Journal of Solution Chemistry

, Volume 44, Issue 3–4, pp 431–439 | Cite as

Refraction Index and Molar Refraction in Ionic Liquid/PEG200 Solutions

  • Adriana S. H. Branco
  • Marta S. Calado
  • João M. N. A. Fareleira
  • Zoran P. Visak
  • José N. Canongia Lopes


Refraction index, n D, data of four pure ionic liquids and their solutions with PEG200 were measured at room temperature (298.15 K) and atmospheric pressure (0.1 MPa) over the entire composition range of the mixtures. The data were combined with existing volumetric data in order to yield the molar refraction of all 27 samples. The results show that although the molar refraction values are strongly dependent on the molar volume of the pure components and exhibit ideal behavior for the solutions, the refraction index values show non-linear trends with the solution composition. These findings are interpreted by taking into account the nano-structured nature of ionic liquids, their strong interactions with the glyme-like chains of the PEG molecules, and the relative intensity of the dispersion forces present in all studied systems.


Ionic liquid PEG200 Refractive index Molar refraction 



This work was financially supported by the projects PTDC/EQU-EPR/103505/2008, PEst-OE/QUI/UI0100/2013, all funded by Fundação para a Ciência e a Tecnologia (FCT), Portugal. The authors also acknowledge the FCT funded Project PTDC/QUI/66826/2006, as the samples of [C4mim][dca] and [P66614][dca] were synthesized and characterized under support of that project at Instituto Superior Técnico, Universidade de Lisboa, in the Centro de Química-Física Molecular and IN – Institute of Nanosciences and Nanotechnology, by Carolina S. Marques, and Carlos A. M. Afonso.


