Acetic Anhydride → HCID 178474341, compound

Temperature

45 °C

To a 2 L glass flask was charged with 200 g (2.36 mol) of 3-aminopyrazole and 900 g of ethyl acetate. The mixture was agitated at 45° C. for 30 min to form a homogeneous solution. To the mixture was added 245 g (2.36 mol) of acetic anhydride over 1.2 h. The mixture was stirred at 60° C. for 3 h. HPLC analysis of reaction mixture indicated the presence of 3-aminopyrazole. Another 9.7 g (0.09 mol) of acetic anhydride was added into the mixture over 15 min at ca. 60° C. The resulting suspension was agitated for another 2 h at ca. 60° C. The mixture was cooled to 20-25° C. and stirred at that temperature for 15 h. The solids were collected by filtration and washed with 630 g of ethyl acetate. The solids were dried in a vacuum oven (45-50° C./P≦−0.1 MPa) for ca. 24 h to afford 295.2 g (94% yield) of N-(1H-pyrazol-3-yl)-acetamide as off-white solid. 1H-NMR (400 MHz, d6-DMSO): δ 12.26 (s, 1H), 10.33 (s, 1H), 7.57 (s, 1H), 6.47 (s, 1H), 1.99 (s, 3H).

1. customto form a homogeneous solution
2. stirringThe mixture was stirred at 60° C. for 3 h
3. customHPLC analysis of reaction mixture
4. stirringThe resulting suspension was agitated for another 2 h at ca. 60° C
5. temperatureThe mixture was cooled to 20-25° C.
6. stirringstirred at that temperature for 15 h
7. filtrationThe solids were collected by filtration
8. washwashed with 630 g of ethyl acetate
9. customThe solids were dried in a vacuum oven (45-50° C./P≦−0.1 MPa) for ca. 24 h

ORD record

ord-495a92ea0c5346599fd31c061ad3da6d

Source dataset

uspto-grants-2016_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09388168B2