Moiety

Definition

In organic chemistry, the term moiety is used to denote a portion of a molecule, which may be a functional group, or to describe a portion of a molecule with multiple functional groups which share common structural aspects. For example, the molecule NAD⁺ (nicotinamide adenine dinucleotide) contains nicotinamide, which includes an amide functional group, in which the amide functional group can be described as containing both amine and carboxylic moieties, in this case ammonia and nicotinic acid, respectively. The two terms (moiety and functional group) are often used synonymously; however, the International Union of Pure and Applied Chemistry (IUPAL) makes a distinction between the two, although in common practice this distinction can be ambiguous. Nevertheless, “functional group” is generally reserved for a portion of a molecule with some common chemical behavior, while “moiety” is more often used as a structural description.