反应详情

260 ml of fuming nitric acid (d =1.5) were added dropwise to 840 ml of concentrated sulphur-ic acid while cooling. 348,2 g of 2,5-dimethy1pyridine 1-oxide were subsequently added portionwise at 0-5° . The mixture was stirred at room temperature for 1 hour, then heated to 90° within 3 hours, left at this temperature overnight and, after cooling, poured on to 6 kg of ice. The mixture was adjusted to pH 3 with concentrated sodium hydroxide solution and extracted three times with 2 1 of methylene chloride. The combined organic phases were washed with 4 1 of water, dried over sodium sulfate and evaporated in vacuo. The residue was crystallized from methylene chloride/petroleum ether and there was obtained 2,5-dimethyl-4-nitropyridine 1-oxide of melting point 142-144° .

1. temperaturewhile cooling
2. temperatureheated to 90° within 3 hours
3. waitleft at this temperature overnight
4. temperatureafter cooling
5. extractionextracted three times with 2 1 of methylene chloride
6. washThe combined organic phases were washed with 4 1 of water
7. dry with materialdried over sodium sulfate
8. customevaporated in vacuo
9. customThe residue was crystallized from methylene chloride/petroleum ether