What are functional groups?

Functional groups are specific groups of atoms or bonds within molecules. They are responsible for the characteristic chemical reactions of those molecules.

Functional groups are attached to the carbon backbone of organic molecules. They determine the characteristics and chemical reactivity of molecules.

The same functional group undergoes the same chemical reactions regardless of the size of the molecule it is a part of.

Functional groups are less stable than the carbon backbone. They are more likely to take part in chemical reactions.

Some common functional groups are:

Example:

Identify the functional groups in the tetracycline molecule shown below.

Solution:

Starting from the left hand ring and going clockwise around the carbon backbone, the functional groups are:

Benzene ring Alcohol Amine Alcohol (this one has a special name — an enol) Alkene Amide Ketone Alcohol Alcohol Alkene Ketone Alcohol (this one has a special name — a phenol)