3-Aminopyridine → 3-Hydrazinylpyridine dihydrochloride

Temperature

0 °C

3-Aminopyridine (20 g) was dissolved in concentrated hydrochloric acid (125 mL), and an a aqueous solution (40 mL) of sodium nitrite (15 g) was added at −10° C. over 20 min. The mixture was stirred at 0° C. for 2 hr. This solution was added to a solution (200 mL) of tin(II) chloride (80 g) in concentrated hydrochloric acid at −2° C. over 20 min. The mixture was stirred for 14 hr. The precipitate was filtered off and ice was added. The mixture was made strongly-basic with a 50% a aqueous potassium hydroxide solution and extracted with dichloromethane. The extract solution was dried and concentrated under reduced pressure. The residue was dissolved in ethyl acetate (400 mL) and 4 mol/L of hydrochloric acid-ethyl acetate (55 mL) was added under ice-cooling. The precipitate was collected by filtration to give 3-hydrazinopyridine dihydrochloride (18 g) as a pale-yellow solid.

1. stirringThe mixture was stirred for 14 hr
2. filtrationThe precipitate was filtered off
3. additionice was added
4. extractionextracted with dichloromethane
5. customThe extract solution was dried
6. concentrationconcentrated under reduced pressure
7. dissolutionThe residue was dissolved in ethyl acetate (400 mL)
8. addition4 mol/L of hydrochloric acid-ethyl acetate (55 mL) was added under ice-
9. temperaturecooling
10. filtrationThe precipitate was collected by filtration

ORD record

ord-ab56a896f7034027b000ddfad58355df

Source dataset

uspto-grants-2010_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07790725B2