Studies on Volumetric and Viscometric Properties on N-Acetylcysteine in Dimethylsulfoxide-Water Mixture

Abstract

The density and viscosity of NAC (~0.10 to ~1.00) mol.L to-1 in H20, DMSO and DMSO-H20 mixed solutions were measured and studied over the entire molarity range at (298.15, 303.15, 308.15, 313.15 and 318.15) K temperatures with a view to determining the molecular interactions among NAC, H20 and DMSO. NAC is a suithydryl substance widely used as medicine known as best free radical and heavy metal scavenger in human body. DMSO is a colorless organic polar solvent has led to its largescale production in recent years with negligible toxicity. DMSO is completely miscible with universal solvent water. So DMSO-H20 mixture can be a vital binary solution in investigating NAC; were taken as topic of research in this study. The apparent molar volumes were obtained from the experimental density data. In the NAC—H20 system the apparent molar volume of NAC increases, whereas in the NAC—DMSO system it decreases smoothly. In addition, apparent molar volume at infinite dilution, apparent molar expansivity, transfer apparent molar volume and S values were also calculated according to the experimental density data. The apparent molar volume at infinite dilution gives an idea about the presence of solute—solvent interactions whereas Sv is the experimental slopes which give an idea about the prevailing solute—solute interactions in the mixtures. The calculated data indicate that there may be solute-solute and solutesolvent interactions present in the binary and ternary solutions. Hepler constant which is used to determine the capacity of solute as a structure maker or structure breaker in mixed solvent system has also determined. It is seen that NAC has good structure making property in ternary solutions than the binary systems. Both binary and ternary systems showed rapid increase of viscosity values with the increased NAC concentration but the values of viscosity decreased with the increase of temperature. The viscosity data were employed to determine the viscosity (A, B) coefficients, change of free energy, AG*, change of enthalpy, H* and change of entropy, S*. From these thermodynamic parameters state of the spontaneity of the investigated systems were known. Moreover, negative A and positive B co-efficients suggesting that weak solute-solute but strong solute-solvent interaction present in the binary and ternary solution. On the basis of this data, the predominant molecular interactions occurring between NAC—H20, NAC— DMSO and NAC—DMSO—H2O were found to be solute-solvent interaction. The results suggest that there is a significant effect of NAC on water and DMSO.