Phosphomolybdic acid

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Phosphomolybdic acid
Phosphomolybdic acid crystals.jpg
Other names
Molybdophosphoric acid; dodecamolybdophosphoric acid
3D model (JSmol)
ECHA InfoCard 100.130.014
EC Number 234-713-5
MeSH Phosphomolybdic+acid
Molar mass 1825.25 g/mol
Density 1.62 g/ml[1] (hydrate)
Melting point 79-90 °C[1]
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

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

Organic synthesis[edit]

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[edit]


  1. ^ a b c "Phosphomolybdic acid hydrate - Safety data sheet" (PDF). 2016-07-18. Retrieved 2018-10-06.
  2. ^ "Masson's Trichrome for Muscle and Collagen". StainsFile.
  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.