Phosphorus oxychloride → 2-Chloro-5-(trifluoromethyl)pyrazine

Participants

Reaction Steps

2-Amino-5-trifluoromethylpyrazine (Miesel, U.S. Pat. No. 4,293,552) was converted into 5-trifluoromethylpyrazin-2-one (Fitzjohn, EP 408196). 5-Trifluoromethylpyrazin-2-one (0.5 g) was heated at reflux in POCl3 (3 ml) containing 1 drop of conc. H2SO4 for 3 h. The cooled mixture was poured onto ice and brought to pH 5 by addition of solid NaHCO3 and extracted (3×) with diethyl ether. The ethereal extracts were washed with water and brine, dried (Na2SO4) and evaporated to give the title compound (D31) as a light yellow oil (0.2 g) which was sufficiently pure for use without further purification. 1H NMR δ [CDCl3]: 8.72 (1H, s), 8.76 (1H, s).

Provenance & Evidence