Sodium dithiophosphate

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Sodium dithiophosphate
Na3PO2S2.png
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/3Na.H3O2PS2/c;;;1-3(2,4)5/h;;;(H3,1,2,4,5)/q3*+1;/p-3
    Key: OFLNOEMLSXBOFY-UHFFFAOYSA-K
  • InChI=1S/3Na.H3O2PS2.H2O/c;;;1-3(2,4)5;/h;;;(H3,1,2,4,5);1H2/q3*+1;;/p-3
    Key: ZBHVOFQECIYLFG-UHFFFAOYSA-K
  • [O-]P(=S)([O-])[S-].[Na+].[Na+].[Na+]
  • O.[O-]P(=S)([O-])[S-].[Na+].[Na+].[Na+]
Properties
Na3PS2O2
Molar mass 196.072 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium dithiophosphate is the salt with the formula Na3PS2O2. It is usually supplied as the hydrated solid or as an aqueous solution together with other thiophosphates such as sodium monothiophosphate and sodium trithiophosphate. Both Na3PS2O2 and its hydrate are colorless solids, but commercial samples can appear dark owing to the presence of impurities. It is used to facilitate the isolation of molybdenum from its ores.

Contents

Preparation

The compound has been prepared in a multistep process starting with the base hydrolysis of phosphorus pentasulfide: [1]

P2S5 + 6 NaOH → 2 Na3PO2S2 + H2S + 2 H2O

The salt is isolated as the hydrate Na3PO2S2.(H2O)11. It is prone to hydrolysis, especially when it is heated as an aqueous solutions:

Na3PO2S2 + 2 H2O → Na3PO3S + H2S

The structure of the anhydrous compound has been examined by X-ray crystallography. The material consists of tetrahedral PO2S23- centers interconnected by Na+ ions. It is assumed that the hydrate retains the tetrahedral PO2S23- centers, but that the Na+ ions are bonded to water. [2] [3]

Applications

The hydrated salt is used as a flotation agent in the purification of molybdenite (MoS2) from other components of the ores. It is a major component of "Nokes reagent" (after Charles M. Nokes, who patented it in 1948 [4] ). The salt is generated by the reaction of phosphorus pentasulfide with sodium hydroxide, often using impure reagents to obtain a mixture of the desired salt and related thiophosphates and oxidized species. Molybdenite particles, which are normally hydrophobic, become hydrophilic in the presence of this salt. [5] [6]

Organic esters of dithiophosphate are sometimes also called dithiophosphates. Diethyl dithiophosphoric acid is the parent of one series of these organic compounds. These compounds are salts with the formula M+(RO)2PS−2 (R = alkyl, usually). These lipophilic salts have also been used as a flotation "collectors" in the purification of various sulfide minerals. [7] [8] Zinc dithiophosphates also refers to this class of organic compounds.

References

  1. ↑ R. Klement "Phosphorus" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 571-2.
  2. ↑ Elias, D. P. (1957). "Crystallographic Data on Some Sodium Phosphorothioates". Acta Crystallographica. 10 (9): 600. Bibcode:1957AcCry..10..600E. doi: 10.1107/S0365110X57002108 .
  3. ↑ Pompetzki, Markus; Dinnebier, Robert E.; Jansen, Martin (2003). "Sodium dithiophosphate(V): Crystal structure, sodium ionic conductivity and dismutation". Solid State Sciences. 5 (11–12): 1439–1444. Bibcode:2003SSSci...5.1439P. doi:10.1016/j.solidstatesciences.2003.07.002.
  4. ↑ U.S. patent 2492936A
  5. ↑ Baki Yarar, "Flotation" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Wienheim, 2005.
  6. ↑ Yarar, Baki (2000). "Flotation". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.b02_23. ISBN   3527306730.
  7. ↑ Baki Yarar, "Flotation" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Wienheim, 2005.
  8. ↑ Yarar, Baki (2000). "Flotation". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.b02_23. ISBN   3527306730.


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