Disodium pyrophosphate

Disodium pyrophosphate
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
PubChem	9837369
ChemSpider	8013090 Y
UNII	H5WVD9LZUD Y
EC number	231-835-0
Jmol-3D images	Image 1
SMILES [Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O
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-4 Y Key: GYQBBRRVRKFJRG-UHFFFAOYSA-J Y 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-4 Key: GYQBBRRVRKFJRG-XBHQNQODAJ
Properties
Molecular formula	Na2H2P2O7
Molar mass	221.94 g/mol
Appearance	white odorless powder
Density	1.1-1.3 g/cm3
Melting point	>600 °C
Solubility in water	11.9 g / 100 ml (20 °C)
Hazards
EU Index	Not listed
Flash point	Non-flammable
Related compounds
Other anions	Disodium phosphate Pentasodium triphosphate Hexasodium metaphosphate
Other cations	Dipotassium pyrophosphate
Related compounds	Tetrasodium pyrophosphate
Y pyrophosphate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Disodium pyrophosphate or sodium acid pyrophosphate is a buffering and chelating agent, with many food and industrial uses. It is polyvalent, and acts as a Lewis base, so is effective at binding polyvalent cations.

Food uses

Sodium acid pyrophosphate is a GRAS substance for food use. It is used in canned seafood to maintain color and reduce purge^{[clarification needed]} during retorting. Retorting achieves microbial stability with heat^[1]. It is an acid source for reaction with baking soda to leaven baked goods.^[2] In cured meats, it speeds the conversion of sodium nitrite to NO₂⁻ by forming the HONO intermediate, and can improve water holding capacity. Disodium pyrophosphate also is found in frozen hash browns and other potato products, where it is used to keep the color of the potatoes from darkening.^[2]

Other uses

In leather treatment, it can be used to remove iron stains on hides during processing. It can stabilize hydrogen peroxide solutions against reduction; it can be used with sulfamic acid in some dairy applications for cleaning, especially to remove soapstone. When added to the scalding water, it facilitates removal of hair and scurf in hog slaughter and feathers and scurf in poultry slaughter. In petroleum production, it can be used as a dispersant in oil well drilling muds.

References

1. ^ [1] -Retorting, Accessed 2010-11-27
2. ^ ^{a b} Ellinger, R.H. (1972) Phosphates in Food Processing in Handbook of Food Additives, 2nd Ed., CRC Press, Cleveland, pp. 617-780.