反应详情

255 ml of acetic anhydride were added to a mixture of 203.2 g (0.85 mol) of diethyl pyridine-2,3-dicarboxylate-N-oxide in 1.2 l of glacial acetic acid. 68.3 g (1.06 mol) of 98% strength nitric acid were then added in the course of 40 minutes at from 20° to 28° C. with gentle cooling and stirring and the mixture was stirred at 30° C. for 12 hours. The reaction solution was poured into 3.5 l of ice-water and extracted with methylene chloride. The organic phase was extracted in succession with water, saturated sodium hydrogencarbonate solution and sodium chloride solution, dried over magnesium sulfate and filtered off with suction through silica gel. After concentration, 177.6 g (78% of theory) of diethyl 5-nitropyridine-2,3-dicarboxylate-N-oxide were obtained of nD25 =1.5290. A sample crystallized after relatively long standing; m.p. 84°-86° C.

1. temperaturewith gentle cooling
2. stirringthe mixture was stirred at 30° C. for 12 hours
3. extractionextracted with methylene chloride
4. extractionThe organic phase was extracted in succession with water, saturated sodium hydrogencarbonate solution and sodium chloride solution
5. dry with materialdried over magnesium sulfate
6. filtrationfiltered off with suction through silica gel
7. concentrationAfter concentration