Aliphatic

Aliphatic


In organic chemistry, compounds composed of carbon and hydrogen are divided into two classes: aromatic compounds, which contain benzene or a similar aromatic-ring configuration of atoms, and aliphatic compounds or non-aromatic compounds (/ˌælɨˈfætɨk/; G. aleiphar, fat, oil), which do not contain those rings.[1] Aliphatic compounds can be saturated, like hexane, or unsaturated, like hexene.

Structure

In aliphatic compounds, carbon atoms can be joined together in straight chains, branched chains, or non-aromatic rings (in which case they are called alicyclic). 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 simplest aliphatic compound is methane (CH4). Aliphatics include alkanes, alkenes, and alkynes. Fatty acids consist of an unbranched aliphatic tail attached to a carboxylic acid functional group.

Properties

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 Alkane
C2H2 Ethyne 74-86-2 Alkyne
C2H4 Ethene 74-85-1 Alkene
C2H6 Ethane 74-84-0 Alkane
C3H4 Propyne 74-99-7 Alkyne
C3H6 Propene - Alkene
C3H8 Propane - Alkane
C4H6 1,2-Butadiene 590-19-2 Diene
C4H6 1-Butyne - Alkyne
C4H8 Butene - e.g. Alkene
C4H10 Butane - Alkane
C6H10 Cyclohexene 110-83-8 Cycloalkene
C5H12 n-pentane 109-66-0 Alkane
C7H14 Cycloheptane 291-64-5 Cycloalkane
C7H14 Methylcyclohexane 108-87-2 Cyclohexane
C8H8 Cubane 277-10-1 Cyclobutane
C9H20 Nonane 111-84-2 Alkane
C10H12 Dicyclopentadiene 77-73-6 Diene, Cycloalkene
C10H16 Phellandrene 99-83-2 Terpene, Diene Cycloalkene
C10H16 α-Terpinene 99-86-5 Terpene, Cycloalkene, Diene
C10H16 Limonene 5989-27-5 Terpene, Diene, Cycloalkene
C11H24 Undecane 1120-21-4 Alkane
C30H50 Squalene 111-02-4 Terpene, Polyene
C2nH4n Polyethylene 9002-88-4 Alkane

A few structures can be shown as example:

But-1-ene can be shown as

CH2=CH-CH2-CH3

Aliphatic acids

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

See also

References