2 - Nitro-5 - Bromo Pyridine

The synthesis of 2-nitro-5-bromopyridine was investigated and improved in this paper.The first step: 2-aminopyridine was reacted with tetrabutylammonium hydrogen dibromi-de to give 2-amino-5-bromopyridine. The second step: in the presence of concentratedsulphuric acid catalyst, oxidation of 2-amino-5-bromopyridine with H₂O₂ gave the targetproduct 2-nitro-5-bromopyridine with high purity. Many factors which effect the reaction,such as reaction temperature, reaction time, ratio of materials and the amounts of solventhave been studied.Results showed that using tetrabutylammonium hydrogen dibromide as brominatingreagent was better than using bromine. The optimal reaction conditions of bromination arethat reaction temperature is about 20℃and the reaction time is 2h; 2-aminopyridine is0.94g; tetrabutylammonium hydrogen dibromide is 4.03g; the amounts of solvent is 20mL.The optimal reaction conditions of oxidation are that reaction temperature is about 50℃and the reaction time is 24h; the amounts of H₂O₂ is 6mL; the amounts of concentratedsulphuric acid is 10mL. Oxidation of 2-amino-5-bromopyridine with H₂O₂ gave the targetproduct 2-nitro-5-bromopyridine with concentrated sulphuric acid as catalyst in 70.8％yield. The process for the production of low-cost, small industrial pollution, will havebroad market prospects.