The Synthesis Of 6-Chloro (Bromo)-2,4-dinitroaniline

6-Halo(chloro or bromo)-2,4-dinitroaniline is an important dye intermediate,which was prepared from 2,4-dinitrochlorobenzen by amination with ammonia water and halogenation with chlorinating agent or bromating agent.Based on the actual industrial production,the synthesis process has been studied and improved in this dissertation.The total yield of 6-halo-2,4-dinitroaniline was 92%.In the amination reaction,phase transfer catalyst(PTC) including tetrabutyl ammonium bromide(TBAB),N,N,N-trimethylbenzenemethanaminium chloride(TMBAC),PEG4000 and PEG4000 were used to catalyze the preparation of 2,4-dinitroaniline through ammonolysis of 2,4-dinitrochlorobenzen with ammonia.TMBAC showed the best performance in this reaction.2,4-Dinitroaniline was synthesized by reacting 2,4-dinitrochlorobenzen suspending in ammonia water(25%,by weight) in the presence of 1%mol/(mol2,4-dinitrochlorobenzen) TMBAC with ammonia for 8h at 80℃,with malor ratio of 2,4-dinitrochlorobenzen to NH₃ was 1:4.The yield was 97.4%.The preparation of 6-chloro-2,4-dinitroaniline comprising chlorination of 2,4-dinitroaniline with NaClO,HCl-H₂O₂,or SO₂Cl₂.Results showed that the most suitable chlorinating agent was sodium hypochlorite.The reaction conditions were simplified through adding NaClO dropwise at a time into the suspension of 2,4-dinitroaniline,HCl(37%,by weight) and water at 45～50℃for 3～4h,n(2,4-dinitroaniline):n(NaClO):n(HCl)=1:1.5:4.5. The total reaction time was 12h,giving yield of 94.8%.Three bromination methods were investigeted in the synthesis of 6-bromo-2,4-dinitroaniline, which used N-bromosuccimimide&N,N-dimethyformamide(NBS-DMF), HBr-H₂O₂ and Br₂-H₂O₂ as bromating agent respectly.The optimum conditions were:using HBr-H₂O₂ as bromating agent,n(2,4-dinitroaniline):n(HBr):n(H₂O₂)=1:1.2:2,1.5%mol/(mol 2,4-dinitroaniline) dose dodecyl sulfonic acid sodium salt was taken as PTC,80～90℃,3h. The yield of 6-bromo-2,4-dinitroaniline reached 94.5%.