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Topic: is this mechanism corect??  (Read 5604 times)

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Offline noork85

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Re: is this mechanism corect??
« Reply #15 on: May 19, 2013, 07:14:17 PM »
Better. Note the cation is stabilised by resonance with the double bond, it is an allylic cation.

gotcha. thanks alot!!

By "shape" of carbocation I meant to guide you towards planarity, then the stereochemistry.

As an exercise, try to predict the products, both the stereochemistry and the regiochemistry when the following is subject to the same reaction condition ( kept in methanol ) :

C1C[14c](Br)C=CC1 

Consider that I've already given you a hint.

the carbon 14 is throwing me off....

but the methanol should be able to attack from the front or the back. product would be racemic??

Offline TheOrganic

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Re: is this mechanism corect??
« Reply #16 on: May 20, 2013, 07:21:38 AM »
Better. Note the cation is stabilised by resonance with the double bond, it is an allylic cation.

gotcha. thanks alot!!

By "shape" of carbocation I meant to guide you towards planarity, then the stereochemistry.

As an exercise, try to predict the products, both the stereochemistry and the regiochemistry when the following is subject to the same reaction condition ( kept in methanol ) :

C1C[14c](Br)C=CC1 

Consider that I've already given you a hint.

but the methanol should be able to attack from the front or the back

Good. Go ahead.

Offline noork85

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Re: is this mechanism corect??
« Reply #17 on: May 22, 2013, 11:51:01 AM »
Better. Note the cation is stabilised by resonance with the double bond, it is an allylic cation.

gotcha. thanks alot!!

By "shape" of carbocation I meant to guide you towards planarity, then the stereochemistry.

As an exercise, try to predict the products, both the stereochemistry and the regiochemistry when the following is subject to the same reaction condition ( kept in methanol ) :

C1C[14c](Br)C=CC1 

Consider that I've already given you a hint.

but the methanol should be able to attack from the front or the back

Good. Go ahead.

how's this? am i on the right track??

https://www.dropbox.com/s/nivqlp2pt36tisr/2013-05-22%2011.49.08.jpg

Offline TheOrganic

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Re: is this mechanism corect??
« Reply #18 on: May 23, 2013, 04:24:20 PM »
You are ignoring the resonating structures of the carbocation. When you label any one of the carbon, the resonating structures won't be equivalent per se.

Offline noork85

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Re: is this mechanism corect??
« Reply #19 on: May 23, 2013, 06:27:47 PM »
You are ignoring the resonating structures of the carbocation. When you label any one of the carbon, the resonating structures won't be equivalent per se.

 :o ofcourse! why didnt i think of that. im going to redo this now. i had something like this on my final...i had to come up with a mechnaism. i finished the exam in 30 mins!! and spent the remaining 1 and a half hour on that problem.

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