Synthesis of 1-(6-isocyanatohexyl)-3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)urea (UPy-NCO) 2-amino-4-hydroxy-6-methylpyrimidine (11.19 g, 0.0895 mol) was added to a round bottom flask equipped with a magnetic stirrer bar. To this solid 1,6-hexadiisocyanate (108.5g, 0.646 mol) was added. The reaction mixture was capped with a rubber septum and purged with nitrogen for 10 min. At this point, 8 mL of anhydrous pyridine was added and the reaction mixture was heated at 100 °C for 16 h. To this reaction mixture 30 mL of hexane was added, and the precipitate was washed with diethyl ether. The white solid was dried under reduced pressure to give UPy-NCO (25.48g, 0.0869 mol, 97% yield). The compound was confirmed by 1H-NMR in agreement with the literature.1 1HNMR( 300 MHz, CDCl3) ppm 13.10 (1H, sing), 11.86 (1H, sing), 10.17 (1H, sing), 5.82 (1H, sing), 3.28 (4H ,multi), 2.23 (3H, sing), 1.62 (4H, quin, J=6.9 Hz), 1.41 (4H, multi) How do I can purify hexamethylene diisocyanate for the synthesis of UPy ? 1) Hexamethylenediisocyanate can be purchased from Sigma or other commercial suppliers at > 98 % purity. Since the substance is polymerizing it could be advised to buy fresh material or small amounts e.g. buy 100 gr bottles and use the opened bottle in one go. 2) Your 2-amino-4-hydroxy-6-methylpyrimidine is perhaps not sufficient pure. Check the melting point (168 °C). It could be advised to purify 2-amino-4-hydroxy-6-methylpyrimidine by crystallization using precipitation. You dissolve it in alkaline solution and then you add drops of acetic acid to get an off-white solid. Collection by filtration and washing with water and diethylether. 2-amino-4-hydroxy-6-methylpyrimidine [m.p. 168° C. Product was off-white solid, soluble in hot acetone, benzene, hot ethanol and dioxane and insoluble in water and chloroform.]

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Dear Saeed

Did you reach your product regarding to the answers? this reaction is my difficulty.

please share with me your results if you don't mind.

thanks