interactions in pure liquids 3 , aqueous solution 4 , and binary mixtures 5. Detailed information about the nature of molecular interactions can be obtained from various ultrasonic parameters computed on the basis of experimental investigations. Measurement of ultrasonic velocity and its related properties in liquid mixtures play an important role to study physico-chemical behaviour and also explain the nature of molecular interactions 6,7. Samatha 8,9 have measured ultrasonic velocity in the mixtures of N,N-Dimethyl acetamide with phenols and found that the excess compressibility and excess volumes have the same sign. Hari Babu and Rama Krishna 10 investigated ultrasonic behaviour of aqueous solutions of N,Ndimethyl formamide and dimethyl sulphoxide and
Journal of Applied Solution Chemistry and Modeling, 2013
Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.
2015
Density, speed of sound and viscosity for the ternary system formed by 1,4-Bis (diphenylaminobenzene), picric acid and chloroform were measured at atmospheric pressure in the temperature range of 298K, 303K and 308K. The present investigation aims at the comparative study of stability constants of the "Acid-Amine" charge transfer complexes at three temperatures to gain a better understanding of the effect of temperature, and different structural aspects of acceptor-donor to the stability constants of charge transfer complexes under investigation. A quantitative relationship has been established among the thermodynamic properties like acoustical impedance (Z), sound velocity (U), Intermolecular free length (L f), excess molar volume (V E) and adiabatic compressibility (β) etc. The results obtained are much comparable and are in good agreement. A molecular interaction study has also been made successfully in the light of these acoustical properties.
Iranian Journal of Chemistry & Chemical Engineering-international English Edition, 2008
The ultrasonic velocity, density and viscosity of some Schiff bases of 4-amino benzoic acid were measured in 1,4-dioxane and dimethylformamide at 308.15 K. Various acoustical properties such as isentropic compressibility (k s), Rao's molar sound function (R m), the Van der Waals constant (b), molar compressibility (W), inter molecular free length (L f), relaxation strength (r), internal pressure (p), solvation number (S n) etc., were calculated. The results are interpreted in terms of molecular interaction occurring in the solutions.
Ultrasonic investigation has been carried out on five binary and four ternary liquid mixtures to identify the dominance of solute-solute interactions. p-Chloranil is used as acceptor and four aromatic amines are used as donors. Primary, secondary and tertiary amines were used mainly to determine the difference in the site of complex formation. The study was made in DMSO at 303 K and at atmospheric pressure. The trend in acoustical and excess thermo acoustical parameters of mixtures containing p-chloranil and amines is used to identify the existence of intermolecular interaction, probably through hydrogen bonded or charge transfer complex formation. The formation of 1:1 complexes between p-chloranil and aromatic amines was established by UV-visible spectroscopic methods at 303 K. The formation constants of the charge transfer complexes were computed by spectroscopic and ultrasonic methods which show similar trends and well establish the influence of structural aspect of the amine (donor) on the stability of charge transfer complexes.
E3S web of conferences, 2022
Understanding non-ideal mixtures of liquids and gases in thermodynamics is paramount for processes marked by significant entropy changes. This article delves into the pivotal role of ultrasonic and acoustic studies in unraveling the intricate behaviour of complex solutions. These studies provide profound insights into molecular interactions, structural properties, and thermodynamic characteristics. Notably, they find widespread applications in diverse industries, including pharmaceuticals, food processing, clinical analysis, and petroleum engineering. This qualitative exploration sheds light on the underlying molecular forces, particularly the influence of hydrogen bonding. Recent advancements in the field, such as the investigation of ionic liquids combined with molecular solvents and the analysis of volumetric and acoustic properties in binary mixtures, underscore their practical importance. This overview offers a comprehensive understanding of how ultrasonic and acoustic studies drive progress in multiple sectors. They play a pivotal role in enhancing the stability of drug formulations, optimizing food-grade mixtures, and ensuring strict compliance with industry standards in the petrochemical sector. 1 Introduction Grasping the concept of mixtures in thermodynamics is vital, especially for procedures that involve substantial changes in entropy. Recent studies, such as those exploring ultrasonic frequencies at 35 kHz and 130 kHz, have shed new light on the intricate behavior of these mixtures. These studies offer profound insights into molecular interactions, structural properties, and thermodynamic characteristics, emphasizing the significance of acoustic parameters and ultrasonic techniques. Crucial characteristics such as density and molar volume in two-component mixtures hold great importance and are greatly influenced by factors like temperature and pressure.[1] Ultrasonic methods are used to study molecular interactions in various liquids and mixtures across industries like pharmaceuticals and textiles. This helps us understand molecular forces, including hydrogen bonding. Ultrasonic technology is also valuable for analyzing the acoustic properties of liquid systems, be it binary, ternary, or pure liquids.[2] Molecular acoustics primarily focuses on examining how the speed and weakening of ultrasonic waves are influenced by the molecular characteristics of a material.[3] Recently, the significance of acoustic parameters has been increasingly recognized in the scientific community, particularly for their utility in elucidating molecular interactions within liquid mixtures. The application of ultrasonic techniques has proven to be indispensable in the analysis of these interactions, applicable to both polar and nonpolar components. This has opened new avenues for understanding the fundamental properties of these mixtures at a molecular level. [4-8] Ionic liquids, which are unique solvents that remain liquid at room temperature, are becoming a popular