Disodium pyrophosphate

Disodium pyrophosphate

Names
IUPAC name Disodium dihydrogen diphosphate
Other names Diphosphoric acid, disodium salt Disodium dihydrogen pyrophosphate Disodium diphosphate Sodium acid pyrophosphate, SAPP
Identifiers
CAS Number	7758-16-9 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3184949
ChemSpider	22859 Y
ECHA InfoCard	100.028.941
EC Number	231-835-0
E number	E450(i) (thickeners, ...)
PubChem CID	24451
UNII	H5WVD9LZUD Y
CompTox Dashboard (EPA)	DTXSID7044261
InChI InChI=1S/2Na.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+1;/p-2 N Key: GYQBBRRVRKFJRG-UHFFFAOYSA-L N InChI=1/2Na.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+1;/p-2 Key: GYQBBRRVRKFJRG-NUQVWONBAI
SMILES [Na+].[Na+].[O-]P(=O)(O)OP([O-])(=O)O
Properties
Chemical formula	Na2H2P2O7
Molar mass	221.936 g·mol−1
Appearance	White odorless powder
Density	2.31 g/cm3
Melting point	> 600 °C
Solubility in water	11.9 g/(100 mL) (20 °C)
Refractive index (nD)	1.4645 (hexahydrate)
Hazards
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	2650 mg/kg (mouse, oral)
Related compounds
Other anions	Disodium phosphate Pentasodium triphosphate Sodium hexametaphosphate
Other cations	Calcium pyrophosphate Dipotassium pyrophosphate
Related compounds	Tetrasodium pyrophosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Disodium pyrophosphate or sodium acid pyrophosphate (SAPP)^[1] is an inorganic compound with the chemical formula Na₂H₂P₂O₇. It consists of sodium cations (Na⁺) and dihydrogen pyrophosphate anions (H₂P₂O2−7). It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallized from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca²⁺.

Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate:

2 NaH₂PO₄ → Na₂H₂P₂O₇ + H₂O