G. Arivazhagan

Solute-solvent interactions of acid-1,4-dioxane mixtures-By dielectric, FTIR, UV-vis and 13C NMR spectrometric methods.

Results of the dielectric studies carried out on the binary mixture of n-butyric and caprylic acids with 1,4-dioxane over the entire composition range and at temperatures 303K, 308K, 313K and 318K, and FTIR, UV-vis and 13C NMR spectral studies are presented in this paper. The excess permittivity and excess free energy were fitted with the Redlich-Kister polynomial. The variation of Kirkwood correlation factors, excess permittivity and excess free energy of mixing with the concentration and temperature has been investigated in view of understanding the ordering of dipoles of solute and solvent molecules. The FTIR, UV-vis and 13C NMR spectral analysis reveals the formation of complex between solute and solvent molecules. The parallel alignment of electric dipoles of the complex predicted by dielectric studies is well supported by UV-vis spectral analysis. The structure of the complex molecule present in the clusters has been deduced.

Molecular interaction study of the diisopropyl ether–propionic acid mixture by spectroscopic and dielectric studies

FTIR and 13C NMR spectral studies have been carried out on diisopropyl ether-propionic acid binary mixture to probe the molecular interactions and stoichiometry of complexation. Density functional theory (DFT) calculations of vibrational frequencies of pure acid and ether-acid binary mixtures have also been performed. In addition, Kirkwood-correlation factors, excess permittivity and excess free energy of mixing have been obtained at various concentrations and at four different temperatures from the dielectric measurements. Excess permittivity is found to have positive deviation and excess free energy deviates negatively from ideal behaviour.

Dielectric and spectrometric investigations of binary mixtures of tetrahydrofuran with propionic acid

The static permittivity (εm ) and the permittivity at the high-frequency limit (ε∞m ) of a binary mixture of propionic acid with tetrahydrofuran (THF) have been determined for different concentrations at temperatures of 303, 308, 313, and 318 K. The data have been used to compute the Kirkwood correlation factor, the excess permittivity, and the excess free-energy of the mixtures. The Kirkwood correlation factor is found to increase with increasing THF concentration. The mixture exhibited positive values of the excess permittivity and negative values of the excess free-energy of mixing, respectively. UV-Vis and FT-IR spectral measurements have also been carried out. The observed bathochromism and hypochromism in the UV-Vis spectra have been explained in terms of complex formation and ordering of dipoles of the complex. The FT-IR spectrum of the mixture shows considerable shifts in the positions of some of the absorption bands, indicating extensive hydrogen bonding between solute and solvent molecules.

A probe on the intermolecular forces in diisopropyl ether-n-butyric acid mixture by dielectric, FTIR studies and quantum chemical calculations.

The results of FTIR spectral measurement on equimolar diisopropyl ether-butyric acid binary mixture and quantum chemical calculations on the complex molecule have been presented. Dielectric studies have been carried out on the binary mixture over the entire composition range and at four different temperatures 303 K, 308 K, 313 K and 318 K. n-Butyric acid seems to prefer less polar ether to interact with it. It appears that the usual interpretation of variation of static dielectric constant and positive deviation of excess permittivity from ideal mixture behavior needs to be relooked.

Dielectric investigation of the tetrahydrofuran+caprylic acid system

Dielectric studies have been carried out for the binary mixture of tetrahydrofuran (THF) with caprylic acid at temperatures 303, 308, 313 and 318 K. The Kirkwood correlation factors, excess permittivity and excess free energy of the mixture were found through dielectric measurements for different concentrations of the system. Analysis of these parameters reveals the existence of H-bonded heterogeneous molecular aggregates in the mixture. Parallel alignment of dipoles of the complex in THF region has been identified.

Time domain reflectometric study on toluene + propionitrile binary mixture

ABSTRACT Time domain reflectometry study has been carried out on toluene + propionitrile binary mixture in the frequency range from 10 MHz to 30 GHz at 298 K. The complex permittivity spectrum in the studied frequency range shows only one dispersion region. The dielectric parameters, such as Kirkwood correlation factor , relaxation time , etc., obtained from the complex permittivity spectrum have been analysed in view of the molecular phenomena taking place in the liquid mixtures. Neat propionitrile seems to exist as dimer with antiparallel dipolar alignment.

Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) CH⋯OC (EA), (EA) methylene CH⋯π electrons (CBZ) and (EA) methyl CH⋯Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (εE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.