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Topic: 1-nitrocyclopentene with -CN and Ethanol  (Read 4503 times)

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Offline Penguinone

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1-nitrocyclopentene with -CN and Ethanol
« on: January 31, 2014, 05:27:09 PM »
Question: "Identify with reasons what products you would expect to obtain when 1-nitrocyclopentene is treated with KCN in Ethanol.

Attempt: -CN attacking carbon-2 and pi bond of carbon-carbon double bond breaking while new pi bond forms between carbon-1 and nitrogen and pi bond between nitrogen and oxygen breaks and lone pair arrives on oxygen. Ethanol acting a solvent.
I do not think my attempt is right due to the orbital orientation of the pi bonds.
Any help would be greatly appreciated. 

Offline zsinger

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Re: 1-nitrocyclopentene with -CN and Ethanol
« Reply #1 on: February 01, 2014, 01:38:09 AM »
That bond with a positive formal charge doesn't look happy :).
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Offline Penguinone

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Re: 1-nitrocyclopentene with -CN and Ethanol
« Reply #2 on: February 01, 2014, 04:00:21 AM »
That bond with a positive formal charge doesn't look happy :).
Thank you for your reply. I've tried to make the formal positive charge happy but I've ended up with a really weird looking compound  :(
I assume the stereogenic centre (carbon-1) would be racemic?
NB. The nitrogen to carbon bond in the fifth drawing is a single bond.

Attempt 2:

Offline discodermolide

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Re: 1-nitrocyclopentene with -CN and Ethanol
« Reply #3 on: February 01, 2014, 05:15:50 AM »
The addition is correct but the electron pushing not.
In the intermediate after the addition of CN- move the electrons back from the oxygen and let the C=N+ get a proton from the solvent to re-generate the nitro group.
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Offline Penguinone

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Re: 1-nitrocyclopentene with -CN and Ethanol
« Reply #4 on: February 01, 2014, 06:39:25 AM »
Thank you so much for your reply discodermoldie.

Attempt 3: See Picture.

Offline discodermolide

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Re: 1-nitrocyclopentene with -CN and Ethanol
« Reply #5 on: February 01, 2014, 06:50:22 AM »
That looks a lot better.
In the second structure, as you move the electrons to make the C=N+ move the electrons in the N=O out towards the oxygen to give the O a full negative charge.

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