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Topic: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?  (Read 4076 times)

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Offline Nescafe

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Hi,

I am trying to convert a primary alkyl halide (-Br) to a primary alcohol. I am thinking of using KOH in distilled water (as a solvent). The only thing is that at the other end of this starting material I have a carboxylic acid. So it basically looks like:

HO-C(=O)-CH2-CH2-CH2Br --> HO-C(=O)-CH2-CH2-CH2OH

I am just wondering if anyone has a working condition for this reaction. Sometimes I have difficulty finding simple chemistry procedures on scifinder.

What about the work up, do I just acidify after the reaction is complete or will that lead to elimination?

Any proper procedures on how to do this sort of transformation in presence of an acid functionality would be highly appreciated!

Nescafe.

Offline Dan

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Re: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?
« Reply #1 on: July 01, 2012, 06:46:40 PM »
I would try a milder base, maybe sodium acetate or a tertiay amine (TEA, DIPEA etc.), to form butyrolactone by intramolecular SN2 and then purify and hydrolyse it with NaOH afterwards.
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Offline Nescafe

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Re: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?
« Reply #2 on: July 01, 2012, 09:29:57 PM »
I would try a milder base, maybe sodium acetate or a tertiay amine (TEA, DIPEA etc.), to form butyrolactone by intramolecular SN2 and then purify and hydrolyse it with NaOH afterwards.

Really? Would it not be simpler to use a strong base to do it in one go? hmmm

Offline nox

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Re: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?
« Reply #3 on: July 01, 2012, 11:09:16 PM »
the problem is that once you deprotonate the carboxylic acid, intramolecular ring closing will be far more facile than hydroxide doing an SN2 at the primary bromide, so the linear substrate is just going to snap shut to the lactone. At best, you can expect a mixture of the lactone along with GHB, but I wouldn't count on it being a high yielding reaction. The 2 step protocol seems like a much safer choice to me.

Offline Babcock_Hall

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Re: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?
« Reply #4 on: July 02, 2012, 09:22:43 AM »
Nesafe, I sometimes find this book to be helpful in finding relatively simple protocols: "Reactions and Syntheses in the organic chemistry laboratory" by L.F. Tietze and Th. Eicher (1989) University Science Books.  I did not see the particular transformation you need, however.

Offline Nescafe

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Re: Primary Alkyl Halide to Primary Alcohol Via SN2, any tricks?
« Reply #5 on: July 02, 2012, 11:22:59 AM »
Thanks everyone. I am going to go with the hydrolyze the lactone method.

Cheers,

Nescafe.

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