What are some examples of Alkenes?

May 13, 2014

Alkenes are molecules containing a carbon-to-carbon double bond, C=C. They form a family of molecules, a homologous series, with general formula ${C}_{n} {H}_{2} n$ where n is the number of carbon atoms.

Starting with the simplest, the members of the family are:

ethene, ${C}_{2} {H}_{4}$
propene, ${C}_{3} {H}_{6}$
butene, ${C}_{4} {H}_{8}$

,,, actually there are two different molecules, isomers of each other, with the formula ${C}_{4} {H}_{8}$ so to be unambiguous we need to show how the atoms are arranged in each molecule, which we could do using the structural formula for each:
but-1-ene, $C {H}_{2} = C H C {H}_{2} C {H}_{3}$
but-2-ene, $C {H}_{3} C H = C H C {H}_{3}$

and so on with increasing numbers of carbon atoms.

In the natural world, alkenes are very common. Alkenes are referred to as 'unsaturated' and this is the origin of terms such as monounsaturates (containing one C=C) and polyunsaturates (containing more than one C=C) relating to oils and fats, for example.