Comments on: The Williamson Ether Synthesis

By: Williamson Ether Synthesis: Definition, Examples, and Mechanism

Williamson Ether Synthesis: Definition, Examples, and Mechanism — Thu, 24 Aug 2023 13:29:39 +0000

[…] Definition – Masterorganicchemistry.com […]

By: Alcohols and Ethers - Easy To Calculate

Alcohols and Ethers - Easy To Calculate — Thu, 13 Apr 2023 12:24:27 +0000

[…] Ethers can also be prepared by Williamson synthesis. […]

By: Aayushi

Aayushi — Sun, 12 Feb 2023 14:25:19 +0000

I had a similar question to the one above–bulky bases are supposed to be an example of a poor nucleophile but a really strong base, so cause E2 reactions, with Hoffmann elimination when applicable for steric reasons. But the textbook and this site also say that using a tert-butoxide ion is a better bet for making an ether by SN2 reaction than say, a tertiary alkyl halide in which case only elimination product comes.
But then, I guess you could make an ether by SN1 reaction on a tertiary alkyl halide? As you said in a response to another comment. The textbook says the reaction of CH3ONa with (CH3)3C-Br gives exclusively 2-methylpropene. Guess that’s an experimental result.

Source:
https://flic.kr/p/2ogyr3S
https://flic.kr/p/2ogxHyZ
NCERT chemistry class 12

By: Shub

Shub — Sat, 28 Jan 2023 15:56:30 +0000

Will reaction of sodium tert-butoxide and chloroethane give ethene (due to E2) or t-butyl ethyl ether (due to SN2) as major product?

By: James Ashenhurst

James Ashenhurst — Mon, 22 Aug 2022 16:07:56 +0000

In reply to Sahil. You are right that it isn't in there. Need to fix that. It's just an SN2.

By: Sahil

Sahil — Sat, 20 Aug 2022 06:23:06 +0000

Mechanism for Williamson synthesis

By: James Ashenhurst

James Ashenhurst — Fri, 12 Aug 2022 03:16:50 +0000

In reply to Annierock. The NaI makes benzyl iodide from benzyl bromide. Benzyl iodide is too unstable to isolate. The pKa of phenol is 10. The pKa of carbonic acid is about 6. The pKa difference is 4. A good rule of thumb is that a pKa difference of 8 or less will be sufficient to get your conjugate base to participate. So although the acid-base reaction will like far on the carbonate side, there will be enough phenoxide to react with your benzyl iodide.

By: James Ashenhurst

James Ashenhurst — Fri, 15 Jul 2022 15:38:54 +0000

In reply to Adrian. Is your product soluble in any organic solvents at all? One way to do it would be to quench the base with saturated NH4Cl solution, and then add equal volumes of brine and n-BuOH. Perform 3 extractions with n-BuOH and your organic molecule should persist in that layer while all the salts will be in the aqueous layer.

By: Adrian

Adrian — Fri, 08 Jul 2022 10:14:33 +0000

Thanks for sharing with such useful details.
If the product is water insoluble, you can get rid of excess base simply by pouring the reaction in water; however, my product is highly water soluble, do you have any suggestions how to separate it from the excess base? (I use K2CO3)

By: James Ashenhurst

James Ashenhurst — Wed, 03 Mar 2021 03:22:19 +0000

In reply to Hyewon Yeo. Sure! There will be an equilibrium between alkoxide and alcohol but will still get the job done. It's best when the solvent is the conjugate acid of the alkoxide (e.g. EtO- / EtOH).