METHOD OF SYNTHESIS OF 4-BROMO-5-NITROPHTHALONITRILE Russian patent published in 2001 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method of synthesis of 4-bromo-5-nitrophthalo-nitrile that can be used as semiproduct in synthesis of monomers for thermostable polymeric materials and biologically active substances. Method involves nitration of 4-bromo-phthalimide with nitric acid in concentrated sulfuric acid solution, amidation of 4-bromo-5-nitrophthalimide with aqueous ammonia and dehydration of 4-bromo-5-nitrophthalimide in dimethylformamide solution. Nitration reaction is carried out at 45-50 C at initial concentration of 4-bromophthalimide 2.6-2.7 mole/l in sulfuric acid and in the mole ratio nitric acid : 4-bromophthalimide = 1.2-1.4 for 5-6 h. Amidation reaction is carried out in the presence of ammonium chloride solution with concentration 25 wt.%, not less, at 35-40 C and in the mole ratio 4-bromo-5-nitrophthalimide : NH₄OH : NH₄Cl = 1:(30-32):(2-4), respectively, for 1.5-2 h. Dehydration reaction of 4-bromo-5-nitrophthalimide is carried out with phosphorus oxychloride at 30-35 C and in the mole ratio 4-bromo-5-nitrophthalimide : POCl₃ : dimethylformamide = 1:(1.2-1.3):(8-10), respectively, for 1.5-2 h. EFFECT: decreased time of amidation reaction, decreased consumption coefficient at nitration and dehydration stages, improved purity and increased yield of product. 3 tbl, 27 ex