A combined experimental and computational investigation of excess molar enthalpies of (nitrobenzene + alkanol) mixtures

https://doi.org/10.1016/j.jct.2014.09.001Get rights and content

Highlights

  • Excess molar enthalpies for the binary mixtures of nitrobenzene + alkanols mixtures were measured.

  • The infinite dilution excess partial molar enthalpies were calculated using the ab initio methods.

  • The PCM calculations were performed.

  • The computed excess partial molar enthalpies at infinite dilution were compared to experimental results.

Abstract

Excess molar enthalpies (HmE) for the binary mixtures of {(nitrobenzene + ethanol), 1-propanol, 2-propanol, 1-butanol and 2-butanol} have been measured over the entire composition range at ambient pressure (81.5 kPa) and temperature 298 K using a Parr 1455 solution calorimeter. From the experimental results, the excess partial molar enthalpies (HiE) and excess partial molar enthalpies at infinite dilution (HiE,) were calculated. The excess molar enthalpies (HmE) are positive for all {nitrobenzene (1) + alkanol (2)} mixtures over the entire composition range.

A state-of-the-art computational strategy for the evaluation of excess partial molar enthalpies at infinite dilution was followed at the M05-2X/6-311++G∗∗ level of theory with the PCM model. The experimental excess partial molar enthalpies at infinite dilution have been compared to the computational data of the ab initio in liquid phase. Integrated experimental and computational results help to clarify the nature of the intermolecular interactions in {nitrobenzene (1) + alkanol (2)} mixtures. The experimental and computational work which was done in this study complements and extends the general research on the computation of excess partial molar enthalpy at infinite dilution of binary mixtures.

Introduction

From an experimental point of view, excess molar functions are a very powerful tool for analyzing structural and other (physical + chemical) properties of systems. Excess thermodynamic properties have extensive applications in several disciplines of fundamental science and industrial as well as to test and to develop new theories and models that are able to describe the behavior of liquid mixtures [1], [2], [3], [4], [5], [6]. In addition, thermodynamic properties are important parameters for the improvement of drugs synthesis and one of the ways to develop new drug compounds [7].

(Vapor + liquid) equilibria (VLE) can be calculated from infinite dilution excess molar enthalpies (HiE,) using thermodynamic models [8]. The thermodynamic properties of infinitely dilute solutions are acknowledged as being very difficult to measure and systems involving these conditions are suitable to have the results from computational methods. Experimental manipulation of thermodynamics data is time-consuming and may require a substantial cost which could be much higher than the cost required for computational study; therefore, the different computational approaches such as ab initio methods have been employed to determine thermodynamic properties. The defined computational methodology succeeds in reproducing correctly the available experimental values [9], [10], [11], [12], [13], [14].

The interest in the chemistry of nitrobenzene mixtures is not only from the widespread industrial use (such as in the production of aniline), but in particular because of their inherent toxicity and hazardous effects to human health. In the pharmaceutical industry, nitrobenzene is used in the production of the analgesic acetaminophen, or paracetamol. There are some reports of thermodynamic properties of binary mixtures containing nitrobenzene as one of the components [15], [16], [17], [18], [19], [20], [21], [22].

In this context, Excess molar enthalpies (HmE) for the binary mixtures of {(nitrobenzene + ethanol), 1-propanol, 2-propanol, 1-butanol and 2-butanol} mixtures have been measured over the entire composition range at ambient pressure and temperature 298 K. From the experimental results, the excess partial molar enthalpies (HiE) and excess partial molar enthalpies at infinite dilution (HiE,) were calculated. Excess partial molar enthalpies at infinite dilution (HiE,) of the studied mixtures were computed by using the M05-2X/6-311++G∗∗ density functional theory (DFT) [23]. The estimation of the solvent effects was attempted by using the self-consistent reaction field (SCRF) and more elaborate polarizable continuum (PCM) models [24], [25]. The experimental and computational excess partial molar enthalpies at infinite dilution (HiE,) of (nitrobenzene + alkanol) mixtures in the solution phase are in agreement. A survey of the literature indicates that no experimental values for these mixtures have been reported earlier.

Section snippets

Materials

All pure components were purchased from commercial sources. Purity grade, densities, refractive indices and sources of the chemical substances are reported in table 1. Determination of densities and refractive indices of pure components was utilized for checking of purities at T = 298.15 K. Values are reported in table 1 along with the corresponding literature values [20]. The agreement between the experimental and literature values is good.

Apparatus and procedure

The densities were obtained by an Anton Paar DMA 4500

Computational methods

Firstly, the geometries of {(nitrobenzene + methanol), ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol} mixtures were optimized using the Gaussian 03 program [28] by the M05-2X density functional theory (DFT) paired with the 6-311++G∗∗ basis sets. The optimized representative geometries of the involved dimers are displayed in figure 1. Further, the optimized structures also serve as the reference structures for frequency calculations. Enthalpy was determined through frequency

Results and discussion

Experimental excess molar enthalpies, HmE of the binary mixtures of {(nitrobenzene + ethanol), 1-propanol, 2-propanol, 1-butanol and 2-butanol} at T = 298 K are summarized in table 2. The excess molar enthalpies as a function of the mole fraction are shown in figure 2. The excess molar enthalpies are positive for the all binary mixtures over the entire range of composition and increase with increase in the alkanol chain length. It indicates that the excess molar enthalpies are strongly influenced by

Conclusions

The present paper reports the results of experimental excess molar enthalpy and excess partial molar enthalpy at infinite dilution for {nitrobenzene (1) + alkanol (2)} mixtures. This positive value of HmE and HiE, is consistent with endothermicity of these solutions. The high accuracy of the M05-2X computations with suitable basis sets in the evaluation of excess partial molar enthalpy at infinite dilution allows us to draw a fully consistent interpretation of the available experimental data. In

Acknowledgment

The author would like to thank Bu-Ali Sina University for providing the necessary facilities to carry out the research.

References (36)

  • M.S. AlTuwaim et al.

    J. Chem. Thermodyn.

    (2012)
  • L. Moravkova et al.

    J. Chem. Thermodyn.

    (2009)
  • R.S. Humphrey et al.

    J. Chem. Thermodyn.

    (1980)
  • D.H.L. Viola et al.

    J. Chem. Thermodyn.

    (2012)
  • A.L.R. Silva et al.

    J. Chem. Thermodyn.

    (2013)
  • A.F.L.O.M. Santos et al.

    J. Chem. Thermodyn.

    (2014)
  • R. Notario et al.

    J. Chem. Thermodyn.

    (2014)
  • T.E. Vittal Prasad et al.

    J. Chem. Thermodyn.

    (2006)
  • G. Dharmaraju et al.

    J. Chem. Thermodyn.

    (1980)
  • S. Miertus et al.

    Chem. Phys.

    (1982)
  • H.A. Zarei et al.

    Thermochim. Acta

    (2003)
  • N.V. Sastry et al.

    J. Chem. Eng. Data

    (2011)
  • J.S. Rowlinson et al.

    Liquids and Liquid Mixtures

    (1982)
  • A.O. Surov et al.

    J. Chem. Eng. Data

    (2011)
  • A.S. Gow

    Ind. Eng. Chem. Res.

    (1993)
  • P.C. Chen et al.

    Int. J. Quantum Chem.

    (2001)
  • F.T.T. Huque et al.

    Org. Biomol. Chem.

    (2003)
  • A. Heintz et al.

    J. Phys. Chem. A

    (2007)
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