Process of preparing 2,2-bis(4-aminophenyl)-hexafluoropropane

Abstract

2,2-Bis(4-aminophenyl)hexafluoropropane is prepared by the steps of (a) reacting 2,2-bis(4-carboxyphenyl)hexafluoropropane with thionyl chloride at 80.degree.-150.degree. C. in a water insoluble organic liquid in the presence of a catalyst such as dimethylformamide to obtain a solution of 2,2-bis(4-chloroformylphenyl)hexafluoropropane, (b) mixing the obtained solution with an aqueous solution of sodium azide to obtain an acid azide solution, (c) heating the organic phase of the acid azide solution to 80.degree. C. or above to cause rearrangement of the acid azide into an isocyanate, (d) hydrolyzing the isocyanate by mixing the isocyanate solution with an acid such as 40-80% sulfuric acid to form a salt of the aimed diamine as an aqueous solution mixed with an organic phase, and (e) neutralyzing the aqueous solution separated from the liquid mixture obtained at step (d) to precipitate the aimed diamine. This process is favorable for industrial practice because the main steps (a) to (d) are all reactions in organic liquids without precipitating solid intermediates.