Diethyl malonate (32 g, 0.2 mol), guanidine hydrochloride (9.6 g, 0.1 mol), sodium ethanolate (27.2 g, 0.4 mol), ethanol 150 mL was heated and refluxed, and the solid obtained after the reaction and sodium nitrite (13.8 g, 0.2 mol) were reacted in the presence of a solution of 200 mL of water, 170 mL of ethanol, and 16 mL of acetic acid for 24 hr at 25 C. The solid obtained after the reaction was reacted at reflux for 8 hours in the presence of sodium dithionite (43.5 g, 0.25 mol) and water 200 mL to obtain 2,5-diamino-4,6-dihydroxypyrimidine in 48% yield.
