Dithionite

File:Dithionite-ion-2D-dimensions.png

The unusual structure of the dithionite anion. It has a remarkably long sulfur-sulfur bond.

File:Dithionite-ion-3D-balls.png

A ball-and-stick model of the dithionite ion.

The dithionite anion, S₂O₄²⁻, is a sulfur oxoanion formally derived from the hypothetical compound dithionous acid, H₂S₂O₄. Dithionous acid has not been detected either as a pure compound or in solution.

Dithionite ions undergo both acid and alkaline hydrolysis:

2 S₂O₄²⁻ + H₂O → S₂O₃²⁻ + 2 HSO₃⁻

3 Na₂S₂O₄ + 6 NaOH → 5 Na₂SO₃ + Na₂S + 3 H₂O

The sodium salt of dithionous acid, sodium dithionite, finds widespread use in industry as a reducing agent.

References

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Dithionites