Sulfuric Acid → 5-Methoxypyridin-3-ol

Temperature

2.5 °C

A mixture of concentrated sulfuric acid (18 M, 2.83 mL), water (3.84 mL) and crushed ice (6.60 g) was added to 5-methoxy-3-pyridylamine (1.64 g, 13.23 mmol). The cold mixture (0-5° C.) was stirred for 10 min and a solution of sodium nitrite (0.91 g, 13.23 mmol) in water (2.7 mL) was then added. After stirring for 10 min, a boiling solution of concentrated sulfuric acid (8.6 mL) and water (6.6 mL) was added. The mixture was heated until all solids dissolved. Ice (5.0 g) was added to cool the solution. The pH was adjusted to 8 with 10% NaOH solution. Saturated NaCl solution (100 mL) was added, and the mixture was extracted with ethyl acetate (4×100 mL). The combined ethyl acetate extracts were dried (MgSO4), filtered and concentrated by rotary evaporation to give 0.50 g (30.1%) of a brown oil.

1. stirringAfter stirring for 10 min
2. temperatureThe mixture was heated until all solids
3. dissolutiondissolved
4. temperatureto cool the solution
5. extractionthe mixture was extracted with ethyl acetate (4×100 mL)
6. dry with materialThe combined ethyl acetate extracts were dried (MgSO4)
7. filtrationfiltered
8. concentrationconcentrated by rotary evaporation

ORD record

ord-241f9effe66b4f24b339fecb7095fe2a

Source dataset

uspto-grants-2003_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06627648B1