Vitamin B4 (Vitamin B4; Adenine) is the old name for adenine, which is no longer regarded as a real vitamin, and is no longer a member of vitamin B. Molecular formula: C5H5N5 Molecular weight: 135.127 Its properties are: white needle-like crystals. It begins to sublime at 220°C and decomposes at 360-365°C. Soluble in acid and alkali, slightly soluble in alcohol, insoluble in ether and chloroform. The aqueous solution is neutral. Has a strong salty taste. It is obtained by ammoniating 4,6-dichloro-5-nitropyrimidine with ammonia to obtain 4,6-diamino-5-nitropyrimidine, which is then cyclized with formic acid, formamide and sodium thiosulfate. Mainly used to participate in the synthesis of DNA and RNA, for leukopenia caused by radiotherapy, benzene poisoning and anti-tumor, for acute neutropenia, medicine and biochemical research