The use of Grignard reagents that people are most familiar with is the production of tertiary alcohols by reaction with a suitable carbonyl compound, whether it be an ester, ketone, or aldehyde. As I understand it, Grignard reagents are strong nucleophiles and will readily attack any electrophilic centers. If so, how would a reagent having the formula RMgX react with a phosphoric acid derivative $\ce{(R^1)(R^2)(R^3)P=O}$, where $\ce{R^1}$, $\ce{R^2}$, and $\ce{R^3}$ can be either alkyl, alkoxy, $\ce{-OH}$, or $\ce{-H}$? Does it result in simply $\ce{(R3)P=O}$, a mixture of products where one or more of the $\ce{R}$ groups in the phosphoric acid derivative is replaced by that of the Grignard reagent, or something else? Is the result controlled by stoichiometry?


1 Answer 1


According to this JOC paper by Hays,[1] diethyl phosphonate $\ce{(EtO)2P(O)H}$ has been reacted with alkyl or aryl Grignards to give secondary phosphines oxides and unsymmetrical tertiary phosphine oxides.

According to this JOC paper by Berlin and Peterson,[2] trimethyl phosphate $\ce{(MeO)3PO}$ has been reacted with phenyl Grignard to give methyl diphenylphosphinate $\ce{Ph2P(O)OMe}$ and triphenylphosphine oxide.

It is worthy of note that this patent[3] describes the use of triethyl phosphate $\ce{(EtO)3PO}$ as a solvent for the preparation of Grignard reagents.


  1. Hays, H. R. Reaction of diethyl phosphonate with methyl and ethyl Grignard reagents. J. Org. Chem. 1968, 33 (10), 3690–3694. DOI: 10.1021/jo01274a003.
  2. Berlin, K. D.; Peterson, M. E. Nucleophilic displacement reaction on organophosphorus esters by Grignard reagents. II. Evidence for competitive displacement on carbon and phosphorus in the reaction of Grignard reagents with simple phosphates. J. Org. Chem. 1967, 32 (1), 125–129. DOI: 10.1021/jo01277a032.
  3. Matsui, M.; Kitahara, T.; Yabuta, G.; Yamada, T. Triethyl phosphate as the solvent for the preparation of Grignard reagents. Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences 1999, 75 (2), 35–36. DOI: 10.2183/pjab.75.35.

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