Overview of Alkenes

Alkenes are a category of hydrocarbons that contain at least one carbon-carbon double bond.
These double bonds make alkenes unsaturated hydrocarbons.
The general formula for alkenes is CnH2n where ‘n’ is the number of carbon atoms.

Properties of Alkenes

The double bonds in alkenes give them greater reactivity than their alkane counterparts.
They are non-polar compounds and hence insoluble in water but soluble in organic solvents.
Like alkanes, as the length of the carbon chain increases, so does the boiling point of alkenes.

The names of alkenes, similar to those of alkanes, start with a prefix denoting the number of carbon atoms (‘meth-’ for 1, ‘eth-’ for 2, ‘prop-’ for 3, and so forth).
This prefix is followed by the suffix ‘-ene’ to denote the presence of a carbon-carbon double bond.
If more than one double bond exists, the suffix changes to denote the number (‘-diene’ for two, ‘-triene’ for three, and so forth).

More structural isomerism potential exists in alkenes than alkanes due to the presence of double bonds.
They can exhibit both chain isomerism and position isomerism.
Alkenes with more than one double bond can display geometric isomerism.

Alkenes can partake in addition reactions due to the presence of double bonds.
A common example of this is the reaction with bromine water, which decolourises in the presence of an alkene.
They can also undergo hydrogenation (addition of hydrogen in the presence of a catalyst) to become alkanes.
Alkenes also undergo combustion, burning in oxygen to produce carbon dioxide and water. However, incomplete combustion can produce carbon (soot) or carbon monoxide.