In [[organic chemistry]], compounds composed of [[carbon]] and [[hydrogen]] are divided into two classes: [[aromatic]] compounds, which contain benzene and other similar compounds, and '''aliphatic compounds''' (G. ''aleiphar'', fat, oil), which do not.<ref>{{GoldBookRef |title=Aliphatic compounds |file=A00217 |year=1995}}</ref> In aliphatic compounds, carbon atoms can be joined together in straight chains, branched chains, or rings. They can be joined by single bonds ([[alkanes]]), double bonds ([[alkenes]]), or triple bonds ([[alkynes]]). Besides [[hydrogen]], other elements can be bound to the carbon chain, the most common being [[oxygen]], [[nitrogen]], [[sulfur]], and [[chlorine]].

The simplest aliphatic compound is [[methane]] ([[Carbon|C]][[Hydrogen|H]]₄). Aliphatics include [[alkanes]] such as [[fatty acid]]s and [[paraffin]] [[hydrocarbon]]s, [[alkene]]s (such as [[ethylene]]) and [[alkyne]]s (such as [[acetylene]]).

Most aliphatic compounds are flammable, thus allowing hydrocarbons such as [[methane]] to fuel Bunsen burners in the laboratory, whereas [[acetylene]] is used in welding.

==Examples==
<gallery>
Image:Ethane.png|[[Ethane]]
Image:Isobutane.png|[[Isobutane]]
Image:Acetylene.png|[[Acetylene]]
</gallery>

== See also ==

* [[Aromaticity|Aromatic compound]]
* [[Carbon-carbon bond]]

==References==
<references />

[[Category:Organic compounds]]

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[[ca:Hidrocarbur alifàtic]]
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[[de:Aliphatische Kohlenwasserstoffe]]
[[es:Hidrocarburo alifático]]
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[[uk:Аліфатичні сполуки]]