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Ether Synthesis by Sn2 displacement

  1. Nov 18, 2012 #1

    I am doing an experiment in which I will have a halophenol, and with KOH in ethanol and an alkyl tosylate, I will need to create an ether.

    The first step is to add the KOH and alkyl tosylate, and I should almost have an ether (ring with halogen attached to it and an OR hanging off the ring)

    The experiment says after adding those two, I need to reflux the solution for an hour. I don't know why we are doing it..is it to remove the halogen on the ring?

    Next we add methylene chloride and water and do an extraction..don't know what this is for.

    Finally the methylene chloride is evaporated.

    After this we put it through column chromatography with 20% methylene chloride/80% petroleum ether...not sure what this is for.

    At what point is this halogen on my ring being removed from the ring?

    Not sure what all the extra steps are for if anyone can enlighten me that would be great.
  2. jcsd
  3. Nov 19, 2012 #2


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    Are you sure about your reaction? What I see is a phenol that is easily deprotonated by KOH attacking the alkyl group with a great leaving group. Were you careful about how much KOH/ethanol you added? Did you use an indicator?

    At the end of all of this you will have your product (ether) and some starting materials. The starting materials will be phenolate (water soluble) and the alkyl tosylate (CH2Cl2 soluble). You might also have some decomposed alkyl tosylate if you have a slight excess of KOH. This might be water soluble or soluble in the CH2Cl2. You need to purify this complex mixture with column chromatography. 1:5 CH2Cl2:pet ether is the mobile phase that allows the separation of these species.
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