**3. Experimental part**

In order to analyse the influence of the alkyl chain length of the IL cation on the extraction of toluene from its mixture with heptane and cyclohexane, liquidliquid equilibrium data of the quaternary systems heptane + cyclohexane + toluene + 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [EMim] [NTf2], and heptane + cyclohexane + toluene + 1-hexyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [HMim][NTf2], were determined. Experimental data were compared to the results obtained for the ternary systems heptane + toluene + [EMim][NTf2], cyclohexane + toluene + [EMim][NTf2], heptane + toluene + [HMim][NTf2] and cyclohexane + toluene + [HMim][NTf2] [27, 28].
