Method for preparing N-hydroxyphthalimide

The invention relates to a method for preparing N-hydroxyphthalimide. The method includes the following steps: 1, phthalic anhydride and hydroxylamine hydrochloride are added into isopropanol; 2, then triethylamine is added, reacting is carried out for 0.5 h to 1.5 h at the temperature of 70 DEG C to 95 DEG C, reduced pressure distillation is carried out to recycle the isopropanol and the triethylamine, then washing and drying are carried out, and the N-hydroxyphthalimide is obtained. The method has the advantages that the isopropanol is used as new reaction media, and the triethylamine is used as accelerants, so that the toxicity of the solvents is reduced, the reaction safety is improved, the purification energy consumption is reduced, the reaction time is shortened, and the obtained product is high in purity. In addition, compared with inorganic-salt and iron-trioxide purification technology, the purification technology relating to the triethylamine serving as the accelerants is simpler, easy to operate and quite suitable for industrial production.