Sciencemadness Discussion Board

How to or where to get alkenes

Gooferking Science - 21-9-2013 at 13:35

Hello! I am trying to get an alkene molecule. I want it to demonstrate how alkenes can be detected by adding bromine water. Is there a way to make an alkene or buy it locally? I will use the internet as a last resort.

sonogashira - 21-9-2013 at 14:29

Animal fats, vegetable oils, turpentine, limonene, most essence oils etc.

[Edited on 21-9-2013 by sonogashira]

Rich_Insane - 21-9-2013 at 17:12

d-Limonene is pretty common.

Cornaboeaux - 21-9-2013 at 21:57

I remember a fact from high school books: Bananas and apples and other similar fruits produce ethene when they ripen. The ethene also quickens the ripening process itself so if you put a banana in a sealed bag it will ripen more quickly than in open air. Maybe you could collect the gas somehow?

Oopsy_daisy - 22-9-2013 at 00:22

Ethanol mixed in a test tube with conentrated sulphuric acid with strong heating yealds ethene gas, simlest of the alkanes. Putting some sand in there helps the reaction IIRC

Eddygp - 22-9-2013 at 00:40

Quote: Originally posted by Cornaboeaux  
I remember a fact from high school books: Bananas and apples and other similar fruits produce ethene when they ripen. The ethene also quickens the ripening process itself so if you put a banana in a sealed bag it will ripen more quickly than in open air. Maybe you could collect the gas somehow?


IIRC, the amounts are quite negligible, but a batch of fruit inside a bag might be a good idea.

DJF90 - 22-9-2013 at 00:43

Easiest source of alkenes is steam distillation of orange peel to get d-limonene (a diterpene). The set-up need not be fancy; when I was back at school we took some orange peel in a flask, added water, and distilled. The alkene appears as a light oil floating on the surface of the aqueous distillate. We also used this material to demonstrate the reaction you described, along with several others

BromicAcid - 22-9-2013 at 06:46

Trichloroethylene is a solvent available in some areas. About 8 years ago I purchased some from the local hardware store in an attempt to make carbon tetrachloride by photochlorination.

subsecret - 22-9-2013 at 11:45

Some grocery stores, in the pharmaceutical section, will carry turpentine, which is mainly made up of pinene.

papaya - 22-9-2013 at 12:48

https://en.wikipedia.org/wiki/Carotene
In fact many of colored organic substances are (poly)unsaturated..