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Which is more stable?

Discussion in 'MCAT Study Question Q&A' started by TawMus, May 21, 2008.

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  1. TawMus

    TawMus 5+ Year Member

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    What is the order of stability??

    Ketone, aldehyde, enol??
     
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  3. RySerr21

    RySerr21 i aint kinda hot Im sauna 7+ Year Member

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    i'm no o chem expert...but i believe enol is the least stable (keto-enol tautomerism comes to mind) followed by aldehyde and then ketone.
     
  4. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    I will assume ketones are most stable because it has two R groups which are EDGs and will supply the partially positive carbonyl carbon with electrons. Therefore I assume:

    Ketone > Aldehyde > Enol

    Also Aldehydes are more reactive in nucleophilic additions because of the less steric hindrance
     
  5. bluemonkey

    bluemonkey 7+ Year Member

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    The reason why aldehydes are more reactive for nucleophillic additions is because ketones have 2 alkyl groups while aldehydes only have. Sterics play a minor role, however. The reason why aldehydes are more reactive is because there is more positive charge on the carbonyl carbon. Ketones, with 2 electron donating groups, have less positive charge on the carbonyl carbon, and are thus less reactive to nucleophillic attack at the carbonyl carbon. Keep in mind that carbonyls are sp2 hybridized and thus planar making sterics less of an issue.
     
  6. BloodySurgeon

    BloodySurgeon Moderator Emeritus Lifetime Donor 7+ Year Member

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    true. that's close to what i was trying to say with my first point.
     

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