摘要：Xanthine was synthesized through a new process using 4-amino-5-phenylazouracil as the intermediate. The new compound, 4-amino-5-phenylazouracil, was prepared by two methods : (i) Coupling 4-aminouracil with phenyldiazonium chloride, and (ii) phenylazocyanoacetylurea, obtained by coupling cyanoacetylurea with phenyldiazonium chloride, cyclized by alkali hydroxide solution. Reduction of 4-amino-5-phenylazouracil to give 4, 5-diaminouracil was carried out by either zinc with a mineral acid or a catalytic hydrogenation. Its reduction with zinc and 90% formic acid resulted in the formation of 4-amino-5-formylaminouracil. Xanthine was obtained when it was heated with formamide or hydrogenated in the presence of formamide using Raney nickel catalyst under pressure. The latter method gave a higher yield of xanthine.
