Hantzsch–Widman_nomenclature
Hantzsch–Widman nomenclature
Naming system for certain heterocyclic organic compounds
In organic chemistry, Hantzsch–Widman nomenclature, also called the extended Hantzsch–Widman system (named for Arthur Rudolf Hantzsch and Karl Oskar Widman [sv; de]), is a type of systematic chemical nomenclature used for naming heterocyclic parent hydrides having no more than ten ring members.[1] Some common heterocyclic compounds have retained names that do not follow the Hantzsch–Widman pattern.[2][3]
A Hantzsch–Widman name will always contain a prefix, which indicates the type of heteroatom present in the ring, and a stem, which indicates both the total number of atoms and the presence or absence of double bonds. The name may include more than a one prefix, if more than one type of heteroatom is present; a multiplicative prefix if there are several heteroatoms of the same type; and locants to indicate the relative positions of the different atoms. Hantzsch–Widman names may be combined with other aspects of organic nomenclature, to indicate substitution or fused-ring systems.