Nitric Acid → Pyridine, 2,5-dimethyl-4-nitro-, 1-oxide

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Reaction Steps

260 ml of fuming nitric acid (d=1.5) were added dropwise to 840 ml of concentrated sulphuric acid while cooling. 348.2 g of 2,5-dimethylpyridine 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 l of methylene chloride. The combined organic phases were washed with 4 l 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°.

Provenance & Evidence