Pyrophosphoric acid

Pyrophosphoric acid
Chemical structure of pyrophosphoric acid
3D model of pyrophosphoric acid
Names
IUPAC names
Diphosphoric acid
μ-oxido-bis(dihydroxidooxidophosphorus)
Other names
Pyrophosphoric acid
Phosphonophosphoric acid
Phosphono dihydrogenphosphate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.017.795 Edit this at Wikidata
UNII
  • InChI=1S/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6) checkY
    Key: XPPKVPWEQAFLFU-UHFFFAOYSA-N checkY
  • InChI=1/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6)
    Key: XPPKVPWEQAFLFU-UHFFFAOYAX
  • O=P(O)(O)OP(=O)(O)O
Properties
H4P2O7
Molar mass 177.97 g/mol
Melting point 71.5 °C (160.7 °F; 344.6 K)
Extremely soluble
Solubility Very soluble in alcohol, ether
Conjugate base Pyrophosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Not to be confused with hypophosphoric acid.

Pyrophosphoric acid, also known as diphosphoric acid, is the inorganic compound with the formula H4P2O7 or, more descriptively, [(HO)2P(O)]2O. Colorless and odorless, it is soluble in water, diethyl ether, and ethyl alcohol. The anhydrous acid crystallizes in two polymorphs, which melt at 54.3 and 71.5 °C. The compound is a component of polyphosphoric acid, an important source of phosphoric acid.[1] Anions, salts, and esters of pyrophosphoric acid are called pyrophosphates.

  1. ^ Cite error: The named reference Ullmann was invoked but never defined (see the help page).