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by | Mar 16, 2018 | Hosta

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Methylphosphonic acid is an organophosphorus compound with the chemical formula CH3P(O)(OH)2. The phosphorus center is tetrahedral and is bonded to a methyl group, two OH groups and an oxygen. Methylphosphonic acid is a white, non-volatile solid that is poorly soluble in organic solvent but soluble in water and common alcohols.[2]

Preparation

Methylphosphonic acid can be prepared from triethylphosphite by first using a Michaelis-Arbuzov reaction to generate the phosphorus(V) centre:[3]

CH3Cl + P(OC2H5)3 → CH3PO(OC2H5)2 + C2H5Cl

The resulting dialkylphosphonate is then treated with chlorotrimethylsilane before hydrolysis of the siloxyphosphonate to generate the desired product.[3]

CH3PO(OC2H5)2 + 2 Me3SiCl → CH3PO(OSiMe3)2 + 2 C2H5Cl
CH3PO(OSiMe3)2 + 2H2O → CH3PO(OH)2 + 2 HOSiMe3

The reaction pathway proceeds via the siloxyphosphonate intermediate due to the difficulty in directly hydrolysing dialkylphosphonates. Katritzky and co-workers published a one-pot synthesis of methylphosphonic acid in 1989.[3]

References

  1. ^ "Methylphosphonic Acid". Sigma-Aldrich. Retrieved 12 December 2013.
  2. ^ "methylphosphonic acid - Compound Summary". NCBI. Retrieved 12 December 2013.
  3. ^ a b c Katritzky, Alan R.; Pilarski, Boguslaw; Johnson, Jack W. (1989). "A One-Pot Procedure For the Preparation of Phosphonic Acids From Alkyl Halides". The New Journal for Organic Synthesis. 22 (2): 209–213. doi:10.1080/00304949009458197.
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