Extraction of Organic Compounds Involved in the Kinetic Resolution of rac-2-Pentanol from n-Hexane by Imidazolium-based Ionic Liquids: Liquid-Liquid Equilibrium

Abstract

This paper focuses on the use of ionic liquids (1-butyl-3-methylimidazolium methylsulphate, [bmim+][MeSO4-], and 1-ethyl-3-methylimidazolium acetate, [emim+][Ac-]) to extract organic compounds involved in the racemic resolution of rac-2-pentanol (rac-2-pentanol, vinyl butyrate, rac-2-pentyl butyrate or butyric acid) from a mixture of one of these organic compounds with n-hexane. Liquid–liquid equilibrium data were experimentally obtained for seven ternary systems comprising an ionic liquid + rac-2-pentanol, vinyl butyrate, rac-2-pentyl butyrate or butyric acid + n-hexane at T=303.15 K and atmospheric pressure. Binodal curves were measured applying the well-known procedure based on the observance of the cloud point while the compositions of the tie lines were calculated from refractive index and density measurements (the phase rich in the ionic liquid) and by gas cromatography (the phase rich in n-hexane). Selectivity values and the solute distribution ratio were utilized to test the possibility of the use of these ionic liquids as extractive solvents of the organic compounds implicated in the kinetic separation of the R- and S-enantiomers of rac-2-pentanol. The liquid-liquid equilibrium data of the ternary systems examined here have not previously been described in the literature.