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温度

0 °C

Ethyl 1-methylimidazole-2-carboxylate was carefully dissolved in 1000 mL of concentrated sulfuric acid cooled to 0° C. 90% nitric acid (1 L) was slowly added maintaining a temperature of 0° C. The reaction was then refluxed with an efficient condenser (−20° C.) in a well ventilated hood for 50 min. The reaction was cooled with an ice bath, and quenched by pouring onto 10 L ice. The resulting blue solution was then extracted with 20 L DCM, the combined extracts dried (sodium sulfate) and concentrated in vacuo to yield a tan solid which was recrystallized from 22 L of 21:1 carbon tetrachloride/ethanol. The resulting white crystals are collected by vacuum filtration to provide pure Ethyl 1-methyl-4-nitroimidazole-2-carboxylate. (103 g, 22% yield). TLC (7:2 benzene/ethyl acetate v/v) Rf 0.5, 1H NMR (DMSO-d6) δ 8.61 (s, 1H), 4.33 (q, 2 H, J=6.4 Hz), 3.97 (s, 3 H), 1.29 (t, 3 H, J=6.0 Hz), 13C NMR (DMSO-d6) δ 158.2, 145.4, 135.3, 127.4, 62.2, 37.3, 14.5; IR (KBr) 3139, 1719, 1541, 1498, 1381, 1310, 1260, 1122, 995, 860, 656.; FABMS m/e 200.066 (M+H 200.067 calc. for C7H10N3O4).

1. temperaturemaintaining a temperature of 0° C
2. temperatureThe reaction was then refluxed with an efficient condenser (−20° C.) in a well ventilated hood for 50 min
3. temperatureThe reaction was cooled with an ice bath
4. customquenched
5. additionby pouring onto 10 L ice
6. extractionThe resulting blue solution was then extracted with 20 L DCM
7. dry with materialthe combined extracts dried (sodium sulfate)
8. concentrationconcentrated in vacuo
9. customto yield a tan solid which
10. customwas recrystallized from 22 L of 21:1 carbon tetrachloride/ethanol
11. filtrationThe resulting white crystals are collected by vacuum filtration