Process for distillative recovery of 1,1,1,3,3,3-hexafluoro-2-propanol (hfip) from mixtures with 4- substituted 1,2,3,4-tetrahydroquinolines

A method for distillative recovery of 1,1,1,3,3,3-hexafluoro-2-propanol from an initial mixture comprising 1,1,1,3,3,3-hexafluoro-2-propanol and a compound of formula (Ia) or (Ib),

• wherein
• R1 is selected from the group consisting of C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy-C1-C6-alkyl, C3-C6-cycloalkyl, C6-C14-aryl, or C6-C14-aryl-C1-C4-alkyl,
• wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
• R2 and R3 are the same and are selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl and C1-C6-alkoxy-C1-C6-alkyl,
• or
• R2 and R3 together with the carbon which they are bound to, form a C3-C6-cycloalkyl ring,
• R4 is hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C1-C6-haloalkoxy, C1-C6-alkylamino, C2-C6-alkenyl, C2-C6-alkynyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C4-alkyl, C2-C6-alkenyloxy, 9-flurorenylmethyleneoxy, C6-C14-aryl, C6-C14-aryloxy, C6-C14-aryl-C1-C4-alkyloxy or C6-C14-aryl-C1-C4-alkyl,
• wherein the C6-C14-aryl as such or as part of a composite substituent is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
• n is 0, 1, 2, 3 or 4,
• each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, hydroxyl, amino and —C(═O)—C1-C6-alkyl,
• the method comprising:
• adding a protic solvent selected from the group consisting of water, alcohols having a boiling point at 1 bar of 115° C. or less, and mixtures thereof to the initial mixture to obtain a distillation mixture, and
• subjecting the distillation mixture to distillation.