5-Amino-1-ethylpyrazole

75-07-0

107-13-1

3528-58-3

1. Hydrazine hydrate (98.7 g, 1.97 mol) was slowly added dropwise to a solution of 2-acrylonitrile (100 g, 1.88 mol) in tetrahydrofuran (350 ml) at 0-5 °C. 2. The reaction mixture was stirred at room temperature for 3 h. 3. Acetaldehyde (86.9 g, 1.9 mol) was slowly added dropwise to the above mixture, and stirring was continued for 3 h at room temperature. 4. The solvent was removed by distillation under reduced pressure to give a yellow oil. 5. The oil was dissolved in n-butanol (100 ml), followed by addition of a solution of n-butanol (250 ml) containing potassium tert-butanolate (221 g, 1.9 mol). 6. The reaction mixture was gradually heated from room temperature to 120 °C and maintained at this temperature for 3 h. 7. After completion of the reaction, the reaction was cooled to room temperature, and diluted with water (500 ml). 8. ) for dilution. 8. The reaction mixture was extracted with ethyl acetate (3 x 500 ml). 9. The organic layers were combined and dried over anhydrous sodium sulfate, followed by concentration in vacuo. 10. Purification was carried out by column chromatography using silica gel saturated with triethylamine (100-200 mesh), with 20% ethyl acetate in hexane as eluent. 11. The target fractions were collected to afford 1-ethyl-1H-pyrazol-5-amine, Yield: 66.0 g (1.0 g). 12. , Yield: 66.0 g (15% yield), mass spectrum (m/z): (M+H)+ 111.98.