Apparent molar properties of benzyldimethylammonium based protic ionic liquids in water and ethanol at different temperaturesby Dasthaiah Keshapolla, Vickramjeet Singh, Akash Gupta, Ramesh L. Gardas

Fluid Phase Equilibria

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Year
2015
DOI
10.1016/j.fluid.2014.11.005
Subject
Physical and Theoretical Chemistry / Physics and Astronomy (all) / Chemical Engineering (all)

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Accepted Manuscript

Title: Apparent molar properties of benzyldimethylammonium based protic ionic liquids in water and ethanol at different temperatures

Author: Dasthaiah Keshapolla Vickramjeet Singh Akash

Gupta Ramesh L. Gardas

PII: S0378-3812(14)00642-6

DOI: http://dx.doi.org/doi:10.1016/j.fluid.2014.11.005

Reference: FLUID 10335

To appear in: Fluid Phase Equilibria

Received date: 17-7-2014

Revised date: 3-11-2014

Accepted date: 5-11-2014

Please cite this article as: Dasthaiah Keshapolla, Vickramjeet Singh, Akash Gupta,

Ramesh L.Gardas, Apparent molar properties of benzyldimethylammonium based protic ionic liquids in water and ethanol at different temperatures, Fluid Phase Equilibria http://dx.doi.org/10.1016/j.fluid.2014.11.005

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Apparent molar properties of benzyldimethylammonium based protic ionic liquids in water and ethanol at different temperatures

Dasthaiah Keshapolla, Vickramjeet Singh, Akash Gupta, Ramesh L. Gardas*

Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India *Corresponding author. Tel.: +91 44 2257 4248; fax: +91 44 2257 4202

E-mail address: gardas@iitm.ac.in ; URL: http://www.iitm.ac.in/info/fac/gardas

Highlights ► ► New benzyldimethylammonium based protic ionic liquids (PILs) were synthesized. ► Density and speed of sound measured for PILs + water/ethanol binary mixtures. ► The apparent molar volume, Vφ∞ follow the order: (PILs+ethanol) ► (PILs+water). ► Excess volumes for PIL+ethanol mixtures are positive while for PIL+water are negative.

Graphical abstractApparent molar volume (Vφ) versus molality (m) of

Benzyldimethylammonium propionate (BDMAP) in (BDMAP + ethanol) binary solution at different temperatures.

Abstract

The apparent molar volumes, Vφ and apparent molar isentropic compressibilities, Ks,φ of three benzyldimethylammonium based protic ionic liquids, namely, benzyldimethylammonium acetate (BDMAA), benzyldimethylammonium propionate (BDMAP), and benzyldimethylammonium hexanoate (BDMAH) in water and ethanol have been determined at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 ) K and at ambient pressure from density, ρ and speed of sound, u measurements. The Redlich-Mayer type of equation has been used to calculate the apparent molar volume, Vφ∞ and apparent molar isentropic compressibility, Kφ∞ at infinite dilution, and the corresponding empirical parameters (Sv, Bv, Sk and Bk). The negative magnitude of limiting volumetric slopes, Sv

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IPT versus m1/2 for (BDMAA + ethanol) binary solutions, suggests that BDMAA-ethanol interactions are strong. Further, the change in thermodynamic properties of binary solutions in relation to the alternation in the anionic structural constitution of protic ionic liquids has also been evaluated.

Keywords: Protic ionic liquid; Benzyldimethylammonium acetate; Apparent molar volume;

Apparent molar isentropic compressibility. 1. Introduction

Ionic liquids (ILs) are special class of “green solvents” formed by the combination of cations and anions. ILs have plenty of successful applications in synthesis and biomimetic, due to inherent uniqueness in physicochemical properties and versatility [1-5]. The research in the field of ILs has witnessed an extraordinary growth, spanning over a broad range of topics covered by the ever-growing heaps of publications. These are broadly classified into protic ionic liquids (PILs)-those containing an acidic proton and aprotic ionic liquids (APILs)- those excluding acidic protons in their molecular framework [6-10].

Benzylic compounds are widely distributed in nature. Mimicking to such species in the synthetic compounds of widespread utility like PILs can provide a new arena of enhanced applicability, even from ecological and biological points of view. Such kind of PILs are very scarcely investigated so far. The thermodynamic studies of pure PILs and their mixture with other compounds are needed to understand their mutual interactions in a better way and henceforth, to widen their application in design and control of chemical processes [3, 11-15].

Furthermore, the volumetric properties characterizing the solvation behaviour of PILs in polar and non-polar solvents can provide in-depth understanding of the nature and extent of various types of interactions among solute and solvent molecules and find significance in industrial applications of mixed PILs solutions.

Various reports are available in literature [15-18] on the density, ρ and speed of sound, u for the binary mixtures of ILs, however, only few present [11,19-20] studies on the thermodynamic and thermophysical behaviour of ammonium based PILs solutions. So, in order to understand the structural and chemical bonding pattern of benzyldimethylammonium based PILs in water and in ethanol, the apparent molar volumes, Vφ, and apparent molar isentropic compressibilities, Ks,φ of aqueous and ethanolic solutions of benzyldimethylammonium acetate, benzyldimethylammonium propionate, and

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IPT benzyldimethylammonium hexanoate, have been determined at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The results have been interpreted in terms of various interactions occurring in binary solutions. Further, excess volume for the studied binary systems have also been evaluated and discussed in terms of various interactions occurring in these solutions. 2. Experimental 2.1. Materials

The provenance, mass fraction purity and CAS number of the chemicals used are given in Table 1. All the chemicals were used as such without further purifications. 2.2. Synthesis and characterization of benzyldimethylammonium based PILs