反应详情

One mole of ethyl 2-hydroxyimino-acetoacetate, prepared from 130 g. (1 m.) of ethyl acetoacetate, was added over 75 minutes to a stirred suspension of 166 ml. (3 m.) of concentrated sulfuric acid and 105 g. (3.5 m.) of paraformaldehyde at 5°-10°. The mixture was stirred at 5°-10° for four hours and aqueous ammonia (28%) was added to pH 5 and the temperature rose to 70°. The reaction mixture was held for 30 minutes at pH 5 at 65°-70° and then neutralized with aqueous ammonia (28%). The mixture was cooled to 10°. The solid material was filtered off, washed with water and isopropanol and dried to give ethyl 5-methyl-4-imidazolecarboxylate (yield 50%).

1. customat 5°-10°
2. customrose to 70°
3. waitThe reaction mixture was held for 30 minutes at pH 5 at 65°-70°
4. temperatureThe mixture was cooled to 10°
5. filtrationThe solid material was filtered off
6. washwashed with water and isopropanol
7. customdried