I carried out an experiment and it goes like this:

2-bromoethanol + dihydropyran (DHP) ---> 2-(2-bromoethoxy)oxane

Acidic ion exchange resin was added alongside as a source of H+ ions (catalyst).

If, instead of using acidic ion exchange resin, a conventional acid such as p-toluenesulfonic acid was used as a catalyst. How can it be removed from the product?

I thought of using a weak base, but would there be any side products formed?

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    $\begingroup$ The catalytic p-TsOH is easily removed at the end of the reaction by washing with aqueous NaHCO3 (bicarb). Failing that, if you plan on clumping the protected product it generally sticks to the silica gel . $\endgroup$
    – NotEvans.
    Commented Sep 10, 2018 at 15:41
  • $\begingroup$ The silica gel that you are talking about is not the acidic ion exchange resin right? $\endgroup$
    – D.Leong
    Commented Sep 11, 2018 at 7:42

1 Answer 1


I have run this exact reaction with pTSA in CH2Cl2 many times. As @NotEvans says above, wash with saturated sodium hydrogen carbonate solution, dry over anhydrous sodium sulfate, filter and concentrate under reduced pressure


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