4,6-Dihydroxy-2-methylpyrimidine was prepared as follows: in a reaction flask equipped with a mechanical stirrer, a reflux condenser, a thermometer and a dropping funnel, 200 ml of isopropanol was put into the reaction flask, 27 g (0.5 mol) of sodium methanol were poured in and heated at 40-50C until completely dissolved, then 20 ml (0.125 mol) of malonate were added and mixed for 10-15 minutes, then 22 g (0.373 mole) of acetamide was added in batches under vigorous stirring. The reaction material was rapidly heated to boiling and boiled for 4 h. The solvent was then evaporated and 100 ml of water was added to the residue at 50-60C. The precipitate was completely dissolved. The resulting salt solution is acidified with glacial acetic acid at 5060C to a pH of 5-6, slowly cooled and settled at a temperature of 18-25C for 10 hours. The precipitated product is filtered out and washed with water (3 x 30 ml), alcohol (2 x 20 ml). 9.9 g (62.9% of the theoretical value) of 4,6-dihydroxy-2-methylpyrimidine was obtained with 95% basic substance content.
