Azines

heterocyclic compounds containing at least two other atoms, of which at least one is a nitrogen atom, in the cycle along with carbon atoms. Azines with two nitrogen atoms in the ring are called diazines—for example, pyrimidine (I); with three nitrogens they are known as triazines—for example, cyanuric acid (II); and so forth. Ox-azine (III) and thiazine (IV) are examples of azines whose cycles include other atoms besides nitrogen. Azines possess a basic character and produce salts with acids.

Many azine derivatives are of great importance. For example, the nucleic acids include pyrimidine bases. The pyrimidine system is found in vitamins B_1, B₂, and folic acid. Chlorpromazine and other phenothiazine derivatives (V) are used in psychiatry and surgery. Azines are also found in other drugs, for example, phenobarbital and sulfamethazine, as well as in dyes—Indanthrene, safranine, and others.