Study On The Synthesis Process Of Nitrobenzoic Acid By Oxidation

PNBA is an important organic intermediate,which can be used to produce reactive brilliant red M-8B,reactive red violet X-2R,filter,color film coupler,metal surface rust remover,sunscreen and other chemical products.TNBA can be used to produce phloroglucinol and is an important raw material for many new explosives.The traditional synthesis methods of PNBA and TNBA are stoichiometry.The chemical reagents include potassium permanganate,potassium dichromate,sodium hypochlorite and nitric acid.Contrary to the concept of sustainable green chemistry,these methods have high production costs,corrode equipment and pollute the environment.PNBA was prepared by one-step reaction with PNT and sodium chlorate as main raw materials and 98%concentrated nitric acid as solvent.The PNBA was analyzed by melting point determination,TLC analysis and infrared spectrum analysis.The process of preparing PNBA was studied in detail,and the optimum conditions were obtained as follows:molar ratio of PNT to sodium chlorate was 1:2.5,reaction time was 4.1h,reaction temperature was80?85?,the yield was 81.37%.The reaction conditions were mild and the yield was high.ClO₃^-in waste liquid could be reduced to Cl^-,and then the concentration of Cl^-could be reduced by electrolysis or anion exchange resin.TNT was prepared by two-step nitration of p-nitrotoluene?PNT?,and TNBA was obtained by oxidation of TNT with NaClO₃in concentrated nitric acid solvent.The melting point of the synthesized TNBA was determined,TLC and IR were analyzed,and the synthesis process of TNBA was optimized.The results showed that the optimum conditions for the synthesis of 2,4,6-trinitrobenzoic acid were as follows:reaction temperature 90?,reaction time 4h,the molar ratio of TNT to NaClO₃was 1:4,and the highest yield was61.8%.