Yield:55321-99-8 91.2%

Reaction Conditions:

with sodium hydroxide in water at -10 - 22; for 4.67 h;

Steps:

1 Example 1: Preparation of compound III

In the reaction flask, add 220 ml of 20% sodium hydroxide aqueous solution, cool to -10°C, and then add 100 g of 2-aminomalonamide to suspend it in the solution. Then, 149.4 g of 40% glyoxal aqueous solution was added dropwise, and the addition was completed in about 40 minutes. After the dropwise addition, the reaction mixture was stirred at -5°C for 1 hour, heated to 22°C, and stirred for another 3 hours. After the reaction is completed, it is cooled to below 5°C, the reaction compound is adjusted to pH 12 by adding 1 mol/l sodium hydroxide, and a solution is made again. The solution was then adjusted to pH 2 by adding 6 mol/l hydrochloric acid. The deposited crystals were collected by filtration and washed with water and 50% (w/w) ethanol successively to obtain 108.6 g of compound II with a yield of 91.2%.

References:

CN111349049,2020,A Location in patent:Paragraph 0044-0048