Sulfuric Acid → 2-(2,6-Dichloro-4-trifluoromethylphenylhydrazono)succinonitrile

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Reaction Conditions

Reaction Steps

Sodium nitrite (3.9 g) was added to stirred concentrated sulfuric acid (12.8 ml) and heated at 80° C. until dissolved. Acetic acid (25 ml) was added at 30° C. A mixture of 2,6-dichloro-4-trifluoromethylphenylaniline (10.0 g) and acetic acid (25 ml) was added over 10 minutes at 20° C. maintaining below 25° C. The mixture was heated at 55° C. for 50 minutes, and further sodium nitrite (0.65 g) and acetic acid (10 ml) added, and after 20 minutes heated to 70° C. and sulfuric acid (2.8 ml) added. After 20 minutes the cooled mixture was added to a mixture of 2-hydroxymethylenesuccinonitrile potassium salt (7.6 g) and sodium acetate (35.6 g) in water and acetic acid (70 ml) at 10° C. After warming to 20° C. during 1 hour, dichloromethane was added followed by ammonium hydroxide solution (210 ml) to give a pH of 8. The organic phase was separated, washed (water and brine), dried (sodium sulfate) and evaporated to give the title compound as a red-brown solid (18.1 g). Recrystallization from hexane/t-butyl methyl ether) gave the pure title compound (6.85 g), m.p. 80-82° C., NMR 3.6 (s, 2H), 7.66 (s, 2H), 9.03 (s, 1H exchangeable with D2O).

Provenance & Evidence