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

HRID 12887Notes

Reaction equation

C([O:3][C:4]([C:6]1[CH:7]=[N:8][N:9]([CH:12]2[CH2:16][CH2:15][CH2:14][CH2:13]2)[C:10]=1[Cl:11])=[O:5])C.O.[OH-].[Li+]>CO>[Cl:11][C:10]1[N:9]([CH:12]2[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: 80 °C

Procedure

5-Chloro-1-cyclopentyl-1H-pyrazole-4-carboxylic acid ethyl ester (0.710 g, 2.93 mmol) was dissolved in methanol (4.3 mL). Water (4.3 mL) and lithium hydroxide (0.097 g, 4.05 mmol) were added and the mixture was heated at 80° C. for 2 hours. After cooling to room temperature, methanol was removed in vacuo. Tetrahydrofuran was added to the residue and then removed in vacuo to ensure complete removal of the methanol. The residue was diluted with water and treated with 6N HCl to pH 2-3, resulting in precipitation of a milky solid. The solid was collected, washed with water and dried under house vacuum at 45° C., yielding 5-chloro-1-cyclopentyl-1H-pyrazole-4-carboxylic acid (0.580 g, 91%). This material was used as is without any further purification.

Workup

temperatureAfter cooling to room temperature
custommethanol was removed in vacuo
additionTetrahydrofuran was added to the residue
customremoved in vacuo
customremoval of the methanol
additionThe residue was diluted with water
additiontreated with 6N HCl to pH 2-3
customresulting in precipitation of a milky solid
customThe solid was collected
washwashed with water
customdried under house vacuum at 45° C.

Sources & evidence

ORD record: ord-6367f5c8181a44338ffe217cb1fd44fc
Source dataset: uspto-grants-2010_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07728029B2

Reaction notes

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