反应详情

温度

0 °C

To an ice cold saturated solution of HCl in methanol (500 ml), pyrazole-4-carboxylic acid (4) (19.2 g, 0.17 m) was added and the solution stirred at 0° C. for 3 hours and at ambient temperature overnight. The solvent was distilled off and the brown residue was dissolved in water. The aqueous solution was neutralized with NaHCO3 and the product was repeatedly extracted with ether (25×100 ml). The ether extract was dried over Mg SO4 and concentrated to give the methyl ester (5) as a pale yellow solid (13.59 g, 79.6%).

1. distillationThe solvent was distilled off
2. dissolutionthe brown residue was dissolved in water
3. extractionthe product was repeatedly extracted with ether (25×100 ml)
4. extractionThe ether extract
5. dry with materialwas dried over Mg SO4
6. concentrationconcentrated