What are olefins?

[Luckygamer]

I was reading an article about using coal to make olefins but I don't know what those are. Can anyone give me a real simple answer? I tried looking them up but they kept talking about or redirecting me to Alkene.

[mississippichem]

That's because they are the synonymous. Alkene is the more modern term.

 

Olefins are simply put, hydrocarbons that aren't already bonded to the maximum number of hydrogens, or more specifically hydrocarbons that contain double bonds. Carbon commonly has a valency of four, so if some of the carbons in the chain have double bonds, then that hydrocarbon is said to be "unsaturated", that is, not saturated with hydrogen.

 

A common saturated hydrocarbon would be propane: [ce]CH_{3}-CH_{2}-CH_{3}[/ce]

each carbon here has four bonds, and there are no double bonds.

 

The analogous alkene is 1-propene (1 means the double bond is at the first carbon):

[ce]CH_{2}=CH-CH_{3}[/ce]

 

If 1-propene was reacted with one molecule of [ce]H_2[/ce] it would be propane and would be saturated. So 1-propene is said to have 1 degree of unsaturation making it an alkene (or olefin).

[CaptainPanic]

The simple answer is:

Alkene = olefin

 

But olefins can have more than 1 double bond.

 

See also this (click).

Edited November 25, 2010 by CaptainPanic