propan-2-ylhydrazine;dihydrochloride

Conditions: temp:140.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution containing 29 g of isopropylhydrazine dihydrochloride in 150 ml of water was added dropwise to a stirred solution of 41.7 g of diethyl oxalacetate, sodium salt in 300 ml of acetic acid and 150 ml of toluene. The mixture was heated at 140° C. for 5 h. The mixture was left to cool to room temperature and then the solvent was evaporated under reduced pressure and the residue azeotroped with toluene. The residue was partitioned between dichloromethane and water. The dichloromethane extract was washed with brine, dried over anhydrous magnesium sulphate, filtered and evaporated under reduced pressure. The residue was triturated with diethyl ether to give a white solid which was filtered then washed three times with cold diethyl ether and dried to give 11.1 g of 5-hydroxy-1-isopropyl-1H-pyrazole-3-carboxylic acid ethyl ester as a white solid which was used without further purification. The mixture was left to cool to room temperature the solvent was evaporated under reduced pressure the residue azeotroped with toluene The residue was partitioned between dichloromethane and water The dichloromethane extract was washed with brine dried over anhydrous magnesium sulphate filtered evaporated under reduced pressure The residue was triturated with diethyl ether to give a white solid which was filtered then washed three times with cold diethyl ether dried