A major impurity is trifluoroacetamide. Add trifluoroacetic anhydride to BTFA, reflux for 2hours and fractionate using a Vigreux column (p 11) at atmospheric pressure. [Donike J Chromatogr 78 273 1973, Beilstein 2 IV 471.]
BISTRIFLUOROACETAMIDE Preparation Products And Raw materials