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Aromatic hydrocarbon
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"Arene" redirects here. For other uses, see Arene (disambiguation).
An aromatic hydrocarbon or arene[1] (or sometimes aryl hydrocarbon)[2] is a hydrocarbon with alternating double and single bonds between carbon atoms forming rings. The term 'aromatic' was assigned before the physical mechanism determiningaromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent. The configuration of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible such hydrocarbon, benzene. Aromatic hydrocarbons can be monocyclic (MAH) or polycyclic (PAH).
Some non-benzene-based compounds called heteroarenes, which follow Hückel's rule,are also aromatic compounds. In these compounds, at least one carbon atom is replaced by one of the heteroatoms oxygen, nitrogen, or sulfur. Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes an oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one nitrogen atom.[3]

|Contents|
|1 Benzene ring model |
|2 Arene synthesis |
|3 Arene reactions |
|3.1 Aromatic substitution |
|3.2 Coupling reactions ||3.3 Hydrogenation |
|3.4 Cycloadditions |
|4 Benzene and derivatives of benzene |
|5 Polyaromatic hydrocarbons |
|5.1 Occurrence and pollution |
|5.2 List of PAHs|
|5.3 Human health |
|5.4 Chemistry |
|5.5 PAH compounds |
|5.6 Aromaticity |
|5.7 Origins of life |
|5.8 Detection|
|6 Tables |
|7 See also |
|8 References |
|9 External links |


Benzene ring model

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Benzene
Main article: aromaticity
Benzene, C6H6, isthe simplest aromatic hydrocarbon and was recognized as the first aromatic hydrocarbon, with the nature of its bonding first being recognized by Friedrich August Kekulé von Stradonitz in the 19th century. Each carbon atom in the hexagonal cycle has four electrons to share. One goes to the hydrogen atom, and one each to the two neighboring carbons. This leaves one to share with one of its twoneighboring carbon atoms, which is why the benzene molecule is drawn with alternating single and double bonds around the hexagon.
The structure is also illustrated as a circle around the inside of the ring to show six electrons floating around in delocalized molecular orbitals the size of the ring itself. This also represents the equivalent nature of the six carbon-carbon bonds all of bond order ~1.5.This equivalency is well explained by resonance forms. The electrons are visualized as floating above and below the ring with the electromagnetic fields they generate acting to keep the ring flat.
General properties:
1. Display aromaticity.
2. The carbon-hydrogen ratio is high.
3. They burn with a sooty yellow flame because of the high carbon-hydrogen ratio.
4. They undergo...