isopropanol cannot be completely removed from isopropanol - isopropyl acetate - water mixtures by distillation because of the presence of the minimum ternary azeotrope . isopropanol can be readily removed from mixtures containing it , isopropyl acetate and water by using extractive distillation in which the extractive agent is a higher boiling ester of phthalic acid . typical examples of effective agents are diethyl phthalate , diisooctyl phthalate and methyl benzoate , dibutyl phthalate , methyl benzoate and nitromethane .