Pyrimidine CAS 289-95-2

Pyrimidine, also known as "meta diazobenzene", is a six membered aromatic heterocyclic compound containing two meta nitrogen atoms, which is isomeric with pyridazine and pyrazine. Molecular formula C4H4N2. Molecular weight 80.09. A colorless liquid or solid crystal with a pungent odor. Melting point of 20-22 ℃. Boiling point 123-124 ℃. Refractive index 1.4998 (20 ℃). Easy to react with water, ethanol, and ether, with weak alkalinity that can form salts with acids. Its alkalinity is weaker than pyridine, and its electrophilic substitution reaction is also more difficult than pyridine. Bromination reaction can only occur at the 5-position, and nitration and sulfonation reactions cannot occur, but nucleophilic substitution is more likely to occur. Pyrimidine derivatives are widely present in nature. For example, vitamin B1, uracil, cytosine, and thymine all contain pyrimidine structures. Its bitter acid salt is a yellow needle shaped crystal. Melting point 156 ℃. Due to the presence of conjugated double bonds in pyrimidine, it has strong absorption of ultraviolet radiation. Obtained by oxidation of barbituric acid with phosphorus oxychloride and reduction with hydroiodic acid. Nucleic acid contains three important pyrimidine derivatives, which are important bases in nucleic acid and play important roles in organisms.