Volumetric and Viscometric Properties of N-Acetylcysteine in Dimethylformamide Containing Binary and Ternary Mixtures

Abstract

The density and viscosity of NAC (0.10 to 1.00) mol.L−1 in H2O, DMF and DMF– H2O mixed solutions were measured and studied over the entire molarity range with in the temperature range of 298.15 to 318.15 K at 5 K interval. The apparent molar volumes, were determined from density values experimented by Density and Sound Velocity Meter (DSA 5000M) Anton Paar, Austria. In the NAC–H2O and NAC in [1:4] and [2:3] [DMFH2O] solvent systems the apparent molar volumes of NAC were found to be increased, whereas in the NAC–DMF and NAC in [4:1] and [3:2] [DMFH2O] solvent systems apparent molar volumes of NAC were found to be decreased. Apparent molar volume at infinite dilution, 0 v  and Sv values were also computed according to the experimented density values. The apparent molar volume at infinite dilution provided an idea about the presence of solutesolvent interactions of the investigated systems. Sv, the experimental slopes which provided an idea about the prevailing solutesolute interactions in the mixtures. Both 0 v  and Sv values indicated that there both solute-solute and solute-solvent interactions present in the binary as well as in ternary solutions. The investigated systems showed hasty increase of viscosity values with the increased NAC concentration but the values of viscosity decreased with the increase of temperature. In binary and ternary systems showed the similar trend viscosity changes but in different order of magnitude. The order for binary and ternary systems are: NAC– DMF > NACH2O and NAC in [3:2] [DMF–H2O] > NAC in [4:1] [DMF–H2O] > NAC in [2:3] [DMF–H2O] > NAC in [1:4] [DMF–H2O] > NAC–DMF > NACH2O, respectively. The viscosity values were employed to determine the viscosity coefficients i.e., A and B-coefficients; change of free energy, G*; change of enthalpy, H* as well as change of entropy, S*. Negative values of A and positive values of B co-efficients suggesting that weak solute-solute but strong solute-solvent interaction present in the binary and ternary solution, respectively. From these thermodynamic parameters state of the spontaneity of the investigated systems were known. On the basis of this data, the predominant molecular interactions occurring between NAC–H2O and NAC in [1:4] and [2:3] [DMFH2O] solvent systems were found to be solute-solute interaction, where as in NAC–DMF and NAC in [4:1] and [3:2] [DMFH2O] solvent systems solute-solvent interaction were predominant.