S2O62

S2O6^2−, commonly called dithionate, is the dianion of dithionic acid (H2S2O6). It consists of two SO3 units linked together, with each sulfur in the +6 oxidation state, giving an overall 2− charge. The ion is typically described as symmetric, and salts of dithionate form with many cations.

Nomenclature and structure: The systematic name is dithonato(2−). The two SO3-like groups are joined in a way that preserves the high oxidation state of both sulfur atoms. In aqueous solution, the S–O framework remains intact, and the ion behaves as a stable dianion under neutral to mildly basic conditions.

Salts and occurrence: Dithionate forms soluble salts with alkali and alkaline earth metals, such as sodium dithionate (Na2S2O6), potassium dithionate (K2S2O6), and calcium dithionate (CaS2O6). These salts are used in laboratories and certain industrial contexts as sources of the dithionate ion and as reagents in analytical chemistry. They can arise as oxidation products of sulfite-containing solutions under controlled conditions and may appear as byproducts in processes involving sulfite chemistry.

Chemistry and reactivity: In water, dithionate is relatively stable under neutral to mildly basic conditions. It can be reduced by suitable reductants to sulfite (S2O6^2− → 2 SO3^2−) and, under sufficiently strong oxidizing conditions, may be oxidized to sulfate (SO4^2−). Dithionate solutions are generally more stable than many sulfite species in mild environments but can decompose in strongly acidic or strongly heated conditions.

Safety: Dithionate compounds should be handled with standard laboratory precautions. Avoid inhalation and contact with skin or eyes, and store away from incompatible oxidants.

See also: Dithionic acid, Dithionite, Sulfate.