Molecular interactions in binary mixtures containing o-toluidine
Introduction
In our systematic investigations of thermodynamic properties of mixtures, we have reported [1], [2], [3], [4], [5], [6], [7], [8] molar excess volumes, molar excess enthalpies and excess isentropic compressibilities of binary and ternary mixtures containing constituents differing in shape, size and polarity. The analysis of the observed data with topology of the constituents of the mixtures has provided knowledge about the molecular interactions and the nature of state of components in pure and mixture state. In the present paper continuing with our study, we report molar excess volumes and molar excess enthalpies of binary mixtures formed by o-toluidine with aromatic hydrocarbons at 308.15 K.
Section snippets
Experimental
o-Toluidine [Fluka], benzene, toluene and o-, p- and m-xylenes (AR grade) were purified by standard methods [9]. The purities of the samples were checked by measuring their densities at 298.15 ± 0.01 K and these agree to within ±0.05 kg m−3 with their corresponding literature values [9].
Molar excess volumes, VE for the binary (i + j) mixtures were determined in a V-shaped dilatometer that has been described elsewhere [10]. The uncertainties in the measured VE values are about 0.5%.
Samples for IR
Results
Molar excess volumes, VE and molar excess enthalpies, HE, data for o-toluidine (i) + benzene or toluene or o- or p- or m-xylene (j) mixtures have been determined as a function of composition at 308.15 K (recorded in Table 1, Table 2 and plotted in Fig. 5, Fig. 6) were expressed aswhere xi is the mole fraction of component (i) and X(n) (n = 0–2) are parameters characteristic of (i + j) binary mixtures. These parameters were determined by fitting XE data
Topology of the constituents of the mixtures and results
According to graph theory, if atoms in a structural formula of a molecule are represented by colored points and bonds joining them by lines, the resulting graph describes the topology of a molecule which in turn provides total information contained in that molecule [13], [14], [15], [16], [17]. If , , , etc. represent the degree of m, n, etc., vertices of the graph of a molecule, then connectivity parameter of third degree, is defined [18] by where , ,
Acknowledgements
The authors are grateful to the Head, Chemistry Department and authorities of M.D. University, Rohtak, for providing research facilities.
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