Tetrasodium pyrophosphate

Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. Toxicity is approximately twice that of table salt when ingested orally.[3] Also known is the decahydrate Na4P2O7 · 10(H2O).[4]

Tetrasodium pyrophosphate
Names
IUPAC name
Tetrasodium diphosphate
Other names
Pyrophosphate, Sodium pyrophosphate, Tetrasodium pyrophosphate (anhydrous), TSPP[1]
Identifiers
3D model (JSmol)
ECHA InfoCard 100.028.880
EC Number
  • 231-767-1
E number E450(iii) (thickeners, ...)
RTECS number
  • UX7350000
Properties
Na4O7P2
Molar mass 265.900 g·mol−1
Appearance Colorless or white crystals[2]
Odor odorless
Density 2.534 g/cm3
Melting point 988 °C (1,810 °F; 1,261 K) (anhydrous)
79.5 °C (decahydrate)
Boiling point decomposes
2.61 g/100 mL (0 °C)
6.7 g/100 mL (25 °C)
42.2 g/100 mL (100 °C)
Solubility insoluble in ammonia, alcohol
1.425
Structure
monoclinic (decahydrate)
Thermochemistry
241 J/mol K
270 J/mol K
-3166 kJ/mol
-3001 kJ/mol
Hazards
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
none[2]
REL (Recommended)
TWA 5 mg/m3[2]
IDLH (Immediate danger)
N.D.[2]
Related compounds
Other anions
Trisodium phosphate
Pentasodium triphosphate
Sodium hexametaphosphate
Other cations
Tetrapotassium pyrophosphate
Related compounds
Disodium 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

Use

Tetrasodium pyrophosphate is used as a buffering agent, an emulsifier, a dispersing agent, and a thickening agent, and is often used as a food additive. Common foods containing tetrasodium pyrophosphate include chicken nuggets, marshmallows, pudding, crab meat, imitation crab, canned tuna, and soy-based meat alternatives and cat foods and cat treats where it is used as a palatability enhancer.

In toothpaste and dental floss, tetrasodium pyrophosphate acts as a tartar control agent, serving to remove calcium and magnesium from saliva and thus preventing them from being deposited on teeth. Tetrasodium pyrophosphate is used in commercial dental rinses before brushing to aid in plaque reduction.

Tetrasodium pyrophosphate is sometimes used in household detergents to prevent similar deposition on clothing, but due to its phosphate content it causes eutrophication of water, promoting algae growth.

Production

Tetrasodium pyrophosphate is produced by the reaction of furnace-grade phosphoric acid with sodium carbonate to form disodium phosphate, which is then heated to 450 °C to form tetrasodium pyrophosphate:[5]

2 Na2HPO4 → Na4P2O7 + H2O

References

  1. CDC - NIOSH Pocket Guide to Chemical Hazards
  2. NIOSH Pocket Guide to Chemical Hazards. "#0606". National Institute for Occupational Safety and Health (NIOSH).
  3. Handbook of food toxicology, S. S. Deshpande, page 260
  4. D.L. Perry S.L. Phillips (1995) Handbook of inorganic compounds CRC Press ISBN 0-8493-8671-3
  5. Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann. "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
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