Methylpyrrolidonium Trifluoroacetate Protic Ionic Liquid: Distillation Boundary in the Ethyl Trifluoroacetate–Trifluoroacetic Acid–N-Methyl-2-pyrrolidone System

Experimental data on the distillation boundary in the ethyl trifluoroacetate (EtTFA)–trifluoroacetic acid (TFA)–N-methyl-2-pyrrolidone (NMP) azeotropic (Az) system are considered. Theoretical qualitative model of the distillation map of the EtTFA–TFA–NMP mixture at atmospheric pressure supposes two distillation areas with TFA or EtTFA having lower volatility and vice versa, and they are split by the separatrix AzEtTFA/TFA–protic ionic liquid (PIL). From the experimental data, for the liquid phase that is located closer to the center of the concentration simplex, the third component traces occurred, but in general, the vapor-phase composition (vapor line) in the distillation map belongs to binary constituents. One more interesting aspect is the vapor composition line across the binary azeotrope EtTFA–TFA and, as a consequence, the separatrix AzEtTFA/TFA–PIL. Therefore, the separation during Rayleigh distillation and thermodynamic constraint (caused by the presence of the azeotrope and the separatrix generated by it) overcoming become possible by reason of PIL formation.