Sulfuric Acid → N-tert-butylpyrazine-2-carboxamide

Participants

Reaction Steps

575 g (5.75 mmol) of sulfuric acid was added dropwise to 900 ml of acetic acid over 35 minutes at 20° C. (cooling), followed by 200.1 g (1.9 mol) of cyanopyrazine over 20 minutes. 142.4 g (2.54 mol) of isobutene was then introduced over 3.5 hours, the temperature being kept below 25° C. by appropriate cooling. The mixture was subsequently stirred for a further 2 hours at room temperature and then poured into 1.8 l of ice-water. The mixture was brought to pH 3.5 by the slow addition of 1527 g of 30 percent sodium hydroxide solution and then extracted continuously for 4 hours with 2.5 l of hot methylcyclohexane in a liquid-liquid extractor. The extract was cooled to 4° C., with stirring, and the product which had crystallized out was filtered off and dried under vacuum. The yield of the title compound was 246 g, content (titration): 99.6 percent. Concentration of the mother liquor gave a further 22.5 g of the title compound with a content of 99.0 percent. The total yield of the title compound was 268.5 g (78 percent).

Provenance & Evidence