Ammonium Hydroxide → 4-Amino-3-chloro-5,6-difluoropicolinonitrile

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Reaction Steps

A solution of 3-chloro-4,5,6-trifluoropicolinonitrile (200 g) in ethyl acetate (EtOAc; 3 L) was cooled to 10° C. To this was slowly added 14% aqueous ammonium hydroxide (NH4OH; 1296 g) keeping the temperature between 18-23° C. The aqueous solution was separated from the organic solution. The organic phase was washed sequentially with a 50/50 solution of aqueous saturated NaCl and water (500 mL) and saturated NaCl solution (250 mL). The organic phase was concentrated under vacuum at 50° C. to about 500 mL volume as the product crystallized out. To this slurry was added heptane (1 L), and the remaining EtOAc was removed under vacuum to give the final slurry. The solids were collected by filtration. This solid was washed with pentane and dried under vacuum to give 4-amino-3-chloro-5,6-difluoropicolinonitrile (173.8 g, 90%, 99.6% purity) as a white crystalline solid: mp 190-191.5° C.; 13C{1H} NMR (101 MHz, DMSO-d6) δ 150.03 (dd, J=232.4, 12.5 Hz, C6), 144.29 (dd, J=11.4, 6.9 Hz, C4), 133.72 (dd, J=257.9, 30.8 Hz, C5), 122.14 (dd, J=19.6, 4.9 Hz, C2), 119.31 (s, C3), 114.25 (s, CN); 19F NMR (376 MHz, DMSO-d6) δ −91.24 (d, J=24.2 Hz), −154.97 (d, J=24.2 Hz); EIMS m/z 189 ([M]+). Anal. Calcd for C6H2ClF2N3: C, 38.02; H, 1.06; N, 22.17. Found: C. 37.91; H. 1.00; 22.02.

Provenance & Evidence