Britannica
Sources used in this answer
What do the prefixes dihydro- and tetrahydro- show in heterocyclic compound names?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
heterocyclic compound
There are many different sulfur-containing heterocycles. One of the best known is thiophene, C4H4S, derivatives of which occur as plant pigments and as other natural products such as biotin.
In the nomenclature of heterocyclic compounds, the prefixes dihydro-, tetrahydro-, and similar terms indicate that a ring is partially saturated. Specifically, these prefixes denote the number of "extra" hydrogen atoms that are bonded to the ring atoms compared to the fully unsaturated or aromatic parent compound.1
For example, the hydrogenation of the aromatic compound furan results in tetrahydrofuran, where the prefix signifies the addition of four hydrogen atoms to the ring system.2