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Topic: Detailed Mechanism  (Read 6455 times)

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Offline lrisNil

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Detailed Mechanism
« on: March 05, 2015, 11:07:31 PM »
    !
I'm not sure how to draw the detailed mechanism for this, but my first concern is that the ester (the one on the far left is an ester right?!) is cyclic and that carbon cannot be attacked by the electrons on the base.
Is that correct? Or is it possible to do a nucleophilic attack on that double-bonded carbon?  :)  ???

Thank you for reading this



Iris Lin

Offline orgopete

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Re: Detailed Mechanism
« Reply #1 on: March 06, 2015, 01:15:38 AM »
The amine can attack.
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Offline lrisNil

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Re: Detailed Mechanism
« Reply #2 on: March 06, 2015, 03:08:32 AM »
Can the amine attack the carbon in the cyclic compound?   ???
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Offline Dan

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Re: Detailed Mechanism
« Reply #3 on: March 06, 2015, 05:38:17 AM »
Why not?
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Offline lrisNil

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Re: Detailed Mechanism
« Reply #4 on: March 06, 2015, 04:15:23 PM »
Because of sterics, I thought it would have to do a backside attack ... >:D
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Offline Babcock_Hall

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Re: Detailed Mechanism
« Reply #5 on: March 06, 2015, 05:39:17 PM »
The carbon atom with the doubly-bonded oxygen has sp2 hybridization.

Offline lrisNil

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Re: Detailed Mechanism
« Reply #6 on: March 06, 2015, 07:02:56 PM »
Thank you Babcock and Daniel.
I attacked the doubly bound carbon with electrons from the NH2,
and pushed the electrons in the double bond to the O underneath.

The two compounds are now connected.
I pushed the electrons back up to form the double bond again,
and this breaks the ring.

Now there's an amide group. 

Above the amide group I have an O- and Cl still there.
I pushed the electrons from the O- onto its C-O bond to make C=O.

This pushed the Cl out.

And finally I AM stuck!  very stuck
How will the C=O and amide group interact to form the final product?

Thank you for reading this
Iris Lin

Offline Babcock_Hall

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Re: Detailed Mechanism
« Reply #7 on: March 06, 2015, 07:17:00 PM »
What about using an electron pair from nitrogen as the nucleophile?

Offline lrisNil

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Re: Detailed Mechanism
« Reply #8 on: March 06, 2015, 09:24:22 PM »
I used an electron pair from the nitrogen as a nucleophile in the beginning (when I attacked the C=O)
But now that I have an amide, (and the compounds are connected now too) I don't think the nitrogen has any lone pairs.

It's connected to 2 carbons and it also has 2 hydrogens  (I think..) so I don't think it can do a nucleophilic attack, But i'm not sure  ???

The new C=O has two lone pairs (I believe) but I can;t find anywhere for them to attack

Thank you for your help and reading this!
Iris Lin

Offline Dan

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Re: Detailed Mechanism
« Reply #9 on: March 07, 2015, 04:41:12 AM »
I think you need to start uploading pictures of your mechanisms so we can see what is going wrong and where the confusion is coming from.

I suspect you have made a N-protonated amide - RC(O)N+H2R, but may not be balancing your charges through the mechanism correctly.
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Offline Dan

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Re: Detailed Mechanism
« Reply #10 on: March 07, 2015, 04:53:23 AM »
Because of sterics, I thought it would have to do a backside attack ... >:D

In response to this, I think you may be missing some fundamental concepts in terms of conformation and stereoelectronics.

In particular, here you need to be aware of the Bürgi–Dunitz angle.
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Offline lrisNil

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Re: Detailed Mechanism
« Reply #11 on: March 07, 2015, 05:04:41 AM »
Here it is, I hope it's readable
This is the part where i'm not sure what the next step is  :)
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Offline Dan

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Re: Detailed Mechanism
« Reply #12 on: March 07, 2015, 05:06:48 AM »
What happened to the Hs on nitrogen?
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Offline lrisNil

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Re: Detailed Mechanism
« Reply #13 on: March 07, 2015, 05:20:13 AM »
They're still on the nitrogen but i forgot to draw them i think
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Offline orgopete

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Re: Detailed Mechanism
« Reply #14 on: March 07, 2015, 09:17:17 AM »
You should add the electrons on the nitrogen as well as the hydrogen.
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