Moiety (chemistry)

In organic chemistry moiety (/ˈmɔɪəti/) is a term used for part of a molecule. Larger moieties are often functional groups.

A functional group is a moiety that participates in similar chemical reactions in most molecules that contain it. In turn the parts of the group are termed moieties. For example, methyl p-hydroxybenzoate contains a phenol functional group within the acyl moiety, which in turn is part of the paraben moiety.

Moieties that are branches extending from the backbone of a hydrocarbon molecule, which can often be broken off and substituted with others, are called substituents or side chains.