Azine
Chemical compound
From Wikipedia, the free encyclopedia
Azines are a functional class of organic compounds with the connectivity RR′C=N−N=CRR′. These compounds are the product of the condensation of hydrazine with ketones and aldehydes, although in practice they are often made by alternative routes. Ketazines are azines derived from ketones.[1] For example, acetone azine is the simplest ketazine. Aldazines are azines derived from aldehydes.[2]
Preparation
The usual method of industrial production is the peroxide process, starting from the ketone, ammonia, and hydrogen peroxide.[3]
In the laboratory, azines are typically prepared by condensation of hydrazine with two equivalents of a carbonyl.[4]
Reactions
Azines characteristically undergo hydrolysis to hydrazines. The reaction proceeds by the intermediacy of a hydrazone:
- R2C=N−N=CR2 + H2O → R2C=N−NH2 + R2C=O
- R2C=N−NH2 + H2O → N2H4 + R2C=O
Azines have been used as precursors to hydrazones:[4][5]
- R2C=N−N=CR2 + N2H4 → 2R2C=N−NH2
They are also precursors to diazo compounds.[6][5][7]
The coordination chemistry of azines (as ligands) has also been studied.[8][9][10]
Acetone is used to derivatize hydrazine into acetone azine for analysis by gas chromatography. This method is used to determine trace levels of hydrazine in drinking water[11] and pharmaceuticals.[12]
Applications
Ketazines are also important intermediates in the industrial production of hydrazine hydrate by the peroxide process.[3] In the presence of an oxidant, ammonia and ketones react to give hydrazine via ketazine:
- 2 Me(Et)C=O + 2 NH3 + H2O2 → Me(Et)C=NN=C(Et)Me + 2 H2O
The ketazine can be hydrolyzed to the hydrazine and regenerate the ketone:
- Me(Et)C=NN=C(Et)Me + 2 H2O → 2 Me(Et)C=O + N2H4
Ketazines have been also used as sources of hydrazine produced in situ, for example in the production of herbicide precursor 1,2,4-triazole.[13]