Phosphomolybdic acid

Phosphomolybdic acid, also known as dodeca molybdophosphoric acid or PMA, is a yellow-green chemical compound that is freely soluble in water and polar organic solvents such as ethanol. It is used as a stain in histology and in organic synthesis.

Phosphomolybdic acid

Names
Other names Molybdophosphoric acid; dodecamolybdophosphoric acid
Identifiers
CAS Number	12026-57-2 51429-74-4 (hydrate)
3D model (JSmol)	Interactive image Interactive image
ChemSpider	9426978
ECHA InfoCard	100.130.014
EC Number	234-713-5
MeSH	Phosphomolybdic+acid
PubChem CID	11251951
InChI InChI=1S/12Mo.H3O4P.36O/c;;;;;;;;;;;;1-5(2,3)4;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;/h;;;;;;;;;;;;(H3,1,2,3,4);;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Key: DHRLEVQXOMLTIM-UHFFFAOYSA-N
SMILES OP(=O)(O)O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O [Mo]18%21%24(O[Mo]%16%18%23(O[Mo]56(O1)(O[Mo]247(O[Mo]9%22(O[Mo]%12%13(O2)(O[Mo]3%11%14(O[Mo]%17%19(O[Mo](O3)(O4)(O5)([O++]67[P+]%15%20[O++]89[Mo]%10(O[Mo](O[Mo](O%10)(O%11)(O%12)([O++]%13%14%15)[O-])(O%16)(O%17)([O++]%18%19%20)[O-])(O%21)(O%22)[O-])[O-])(O%23)[O-])[O-])O)(O%24)[O-])[O-])O)[O-])O
Properties
Chemical formula	H3PMo12O40
Molar mass	1825.25 g/mol
Density	1.62 g/ml[1] (hydrate)
Melting point	79-90 °C[1]
Solubility in water	soluble
Hazards
Main hazards	Oxidiser[1] (hydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Histology

Phosphomolybdic acid is a component of Masson's trichrome stain.[2]

Organic synthesis

Phosphomolybdic is used as a stain for developing thin-layer chromatography plates,[3] staining phenolics, hydrocarbon waxes, alkaloids, and steroids. Conjugated unsaturated compounds reduce PMA to molybdenum blue. The color intensifies with increasing number of double bonds in the molecule being stained.[4]

Phosphomolybdic acid is also occasionally used in acid-catalyzed reactions in organic synthesis. It has been shown to be a good catalyst for the Skraup reaction for the synthesis of substituted quinolines.[5]

See also

• Phosphotungstic acid
• Folin-Ciocalteu reagent

References

1. "Phosphomolybdic acid hydrate - Safety data sheet" (PDF). www.sigmaaldrich.com. 2016-07-18. Retrieved 2018-10-06.
2. "Masson's Trichrome for Muscle and Collagen". StainsFile. Archived from the original on 2013-07-02. Retrieved 2018-10-06.
3. "Stains for Developing TLC Plates" (PDF). McMaster University.
4. Burstein, Shlomo (1953). "Reduction of Phosphomolybdic Acid by Compounds Possessing Conjugated Double Bonds". Analytical Chemistry. 25 (3): 422–424. doi:10.1021/ac60075a012. ISSN 0003-2700 – via ACS Publications.
5. Chaskar, Atul; Padalkar, Vikas; Phatangare, Kiran; Langi, Bhushan; Shah, Chetan (2010). "Miceller-Mediated Phosphomolybdic Acid: Highly Effective Reusable Catalyst for Synthesis of Quinoline and Its Derivatives". Synthetic Communications. 40 (15): 2336–2340. doi:10.1080/00397910903245141. ISSN 0039-7911 – via Taylor & Francis Online.