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In organic chemistry, hydrocarbons (compounds composed of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (/ˌælɪˈfætɪk/; G. aleiphar, fat, oil) also known as non-aromatic compounds. Aliphatics can be cyclic, but only aromatic compounds contain an especially stable ring of atoms, such as benzene.[1] Aliphatic compounds can be saturated, like hexane, or unsaturated, like hexene and hexyne. Open-chain compounds (whether straight or branched) contain no rings of any type, and are thus aliphatic.

Contents

1 Structure 2 Properties 3 Examples of aliphatic compounds / non-aromatic 4 References

Structure[edit] 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, sulfur, and chlorine. The least complex aliphatic compound is methane (CH4). Properties[edit] Most aliphatic compounds are flammable, allowing the use of hydrocarbons as fuel, such as methane in Bunsen burners and as liquefied natural gas (LNG), and acetylene in welding. Examples of aliphatic compounds / non-aromatic[edit] 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 Structural Formula Chemical Classification

CH4 Methane

Alkane

C2H2 Acetylene

Alkyne

C2H4 Ethylene

Alkene

C2H6 Ethane

Alkane

C3H4 Propyne

Alkyne

C3H6 Propene

Alkene

C3H8 Propane

Alkane

C4H6 1,2-Butadiene

Diene

C4H6 1-Butyne

Alkyne

C4H8 1-Butene

Alkene

C4H10 Butane

Alkane

C6H10 Cyclohexene

Cycloalkene

C5H12 n-pentane

Alkane

C7H14 Cycloheptane

Cycloalkane

C7H14 Methylcyclohexane

Cyclohexane

C8H8 Cubane

Octane

C9H20 Nonane

Alkane

C10H12 Dicyclopentadiene

Diene, Cycloalkene

C10H16 Phellandrene

Terpene, Diene Cycloalkene

C10H16 α-Terpinene

Terpene, Cycloalkene, Diene

C10H16 Limonene

Terpene, Diene, Cycloalkene

C11H24 Undecane

Alkane

C30H50 Squalene

Terpene, Polyene

C2nH4n Polyethylene

Alkane

References[edit]

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

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