Sodium trimetaphosphate

Structural formula
General
Surname	Sodium trimetaphosphate
other names	Sodium cyclotriphosphate
Molecular formula	Na 3 P 3 O 9
Brief description	white solid
External identifiers / databases
CAS number 7785-84-4 ECHA InfoCard 100.029.171 PubChem 24579 Wikidata Q7553388
properties
Molar mass	305.89 g mol −1
Physical state	firmly
density	2.49 g cm −3
solubility	soluble in water practically insoluble in ethanol
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
Toxicological data	10,300 mg kg −1 ( LD 50 ,  mouse ,  oral ) > 4650 mg kg −1 ( LD 50 ,  rabbit ,  transdermal )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium trimetaphosphate is an inorganic chemical compound of sodium from the group of phosphates . The connection was discovered in 1834 by Thomas Graham .

Extraction and presentation

Sodium trimetaphosphate can be prepared by annealing sodium hexametaphosphate at about 500 ° C, by heating disodium hydrogen phosphate and ammonium nitrate to 320 ° C, or by heating disodium hydrogen phosphate to 530 ° C. be won. The representation is also possible by heating an aqueous sodium phosphate solution and others are possible. It is also possible to obtain by reacting sodium diphosphate with ammonium chloride or disodium hydrogen phosphate with ammonium nitrate .

${\displaystyle {\ce {3 Na4P2O7 + 6 NH4Cl -> 2 Na3P3O9 + 6 NaCl + 3 H2O}}}$

${\displaystyle {\ce {3 Na2HPO4*12H2O + 3 NH4NO3 -> Na3P3O9 + 3 NaNO3 + 3 NH3 + 39 H2O}}}$

properties

Sodium trimetaphosphate is a white solid that is soluble in water. At room temperature it is usually present as a hexahydrate, although other hydrates are also known. The hexahydrate has a triclinic crystal structure with the space group P 1 (space group no. 2) . The anhydrate and the monohydrate have an orthorhombic crystal structure with the space group Pmcn (space group no. 62, position 5) . Above 100 ° C it quickly converts to sodium tripolyphosphate .

use

Sodium trimetaphosphate is used as a crosslinking agent for amylase-resistant starch and for starch esterification. The compound also functions as an intermediate in the food industry. In addition, it serves as a corrosion inhibitor, anti-limescale agent, filler, finishing agent, galvanizing agent and surface treatment agent. It is also used in toothpaste.

Individual evidence

1. ↑ ^{a b c d} H. J. Emeléus, AG Sharpe: Advances in Inorganic Chemistry and Radiochemistry . Academic Press, 1962, ISBN 978-0-08-057853-8 , pp. 18 ( limited preview in Google Book search).
2. ↑ ^{a b c d e} data sheet Trisodium trimetaphosphate, ≥95% from Sigma-Aldrich , accessed on February 11, 2019 ( PDF ).
3. ↑ ^{a b c d e} data sheet Sodium trimetaphosphate at AlfaAesar, accessed on February 11, 2019 ( PDF )(JavaScript required) .
4. ↑ ^{a b} Entry on sodium trimetaphosphate in the Hazardous Substances Data Bank , accessed February 11, 2019.
5. ↑ ^{a b} Document DE19724613A1: Process for the production of sodium trimetaphosphate - Document DE19724613A1 , accessed on February 11, 2019
6. ^ ^{A b} William A. Hart, OF Beumel, Thomas P. Whaley: The Chemistry of Lithium, Sodium, Potassium, Rubidium, Cesium and Francium Pergamon Texts in Inorganic Chemistry . Elsevier, 2013, ISBN 978-1-4831-8757-0 , pp. 496 ( limited preview in Google Book search).
7. ↑ Doan Pham Minh, Jocelyn Ramaroson, Ange Nzihou, Patrick Sharrock: One-Step Synthesis of Sodium Trimetaphosphate (Na PO) from Sodium Chloride and Orthophosphoric Acid. In: Industrial & Engineering Chemistry Research. 51, 2012, p. 3851, doi : 10.1021 / ie201085b .
8. ^ I. Tordjman, A. Durif, JC Guitel: Structure cristalline du trimétaphosphate de sodium hexahydraté: Na3P3O9.6H2O. In: Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 32, 1976, p. 1871, doi : 10.1107 / S0567740876006560 .
9. ↑ HM Ondik: The structure of anhydrous sodium trimetaphosphate Na3P3O9, and the monohydrate, Na3P3O9.H2O. In: Acta Crystallographica. 18, 1965, p. 226, doi : 10.1107 / S0365110X65000518 .
10. ^ Arthur DF Toy: The Chemistry of Phosphorus Pergamon Texts in Inorganic Chemistry . Elsevier, 2016, ISBN 978-1-4831-3959-3 , pp. 526 ( limited preview in Google Book search).