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Topic: Predicting substitution and elimination products  (Read 2855 times)

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Offline monkeyfeet228

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Predicting substitution and elimination products
« on: April 16, 2010, 02:15:14 AM »
So I have 2 questions, one I think I have right but a sanity check would be nice and the other I'm pretty lost on.

First: If I react 2-bromo-2-methyl-cyclohexene (I think thats the name, image M1 is what it's supposed to be) with etOH I should get 4 products, 2 substitution and 2 elimination. The question is, what are they? Image elimA and SubA are the answers I think are it (I only drew one for SubA because I think the answer is a racimization so the other substitution product would just be the inverse steriochemistry).

The other question is: 1,2,3,4,5,6-hexachlorocyclohexane has 9 sterioisomers, which one reacts the slowest in an E2 reaction. I think it's the thing in Q2A but I'm not really sure at all. My only basis is that I can't think of any other E2 products that are different (all the ones I think of are just rotations of the same thing).

Thanks for any help you can give :)

Offline Smrt guy

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Re: Predicting substitution and elimination products
« Reply #1 on: April 16, 2010, 09:04:06 PM »
It's 3-bromo-3-methyl, but the elimination products look fine.  As for the substitution, you said reaction with EtOH but you show OH substitution.  Also, the second substitution product is the result of the delocalization of the intermediate carbocation (there are 2 potential sites of attack).  As for the other problem, you have to draw conformers of the cyclohexane derivative and remember that it is a stereospecific anti elimination.  Therefore, the isomer that does not allow for proper orientation of the requisite atoms would be the least reactive

Offline AC Prabakar

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Re: Predicting substitution and elimination products
« Reply #2 on: April 17, 2010, 03:22:38 AM »
It will give better understanding if you draw the conformers for the second question statring material.At that time it will be easy to see the stereo specific anti elimination.

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