Aliphatic compound

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Acyclic aliphatic compound or non-aromatic (Butane)
Cyclic aliphatic /non-aromatic compounds(Cyclobutane)

In organic chemistry, hydrocarbons (compounds composed of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (/ˌælˈfætk/; G. aleiphar, fat, oil) also known as non-aromatic compounds. Aromatic compounds contain an aromatic-ring configuration of atoms, such as benzene, whereas aliphatic compounds do not.[1] Aliphatic compounds can be saturated, like hexane, or unsaturated, like hexene.


Aliphatic compounds can be saturated, joined by single bonds (alkanes), or unsaturated, with double bonds (alkenes) or triple bonds (alkynes). Besides hydrogen, other elements can be bound to the carbon chain, the most common being oxygen, nitrogen, sulphur, and chlorine.

The simplest aliphatic compound is methane (CH4). Aliphatics include alkanes, alkenes, and alkynes.


Most aliphatic compounds are flammable, allowing the use of hydrocarbons as fuel, such as methane in Bunsen burners and as liquified natural gas (LNG), and acetylene in welding.

Examples of aliphatic compounds / non-aromatic

The most important aliphatic compounds are:

  • n-, iso- and cyclo-alkanes (saturated hydrocarbons)
  • n-, iso- and cyclo-alkenes and -alkynes (unsaturated hydrocarbons).

Important examples of low-molecular aliphatic compounds can be found in the list below (sorted by the number of carbon-atoms):

Formula Name CAS-Number Structural Formula Chemical Classification
CH4 Methane 74-82-8 Methane-2D-stereo.svg Alkane
C2H2 Ethyne 74-86-2 Ethyne-2D-flat.png Alkyne
C2H4 Ethene 74-85-1 Ethene structural.svg Alkene
C2H6 Ethane 74-84-0 Ethan Lewis.svg Alkane
C3H4 Propyne 74-99-7 Propyne-2D-flat.png Alkyne
C3H6 Propene - Propen21.PNG Alkene
C3H8 Propane - Propane-2D-flat.png Alkane
C4H6 1,2-Butadiene 590-19-2 Buta-1,2-dien.svg Diene
C4H6 1-Butyne - Ethylacetylene.svg Alkyne
C4H8 Butene - e.g. Buten21.PNG Alkene
C4H10 Butane - Butane-2D-flat.png Alkane
C6H10 Cyclohexene 110-83-8 Cyclohexen - Cyclohexene.svg Cycloalkene
C5H12 n-pentane 109-66-0 Pentan Skelett.svg Alkane
C7H14 Cycloheptane 291-64-5 Cycloheptane.svg Cycloalkane
C7H14 Methylcyclohexane 108-87-2 Methylcyclohexane.png Cyclohexane
C8H8 Cubane 277-10-1 Cuban.svg Cyclobutane
C9H20 Nonane 111-84-2 Nonan Skelett.svg Alkane
C10H12 Dicyclopentadiene 77-73-6 Di-Cyclopentadiene ENDO & EXO V.2.svg Diene, Cycloalkene
C10H16 Phellandrene 99-83-2 Alpha-phellandren.pngBeta-phellandren.png Terpene, Diene Cycloalkene
C10H16 α-Terpinene 99-86-5 Alpha-Terpinene Structure V.1.svg Terpene, Cycloalkene, Diene
C10H16 Limonene 5989-27-5 (R)-Limonen.svg(S)-Limonen.svg Terpene, Diene, Cycloalkene
C11H24 Undecane 1120-21-4 Undecan Skelett.svg Alkane
C30H50 Squalene 111-02-4 Squalene.svg Terpene, Polyene
C2nH4n Polyethylene 9002-88-4 Polyethylene repeat unit.svg Alkane

A few structures can be shown as example:

But-1-ene can be shown as


Aliphatic acids

Aliphatic acids are the acids of nonaromatic hydrocarbons, such as acetic, propionic, and butyric acids.

See also


  1. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (1995) "Aliphatic compounds".