Hydrocarbons

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Revision as of 12:22, 22 March 2009 by imported>Milton Beychok (Expanded table of example alkenes)
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Hydrocarbons are a class of molecules that contain only carbon and hydrogen atoms. Some of them make very good fuels. Gasoline contains a mixture of hydrocarbons. Unsaturated hydrocarbons, which contain one or more double bonds, are useful chemicals for many reactions.

Linear saturated hydrocarbons

The simplest hydrocarbons are linear molecules in which each carbon atoms is bonded to two other carbons atoms, in a linear fashion, except for the carbon atoms at the ends, which are only bonded to one other carbon atom. Saturated hydrocarbon names generally end with the suffix "ane" which distinguishes them from unsaturated hydrocarbons, which end with the suffix "ene".

Linear saturated hydrocarbons are also referred to as paraffins or alkanes. Their general formula is CnHn+2.

Some example alkanes
Name Formula CnH2n+2
Methane CH4 CH4
Ethane CH3–CH3 C2H6
Propane CH3–CH2–CH3 C3H8
Butane CH3–(CH2)2–CH3 C4H10
Pentane CH3–(CH2)3–CH3 C5H12
Hexane CH3–(CH2)4–CH3 C6H14
Heptane CH3–(CH2)5–CH3 C7H16
Octane CH3–(CH2)6–CH3 C8H18
Nonane CH3–(CH2)7–CH3 C9H20
Decane CH3–(CH2)8–CH3 C10H22

Linear unsaturated hydrocarbons

Unsaturated hydrocarbons are useful precursor molecules for many reactions. Because they contain one or more double bonds, a large variety of chemical transformations are possible. Unsaturated hydrocarbons generally end with the "ene" suffix, although common names are sometimes used instead of the IUPAC designation. In addition, a numerical prefix is used to indicate the position of the double bond(s).

Linear unsaturated hydrocarbons are also referred to as olefins or alkenes. Their general formula is CnH2n.

Some example alkenes
Name Formula CnH2n
Ethene CH2=CH2 C2H4
Propene CH2=CH-CH3 C3H6
1-Butene CH2=CH-CH2-CH3 C4H8
2-Butene CH3-CH=CH-CH3 C4H8
1-Pentene CH2=CH-(CH2)2-CH3 C5H10
1-Hexene CH2=CH-(CH2)3-CH3 C6H12

Cyclic saturated hydrocarbons

Cyclic unsaturated hydrocarbons

aromatic hydrocarbons