About Williamson ether synthesis

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    Ether Synthesis
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Discussion Overview

The discussion revolves around the Williamson ether synthesis, focusing on procedural details, solubility issues related to specific alcohols, and potential risks associated with the use of certain reagents. Participants share their experiences and seek advice on optimizing their synthesis approach.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant outlines a plan for Williamson synthesis involving sodium and alkyl halides, questioning the need for a detailed procedure and the logic of their approach.
  • Another participant confirms the procedure appears acceptable, advising to keep the alcohol solution cold and to add sodium gradually.
  • A participant inquires about the potential for improved solubility of their macrocyclic alcohol after alkylation with 2-bromoethanol or monochloroacetic acid.
  • Responses regarding solubility improvements are uncertain, with one participant suggesting a chance for enhancement but lacking definitive knowledge.
  • Concerns are raised about the risk of self-reaction with 2-bromoethanol, with a participant asking for strategies to mitigate this risk, such as using sodium ethylate.
  • Another participant acknowledges the potential problem of self-reaction but does not provide a specific solution, indicating a lack of detailed knowledge on the matter.
  • A different participant shares their own successful experience with Williamson etherification using various bromoalkanes, detailing their method involving KOH, KI, and DMF.

Areas of Agreement / Disagreement

Participants express varying levels of confidence regarding the procedural details and potential outcomes, particularly concerning solubility and self-reaction risks. There is no consensus on the best approach to avoid self-reaction or the exact effects of alkylation on solubility.

Contextual Notes

Participants mention specific conditions and reagents, but there are unresolved questions regarding the solubility of the macrocyclic alcohol and the risks associated with 2-bromoethanol. The discussion reflects a range of experimental knowledge and uncertainty about the outcomes of proposed methods.

chem_tr
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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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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.
 
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)?
 
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.
 
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.
 
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.
 
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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