tetrahydro

Tetrahydro is a chemical prefix used in organic nomenclature to indicate that a compound has been saturated by the addition of four hydrogen atoms relative to a referenced unsaturated parent structure. The designation signals hydrogenation of pi bonds or reduction of rings such that four hydrogens have been added, resulting in a more saturated, typically less unsymmetric molecule.

In systematic naming, tetrahydro describes a derivative that has been partially or fully saturated compared with the original aromatic or unsaturated framework. The exact structural outcome depends on the parent compound; the prefix does not alone specify the precise arrangement of atoms but rather the overall level of hydrogen saturation.

Common examples illustrate how the prefix is applied. Tetrahydrofuran, abbreviated THF, is a five-membered ring containing an ether oxygen, formed by hydrogenating the furan ring. It is widely used as a polar aprotic solvent in organic synthesis. Tetralin, or 1,2,3,4-tetrahydronaphthalene, is a partially hydrogenated form of naphthalene and serves as a solvent and chemical intermediate in various applications. Tetrahydrofolate refers to the reduced, polyglutamyl form of folic acid, a coenzyme involved in one-carbon transfer reactions.

The term is primarily descriptive rather than indicative of a single chemical class. It appears across a range of compounds where varying degrees of unsaturation have been removed by hydrogenation to yield saturated or partially saturated derivatives.