Densities and viscosities of binary liquid mixtures of N-methylacetamide with some chloroethanes and chloroethenes at T = 308.15 K
Introduction
A thorough knowledge of transport properties of non-aqueous solutions is essential in many chemical industrial applications, such as design involving chemical separations, heat transport, mass transport, fluid flow, molecular structure, etc. The studies of excess properties such as excess molar volume (VE), deviation in viscosity (Δη), excess Gibbs free energy of activation of viscous flow () and Grunberg–Nissan interaction constant (d′) of binary mixtures are useful in understanding the nature of inter molecular interactions between two liquids.
Jan Zielkiewicz [1] has reported excess volumes of the binary and ternary mixtures containing N-methylacetamide, water and ethanol at T = 313.15 K while Naidu et al. [2] have studied excess volumes and excess viscosities for the mixtures of ethylene glycol, triethylene glycol, poly(ethylene glycol)-200 and poly(ethylene glycol)-300 with N-methylacetamide at T = 308.15 K. Victor and Hazra [3] have determined excess molar volumes, viscosity deviations and isentropic compressibility changes for binary mixtures of N-methyl-acetamide with 2-methoxyethanol and water at T = (308.15 to 318.15) K while Rao et al. [4] have studied the ultrasonic studies for binary mixtures of N-methylacetamide with glycols at T=308.15 K. Tangeda and Nallani [5], [6] have investigated excess molar volumes, viscosity deviations and isentropic compressibilities for (N-methylacetamide + aromatic ketone) systems at T = 308.15 K.
In this study N-methylacetamide is chosen as a solvent due to its close relationship to peptides and proteins. N-methylacetamide is a dipolar protic solvent with high dielectric constant (ε = 191.3 at T = 305.15 K) [3], which is attributed to the liquid being highly structured with polymeric chains linked by hydrogen bond formation. On the otherhand, chloroethanes and chloroethenes have relatively low values of dielectric constants (ε = 2 to 11) [7], even though they are familiar solvents in the industrial applications. The most common use of 1,2-dichloroethane is in the production of vinyl chloride which is used to make a variety of plastic and vinyl products including polyvinyl chloride (PVC) pipes, furniture and automobile upholstery, wall coverings and housewares. It is also used as a solvent and added to leaded gasoline to remove lead whereas 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and trichloroethene are non-flammable solvents used in fats, waxes, resins, oils, rubber, paints, varnishes, natural resins and alkaloids. Tetrachloroethene has its importance in dry cleaning, textile processing, degreasing metals, insulating fluid and cooling gas in electrical transformers [7]. The industrial significance of these compounds motivated us to study the binary solvent mixtures of N-methylacetamide with chloroethanes and chloroethenes. Moreover, a study of literature indicates that no transport and volume data on these mixtures have been produced.
In the present paper we report the experimental densities and viscosities along with the computed excess molar volume (VE), deviation in viscosity (Δη), excess Gibbs free energy of activation of viscous flow () and Grunberg–Nissan interaction constant (d′) at T = 308.15 K for the binary systems of N-methylacetamide with 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethene and tetrachloroethene. Based on the experimental results molecular interactions between like and unlike molecules have been interpreted.
Section snippets
Chemicals
N-methylacetamide (Merck-Schuchrdt Germany GR) is dried twice over freshly ignited calcium sulfate, filtered and distilled. The middle fraction is collected and stored over freshly ignited 0.4 nm molecular sieves [1]. 1,2-Dichloroethane (99% Merck, India GR grade) is washed with a dilute solution of potassium hydroxide followed by hot water and dried over phosphorous pentaoxide and distilled twice. The middle fraction of the second distillation is collected and stored in amber coloured bottles
Results and discussion
The values of density and viscosity of the mixtures of N-methylacetamide with 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethene and tetrachloroethene at T = 308.15 K and their corresponding excess molar volumes (VE), deviation in viscosity (Δη), excess Gibbs free energy of activation of viscous flow () and Grunberg–Nissan interaction constant (d′) along with the mole fraction of chlorinated compounds are given in table 2.
The excess molar volumes (VE) have
Conclusions
The excess molar volumes and deviation in viscosity of N-methylacetamide with chloroethanes and chloroethenes have been reported at T = 308.15 K. Thus, it can be concluded that the evaluated experimental results are interpreted in terms of specific interactions through complex formation, dipole–dipole and π–π interactions and contribution due to the size and shape of the molecules.
Acknowledgements
One of the authors (B.S.) thank the University Grants Commission, New Delhi for the award of senior Research Fellowship. The authors are also thankful to Dr. K.N.S. Kashi Vishwanadam, Professor of Mathematics, National Institute of Technology, Warangal, for his assistance in calculating the coefficients of polynomial equation of various degrees through non-linear regression analysis.
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