Synthesis And Improvement On Process Of Tetrafluoro Benzoic Acid

The synthetic technology of tetrafluoro benzoic acid was improved in this paper. The target product was synthesized by imidization, fluorination, hydrolysis and decarboxylation. Several conditions were approximated based on previous work in our group.Distillation apparatus was adopted in imidization .The water produced in the reaction was removed in time. The reaction time was changed into 0.5h from 0.25h. The yield increased to 98.2% from 95.1%. In aftertreatment process water was replaced by ethanol. So the after treatment cost decreased. In fluorination sulfolane was replaced by DMF and solvent treatment became easier .Spray dried KF was replaced by industrial KF whose cost was lower. The reaction time was 8h. The yield was 72.8%. In hydrolysis, surfactants were added and reaction time became longer. The acid concentration decreased to 25% from 50%. Ethyl ether was replaced by dichloromethane. And large amount of etheyl ether was avoided.and reaction effect was good. The reaction time was 8h. The yield was 91%. In decarboxylation, the aftertreatment became simple. The solvent was recovered and the high purity product was obtained by adding toluene and purifying. The reaction time was 3.5h. The yield was 88.6%. After approximation, the total yield was 57.6%. A synthetic process having industrial application potential was obtained.