aromatic hydrocarbons

An aromatic hydrocarbon or arena  (sometimes also called aryl hydrocarbon)  is a hydrocarbon with a single bond or a double bond, and between carbon atoms. Configuration 6 carbon atoms in an aromatic compound called benzene rings. Aromatic hydrocarbons can be monocyclic or polycyclic.
Some aromatic compounds that are not called heteroarena benzene derivatives, these compounds mengikutiAturan Hückel. In these compounds, at least one carbon atom is replaced by another atom, such as oxygen, nitrogen, or sulfur. One contohn compound is furan, a heterocyclic ring compound having 5 members, one oxygen atom. Another example is pyridine, a heterocyclic ring compound with 6 members, one nitrogen atom.
In aromatic substitution, 1 substituents on the ring arena (usually hydrogen) will be replaced with other substituents. 2 main types are electrophilic aromatic substitution (active electrophile reagent) and nucleophilic aromatic substitution (reagennya nucleophile). Padasubstitusi radical-nucleophilic aromatic, active form of radical reagents. One example is the nitration of salicylic acid:

Benzene (C6H6) is the parent compound of a large class of these organic substances.

Benzene molecules form a flat hexagon with carbon atoms located on the sixth corner. All the same carbon-carbon bond length and strength, as well as all the carbon-hydrogen bonds, and all the angles CCC and HCC is 1200. Thus, each carbon atom sp2 hybridise, every atom that form three sigma bonds with two carbon atoms next to them and the hydrogen atom. This arrangement leaves one that did not hybridise 2pz orbital on each carbon atom, perpendicular to the plane of the molecule of benzene or benzene ring. In the ethylene molecule, overlapping two 2pz orbitals produces a bonding molecular orbital and one antiikatan molecular orbitals, which are localized in both atom C. However, 2pz orbital interactions in benzene leads to the formation of delocalized molecular orbitals, which are not confined between two adjacent atoms bonded to each other, but also extends to three or more atoms.
Benzene molecule can undergo substitution reactions. If benzene with one H atom is replaced by one atom to another atom group called monosubstituen. For example: etilenbenzena, chlorobenzene, aminobenzena, nitrobenzene, hidroksibenzena, and many more with different groups.

chlorobenzene ethylbenzene aminobenzena hidroksibenzena
(Aniline) (phenol)
If benzene with two H atoms is replaced by another atom or group called disubstituen and produce three kinds of isomers based on the location of the two groups. If the two adjacent groups called ortho, if the two groups are separated one C atom is called meta, and if the two groups separated by two C atoms is called the. Group replaces the H atom in benzene can be the same or different which enables the production of benzene derivative compounds as much as a part of the carbon compounds.

dibromobenzena ortho-meta-para-dibromobenzena dibromobenzena
A large number of compounds can be made from substances that are combined with the benzene ring. The most famous of these compounds are naphthalene, used in mothballs. These compounds and many other similar compounds found in coal tar. Several compounds with multiple rings is a strong carcinogen-compound can cause cancer in humans and animals