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Azo compound

In chemistry Chemistry

Chemistry is the science [i] of matter [i] at the atom [i]ic to molecular [i] scale, dealing primarily ... 

, azo compounds generally have a molecular formula Chemical formula

A chemical formula is a concise way of expressing information about the atom [i]s that constitute a par ... 

 of the form R-N=N-R', in which R and R' can be either aromatic Aromaticity

Aromaticity is a chemical property in which a conjugated [i] ring of unsaturated bonds ... 

 or aliphatic. The N=N group is called an azo or diimide functional group Functional group

In organic chemistry [i] functional groups are specific groups of atom [i]s within molecule [i]s, that ... 

. This helps to stabilise the N=N group by making it part of an extended delocalised system. This also has the effect of making many azo compounds coloured, as delocalised or conjugated systems often absorb visible frequencies of light. The name azo comes from azote, an old name of nitrogen Nitrogen

Nitrogen is a chemical element [i] which has the symbol N and atomic number [i] 7 in the periodic table [i] ... 

 that originates in French and is derived from the Greek a + zoe .

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In chemistry Chemistry

Chemistry is the science [i] of matter [i] at the atom [i]ic to molecular [i] scale, dealing primarily ... 

, azo compounds generally have a molecular formula Chemical formula

A chemical formula is a concise way of expressing information about the atom [i]s that constitute a par ... 

 of the form R-N=N-R', in which R and R' can be either aromatic Aromaticity

Aromaticity is a chemical property in which a conjugated [i] ring of unsaturated bonds ... 

 or aliphatic. The N=N group is called an azo or diimide functional group Functional group

In organic chemistry [i] functional groups are specific groups of atom [i]s within molecule [i]s, that ... 

. This helps to stabilise the N=N group by making it part of an extended delocalised system. This also has the effect of making many azo compounds coloured, as delocalised or conjugated systems often absorb visible frequencies of light.



The name azo comes from azote, an old name of nitrogen Nitrogen

Nitrogen is a chemical element [i] which has the symbol N and atomic number [i] 7 in the periodic table [i] ... 

 that originates in French and is derived from the Greek a + zoe .
Aromatic azo compounds are usually stable and have vivid colors such as red, orange, and yellow. Therefore, they are used as dye Dye

A dye can generally be described as a color [i]ed substance that has an affinity [i] t ... 

s, which are called azo dyes. Some azo compounds, eg. Methyl orange Methyl orange

Methyl Orange is a pH indicator [i] frequently used in titrations [i]. ... 

, can also be used as acid-base indicators, due to their ability to function as weak acids, and the different colours of the acid and salt forms. Azobenzene Azobenzene

Azobenzene is a chemical [i] compound composed of two phenyl [i] rings linked by a N=N double bond [i]. ... 

 is another typical aromatic azo compound. Their colour originates from absorbance in the visible region of the spectrum due to the delocalization Delocalized electron

In physics delocalized electrons are electron [i]s in a molecule [i] that are not associated with a sing ... 

 of electrons in the benzene and azo groups forming a conjugated system Conjugated system

A chemically conjugated system is a system of atoms covalent [i]ly bonded [i] with alterna ... 

, whereby the N=N group is the chromophore.

Aliphatic azo compounds are rather unstable. At an elevated temperature or by irradiation, two carbon Carbon

Carbon is a chemical element [i] in the periodic table [i] that has the symbol [i] C' ... 

-nitrogen bonds are cleaved simultaneously with the loss of nitrogen gas to generate carbon-centered radicals Radical (chemistry)

In chemistry [i], radicals are atom [i]ic or molecular [i] species with unpaired electron [i]s ... 

. Owing to this process, some aliphatic azo compounds are utilized as radical initiators. Azobisisobutylonitrile Azobisisobutylonitrile

Azobisisobutyronitrile is a toxic [i] compound often used as a foamer in plastics [i] and rubber [i] and ... 

  is a typical one and is widely used in industrial processes and in laboratory experiments.

Aromatic azo compounds can be synthesized by using an azocoupling reaction, that is, an electrophilic substitution reaction Electrophilic aromatic substitution

Electrophilic aromatic substitution or EAS is an organic reaction [i] in which an atom, usually Hydrogen [i] ... 

 on aromatic rings with diazonium salt Diazonium compound

Diazonium compounds or diazonium salts are a group of organic compounds [i] sharing a common functional group [i]... 

s. Diazonium salts decompose at temperatures warmer than about 5 degrees Celsius, so the reaction must take place in solution under freezing conditions:

An oxidation Redox

Redox reactions include all chemical processes [i] in which atoms have their oxidation number [i] ... 

 reaction of hydrazine Hydrazine

Hydrazine is the chemical compound [i] with formula [i] N [i]2H [i]4.... 

  also gives an azo compound.

Because of their instability, especially for aliphatic ones, care should be taken with the handling of azo compounds or an explosion Explosion

An explosion is a sudden increase in volume [i] and release of energy [i] in a violent manner, usually w ... 

 may occur.