1. 2,5-diamino-4,6-dichloropyrimidine (0.01 mol, 2.0 g) was mixed with water (0.25 mol, 4.55 mL) at room temperature and stirred.
2. 98% formic acid (0.4 mol, 18.27 g, 14.97 mL) was slowly added to the reaction system.
3. The reaction mixture was heated to 50-55 °C and maintained at this temperature for 3 hours.
4. Upon completion of the reaction, toluene (0.38 mol, 34.6 g, 40 mL) was added to the reaction system at 50 °C for azeotropic distillation. This process was repeated once, using a total of 80 mL of toluene to ensure adequate distillation.
5. After the reaction mixture was cooled, the solid product was collected by filtration and washed with cold water.
6. The washed product was dried under vacuum at 60°C. 7.
7. 2-amino-4,6-dichloro-5-formamidopyrimidine (0.01 mol, 2.0 g) was finally obtained in about 90% yield.
