Azines are a functional class of

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

s 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. For example,

acetone azine Acetone azine is the simplest ketazine. It is an intermediate in some hydrazine manufacturing processes. Synthesis Acetone azine can be prepared from acetone and hydrazine: :2 (CH3)2CO + N2H4 → 2 H2O + CH3)2C=Nsub>2 It can also be produc ...

is the simplest ketazine. Aldazines are azines derived from aldehydes.

Preparation

The usual method of industrial production is the

peroxide process The peroxide process is a method for the industrial production of hydrazine. In this process hydrogen peroxide is used as an oxidant instead of sodium hypochlorite, which is traditionally used to generate hydrazine. The main advantage of the peroxi ...

, starting from the ketone,

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...

, and

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...

. :

In the laboratory, azines are typically prepared by condensation of hydrazine with two equivalents of a carbonyl. Azines are also produced when

chalcone Chalcone is the organic compound C6H5C(O)CH=CHC6H5. It is an α,β-unsaturated ketone. A variety of important biological compounds are known collectively as chalcones or chalconoids. Chemical properties Chalcones have two absorption maxima at ...

reacts with a

hydrazone Hydrazones are a class of organic compounds with the structure . They are related to ketones and aldehydes by the replacement of the oxygen =O with the = functional group. They are formed usually by the action of hydrazine on ketones or aldehydes. ...

to produce 3,5-diphenyl-1''H''-

pyrazole Pyrazole is an organic compound with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms, which are in ortho-substitution. Pyrazole is a weak base, with p''K''b 11.5 ( ...

, in a conversion also carried out with

hydrazine hydrate Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...

. :

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

s: :R₂C=N-N=CR₂ + N₂H₄ → 2 R₂C=N-NH₂ They are also precursors to

diazo compound The diazo group is an organic moiety consisting of two linked nitrogen atoms ( azo) at the terminal position. Overall charge neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes ...

s..

The

coordination chemistry A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ''ligands'' or complexing ...

of azines (as

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...

s) has also been studied.

Acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscible wi ...

is used to derivatize hydrazine into

for analysis by

gas chromatography Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...

. This method is used to determine trace levels of hydrazine in drinking water and pharmaceuticals.

Applications

Ketazines are also important intermediates in the industrial production of hydrazine hydrate by the

.Jean-Pierre Schirmann, Paul Bourdauducq "Hydrazine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. . In the presence of an

oxidant An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or "Electron acceptor, accepts"/"receives" an electron from a (called the , , or ). In ...

, ammonia and ketones react to give hydrazine via

ketazine 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 ...

: :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 1,2,4-Triazole (as ligand in coordination compounds, Htrz abbreviation is sometimes used) is one of a pair of isomeric chemical compounds with molecular formula CHN, called triazoles, which have a five-membered ring of two carbon atoms and three n ...

Preparation

Reactions

Applications

References

Further reading