Removing Triphenylphosphine Oxide

Triphenylphosphine oxide (produced in Wittig, Mitsunobu, bromination, and other reactions)

  1. If your product is stable and relatively-non polar, a good way of removing triphenylphosphine oxide is to concentrate the reaction mixture to a lower follow, suspend the residue in pentane (or hexane)/ether and filter over a silica plug. The compound can then be eluted with ether, leaving most of the phosphine oxide at the top of the column. Sometimes it is necessary to repeat this procedure 2-3 to remove most of the phosphine oxide.
  2. Triphenylphosphine oxide crystallizes quite nicely from a benzene-cyclohexane mixture, so if your product is reasonably soluble you can dissolve the mix in benzene, dilute with cyclohexane and let it precipitate. The filtrates can be often applied onto a column directly, without evaporation. Excerpt from Notes on Lousy Reactions
  3. Workup with oxalyl chloride generates an insoluble chlorophosphonium salt at low temperature, as described in the following report:

    Byrne, P. A.; Rajendran, K. V.; Muldoon, J.; Gilheany, D. G. A Convenient and Mild Chromatography-Free Method for the Purification of the Products of Wittig and Appel Reactions. Org. Biomol. Chem. 2012, 10, 3531-3537. doi:10.1002/ejoc.200600044

    Tip submitted by Perry Devo.

    Link
  4. Addition of zinc(II) chloride will precipitate triphenylphosphine oxide in several common polar organic solvents, as described in the following report:

    Batesky, D. C.; Goldfogel, M. J.; Weix, D. J. Removal of Triphenylphosphine Oxide by Precipitation with Zinc Chloride in Polar Solvents. J. Org. Chem. 2017, 82, 9931–9936. doi; 10.1021/acs.joc.7b00459

    Tip submitted by Joachim Demaerel.

    5. Link (including procedures and a video)