Thianthrene

Thianthrene is a sulfur-containing heterocyclic chemical compound. It is a derivative of the parent heterocycle called dithiin. It is notable for its ease of oxidation.

Structure and synthesis

Like other 1,4-dithiins but unlike its oxygen analog dibenzodioxin, the shape of thianthrene is not planar. It is bent, with a fold angle of 128° between the two benzo groups.

Synthesis

Thianthrene was first synthesized by John Stenhouse by dry distillation of sodium benzenesulfonate. Thianthrene is oxidized by sulfuric acid forming a red radical cation. Thianthrene can be prepared by treating benzene with disulfur dichloride in the presence of aluminium chloride.

Reactions

Thianthrene^•+ has been characterized by Electron paramagnetic resonance. Four different publications describe the crystal structure of salts of thianthrene^•+. The cation is nearly planar, depending on the particular salt. In addition to flattening the heterocycle, removal of an electron causes the C-S distances to contract by 3%. It also can function as a Lewis base. Oxidation of thianthrene can also give the sulfoxides and sulfones.