Dithionic acid, H₂S₂O₆, is a chemical compound known only in

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...

. pp. 715-716

Salts

Dithionic acid is diprotic and

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...

called

dithionate The dithionate (or metabisulfate) anion, , is a sulfur oxoanion derived from dithionic acid, H2S2O6. Its chemical formula is sometimes written in a semistructural format, as 3SSO3sup>2−. It is the first member of the polythionates. The sul ...

s are known. No

acid salt Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made duri ...

s (i.e.: one proton lost) have been discovered. All dithionates are readily soluble in

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. They are mild oxidizing and mild reducing agents. The shape of the dithionate ion is like

ethane Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petr ...

, but two SO₃ groups adopt an almost eclipsed conformation. The S—S bond length is about 2.15 Å; the S—O bonds are rather short with a bond length of 1.43 Å.

Synthesis

Dithionates can be made by

oxidizing Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

sulfite Sulfites or sulphites are compounds that contain the sulfite ion (or the sulfate(IV) ion, from its correct systematic name), . The sulfite ion is the conjugate base of bisulfite. Although its acid ( sulfurous acid) is elusive, its salts are wide ...

(from the +4 to the +5

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

), but on a larger scale they are made by oxidizing a cooled aqueous solution of

sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...

with

manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell ...

: :2 MnO₂ + 3 SO₂ → MnS₂O₆ + MnSO₄ The manganese dithionate solution formed can then be converted to dithionate salts of other metals by metathesis reactions: :Ba²⁺() + MnS₂O₆() + MnSO₄() → BaSO₄()↓ + BaS₂O₆·2H₂O() Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid: :BaS₂O₆() + H₂SO₄() → H₂S₂O₆() + BaSO₄()↓

References

www.chemindustry.com/chemicals/1022920.html - CASNo reference
{{DEFAULTSORT:Dithionic Acid Dithionates Sulfur oxoacids Oxoacids

Salts

Synthesis

See also

References