Organic Chemistry Functional Groups

The average bond strength of a carbon – carbon single bond is 346 kJ mol-1 and a carbon = carbon double bond has a bond strength of 602 kJ mol-1.

To break carbon-carbon bonds requires large amounts of energy, meaning that the carbon skeleton is particularly stable. Organic compounds react in many different ways, but the carbon skeleton is rarely broken. For this reason, the atoms that are attached to the carbon skeleton are very important as they often confer reactivity to the molecule. Such atom or groups are called ‘functional groups’ – they give the molecule functionality.

Common functional groups

Atom or groupingname
-Clchlorine atom
-F, -Cl, -Br, -Ihalide ‘group’
-OHalcohol group
-CHOaldehyde group
-COOHcarboxylic acid group
-NH2amine group
-CONH2amide group
-CNnitrile group

Groups or atoms may also be used to join two carbon chains together. Such groups are sometimes called ‘linkages’

Linkage groups

Linking atom or groupname
Oether link
-COO-ester link
-NHCO-amide link
-O-O-peroxide link