O-Xylene → Tetrafluorophthalic anhydride

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Reaction Steps

350 g of crude tetrafluorophthalic acid are heated with 800 g of xylene using a water separator, until no further water passes over (5 hours). The resulting suspension is allowed to cool and the anhydride which has precipitated is filtered off. 301 g of tetrafluorophthalic anhydride are obtained, the mother liquor, which still contains about 5 g of tetrafluorophthalic anhydride, being used for further dehydrations. The tetrafluorophthalic anhydride is then purified by fractionation, whereupon it passes over as a colorless liquid (under 1 mbar/95° C.-105° C.) and solidifies as a colorless, crystalline mass of melting point 93°-94° C. 255 g (1.16 mol) of tetrafluorophthalic anhydride with a purity of >99% (GC, HPLC) are obtained in this manner.

Provenance & Evidence