Diphosphate

Pyrophosphate

Names
Other names Diphosphate or dipolyphosphate
Identifiers
3D model (Jmol)	Interactive image
ChEBI	CHEBI:18361 Y
ChemSpider	559142 Y
DrugBank	DB04160 Y
ECHA InfoCard	100.229.545
E number	E450 (thickeners, ...)
PubChem	644102
InChI InChI=1S/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6)/p-4 Y Key: XPPKVPWEQAFLFU-UHFFFAOYSA-J Y InChI=1/H4O7P2/c1-8(2,3)7-9(4,5)6/h(H2,1,2,3)(H2,4,5,6)/p-4 Key: XPPKVPWEQAFLFU-XBHQNQODAI
SMILES [O-]P(=O)([O-])OP(=O)([O-])[O-]
Properties
Chemical formula	P2O74−
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

In chemistry, a pyrophosphate is a phosphorus oxyanion. Compounds such as salts and esters are also called pyrophosphates. The group is also called diphosphate or dipolyphosphate, although this should not be confused with phosphates. As a food additive, diphosphates are known as E450. A number of hydrogen pyrophosphates also exist, such as Na₂H₂P₂O₇, as well as the normal pyrophosphates.

Pyrophosphates were originally prepared by heating phosphates (pyro from the Greek, meaning "fire"). They generally exhibit the highest solubilities among the phosphates; moreover, they are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyrophosphate is the first member of an entire series of polyphosphates.

The term pyrophosphate is also the name of esters formed by the condensation of a phosphorylated biological compound with inorganic phosphate, as for dimethylallyl pyrophosphate. This bond is also referred to as a high-energy phosphate bond.

The synthesis of tetraethyl pyrophosphate was first described in 1854 by Philippe de Clermont at a meeting of the French Academy of Sciences.

Pyrophosphates are very important in biochemistry. The anion P₂O₇⁴⁻ is abbreviated PP_i and is formed by the hydrolysis of ATP into AMP in cells.

For example, when a nucleotide is incorporated into a growing DNA or RNA strand by a polymerase, pyrophosphate (PP_i) is released. Pyrophosphorolysis is the reverse of the polymerization reaction in which pyrophosphate reacts with the 3'-nucleosidemonophosphate (NMP or dNMP), which is removed from the oligonucleotide to release the corresponding triphosphate (dNTP from DNA, or NTP from RNA).