Sodium monothiophosphate

Chembox new
Name = Sodium monothiophosphate
ImageFile = Sodium_monothiophosphate.png ImageSize = 200px
ImageName = Molecular model of sodium monothiophosphate
IUPACName = Sodium monothiophosphate
Section1 = Chembox Properties
Formula = Na₃PO₃S
MolarMass = 180.03 g/mol
Appearance = Crystalline white solid
Solubility = Miscible
MeltingPt = 120-125 °C (decomposition)

Sodium monothiophosphate, or sodium phosphorothioate, is a chemical compound with the molecular formula Na₃PO₃S. It is a crystalline white solid that decomposes without melting at 120-125 °C.

Preparation

Sodium monothiophosphate is created via the reaction between thiophosphoryl chloride and sodium hydroxide according to the method of Yasuda and Lambert. [S. K. Yasuda and J. L. Lambert, "Inorganic Syntheses", 5, 102 (1957).]

:PSCl₃ + 6 NaOH → Na₃PO₃S + 3 NaCl + 3 H₂0

The yield depends on the purity of the sodium hydroxide. Also, sodium phosphorothiolate decomposes at neutral pH and so it was found that using an excess of sodium hydroxide will allow for a greater yield since the reaction will not near a neutral pH. Also, it was noted that silicone grease catalyses the hydrolysis of the phosphorothioate ion, so it is recommended that it is not used in the glass joints. The reported average yield was 59% and it is possible to get higher if you tweak the pH. [L. C. Washburn and R. L. Hayes, "Inorganic Syntheses", 17, 193]

References