Pyrophosphoric acid

Pyrophosphoric acid

Names
IUPAC names Diphosphoric acid μ-oxido-bis(dihydroxidooxidophosphorus)
Other names Pyrophosphoric acid Phosphonophosphoric acid Phosphono dihydrogenphosphate
Identifiers
CAS Number	2466-09-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29888 Y
ChEMBL	ChEMBL1160571 Y
ChemSpider	996 Y
ECHA InfoCard	100.017.795
IUPHAR/BPS	3151
PubChem CID	1023
UNII	4E862E7GRQ Y
CompTox Dashboard (EPA)	DTXSID4075035
InChI InChI=1S/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6) Y Key: XPPKVPWEQAFLFU-UHFFFAOYSA-N Y InChI=1/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6) Key: XPPKVPWEQAFLFU-UHFFFAOYAX
SMILES O=P(O)(O)OP(=O)(O)O
Properties
Chemical formula	H4P2O7
Molar mass	177.97 g/mol
Melting point	71.5 °C (160.7 °F; 344.6 K)
Solubility in water	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). Y verify (what is YN ?) Infobox references

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.