Pyrosulfate

In chemistry, disulfate or pyrosulfate is the anion with the molecular formula S
₂O²⁻
₇. Disulfate is the IUPAC name. ^[1] It has a dichromate-like structure and can be visualised as two corner-sharing SO₄ tetrahedra, with a bridging oxygen atom.^[2] In this anion, sulfur has an oxidation state of +6. Disulfate is the conjugate base of the hydrogen disulfate (hydrogen pyrosulfate) ion HS
₂O⁻
₇, which in turn is the conjugate base of disulfuric acid (pyrosulfuric acid).

Chemical structure of the disulfate anion

Role in sulfation

Industrial production of sulfate ester-based surfactants involves the reaction (sulfation) of fatty alcohols with sulfur trioxide. For example, dodecyl alcohol is sulfated using sulfur trioxide. The reaction proceeds by initial formation of the pyrosulfate:

2 SO₃ + ROH → ROSO₂−O−SO₃H

ROSO₂−O−SO₃H → ROSO₃H + SO₃

Several million tons are produced annually.^[3]

See also

• Potassium pyrosulfate
• Sodium pyrosulfate
• Pyrophosphate
• Pyrocarbonate