In physical organic chemistry moiety is generally used to signify part of a molecule, e.g. in an ester R1COOR2 the alcohol moiety is R2O. The term should not be used for a small fragment of a molecule.
Source: PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1141 [Terms] [Paper]
Citation: 'moiety' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1, 2019. https://doi.org/10.1351/goldbook.M03968 RISBibTexEndNote