Hydrochloric Acid → HCID 54485817, compound

Participants

Reaction Steps

A stirred slurry of 50.2 g (0.133 mole) of 3-amino-5-(4-methylphenyl)-1H-pyrazole-4-acetic acid butyl ester ethanedioate (1:1) in 500 mL of 190 ethanol was treated first with 5 mL of hydrochloric acid (37%) and then with 21.8 g (0.133 mole) of malonaldehyde bis(dimethyl acetal). After stirring for 24 hours at ambient temperature, the reaction mixture was concentrated in vacuo. The residue was dissolved in 500 mL of methylene chloride and washed with saturated sodium bicarbonate solution. The combined aqueous layers were extracted with methylene chloride then the methylene chloride solutions were combined and washed with water. After drying the methylene chloride solution was concentrated in vacuo. The residue was dissolved in 500 mL of 200 ethanol, treated with 1 mL of concentrated sulfuric acid, and heated on a steam bath for 24 hours. The ethanol solution was treated with 50 g of potassium carbonate and 5 mL of H2O. After stirring for 30 minutes, the inorganic material was removed by filtration and the filtrate concentrated in vacuo to a black tar-like residue. The residue was dissolved in 2-propyl ether, filtered, and treated with ethereal hydrogen chloride. The salt which precipitated was collected by filtration, yielding 44 g of crude yellow-green product. The crude product was dissolved in 190 ethanol, diluted with water, then treated with 20 g of potassium carbonate. The precipitated product was collected by filtration in 2 batches to yield 33.4 g (85%) of tan product, mp 69°-71.5° C. An analytical sample was recrystallized from ethanol-water with charcoal treatment yielding a pale yellow crystalline powder, mp 71°-73° C.

Provenance & Evidence