Water → 5-chloro-1-cyclohexyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

5-Chloro-1-cyclohexyl-1H-pyrazole-4-carboxylic acid ethyl ester (1.969 g, 7.67 mmol) was dissolved in methanol (11.5 mL). Lithium hydroxide (0.250 g; 10.44 mmol) and water (11.5 mL) were added. The mixture was heated at 80-85° C. for 1.5 hours, cooled to room temperature and concentrated in vacuo to remove the methanol. The residue was diluted with tetrahydrofuran and concentrated again to ensure complete removal of the methanol. This residue was then diluted with water and acidified with 6N HCl (1.80 mL) to pH 2-2.5. The solid which precipitated out of solution was collected by filtration, washed with water and dried under reduced pressure at 100° C. to give 5-chloro-1-cyclohexyl-1H-pyrazole-4-carboxylic acid (1.676 g, 96%) which was used without further purification. Mass spectrum: m/z: 229.0 (M+H)

Provenance & Evidence