  1. 1.
    Dean, P.M., Pringle, J.M., MacFarlane, D.R.: Structural analysis of low melting organic salts: perspectives on ionic liquids. Phys. Chem. Chem. Phys. 12, 9144–9153 (2010)CrossRefGoogle Scholar
  2. 2.
    Plechkova, N.V., Seddon, K.R.: Applications of ionic liquids in the chemical industry. Chem. Soc. Rev. 37, 123–150 (2008)CrossRefGoogle Scholar
  3. 3.
    Henderson, W.A., Young Jr., V.G., Fox, D.M., De Long, H.C., Trulove, P.C.: Alkyl vs. alkoxy chains on ionic liquid cations. Chem. Commun., 3708–3710 (2006)Google Scholar
  4. 4.
    Russina, O., Triolo, A.: New experimental evidence supporting the mesoscopic segregation model in room temperature ionic liquids. Faraday Discuss. 154, 97–109 (2012)CrossRefGoogle Scholar
  5. 5.
    Yoshida, K., Nakamura, M., Kazue, Y., Tachikawa, N., Tsuzuki, S., Seki, S., Dokko, K., Watanabe, M.: Oxidative-stability enhancement and charge transport mechanism in glyme–lithium salt equimolar complexes. J. Am. Chem. Soc. 133, 13121–13129 (2011)CrossRefGoogle Scholar
  6. 6.
    Willauer, H.D., Huddleston, J.G., Rogers, R.D.: Solvent properties of aqueous biphasic systems composed of polyethylene glycol and salt characterization by the free energy of transfer of a methylene group between the phases and by a linear solvation energy relationship. Ind. Eng. Chem. Res. 41, 2591–2601 (2002)CrossRefGoogle Scholar
  7. 7.
    Harvey, A.H., Gallagher, J.S., Levelt Sengers, J.M.H.: Revised formulation for the refractive index of water and steam as a function of wavelength, temperature and density. J. Phys. Chem. Ref. Data 27, 761–774 (1998)CrossRefGoogle Scholar
  8. 8.
    Nieto de Castro, C.A., Langa, E., Morais, A.L., Matos Lopes, M.L., Lourenço, M.J.V., Santos, F.J.V., Soledade, M., Santos, C.S., Canongia Lopes, J.N., Veiga, H.I.M., Macatrão, M., Esperança, J.M.S.S., Marques, C.S., Rebelo, L.P.N., Afonso, C.A.M.: Studies on the density, heat capacity, surface tension and infinite dilution diffusion with the ionic liquids [C4mim][NTf2], [C4mim][dca], [C2mim][EtOSO3] and [Aliquat][dca]. Fluid Phase Equilib. 294, 157–179 (2010)CrossRefGoogle Scholar
  9. 9.
    Diogo, J.C.F., Caetano, F.J.P., Fareleira, J.M.N.A., Wakeham, W.A., Afonso, C.A.M., Marques, C.S.J.: Viscosity measurements of the ionic liquid trihexyl(tetradecyl)phosphonium dicyanamide [P6,6,6,14][dca] using the vibrating wire technique. J. Chem. Eng. Data 57, 1015–1025 (2012)CrossRefGoogle Scholar
  10. 10.
    Calado, M.S., Branco, A.S.H., Diogo, J.C.F., Fareleira, J.M.N.A., Visak, Z.P.: to be published (2014)Google Scholar
  11. 11.
    Tariq, M., Forte, P.A.S., Costa Gomes, M.F., Canongia Lopes, J.N., Rebelo, L.P.N.: Densities and refractive indices of imidazolium- and phosphonium-based ionic liquids: effect of temperature, alkyl chain length, and anion. J. Chem. Thermodyn. 41, 790–798 (2009)CrossRefGoogle Scholar
  12. 12.
    Ottani, S., Vitalini, D., Comelli, F., Castellari, C.: Densities, viscosities, and refractive indices of poly(ethylene glycol) 200 and 400 + cyclic ethers at 303.15 K. J. Chem. Eng. Data 47, 1197–1204 (2002)CrossRefGoogle Scholar
  13. 13.
    Almeida, H.F.D., Lopes da Silva, J.A., Freire, M.G., Coutinho, J.A.P.: Surface tension and refractive index of pure and water-saturated tetradecyltrihexyl-phosphonium-based ionic liquids. J. Chem. Thermodyn. 57, 372–379 (2013)CrossRefGoogle Scholar
  14. 14.
    Abdullah, S.B., Man, Z., Ismail, L., Maulud, A., Bustam, M.A.: Ionic liquids classification for fuel desulphurization. Int. J. Gen. Eng. Technol. 2, 29–38 (2013)CrossRefGoogle Scholar
  15. 15.
    Hirschfelder, J.O., Curtiss, C.F., Bird, R.B.: Molecular Theory of Gases and Liquids. Wiley, London (1964)Google Scholar
  16. 16.
    Widegren, J.A., Magee, J.W.: Density, viscosity, speed of sound, and electrolytic conductivity for the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide and its mixtures with water. J. Chem. Eng. Data 52, 2331–2338 (2007)CrossRefGoogle Scholar
  17. 17.
    Tomé, L.I.N., Carvalho, P.J., Freire, M.G., Marrucho, I.M., Fonseca, I.M.A., Ferreira, A.G.M., Coutinho, J.A.P., Gardas, R.L.J.: Measurements and correlation of high-pressure densities of imidazolium-based ionic liquids. Chem. Eng. Data 53, 1914–1921 (2008)CrossRefGoogle Scholar
  18. 18.
    Neves, C.M.S.S., Carvalho, P.J., Freire, M.G., Coutinho, J.A.P.: Thermophysical properties of pure and water-saturated tetradecyltrihexyl-phosphonium-based ionic liquids. J. Chem. Thermodyn. 43, 948–957 (2011)CrossRefGoogle Scholar
  19. 19.
    Neves, C.M.S.S., Adi Kurnia, K., Coutinho, J.A.P., Marrucho, I.M., Canongia Lopes, J.N., Freire, M.G., Rebelo, L.P.N.: Systematic study of the thermophysical properties of imidazolium-based ionic liquids with cyano-functionalized anions. J. Phys. Chem. B 117, 10271–10283 (2013)CrossRefGoogle Scholar
  20. 20.
    Wang, J., Zhu, A., Zhao, Y., Zhuo, K.: Excess molar volumes and excess logarithm viscosities for binary mixtures of the ionic liquid 1-butyl-3-methylimidazolium hexaflurophosphate with some organic compounds. J. Solution Chem. 34, 585–596 (2005)CrossRefGoogle Scholar
  21. 21.
    Canongia Lopes, J.N., Cordeiro, T.C., Esperança, J.M.S.S., Guedes, H.J.R., Huq, S., Rebelo, L.P.N., Seddon, K.R.: Deviations from ideality in mixtures of two ionic liquids containing a common ion. J. Phys. Chem. B 109, 3519–3525 (2005)CrossRefGoogle Scholar
  22. 22.
    Rodríguez, H., Brennecke, J.F.: Temperature and composition dependence of the density and viscosity of binary mixtures of water + ionic liquid. J. Chem. Eng. Data 51, 2145–2155 (2006)CrossRefGoogle Scholar
  23. 23.
    Shimizu, K., Tariq, M., Costa Gomes, M.F., Rebelo, L.P.N., Canongia Lopes, J.N.: Assessing the dispersive and electrostatic components of the cohesive energy of ionic liquids using molecular dynamics simulations and molar refraction data. J. Phys. Chem. B 114, 5831–5834 (2010)CrossRefGoogle Scholar
  24. 24.
    Freitas, A.A., Shimizu, K., Canongia Lopes, J.N.: Complex structure of ionic liquids. Molecular Dynamics studies with different cation–anion combinations. J. Chem. Eng. Data 59, 3120–3129 (2014)Google Scholar
  25. 25.
    van Duijnen, PTh, Swart, M.: Molecular and atomic polarizabilities: Thole’s model revisited. J. Phys. Chem. A 102, 2399–2407 (1998)CrossRefGoogle Scholar
  26. 26.
    Bica, K., Deetlefs, M., Schröder, C., Seddon, K.R.: Polarisabilities of alkylimidazolium ionic liquids. Phys. Chem. Chem. Phys. 15, 2703–2711 (2013)CrossRefGoogle Scholar
  27. 27.
    Shimizu, K., Bernardes, C.E.S., Triolo, A., Canongia Lopes, J.N.: Nano-segregation in ionic liquids: scorpions and vanishing chains. Phys. Chem. Chem. Phys. 15, 16256–16262 (2013)CrossRefGoogle Scholar
  28. 28.
    Bernardes, C.E.S., Minas da Piedade, M.E., Canongia Lopes, J.N.: The structure of aqueous solutions of a hydrophilic ionic liquid: the full concentration range of 1-ethyl-3-methylimidazolium ethylsulfate and water. J. Phys. Chem. B 115, 2067–2074 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Adriana S. H. Branco
    • 1
  • Marta S. Calado
    • 1
  • João M. N. A. Fareleira
    • 1
  • Zoran P. Visak
    • 1
  • José N. Canongia Lopes
    • 1
  1. 1.Centro de Química Estrutural, Instituto Superior TécnicoUniversidade de LisboaLisbonPortugal

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