Water → HOAt

To 13.58 g of 2-nitro-3-methoxypyridine was added 26.4 mL of 95% hydrazine, 10.4 mL of water and 15.3 mL of DMF. The mixture was carefully warmed to about 70° on a hot plate. Spontaneous warming then set in, the temperature rising to about 80° as the solid dissolved. The solution was set aside for 24 hr and then evaporated from a water bath with the aid of a water aspirator to remove excess hydrazine and water. The dark green residue was cooled in an ice bath, diluted with 50 mL of water and acidified to Congo Red with concentrated hydrochloric acid (ca. 17 ml). A yellow-straw-colored solid separated and was filtered and washed with a little cold water to give 6.25 g (52.1%) of HOAt upon recrystallization from 75 mL of water gave 5.46 g (45.5%) of nearly colorless crystals, mp 216°-217° 1H NMR (CDCl3 -DMSO-d6): δ7.35 (dd, 1, β-H), 8.3 (dd, 1, γ-H), 8.66 (dd, 1, α-H); Jα,β =4.2 Hz, Jβ, γ=8.2 Hz, Jα, γ=1.6 Hz. Evaporation of the filtrate gave an additional 0.14 g of the pure hydroxy compound so the total yield was 5.6 g (46.7%).

1. temperatureThe mixture was carefully warmed to about 70° on a hot plate
2. temperatureSpontaneous warming
3. customrising to about 80° as the solid
4. dissolutiondissolved
5. customevaporated from a water bath with the aid of a water
6. customto remove excess hydrazine and water
7. temperatureThe dark green residue was cooled in an ice bath
8. additiondiluted with 50 mL of water
9. customA yellow-straw-colored solid separated
10. filtrationwas filtered
11. washwashed with a little cold water

ORD record

ord-ff62765be21f4833acf994a8ef5718f1

Source dataset

uspto-grants-1997_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05698675