Dithionic acid

Dithionic acid

Names
IUPAC name dithionic acid
Other names hypodisulfuric acid
Identifiers
CAS Number	14970-71-9 N
3D model (Jmol)	Interactive image
ChEBI	CHEBI:29208 Y
ChemSpider	25128 Y
PubChem CID	26985
InChI InChI=1S/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) Y Key: RMGVZKRVHHSUIM-UHFFFAOYSA-N Y InChI=1/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) Key: RMGVZKRVHHSUIM-UHFFFAOYAM
SMILES O=S(=O)(O)S(=O)(=O)O
Properties
Chemical formula	H2S2O6
Molar mass	162.14 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

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

Dithionic acid is diprotic and salts called dithionates are known. No acid salts (i.e.: one proton lost) have been discovered. All dithionates are readily soluble in water. They are mild oxidizing and mild reducing agents. The shape of the dithionate ion is like ethane, 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.

Dithionates can be made by oxidizing a sulfite (from the +4 to the +5 oxidation state), but on a larger scale they are made by oxidizing a cooled aqueous solution of sulfur dioxide with MnO₂:

The manganese dithionate solution formed can then be converted to dithionate salts of other metals by metathesis reactions:

Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid:

www.chemindustry.com/chemicals/1022920.html - CASNo reference