Lithium Hydroxide → 5-chloro-1-(2-methoxyethyl)-1H-pyrazole-4-carboxylic acid

To a solution of 5-chloro-1-(2-methoxyethyl)-1H-pyrazole-4-carboxylic acid ethyl ester (4.60 g, 19.77 mmol) in methanol (32 mL) and water (32 mL) was added lithium hydroxide (1.10 g, 26.22 mmol). The reaction mixture was stirred at reflux for 3 h, and then the solution was concentrated under reduced pressure to remove the methanol. The residue was then acidified carefully with 6.0 N aqueous HCl. The resulting mixture was extracted with methylene chloride (3×50 mL). The combined organic extracts were dried over anhydrous Na2SO4, filtered and concentrated in vacuo to provide 5-chloro-1-(2-methoxyethyl)-1H-pyrazole-4-carboxylic acid as a white solid (1.27 g, 31%). Mass spectrum: m/z: 205.3 (M+1).

1. temperatureat reflux for 3 h
2. concentrationthe solution was concentrated under reduced pressure
3. customto remove the methanol
4. extractionThe resulting mixture was extracted with methylene chloride (3×50 mL)
5. dry with materialThe combined organic extracts were dried over anhydrous Na2SO4
6. filtrationfiltered
7. concentrationconcentrated in vacuo

ORD-Eintrag

ord-313b876f6b9a4d209cb096147d69c3aa

Quelldatensatz

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07728029B2