Excess heat capacities of 1-methyl pyrrolidin-2-one and pyridine or picolines mixtures
Introduction
The chemical industries have recognized the importance of the thermodynamic properties of liquid mixtures in design calculations involving chemical separations, heat transfer, mass transfer and fluid flow [1]. These properties provide information about the state of components as well as nature and extent of interactions operating among the constituent of mixtures. Heat capacities of liquid mixtures are required for the calculation of heat balances around the absorbers, regenerators and heat exchanges used in gas-treating industries [2]. 1-Methylpyrrolidin-2-one or its mixtures with organic liquids like benzene, methyl benzene, cyclohexane are used in the petrochemical industry in the extraction of aromatics and in the removal and purification of acetylene. 1-Methylpyrrolidin-2-one is also used in the manufacture of cosmetics, pigments, insecticides, herbicides and fungicides. In continuation of our work on thermodynamic properties of binary and ternary mixtures containing 1-methylpyrrolidin-2-one as one of the component [3], [4], we report here excess heat capacities, of 1-methylpyrrolidin-2-one (i) + pyridine or α- or β- or γ-picoline (j) mixtures. The topology (Graph theory) of the constituents of mixtures has been successfully utilized to determine excess molar volumes, VE, excess molar enthalpies, HE, excess Gibb's free energy, GE, and excess isentropic compressibilities, of the binary [5], [6], [7], [8], [9] as well as ternary [10], [11], [12], [13], [14] mixtures. An attempt has been made here to predict excess heat capacities, of the investigated binary liquid mixtures by employing topology of the constituent molecules.
Section snippets
Experimental
1-Methylpyrrolidin-2-one (NMP) (Fluka 0.99 GC), pyridine (Py) (Fluka, 0.99 GC), α-picoline (Fluka, 0.98 GC), β-picoline (Fluka, 0.99 GC) and γ-picoline (Fluka, 0.99 GC) were purified by standard methods [15]. The densities and speed of sound values of the purified liquids measured by using density and sound analyzer apparatus [16] (Anton Paar DSA 5000) at 298.15 ± 0.01 K are presented in Table 1 and also compared well with their literature values [6], [7]. The uncertainties in the density and
Results
The excess heat capacities, data of the investigated mixtures were determined from the following relationwhere Cp, (Cp)i, (i = i or j), xi (i = i or j) denote heat capacity of the mixture, heat capacity of pure components and mole fraction of components respectively. Such values for NMP (i) + Py or α- or β- or γ-picolines (j) mixtures are recorded in Table 2 and plotted in Fig. 3.
The values for the present mixtures were expressed by Redlich–Kister equation [20]:
Discussion
No literature values of excess heat capacities, for the investigated mixtures at 293.15, 298.15 and 303.15 K were found for comparison with our measured data. The values for NMP (i) + Py or β- or γ-picoline (j) mixtures are positive over entire composition range. However values for NMP (i) + α-picoline (j) mixture change sign from negative to positive with increase in mole fraction of NMP and for an equimolar composition data for the present mixtures vary in the order β-picoline ≈
Conclusion
Excess heat capacities, of NMP (i) + Py or β- or γ-picolines (j) are positive over entire mole fraction range. However sign of values for NMP (i) + α-picoline mixture is dictated by the concentration of NMP. The data for the studied mixtures at equimolar composition vary as: β-picoline ≈ γ-picoline > α-picoline > Py. The topology of the constituents of mixtures has been successfully employed to obtain expression that describes well the measured data of the studied mixtures.
Acknowledgements
Anand Rohilla is thankful to UGC, New Delhi, for providing fellowship under FIP scheme. The authors are also thankful to the Head, Department of Chemistry and authorities of M. D. University, Rohtak, for providing research facilities.
References (34)
- et al.
Thermodynamic and topological investigations of molecular interactions in binary and ternary mixtures containing 1-methylpyrrolidin-2-one at T = 308.15 K
J. Chem. Thermodyn.
(2011) - et al.
Topological investigations of binary mixtures containing 1-ethyl-3-methyl imidazolium tetrafluoroborate and anilines
J. Mol. Liq.
(2013) - et al.
Topological investigations of binary mixtures containing ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate and pyridine or isomeric picolines
J. Chem. Thermodyn.
(2013) - et al.
Thermodynamic studies of molecular interactions in mixtures of o-toulidine with pyridine and picolines: excess molar volumes, excess molar enthalpies, and excess isentropic compressibilities
J. Chem. Thermodyn.
(2011) - et al.
Thermodynamic properties of liquid mixtures containing 1,3-dioxolane and anilines: excess molar volumes, excess molar enthalpies, excess Gibb's free energy and isentropic compressibilities changes of mixing
Thermochim. Acta
(2010) - et al.
Thermodynamic and topological investigations of ternary mixtures o-toulidine, tetrahydropyran, and picolines: excess molar volume and excess isentropic compressibilities
J. Chem. Thermodyn.
(2012) - et al.
Topological and thermodynamic studies of ternary mixtures containing cyclic ethers: excess molar enthalpies
J. Mol. Liq.
(2011) - et al.
Thermodynamic and topological investigations of ternary mixtures with o-toluidine, tetrahydropyran, and picolines: excess molar volume and excess isentropic compressibility
J. Chem. Thermodyn.
(2012) - et al.
Excess heat capacities of mixtures of benzene with cyclohexane at 298.15 K
Thermochim. Acta
(1977) - et al.
Molecular connectivity and substructure analysis
J. Pharm. Sci.
(1978)