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

HRID 12880Notes

Reaction equation

C([O:3][C:4]([C:6]1[CH:7]=[N:8][N:9]([CH:12]2[CH2:17][CH2:16][CH2:15][CH2:14][CH2:13]2)[C:10]=1[Cl:11])=[O:5])C.[OH-].[Li+].O>CO>[Cl:11][C:10]1[N:9]([CH:12]2[CH2:17][CH2:16][CH2:15][CH2:14][CH2:13]2)[N:8]=[CH:7][C:6]=1[C:4]([OH:5])=[O:3]

Participants

Conditions

Temperature: 82.5 °C

Procedure

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)

Workup

temperaturecooled to room temperature
concentrationconcentrated in vacuo
customto remove the methanol
additionThe residue was diluted with tetrahydrofuran
concentrationconcentrated again
customremoval of the methanol
additionThis residue was then diluted with water
customThe solid which precipitated out of solution
filtrationwas collected by filtration
washwashed with water
customdried under reduced pressure at 100° C.

Sources & evidence

ORD record: ord-b033e010fefa4855a1aa24996e1e5544
Source dataset: uspto-grants-2010_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07728029B2

Reaction notes

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