To a 2-L Erlenmeyer flask, 1 L of acetonitrile, 120 mL of benzylamine and 4.8 mL of 80-90% formic acid (5.76 g) is added. The flask is immersed in an ice-water bath and stirred until the temperature drops below 15°C. A slow addition of 57 mL of 40% glyoxal solution is then started with vigorous stirring over the course of 1h. The temperature should be kept below 20°C. Subsequently, the flask is removed from the cooling bath and agitated for 0.5 h. The mixture is then left at room temperature for 24 h, after which filtered and washed twice with acetonitrile. The product can be recrystallized with hot acetonitrile.
The mixture before the addition of the glyoxal
The mixture after the addition of the glyoxal
The mixture after left to stand