Sulfuric Acid → 3-Hydroxyisoquinoline

Participants

Reaction Steps

200 g. N-formyl-2-phenyl-acetamide are dissolved in an inert atmosphere (nitrogen) in 1250 ml. concentrated sulfuric acid, while stirring and cooling in a bath of cold water in order to maintain the temperature at about 20°-25°C., whereafter the reaction mixture is left to stand for 4 hours at ambient temperature. The sulfuric acid solution is then poured, with stirring, into about 4 liters of a mixture of ice and water, the temperature not exceeding 50°C. The reaction mixture is then filtered through "Hyflo Super-Cel" a very pure diatomaceous silica filter-aid sold by Johns-Manville Sales Corp. (HYFLO is a Trade Mark). The filtrate obtained is poured, while stirring mechanically and cooling in ice (temperature of the reaction medium about 20°C.), into 3.5 liters concentrated ammonium hydroxide solution. The yellow precipitate of 2H-3-isoquinolone obtained is filtered off, washed with water and dried. There are obtained 72 g. of product; m.p. 201°C.; yield 40% of theory.

Provenance & Evidence