About Williamson ether synthesis

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chem_tr
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Main Question or Discussion Point

I am planning to perform some Williamson synthesis. However, I have not been successful on obtaining a literature with described procedure. Will I need any procedures? I have looked at Organic Syntheses website (website url), but no procedures on the Williamson's technique.

My plan is simple; I will add some purified sodium (gasoline-polluted sodium grains will be washed with diethyl ether) on the non-reactive solution of my alcohol, then add the alkyl halide. I will calculate and add the sodium 1.1 moles excess per mole of my alcohol, and the alkyl halide 1.1 moles excess per mole of sodium. Is this approach logical? I will add the halide in portions, e.g., 10% of the required amount in 10 minutes, etc.

Can anyone who has done this procedure help me?

PS: You might also help me by speculating about my present problem; my alcohol is a macrocyclic one, and is somewhat insoluble in common solvents except dmso and dmf, in which my alcohol is not completely soluble. I might receive a better solubility after alkylating my alcohol with 2-bromoethanol; so my alcohol endgroups will remain, but the compound will be more soluble.

My second plan is to alkylate the alcohol with monochloroacetic acid; so I may have carboxylic acid groups to facilitate aqueous solubility.
 
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Answers and Replies

  • #2
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The procedure looks okay to me.

Make sure that your alcohol solution is cold when you add the sodium and add the sodium piece by piece.
 
  • #3
chem_tr
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Thank you very much! May I learn your comments about my second question? Will I be able to obtain a better solubility in common organic solvents after alkylation with BrCH2CH2OH or ClCH2COOH (this one will be water-soluble, I think)?
 
  • #4
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It's hard to say what the solubility will be. I guess they have a chance to improve the solubility, but I don't know for sure.
 
  • #5
chem_tr
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A last question: Is there any danger of self-reaction for 2-bromoethanol? What must I do to avoid this? I mean, when I add 2-bromoethanol into the sodium salt of my alcohol, I want that the alcoholate attacks 2-bromoethanol but not else. Shall I react 2-bromoethanol with sodium ethylate to decrease the risk? My experimental organic knowledge is a bit poor, so I wanted do refer to who knows these better.
 
  • #6
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Yeah, it might be a problem. I don't know what the best work-around for that would be though. I'm sure that it's been done before, but I don't know the details.
 
  • #7
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Hi.... I have been doing williamson etherification with single bromo eg 1-bromoheptane,1-bromononane and 1-bromoundecane. ok, i uses KOH (equivalent amount to the alcohol) and catalytic amount of KI. Solvent : DMF (mininum amount!!). 1-bromoalkane (in exess) is added dropwise and the reaction mixture is refluxed overnight eg 12 hours. The mixture thus obtained is cooled and the excess solvent is evaporated off. The precipitate formed is washed several times with dilute hydrochoric acid. Hope that it helps !!! Good luck =)
 

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