Study On Synthesis Of 2,4,5-Trifuorobenzoic Acid

2,4,5-trifuorobenzoic acid is a useful intermediate in the manufacture of quinolone antibacterial drugs such as clinafloxacion and sitafloxacion. It also can be applied to synthesize dyestuff, herbicide and liquid crystals.At present, there are many difficulties in synthesis of 2,4,5-trifuorobenzoic acid, such as long synthetic route, harsh fluorination conditions, waste disposal, high quality requirement and expensive cost. Its high demand and profit make it very important to go to its research work.In this paper 2,4,5-trifluorobenzoic acid was synthesized respectively with 2,4-dichloro-5-fluorobenzoic acid and 2,3,4,5-tetrachlorophthalide. The two synthetic routes optimized reaction conditions and improved the reaction yield.In the first method, 2,4,5-trifluorobenzoic acid was synthesized by step-fluorinating, which saved reaction time and reduced cost. So this method is fit for commercial production. In the method GC was applied to in the process of synthesis 2,4,5-trifuorobenzonitrile, which obtained good result.In the second method, adopting N-methylpyrolidone as solvent contributed to the purification and isolation of 2,4,5-trifluorobenzoic acid. HPLC was applied to trace and detect the reaction process, which can also estimate the product content.The whole processes of the reactions were traced by TLC. The method has pivotal effect on judging percent conversion of raw materials, reaction time and the quality of the products.