Role of glycine as a ‘3D-structure’ maker in aqueous mixture of protophilic dipolar aprotic dimethylsulfoxide.

S. Roya, K. Mahalib, S. Mondal

Abstract

Solubilities of an α-amino acid, glycine (Gly.) have been measured using ‘formol titrimetry’ method at five equidistant temperatures i.e. from 288.15 K to 308.15 K in aqueous mixtures of protophilic dipolar aprotic Dimethylsulfoxide (DMSO). The various solvent parameters as well as thermodynamic parameters like molar volume, densities, dipole moment, solvent diameter of aqueous DMSO have been reported and standard free energies ( )( 0 G i ∆ t ) and entropies ( )( 0 S i ∆ t ) of transfer of glycine from water to aqueous mixture of DMSO have been evaluated in this paper at 298.15 K. The chemical effects of the transfer Gibbs energies ( )( 0 , G i ∆ cht ), as obtained by subtracting theoretically computed )( 0 G i ∆ t due to cavity effect and dipole-dipole interaction effects from the corresponding experimental total transfer free energies. Again )( 0 , S i Τ∆ cht have been evaluated after elimination of cavity effect and dipole- dipole interaction effects from the total transfer ( )( 0 T S i ∆ t ) entropies.

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