Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: LocGMD on January 21, 2016, 09:42:52 PM
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I'm starting with 1,6 dibromohexane and I need to find a way to get to a 1,6 hexanediol
I was thinking of adding a sort of OH base to undergo a substitution reaction
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Did you just cover SN2 in class?
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Can you clarify what you mean by a sort of OH base?
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Can you clarify what you mean by a sort of OH base?
Well I was thinking about using water to get my desired product or a base like NaOH since I need to achieve the 1,6 alcohol subs. I'm trying my best to understand Sn2 in class but I just need a little help with this one issue. Any help is much appreciated :D
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If we are choosing between water and hydroxide ion (OH)1-, which is the stronger nucleophile, and why?
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You can add 2.5 eq n-buLi and stir the mixture for a while. And then, dump everything into water.
This will be a fun reaction.
When you are doing this, try stay safe.
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You can add 2.5 eq n-buLi and stir the mixture for a while. And then, dump everything into water.
I'm skeptical that this will give the desired diol (though it could if ...). Please show the mechanism.
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If solubility of NaOH is a problem, there are ways around this in theory. I don't have direct experience, however.
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You can add 2.5 eq n-buLi and stir the mixture for a while. And then, dump everything into water.
I'm skeptical that this will give the desired diol (though it could if ...). Please show the mechanism.
NVM, I was wrong. The cold whether decreases the momentum of my mind.
If you do as what I just said, the reaction goes the other way. And you will end up having hexane, not diol.
However, you use 1,4-dibromobutane and t-BuLi mixture to have the lithium halogen exchange, then react with excess amount of Formyl chloride, you should end up having dialdehyde. And you can reduce this to diol.
---------------------------The reaction above will be highly exothermic, even explosive.----------------------------------------------
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Do you think the Li-X exchange will happen faster (consistently enough for high yield) than deprotonation/elimination, or Li-X on one end which cyclizes on the other bromide?
I know in some cases Li-X exchange can happen faster than deprotonation events, but I wonder if it would preferentially form the di-lithiated species or go down a different pathway.
Given the cheapness of the material, to get oxidative dehalogenation I would probably just hit it with a hydroxide source and assume some loss to the elimination pathway. If it was a more precious material, you could use an Ag+ source as well... but that seems like over kill on such a simple substrate... and probably overkill for the OP's sophomore organic chemistry class for that matter :P.
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@OP,
How would you choose conditions to maximize the substitution products over the elimination products?