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Topic: Resolvable Amines  (Read 5951 times)

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Offline savy2020

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Resolvable Amines
« on: December 12, 2009, 01:19:31 AM »
The question states
Which of the following amine/s is/are resolvable?
{Pls refer to the attachment}
 
My answer is as follows.
Since the lone pair on N(if present) will flip from one configuration to other the amines (i) and (iii) are not resolvable thought he N is chiral. But in (ii) there is H -not lone pair as the fourth bond and hence it is resolvable into two enentiomers.
The problem is with the (iv). Do you think it is resolvable?
I think that due to ring strain and rigidity the flipping of lone pair on N may not be possible and hence think it is resolvable.
Please explain.
:-) SKS

Offline orgoclear

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Re: Resolvable Amines
« Reply #1 on: December 12, 2009, 04:20:03 AM »
Yeah in (iv) you are correct that the N might not be flipped .. but are all three groups attached to the N different?even in (iii) the N is not chiral

In (i) it can flip.
(iii) and (iv) have no chiral N

(ii) has chiral N with all 4 groups different

So the answer is (ii)

Offline savy2020

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Re: Resolvable Amines
« Reply #2 on: December 12, 2009, 05:10:12 AM »
Yeah in (iv) you are correct that the N might not be flipped .. but are all three groups attached to the N different?
Oh :o I overlooked that. Thanks
If the groups are different(say some methyl group is there on one of the carbons of the ring) then would it be resolvable?
:-) SKS

Offline sjb

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Re: Resolvable Amines
« Reply #3 on: December 12, 2009, 09:53:07 AM »
Yeah in (iv) you are correct that the N might not be flipped .. but are all three groups attached to the N different?
Oh :o I overlooked that. Thanks
If the groups are different(say some methyl group is there on one of the carbons of the ring) then would it be resolvable?


In principle, yes, though it may take low temperatures, if you're just talking about the asymmetry due to the nitrogens. If you had simply a methyl on a carbon, then that too would be asymmetric in it's own right.

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