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 component of Masson's trichrome stain. It is a yellow-green compound, freely soluble in water and polar organic solvents such as ethanol. It is used as a reagent in thin layer chromatography for 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.[2]

Organic synthesis[edit]

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.[3]

See also[edit]


  1. ^ a b c Retrieved 25 November 2015.  Missing or empty |title= (help)
  2. ^ Reduction of Phosphomolybdic Acid by Compounds Possessing Conjugated Double Bonds, S. Burstein, Anal. Chem., 1953, 25 (3), pp 422–424
  3. ^ 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: 2336–2340. doi:10.1080/00397910903245141.