The reduction of 2,4-diamino-5-nitroso-6-hydroxy-pyrimidine(DAHNP)to 2,4,5-triamino-6-hydroxy-pyrimidine(TAHP)and the formation of TAHP sulfate is complicated and involves a large amount of inorganic salts,making it difficult to purify crude guanine(GA).Directly synthesizing GA from DAHNP can not only solve this problem,but also shorten the reaction process and improve the reaction efficiency.Therefore,this article designed a green route for the synthesis of GA by formamide method.This study used methyl cyanoacetate(MC)and guanidine hydrochloride(GH)as raw materials to obtain DAHNP through cyclization and nitrification in one-pot method.The separated DAHNP was then reduced by sodium bisulfite and reacted with formamide dehydration in a closed loop in one-pot to obtain GA.The effects of molar ratio of raw material,dosage of sodium nitrite and mass fraction of sodium methanolate solution on the yield of DAHNP were systemically investigated.The effects of types of reducing agent,dosage and mass fraction of formamide solution on GA yield were studied.When using sodium bisulfite as reducing agent,n(MC)∶n(GH)∶n(CH3ONa)∶n(NaNO2)=1∶1.14∶1.6∶1.2,m(NaHSO3)=3.5g,80%formamide solution and 20%sodium methanolate methanol solution,GA yield could reach 80.7%with purity≥99.0%.The synthesis process was easy to operate and had a simple process,achieving the recovery and utilization of formamide solvent,which was suitable for industrial production.
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