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Do we count chiral Ns as chiral centers when counting the chiral centers in a molecule?

Discussion in 'DAT Discussions' started by 510586, Aug 12, 2015.

  1. 510586

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    A 3 degree N with different alkyl groups and a lone pair is considered a chiral amine. Would it count as a chiral center if in a molecule? Example shown below.
     

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  2. FloorMatt

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    I saw a question on QVault before that said lone pairs for nitrogen ONLY don't count towards the chirality due to some type of nitrogen inversion. But for other elements like oxygen, you would count the lone pairs. I'm just the messenger though and don't really understand in depth why this is so.
     
  3. 510586

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    There is pyramidal inversion, but I'm not sure if that makes it nonchiral. Hope orgoman comes to the rescue
     
  4. FeralisExtremum

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    Nope, not chiral due to amine inversion. An amine with a lone pair readily interconverts with an enantiomer.
    "- Amine inversion means that an N with a lone pair on it won’t be chiral because its lone pairs flip around!"

    -from Chad's videos
     
  5. RenzyBoy

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    I'm taking OChem right now, and we just covered amines, so I think I might be able to answer this? I believe that it doesn't count as chiral. Since the interconversion of the lone pair on nitrogen creates two chiral molecules already, you can't really have two enantiomers that exist separately.
     
  6. 510586

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    Augh odyssey said that it was chiral in principle but cannot be resolved. Guess I should just know that it is achiral for counting purposes? If it was a quaternary amine would we count it as chiral?
     
  7. FeralisExtremum

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    Yes, consider it achiral for counting purposes. If you had a quaternary amine (with four different substituents and none of them are lone pairs), that would count as chiral.
     
  8. 510586

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    Got it thank you very much!
     
  9. 510586

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    Thanks!
     

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