The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ether, referring to an oxygen-containing compound having the general chemical structure R−O−R′, where R and R′ are organic functional groups and O is an oxygen atom, comes the word thioether, which refers to an analogous compound with the general structure R−S−R′, where S is a sulfur atom covalently bonded to two organic groups. ^[1] A chemical reaction involving the replacement of oxygen to sulfur is called thionation or thiation.

Thio- can be prefixed with di- and tri- in chemical nomenclature.

The word derives from Ancient Greek θεῖον (theîon) 'sulfur' (which occurs in Greek epic poetry as θέ(ϝ)ειον, théweion and may come from the same root as Latin fumus ( Indo-European dh-w) and may have originally meant " fumigation substance".)

Examples

• Thioamide
• Thiocyanate
• Thioether
• Thioketone
• Thiol
• Thiophene
• Thiourea
• Thiosulfate

See also

• Organosulfur compounds
• IUPAC nomenclature of organic chemistry

References