Propene, also known as propylene, is an unsaturated organic compound having the chemical formula C3H6. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons, and it is also second in natural abundance.
At room temperature
, propene is a colourless, odourless gas, though when used as a fuel, it is mixed with minute quantities of foul-smelling sulfurous compounds (mercaptans
) so that gas leaks can be readily detected.
Propene has a higher density and boiling point than ethylene due its greater size. It has a slightly lower boiling point than propane and is thus more volatile. It lacks strongly polar bonds, yet the molecule has a small dipole moment due to its reduced symmetry (its point group is Cs).
Propene has the same formula as cyclopropane but a different connectivity of atoms, making these molecules structural isomers.
All propene is obtained from non-renewable
or natural gas
deposits (and coal to a lesser extent). It is a fossil fuel
. Propene is extracted from these by fractional distillation during oil refining
, but demand exceeds supply so most is manufactured by cracking
. The products from this process contain a mixture of products and the propene is separated from the other products by fractional distillation
Production and Uses
Propene is the raw material for the production of polypropylene
, a versatile polymer
widely used in several different grades for packaging
. Most propene is polymerized using Ziegler-Natta catalysis
, which produces isotactic
polypropylene. Along with benzene
, propene is a key feedstock in the cumene process
, a reaction carried out on industrial scales to produce acetone
. Propene is also used during the production of many other chemical products such as isopropanol
, and propylene oxide
The production of propene has remained static at around 35 million tonnes (Europe and North America only) from 2000 – 2008 but has been increasing in East Asia, most notably Singapore and China.Total world production of propene is currently about half that of ethylene.