Preparation method of 3-nitro-2-fluorobenzoic acid

The invention relates to 3-nitro-2-fluorobenzoic acid, in particular to a preparation method of 3-nitro-2-fluorobenzoic acid. A basic raw material o-fluorobenzoic acid is synthesized, 2-fluoro-5-sulfonyl-benzoic acid is generated through sulfonation protection of sulfur trioxide, then 2-fluoro-3-nitro-5-sulfonyl benzoic acid is synthesized through nitric acid and sulfuric acid, and finally, 3-nitro-2-fluorobenzoic acid and a byproduct sodium sulfite are obtained through desulfonation under an acidic condition. The equipment investment is low. 本发明涉及3-硝基-2-氟苯甲酸，具体涉及3-硝基-2-氟苯甲酸的制备方法；从基本原料邻氟苯甲酸开始合成，经过三氧化硫磺化保护生成2-氟-5-磺酸基-苯甲酸，再经过硝酸硫酸合成2-氟-3-硝基-5-磺酸基苯甲酸，最后在酸性条件下脱磺酸基成3-硝基-2-氟苯甲酸副产亚硫酸钠，该工艺路线短，三废少，设备投资少。