What Is Perazine?

Azines are a class of organic heterocyclic compounds. Generally refers to a six-membered single heterocyclic ring containing two heteroatoms including pyridazine, pyrazine, and piperazine. There are two nitrogen atoms in such compounds. In addition, phenazine and phenothiazine in five-membered and six-membered condensed heterocycles, among which phenothiazine contains a sulfur atom. The common drug dichloropromazine hydrochloride contains azine compounds.

Azine is a general term for a class of organic compounds. It mainly includes six-membered single heterocycles containing two heteroatoms such as pyridazine, pyrazine, diazine of pyrimidine, and phenazine and phenothiazine in the structure of five-membered and six-membered condensed heterocycles. Which contains a sulfur atom in phenothiazine. Piperazine is also a type of azine compound. Diazine refers to a six-membered heterocyclic ring system containing two nitrogen atoms. Due to the different positions of the two nitrogen atoms in the ring, diazines have three isomers, named pyridazine, pyrimidine, and pyrazine. Pyridazine is a position where two nitrogen atoms are adjacent, pyrimidine is a position where two nitrogen atoms are in meta position, and pyrazine is a position where two positions are in para position.

Pyridazine, pyrimidine, and pyrazine are the mother nucleus of many important heterocyclic compounds. Among them, the pyrimidine ring system is the most important. It exists widely in plants and animals and plays an important role in the metabolism of plants and animals. Derivatives of pyrimidine such as uracil, cytosine, and thymine are the material bases of life phenomena and genetic phenomena-important bases of nucleic acids.

The diazine compounds are all planar molecules. The two nitrogen atoms on the ring have the same electronic configuration as the nitrogen atom in pyridine, and each has a pair of unpublished electron pairs, which are located on unequal sp2 hybrid orbitals. Its physical and chemical properties are similar to pyridine, but there are some differences. The physical constants of the three diazines are shown in the figure below.

Physical constants of diazine

Due to the structural asymmetry of pyridazine and pyrimidine, the molecules have a certain polarity, and their unshared electron pair can form hydrogen bonding with water, so pyridazine and pyrimidine are miscible with water. Pyrazine is slightly less water soluble due to its small molecular polarity.

Although diazine compounds contain two nitrogen atoms, they are both monobasic bases, and they are less basic than pyridine. When one nitrogen atom interacts with an acid to protonate into a nitrogen positive ion, the electron cloud density of the other nitrogen atom is greatly reduced, and it is difficult to reprotonate, so it is a monobasic base. Diazine compounds can undergo nucleophilic reactions with haloalkanes to form quaternary ammonium salts, usually monoquaternary ammonium salts, and diquaternary ammonium salts are more difficult. The three diazine compounds are more difficult to undergo electrophilic substitution compared with pyridine due to the strong electron-withdrawing effect of two nitrogen atoms, and the 5-position is meta-2 for both nitrogens, and the electron cloud density The decrease is relatively small, and it is the position where an electrophilic substitution reaction is likely to occur, such as a halogenation reaction. However, both the nitration and sulfonation reactions are difficult to proceed. ^[1]