Preparation method of 3-hydroxyphthalic anhydride

The invention discloses a preparation method of 3-hydroxyphthalic anhydride, and relates to the technical field of organic synthesis. According to the method, 3-nitrophthalic acid is taken as an initial reaction material, the raw materials are low in price and easy to obtain, a process route is optimized, a reduction step and a cyclization step are combined into one step, then two-step reaction of diazotization and hydrolysis is carried out, and more pre-purification treatment does not need to be additionally carried out on a process product. Compared with a traditional method, the synthesis method has the advantages of few reaction steps, simple and easy process and low requirements on production equipment; reaction conditions are mild and easy to achieve, industrial amplification production is facilitated, and the method has a better industrial application prospect. 本发明公开了一种3-羟基邻苯二甲酸酐的制备方法，涉及有机合成技术领域。以3-硝基邻苯二甲酸为起始反应物料，原材料价格低廉易得，通过优化工艺路线，将还原与环化步骤合并在一步，再经过重氮化水解共两步反应，不用对过程产物额外做更多的预提纯处理。相对于传统方法，本发明的合成方法反应步骤少，工艺