In a beaker 2.2 g of resorcinol is dissolved in 50 mL of cold water, the beaker is immersed in an ice bath. A slow addition of 2.9 g of sodium nitrite dissolved in 4 mL is started with stirring. An addition of 4 g of conc. sulfuric acid diluted with 30 mL of ice is started, with stirring, while maintaining the temperature below 5°C. After the addition, the mixture is stirred for 2h thereafter filtered and washed with some cold water. The crude product is recrystallized with hot ethyl acetate.
The mixture before filtration and washing
The crude dry product
The recrystallized product