Sodium monothiophosphate

Sodium monothiophosphate
Names
	IUPAC name Sodium monothiophosphate
Identifiers
CAS Number	10101-88-9 (anhydrous) ; 51674-18-1 (nonahydrate); 51674-17-0 (dodecahydrate) ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.030.224
EC Number	233-26-1;
PubChem CID	6913045;
UNII	AN1017219I ; 4VBT402QNM (dodecahydrate) ;
CompTox Dashboard (EPA)	DTXSID30889527 ;
	InChI InChI=1S/3Na.H3O3PS/c;;;1-4(2,3)5/h;;;(H3,1,2,3,5);
	SMILES [O-]P(=S)([O-])[O-].[Na+].[Na+].[Na+];
Properties
Chemical formula	Na3PO3S
Molar mass	180.00 g·mol−1
Appearance	White solid
Density	1.58 g/cm3 (dodecahydrate); 2.40 g/cm3 (anhydrous)
Melting point	120 to 125 °C (248 to 257 °F; 393 to 398 K) (decomposition)
Solubility in water	soluble
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Sodium monothiophosphate, or sodium phosphorothioate, is an inorganic compound with the chemical formula Na₃P O₃S. It is a sodium salt of monothiophosphoric acid (H₃PO₃S). Sodium monothiophosphate forms hydrates Na₃PO₃S·xH₂O. The anhydrous form and all hydrates are white solids. The anhydrous salt (x = 0) (Na₃PO₃S) decomposes without melting at 120-125 °C. More common is the dodecahydrate (Na₃PO₃S·12H₂O). A nonahydrate is also known (Na₃PO₃S·9H₂O).

Related salts are the sodium dithiophosphate undecahydrate Na₃PO₂S₂·11H₂O, sodium trithiophosphate undecahydrate Na₃POS₃·11H₂O, and sodium tetrathiophosphate octahydrate Na₃PS₄·8H₂O.^[1]

Preparation

Sodium monothiophosphate is prepared by the base hydrolysis of thiophosphoryl chloride using aqueous sodium hydroxide:^[2]^[3]

PSCl₃ + 6 NaOH + 9 H₂O → Na₃PO₃S·12H₂O + 3 NaCl

This reaction affords the dodecahydrate, which is easily dehydrated.

Partial dehydration over 6.5 M H₂SO₄ gives the nonahydrate. Under flowing N₂, the anhydrous salt is formed.^[4]

Sodium monothiophosphate decomposes at neutral pH. Silicone grease catalyses the hydrolysis of the monothiophosphate ion PO₃S³⁻, so it is recommended that it is not used in the glass joints.^[5]

In the anhydrous salt, the P-S bond is 211 pm and the three equivalent P-O bonds are short at 151 pm. These disparate values suggest that the P-S bond is single.^[6]

References

^ Elias, D. P. (1957). "Crystallographic Data on Some Sodium Phosphorothioates". Acta Crystallographica. 10 (9): 600. Bibcode:1957AcCry..10..600E. doi:10.1107/S0365110X57002108.
^ Stanley K. Yasuda; Jack L. Lambert (1957). "Sodium Monothiophosphate". Inorganic Syntheses. Vol. 5. pp. 102–104. doi:10.1002/9780470132364.ch28. ISBN 978-0-470-13236-4.
^ L. C. Washburn; R. L. Hayes (1977). "Importance of Excess Base in the Synthesis of Sodium Monothiophosphate: (Sodium Phosphorothioate)". Inorganic Syntheses. Vol. 17. pp. 193–4. doi:10.1002/9780470132487.ch53. ISBN 978-0-470-13248-7.
^ Palazzi, Marcel (1973). "Trisodium monothiophosphate. Radiocrystallographic study". Bulletin de la Société Chimique de France. 12: 3246–8.
^ Lucian C. Pop and M. Saito (2015). "Serendipitous Reactions Involving a Silicone Grease". Coordination Chemistry Reviews. 314: 64–70. doi:10.1016/j.ccr.2015.07.005.
^ Pompetzki, M.; Jansen, M. (2002). "Natriummonothiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit" [Sodium monothiophosphate(V). Crystal structure and sodium ionic conductivity]. Zeitschrift für Anorganische und Allgemeine Chemie. 628 (3): 641–646. doi:10.1002/1521-3749(200203)628:3<641::AID-ZAAC641>3.0.CO;2-8.

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[1] Elias, D. P. (1957). "Crystallographic Data on Some Sodium Phosphorothioates". Acta Crystallographica. 10 (9): 600. Bibcode:1957AcCry..10..600E. doi:10.1107/S0365110X57002108.

[2] Stanley K. Yasuda; Jack L. Lambert (1957). "Sodium Monothiophosphate". Inorganic Syntheses. Vol. 5. pp. 102–104. doi:10.1002/9780470132364.ch28. ISBN 978-0-470-13236-4.

[3] L. C. Washburn; R. L. Hayes (1977). "Importance of Excess Base in the Synthesis of Sodium Monothiophosphate: (Sodium Phosphorothioate)". Inorganic Syntheses. Vol. 17. pp. 193–4. doi:10.1002/9780470132487.ch53. ISBN 978-0-470-13248-7.

[4] Palazzi, Marcel (1973). "Trisodium monothiophosphate. Radiocrystallographic study". Bulletin de la Société Chimique de France. 12: 3246–8.

[5] Lucian C. Pop and M. Saito (2015). "Serendipitous Reactions Involving a Silicone Grease". Coordination Chemistry Reviews. 314: 64–70. doi:10.1016/j.ccr.2015.07.005.

[6] Pompetzki, M.; Jansen, M. (2002). "Natriummonothiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit" [Sodium monothiophosphate(V). Crystal structure and sodium ionic conductivity]. Zeitschrift für Anorganische und Allgemeine Chemie. 628 (3): 641–646. doi:10.1002/1521-3749(200203)628:3<641::AID-ZAAC641>3.0.CO;2-8.

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