Azine
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Azines are a functional class of organic compounds with the connectivity Template:Chem2. 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]
Azines are also produced when chalcone reacts with a hydrazone to produce 3,5-diphenyl-1H-pyrazole,[5] in a conversion also carried out with hydrazine hydrate.[6][7]
Reactions
Azines characteristically undergo hydrolysis to hydrazines. The reaction proceeds by the intermediacy of a hydrazone:
Azines have been used as precursors to hydrazones:[4][8]
They are also precursors to diazo compounds.[9][8][10]
The coordination chemistry of azines (as ligands) has also been studied.[11][12][13]
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[14] and pharmaceuticals.[15]
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.[16]
References
Further reading
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- ↑ a b Jean-Pierre Schirmann, Paul Bourdauducq "Hydrazine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. Script error: No such module "doi"..
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