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A solution of sodium ethoxide in ethanol was prepared by dissolving sodium (0.5 g, 21.9 mmol) in ethanol (25 ml) in a dry nitrogen atmosphere and 3,4-dichlorophenylhydrazine hydrochloride (1.85 g, 8 mmol) was added. The mixture was warmed to reflux for 45 min. with stirring, then cooled to room temperature and ethoxyacrylonitrile (1.4 g, 14 mmol) added and warmed again to reflux for 24 hours. The reaction mixture was cooled to room temperature and followed by addition of water (7 ml) and 6N HCl to adjust the pH to ˜2. The resulting aqueous-ethanolic solution was stirred at room temperature for 3 hours, treated with 10% aq. NaOH to a pH 7-8 and stirred overnight. A red colour solid appeared and it was filtered, washed with water and dried to give 1-(3,4-dichlorophenyl)-1H-pyrazol-3-amine (1.57 g, 88% yield)

1. additionwas added
2. temperatureThe mixture was warmed
3. temperatureto reflux for 45 min.
4. temperaturewarmed again
5. temperatureto reflux for 24 hours
6. temperatureThe reaction mixture was cooled to room temperature
7. stirringThe resulting aqueous-ethanolic solution was stirred at room temperature for 3 hours
8. stirringstirred overnight
9. filtrationit was filtered
10. washwashed with water
11. customdried