Difference between revisions of "Dithionic acid"
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| − | + | {{chembox | |
| − | + | | ImageFile1 =Dithionic-acid-2D.png | |
| + | | ImageSize1 = 150px | ||
| + | | ImageName1 = Structural formula of the dithionic acid molecule | ||
| + | | ImageFile2 = Dithionic-acid-3D-balls.png | ||
| + | | ImageSize2 = 150px | ||
| + | | ImageName2 = Ball-and-stick model of the dithionic acid molecule | ||
| + | | IUPACName = Dithionic acid<br/>Bis(hydroxidodioxidosulfur)(''S–S'') | ||
| + | | Section1 = {{Chembox Identifiers | ||
| + | | InChI = 1/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) | ||
| + | | StdInChI = 1S/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) | ||
| + | | InChIKey = RMGVZKRVHHSUIM-UHFFFAOYAM | ||
| + | | StdInChIKey = RMGVZKRVHHSUIM-UHFFFAOYSA-N | ||
| + | | CASNo = 14970-71-9 | ||
| + | | EC-number = | ||
| + | | ChemSpiderID = 25128 | ||
| + | }} | ||
| + | | Section2 = {{Chembox Properties | ||
| + | | Formula = H<sub>2</sub>S<sub>2</sub>O<sub>6</sub> | ||
| + | | MolarMass = 162.14 g/mol | ||
| + | }} | ||
| + | | Section8 = {{Chembox Related | ||
| + | | OtherCpds = [[Potassium dithionate]] | ||
| + | }} | ||
| + | }} | ||
| − | '''Dithionic acid''', H<sub>2</sub>S<sub>2</sub>O<sub>6</sub>, is a chemical compound known only in [[solution]]<ref name="G&E">{{Greenwood&Earnshaw2nd|pages=715–16}}.</ref> | + | '''Dithionic acid''', H<sub>2</sub>S<sub>2</sub>O<sub>6</sub>, is a chemical compound known only in [[solution]].<ref name="G&E">{{Greenwood&Earnshaw2nd|pages=715–16}}.</ref> |
== Salts == | == Salts == | ||
{{main|dithionate}} | {{main|dithionate}} | ||
| − | Dithionic acid is dibasic and [[Salt (chemistry)|salts]] called [[dithionate]]s are known. No [[acid salt]]s have been discovered. All dithionates are readily soluble in [[water]]<ref name="G&E"/> | + | Dithionic acid is dibasic and [[Salt (chemistry)|salts]] called [[dithionate]]s are known. No [[acid salt]]s have been discovered. All dithionates are readily soluble in [[water]].<ref name="G&E"/> They are mild oxidizing and mild reducing agents. The structure of dithionate ion is like [[ethane]], but two SO<sub>3</sub> groups adopt an almost eclipsed conformation. The S–S length is 215 pm; S–O bonds are rather short with bond length of 143 pm. |
== Synthesis == | == Synthesis == | ||
Dithionates can be made by [[Redox|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 MnO<sub>2</sub>: | Dithionates can be made by [[Redox|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 MnO<sub>2</sub>: | ||
| − | |||
:2MnO<sub>2</sub> + 3SO<sub>2</sub> → MnS<sub>2</sub>O<sub>6</sub> + MnSO<sub>4</sub> | :2MnO<sub>2</sub> + 3SO<sub>2</sub> → MnS<sub>2</sub>O<sub>6</sub> + MnSO<sub>4</sub> | ||
The manganese dithionate solution formed can then be converted to dithionate salts of other metals by [[metathesis reaction]]s: | The manganese dithionate solution formed can then be converted to dithionate salts of other metals by [[metathesis reaction]]s: | ||
| + | :Ba<sup>2+</sup> + MnS<sub>2</sub>O<sub>6</sub> + MnSO<sub>4</sub> → BaSO<sub>4</sub> ↓ + BaS<sub>2</sub>O<sub>6</sub>·2H<sub>2</sub>O | ||
| − | + | Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid:<ref name="G&E"/> | |
| − | + | :BaS<sub>2</sub>O<sub>6</sub> + H<sub>2</sub>SO<sub>4</sub> → H<sub>2</sub>S<sub>2</sub>O<sub>6</sub> (aq) + BaSO<sub>4</sub> ↓ | |
| − | Concentrated solutions of dithionic acid can subsequently be obtained treating a barium dithionate solution with sulfuric acid: | ||
| − | |||
| − | :BaS<sub>2</sub>O<sub>6</sub> | ||
== References == | == References == | ||
Latest revision as of 07:17, 24 August 2009
| Dithionic acid | |
|---|---|
| |
| |
| IUPAC name | Dithionic acid Bis(hydroxidodioxidosulfur)(S–S) |
| Identifiers | |
| InChI | InChI=1/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) |
| InChIKey | RMGVZKRVHHSUIM-UHFFFAOYAM |
| Standard InChI | InChI=1S/H2O6S2/c1-7(2,3)8(4,5)6/h(H,1,2,3)(H,4,5,6) |
| Standard InChIKey | RMGVZKRVHHSUIM-UHFFFAOYSA-N |
| CAS number | [] |
| ChemSpider | |
| Properties | |
| Chemical formula | H2S2O6 |
| Molar mass | 162.14 g/mol |
| Related compounds | |
| Other compounds | Potassium dithionate |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Dithionic acid, H2S2O6, is a chemical compound known only in solution.[1]
Salts
Dithionic acid is dibasic and salts called dithionates are known. No acid salts have been discovered. All dithionates are readily soluble in water.[1] They are mild oxidizing and mild reducing agents. The structure of dithionate ion is like ethane, but two SO3 groups adopt an almost eclipsed conformation. The S–S length is 215 pm; S–O bonds are rather short with bond length of 143 pm.
Synthesis
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:
- 2MnO2 + 3SO2 → 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:[1]
- BaS2O6 + H2SO4 → H2S2O6 (aq) + BaSO4 ↓
References
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