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Topic: Converting (R)-butyl alchohol to (R)-butyl bromide  (Read 2844 times)

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Offline Gulo

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Converting (R)-butyl alchohol to (R)-butyl bromide
« on: October 16, 2012, 03:02:19 PM »
If I do this with a Sn2 reaction, then I get an inversion of stereochemistry. A Sn1 reaction will give me a racemic product...is there something obvious that I'm just missing here? Thanks.

Offline Schrödinger

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #1 on: October 16, 2012, 03:10:42 PM »
Google : SNi (substitutiion nucleophilic intramolecular) mechanism.
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Offline Babcock_Hall

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #2 on: October 16, 2012, 04:44:13 PM »
Do you have to be able to do it in one step, or are you allowed to use two steps?

Offline orgopete

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #3 on: October 16, 2012, 09:10:40 PM »
Google : SNi (substitutiion nucleophilic intramolecular) mechanism.

Just out of curiosity, using the best conditions, what is the best yield and purity for an SNi reaction. I ask because I would have thought the kinetics would greatly favor inversion, so even with a mechanism giving same side attack, how good is it?
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Offline Schrödinger

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #4 on: October 17, 2012, 03:49:48 AM »
I have no idea about the experimental details. I thought this was more of a theoretical/hypothetical  question. So I said SNi just off the top of my head.
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Offline discodermolide

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #5 on: October 17, 2012, 05:16:42 AM »
The SNi could be shown as in the picture. It is a sort of concerted reaction (loosely described) where the SO2 leaves as the Br (which is eliminated) attacks the chiral carbon from the same side, resulting in retention of configuration.
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Offline Babcock_Hall

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Re: Converting (R)-butyl alchohol to (R)-butyl bromide
« Reply #6 on: October 17, 2012, 09:31:48 AM »
I would use a two-step approach.

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