The components of organic molecules that are most commonly involved in chemical reactions are known as functional groups.
If we think of hydrocarbons as the simplest organic molecules, we can view functional groups as attachments that replace one or more of the hydrocarbons bonded to the carbon skeleton of the hydrocarbon.
Organic molecules are classified by functional group. Carbon atoms can bond to one another and to hydrogen atoms in many ways, which results in an incredibly large number of hydrocarbons. But carbon atoms can bond to atoms of other elements as well, further increasing the number of possible organic molecules.
Benzyl acetate has an ester functional group, an acetyl moiety and a benzyloxy moiety.
Functional groups are clusters of specific atoms bonded to the carbon skeleton with characteristic structure and functions. Functional groups are chemically reactive groups of atoms within an organic molecule that give the molecule distinctive chemical properties.
Six important functional groups: The hydroxyl group (–OH) is polar, thus helping compounds dissolve in water. The carbonyl group ( =CO) can be either at the end of a carbon skeleton (aldehyde) or within the skeleton (ketone). The carboxyl group (–COOH) is found in carboxylic acids. The hydrogen of this group can dissociate, making such molecules as acids. The amino group (–NH2) can accept a proton (H+), thereby acting as a base. The sulfhydryl group (–SH) helps stabilize the structure of some proteins. The phosphate group (–OPO32−) has an important role in the transfer of energy.