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Polarity question

Discussion in 'MCAT Discussions' started by ImmunoRocks, Apr 16, 2004.

  1. ImmunoRocks

    ImmunoRocks Member
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    Hello!

    There was this question on AAMC 7 about the Rf value of this ketone cyclic-ring vs just a hydroxyl group on the cyclic-ring. Which one is more polar? And if it's more polar, then it probably doesn't travel up the TLC as far? Is this right?

    Thanks
     
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  3. akalin24

    akalin24 Member
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    Correct! Anytime you compare the polarity of two different molecules.... the molecule that can act as both a H-bond donor and acceptor has the higher dipole moment. TLC usually has a polar (adsorbant) stationary phase so the molecule with the greatest polarity will have the smallest Rf value.

    Good Luck tomorrow!

    AK
     
  4. Cerberus

    Cerberus Heroic Necromancer
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    The hydroxyl is more polar than the =O, this means it has a smaller Rf value (so yeah, it travels less).
     

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