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Topic: nucleophilic attack  (Read 2942 times)

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Offline helper

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nucleophilic attack
« on: July 14, 2013, 07:28:43 AM »
hello,


thanks

Offline Dan

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Re: nucleophilic attack
« Reply #1 on: July 14, 2013, 08:53:29 AM »
Your logic is good. The Meisenheimer complex arising from attack at the para position has a negative charge conjugated with the nitro group. Attack at the meta position give a carbanion that is not conjugated with the nitro group (and is therefore less stable).

Be careful with your generalisation, what do you think you would get if this was the starting material:

c1([N+]([O-])=O)c(Cl)c(Cl)ccc1
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Offline helper

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Re: nucleophilic attack
« Reply #2 on: July 14, 2013, 10:31:24 AM »
thanks,

the attack would be on the meta cl  to the nitro.

so we have to exmaine each case on its merits!

Offline orgopete

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Re: nucleophilic attack
« Reply #3 on: July 14, 2013, 12:08:53 PM »
Please draw the Meisenheimer intermediate(s).
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Offline Dan

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Re: nucleophilic attack
« Reply #4 on: July 15, 2013, 05:31:40 AM »
the attack would be on the meta cl  to the nitro.

Why?
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Offline orgopete

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Re: nucleophilic attack
« Reply #5 on: July 15, 2013, 10:40:30 AM »
the attack would be on the meta cl  to the nitro.

Why?

Although the answer was explained by Dan, it is my opinion the poster has simply not drawn the Meisenheimer intermediates that confirm Dan's explanation. I am guessing because the question was being asked, the poster is either unwilling or unable to draw them. I am aware that some professors place little emphasis on mechanisms and thus students avoid writing them. I suspect this is such a case. Had the poster simply drawn the complexes, I believe the poster would have discovered the answer for him or herself.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline antimatter101

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Re: nucleophilic attack
« Reply #6 on: July 17, 2013, 07:00:07 AM »
Search up:

Nucleophilic substitution,

Ortho-para deactivators,

Ortho-para activators,

and Meta deactivators.

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