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Sodium triphosphate

Names
IUPAC name Pentasodium triphosphate
Other names sodium tripolyphosphate, polygon, STPP
Identifiers
CAS Number	7758-29-4
ECHA InfoCard	100.028.944
E number	E451 (thickeners, ...)
PubChem CID	517047
RTECS number	YK4570000
UNII	9SW4PFD2FZ
CompTox Dashboard (EPA)	DTXSID9036307
Properties
Chemical formula	Na5P3O10
Molar mass	367.864 g/mol
Appearance	white powder
Density	2.52 g/cm
Melting point	622 °C (1,152 °F; 895 K)
Solubility in water	14.5 g/100 mL (25 °C)
Hazards
NFPA 704 (fire diamond)	2 0 0
Flash point	Non-flammable
Safety data sheet (SDS)	ICSC 1469
Related compounds
Other anions	Trisodium phosphate Tetrasodium pyrophosphate Sodium hexametaphosphate
Other cations	Pentapotassium triphosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

Sodium triphosphate (STP), also sodium tripolyphosphate (STPP), or tripolyphosphate (TPP),) is an inorganic compound with formula Na₅P₃O₁₀. It is the sodium salt of the polyphosphate penta-anion, which is the conjugate base of triphosphoric acid. It is produced on a large scale as a component of many domestic and industrial products, especially detergents. Environmental problems associated with eutrophication are attributed to its widespread use.

Preparation and properties

Sodium tripolyphosphate is produced by heating a stoichiometric mixture of disodium phosphate, Na₂HPO₄, and monosodium phosphate, NaH₂PO₄, under carefully controlled conditions.

2 Na₂HPO₄ + NaH₂PO₄ → Na₅P₃O₁₀ + 2 H₂O

In this way, approximately 2 million tons are produced annually.

STPP is a colourless salt, which exists both in anhydrous form and as the hexahydrate. The anion can be described as the pentanionic chain . Many related di-, tri-, and polyphosphates are known including the cyclic triphosphate (e.g. sodium trimetaphosphate). It binds strongly to metal cations as both a bidentate and tridentate chelating agent.

Uses

Detergents

The majority of STPP is consumed as a component of commercial detergents. It serves as a "builder", industrial jargon for a water softener. In hard water (water that contains high concentrations of Mg and Ca), detergents are deactivated. Being a highly charged chelating agent, TPP binds to dications tightly and prevents them from interfering with the sulfonate detergent.

Food

STPP is a preservative for seafood, meats, poultry, and animal feeds. It is common in food production as E number E451. In foods, STPP is used as an emulsifier and to retain moisture. Many governments regulate the quantities allowed in foods, as it can substantially increase the sale weight of seafood in particular. The United States Food and Drug Administration lists STPP as Generally recognized as safe.

Other

Other uses (hundreds of thousands of tons/year) include ceramics (decrease the viscosity of glazes up to a certain limit), leather tanning (as masking agent and synthetic tanning agent - SYNTAN), anticaking agents, setting retarders, flame retardants, paper, anticorrosion pigments, textiles, rubber manufacture, fermentation, antifreeze." TPP is used as a polyanion crosslinker in polysaccharide based drug delivery. Toothpaste may contain sodium triphosphate.

Health effects

High serum phosphate concentration has been identified as a predictor of cardiovascular events and mortality. Whilst phosphate is present in the body and food in organic forms, inorganic forms of phosphate such as sodium triphosphate are readily adsorbed and can result in elevated phosphate levels in serum. Salts of polyphosphate anions are moderately irritating to skin and mucous membranes because they are mildly alkaline.

Environmental effects

Because it is very water-soluble, STPP is not significantly removed by waste water treatment. STPP hydrolyses to phosphate, which is assimilated into the natural phosphorus cycle. Detergents containing phosphorus contribute to the eutrophication of many fresh waters.

See also

• Sodium trimetaphosphate, a cyclic triphosphate

• Acceptable daily intake

References

1. ^ Complexing agents, Environmental and Health Assessment of Substances in Household Detergents and Cosmetic Detergent Products, Danish Environmental Protection Agency Archived 2017-08-24 at the Wayback Machine, Accessed 2008-07-15
2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
3. ^ Schrödter, Klaus; Bettermann, Gerhard; Staffel, Thomas; Wahl, Friedrich; Klein, Thomas; Hofmann, Thomas (2008). "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a19_465.pub3. ISBN 978-3527306732. S2CID 94458523.
4. Corbridge, D. E. C. (1 March 1960). "The crystal structure of sodium triphosphate, Na₅P₃O₁₀, phase I". Acta Crystallographica. 13 (3): 263–269. Bibcode:1960AcCry..13..263C. doi:10.1107/S0365110X60000583.
5. Davies, D. R.; Corbridge, D. E. C. (1 May 1958). "The crystal structure of sodium triphosphate, Na₅P₃O₁₀, phase II". Acta Crystallographica. 11 (5): 315–319. Bibcode:1958AcCry..11..315D. doi:10.1107/S0365110X58000876.
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8. Saxton, C. A.; Ouderaa, F. J. G. (January 1989). "The effect of a dentifrice containing zinc citrate and Triclosan on developing gingivitis". Journal of Periodontal Research. 24 (1): 75–80. doi:10.1111/j.1600-0765.1989.tb00860.x. PMID 2524573.
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12. Mankodi, S; Petrone, DM; Battista, G; Petrone, ME; Chaknis, P; DeVizio, W; Volpe, AR; Proskin, HM (1997). "Clinical efficacy of an optimized stannous fluoride dentifrice, Part 2: A 6-month plaque/gingivitis clinical study, northeast USA". Compendium of Continuing Education in Dentistry. 18 Spec No: 10–5. PMID 12206029.
13. Mallatt, Mark; Mankodi, Suru; Bauroth, Karen; Bsoul, Samer A.; Bartizek, Robert D.; He, Tao (September 2007). "A controlled 6-month clinical trial to study the effects of a stannous fluoride dentifrice on gingivitis". Journal of Clinical Periodontology. 34 (9): 762–767. doi:10.1111/j.1600-051X.2007.01109.x. PMID 17645550.
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• Food additives
• Sodium compounds
• Phosphates
• E-number additives