Abstract
1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) was synthesized and purified to be used as a ionic liquid solvent. Its physicochemical properties were studied. The ionic liquid/water (P il/water) and ionic liquid/heptane (P il/heptane) distribution coefficients of a set of 40 compounds with various functionalities, including organic acids, organic bases, amino acids, antioxidants, and neutral compounds, were measured using liquid chromatography. For ionizable compounds, the P il/water values measured at pH 2, 5.1, and 10 were very different. These allowed the determination of both the molecular Poil/water values and the ion P−il/water value for each compound. These coefficients were compared to the corresponding P oct/water coefficients. Marked differences in the partitioning behavior of basic, acidic, and neutral compounds were observed. The relationship between P il/water and P oct/water is different from that reported previously. By using the linear free energy solvation approach and the descriptors found for 12 solutes, the BMIM-PF6 solvent parameters were calculated for the ionic liquid/water and ionic liquid/heptane biphasic systems. The regression parameters show a low basicity of the BMIM-PF6 solvent compared to octanol. The high cohesion of the ions in the ionic liquid phase is also indicated by the regression equations obtained. Ionized phenols (phenoxide ions) associate more strongly with BMIM-PF6 than most other ionized molecules. Amino acids were not soluble in ionic liquid; however, it is possible to extract them partially by adding a crown ether to the ionic liquid phase and working at pH 1. The positive form of amino acids is complexed by the crown ether and the complex is extracted in the ionic liquid phase.
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References
Wassercheid P, Keim W (2000) Angew Chem Int Ed 39:3772–3789
Appleby D, Hussey CL, Seddon KR, Turp JE (1986) Nature 323:614–616
Seddon KR (1996) Kinet Catal 37:693–697
Earle NJ, Seddon KR (2000) Pure Appl Chem 72:1391–1398
Welton T (1999) Chem Rev 99:2071–2083
Chauvin Y, Olivier-Bourbigou H (1995) Chemtech 25:26–30
Ngo HL, LeCompte K, Hargens L, McEwen AB (2000) Thermochim Acta 357:97–102
Armstrong DW, He L, Liu YS (1999) Anal Chem 71:3873–3876
Poole CF, Kersten BR, Ho SSJ, Coddens ME, Furton KJ (1986) J Chromatogr 352:407–425
Berthod A, He L, Armstrong DW (2001) Chromatographia 53:63–68
Yanes EG, Gratz SR, Baldwin MJ, Robinson SE, Stalcup AM (2001) Anal Chem 73:3838–3844
Bonhôte P, Dias AP, Papageorgiou N, Kalyanasundaram K, Grätzel M (1996) Inorg Chem 35:1168–1178
Hagiwara R, Ito Y (2000) J Fluorine Chem 105:221–227
Gordon CM, Holbrey JD, Kennedy AR, Seddon KR (1998) J Mater Chem 8:2627–2636
Muldoon MJ, Gordon CM, Dunkin IR (2001) J Chem Soc Perkin Trans 2:433–435
Park S, Kazlauskas RJ (2001) J Org Chem 66:8395–8401
Berthod A (1995) In: Foucault AP (ed) Centrifugal Partition Chromatography. Dekker NY, Chromatogr Sci Ser 68:167–197
Holbrey JH, Seddon KR (1999) J Chem Soc Dalton Trans 2133–2139
Fannin AA, Floreani DA, King LA, Landers JS, Piersma BJ, Stech DJ, Vaughn RL, Wilkes JS, Williams JL (1984) J Phys Chem 88:2614–2621
Seddon KR, Stark A, Torres MJ (2000) Pure Appl Chem 72:2275–2287
Berthod A, Carda-Broch S, Garcia–Alvarez–Coque MC (1999) Anal Chem 71:879–888
Huddleston JG, Willauer HD, Swatloski RP, Visser AE, Rogers RD (1998) Chem Comm 1765–1766
Abraham MH (1993) Chem Soc Rev 22:73–83
Abraham MH, McGowan JC (1987) Chromatographia 23:243–246
Platts JA, Butina D, Abraham MH, Hersey A (1999) J Chem Inf Comput Sci 39:835–845
Abraham MH, Poole CF, Poole SW (1999) J Chromatogr A 842:79–114
Martin SD, Poole CF, Abraham MH (1998) J Chromatogr A 805:217–235
Anderson JL, Ding J, Welton T, Armstrong DW (2002) J Am Chem Soc 124:14247–14254
Carmichael AJ, Earle MJ, Holbrey JD, McCormac PB, Seddon KR (1999) Org Lett 1:997–1000
Son S, Lewis BE (2002) J Agric Food Chem 50:468–472
Rodis PS, Karathanos VT, Mantzavinou A (2002) J Agric Food Chem 50:426–430
Miller NJ, Sampson J, Candeias LP, Bramley PM, Rice–Evans CA (1996) FEBS Lett 384:240–242
Bohm V, Nienaber NLP, Ferruzzi MG, Schwartz SJ (2002) J Agric Food Chem 50:221–226
Dai S, Ju YH, Barnes CE (1999) J Chem Soc Dalton Trans 1201–1202
Chun S, Dzyuba SV, Bartsch RA (2001) Anal Chem 73:3737–3741
Acknowledgments
Support by the National Institute of Health NIH R01 GM 53825 is gratefully acknowledged. AB thanks the French Centre National de la Recherche Scientifique (UMR5619 ERS2007 FRE2496) for a one-year sabbatical leave at ISU. SCB and AB thank the European Community for the Marie-Curie Fellowship HPMF-CT-2000–00440.
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S. Carda–Broch and A. Berthod were on leave from Laboratoire des Sciences Analytiques, CNRS, Université de Lyon 1, Bat CPE-308, 69622 Villeurbanne, France
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Carda–Broch, S., Berthod, A. & Armstrong, D.W. Solvent properties of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid. Anal Bioanal Chem 375, 191–199 (2003). https://doi.org/10.1007/s00216-002-1684-1
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DOI: https://doi.org/10.1007/s00216-002-1684-1