Sodium Hydroxide → 5-Chloropyrazinoic acid

Temperature

0 °C

Dissolve 5-chloro-pyrazine-2-carboxylic acid methyl ester (10.0 g, 57.9 mmol) in THF (65 mL) and MeOH (65 mL). Cool the solution to 0° C. before adding 1N NaOH (63.7 mL) with stirring. Warm the mixture to room temperature and stir for 5 h. Concentrate the mixture in vacuo to 1/3 volume. Quench with 1N HCl (75 mL) to form a white precipitate. Dilute with CH2Cl2 (200 mL) and filter. Wash the filter cake with water and CH2Cl2. Separate the phases, dry the organic phase over MgSO4, filter, and concentrate. Add the aqueous layer to the concentrated organic residue and concentrate. Purify by silica gel flash column chromatography, eluting with 40% ethyl acetate/n-hexane, followed by 10% MeOH, 3% acetic acid and 87%

1. temperatureWarm the mixture to room temperature
2. stirringstir for 5 h
3. concentrationConcentrate the mixture in vacuo to 1/3 volume
4. customQuench with 1N HCl (75 mL)
5. customto form a white precipitate
6. filtrationfilter
7. washWash the filter cake with water and CH2Cl2
8. customSeparate the phases
9. dry with materialdry the organic phase over MgSO4
10. filtrationfilter
11. concentrationconcentrate
12. additionAdd the aqueous layer to the concentrated organic residue
13. concentrationconcentrate
14. customPurify by silica gel flash column chromatography
15. washeluting with 40% ethyl acetate/n-hexane

ORD record

ord-c7ea2c61c43b41d387c4b09f0527021a

Source dataset

uspto-grants-2010_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07838543B2