8-Azaguanine production method: 8-Azaguanine is obtained by nitrosation, reduction, diazotization and cyclization of 2,4-diamino-6-hydroxypyrimidine. (1) nitrosation to obtain 2,4-diamino-5-nitroso-6-hydroxypyrimidine: at 15 ° C or lower, sodium nitrite is added to an aqueous solution of 2,4-diamino-6-hydroxypyrimidine, Concentrated hydrochloric acid was added dropwise to precipitate a rose red precipitate with a pH of about 3.5. Filtration, washing with water until neutral, gave 2,4-diamino-5-nitroso-6-hydroxypyrimidine (nitroso). (2) Reduction to obtain 2,4,5-triamino-6-hydroxypyrimidine sulfate (triamino compound): The nitroso compound was suspended in water, and the powder was gradually introduced under stirring. Subsequently, a sodium hydroxide solution was added to bring the pH to 9, and the mixture was heated to boiling to change the reaction liquid from red to pale yellow. Add decolorization with activated carbon and filter. After the filtrate was cooled, it was adjusted to be Congo red with sulfuric acid, and a yellow precipitate precipitated. Filtration and washing with ethanol gave a triamino compound. (3) Diazotization and cyclization to give 8-azaguanine: The triamino compound is suspended in water, and a sodium hydroxide solution is added to dissolve by heating. Then, sodium nitrite was added, stirred and dissolved, and glacial acetic acid was added. The reaction was heated to 90 ° C for 1 h. After cooling and filtration, a crude 8-azaguanine was obtained, which was purified to give 8-Azaguanine.
