A sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central hexavalent sulfur atom is double bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents.
The general structural formula is R–S(=O)2–R′ where R and R′ are the organic groups. Thioethers, often referred to as sulfides, are often the precursors to sulfones by organic oxidation through the intermediate formation of sulfoxides. For example, dimethyl sulfide is oxidized to dimethyl sulfoxide and then to dimethyl sulfone. In the Ramberg-Bäcklund Reaction and the Julia olefination sulfones are converted to alkenes through the elimination of sulfur dioxide.
The industrially useful sulfone is sulfolane, a cyclic molecule with the formula (CH2)4SO2. It is typically prepared, not by oxidation of the thioether, but by addition of sulfur dioxide to 1,3-butadiene, followed by hydrogenation of the resulting sulfolene.
Sulfolane is used to extract valuable aromatic compounds from petroleum.
Some polymers containing sulfone groups have gained prominence in the field of engineering plastics. Various materials exhibit high strength and resistance to oxidation, corrosion, high temperatures, and creep under stress. For example, some are valuable as replacements for copper in domestic hot water plumbing. Precursors to such polymers are the sulfones bisphenol S and 4,4'-dichlorodiphenyl sulfone.