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To a stirred cold (0°) suspension of concentrated hydrochloric acid (516 ml.) and paraformaldehyde (105 g.) was added ethyl 2-hydroxyiminoacetoacetate prepared from 130 g. (1 m.) of ethyl acetoacetate over two hours maintaining the reaction temperature at 5°-15°. After stirring one hour at 5°-15°, aqueous ammonia (28%) was added slowly until pH reached 5 and temperature rose to 70° over 35 minutes. The reaction mixture was held at pH 5 at 65°-70° for 30 minutes and then aqueous ammonia (28%) was added until the mixture was neutral. The mixture was cooled to 10° and the solid material was filtered off and washed with water and isopropanol and dried to give ethyl 5-methyl-4-imidazolecarboxylate, m.p. 204°-206°, yield 61-65%.

1. customprepared from 130 g
2. waitrose to 70° over 35 minutes
3. waitThe reaction mixture was held at pH 5 at 65°-70° for 30 minutes
4. temperatureThe mixture was cooled to 10°
5. filtrationthe solid material was filtered off
6. washwashed with water and isopropanol
7. customdried