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Topic: Will this proposed synthesis work?  (Read 2479 times)

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Offline Brook

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Will this proposed synthesis work?
« on: July 14, 2013, 12:13:10 PM »
My answer differs from that in the book so I just wanted to make sure what I am doing is plausible.
Radical halogenation, elimination , hydroboration oxidation, forming an alkoxide ion by treatment with sodium hydride, and a williamson ether synthesis.  Thank you for your help.

Offline orgopete

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Re: Will this proposed synthesis work?
« Reply #1 on: July 14, 2013, 01:08:12 PM »
I am guessing the difference is in step 2. Ethanol, in the absence of base, will not guarantee elimination. Remember, HBr is the by-product. The butene can revert to an ethyl ether. NaOEt would be much better.

I like NaH, but your book may have used something different. That would be okay.
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Offline Brook

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Re: Will this proposed synthesis work?
« Reply #2 on: July 14, 2013, 02:02:57 PM »
Thank you for reply. I will add the base to favor elimination. My book actually did this for the synthesis. I am not quite sure I understand it though. Is it just like an oxymercuration demercuration? If someone could please explain a bit , it will be greatly appreciated.

Offline spirochete

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Re: Will this proposed synthesis work?
« Reply #3 on: July 14, 2013, 03:18:40 PM »
Yes it is essentially the same as hydroboration/oxidation, but using a different nucleophile than water. Methanol and water have about the same nucleophilicity, so it makes sense that they could both attack a mercuinium ion.

The use of the weaker base trifluoroacetate rather than acetate probably enhances the electrophilicity of the Mercury(II) ion and the mercuinium ion.

Offline orgopete

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Re: Will this proposed synthesis work?
« Reply #4 on: July 14, 2013, 09:30:04 PM »
@Brook, your textbook has an error. Your hydroboration route is correct, the oxymercuration gives the wrong alcohol.
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Offline Brook

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Re: Will this proposed synthesis work?
« Reply #5 on: July 15, 2013, 01:59:29 PM »
Thank you orgopete, but I performed the synthesis as the book outlined, and it does not yield an alcohol, but in fact an ether as in the book due t the fact that water is not used in the mercuration as a nucleophile, but CH3OH. When the CH3OH is deprotonated by the trifluoroacetate anion, it leaves an OCH3 attached instead of a hydroxyl group.

Thank you also to spirochete.
« Last Edit: July 15, 2013, 02:45:37 PM by Brook »

Offline orgopete

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Re: Will this proposed synthesis work?
« Reply #6 on: July 15, 2013, 04:43:04 PM »
Honestly, I didn't look at the solvent. I just knew this would give the wrong isomer.
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Offline Brook

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Re: Will this proposed synthesis work?
« Reply #7 on: July 15, 2013, 09:31:01 PM »
Thanks again orgopete.

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