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Orgo Destroyer #44.

Discussion in 'DAT Discussions' started by ddsjc2014, Jun 18, 2008.

  1. ddsjc2014

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    Why the answer is e?? someone please explain in detail.
    Thanks.
     
  2. Orgodox

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    Well since the question says SN1 (2 steps first form carbocation then attack) just think if the Cl (or I for a) leaves which will be left with the most sable carbocation. Each one is drawn out in the answer key:
    a) only secondary its not bad
    b)wont happen
    c)this one might be tricky. It looks nice because has 2 double bonds that should be able to help out with resonance but you cant forget about aromaticity. By creating that vacant orbital we now created an antiaromatic species. SO lets stay away from that answer choice.
    d) its not bad secondary and doubly allylic
    e)Best has a lot of resonance and by creating this vacant orbital you now have an aromatic species
     
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  3. snooper92

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    Can you explain why choice "B" would not happen?

    Thanks.
     
  4. pidbull

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    I dont get it either. He said E is great because aromatic, but B is also aromatic? Can someone help? And what is antiaromatic?
     
  5. jjw822

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    I don't know the reason but i just know you just cannot have + charge in B..

    but for E, by loosing Cl, it becomes aromatic which is very stable.

    and Antiaromatic is 4n. You know 4n+2 makes aromatic? but if you have just 4n it is anti aromatic.

    hope it helps./.
     
  6. pidbull

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    thanks for the explanation, helped me understand
    but according to that, shouldnt D be anti-aromatic as well? In the solutions it says C is anti-aromatic but for D it says "fair" even though it is also just 4n...hope that makes sense, and appreciate the help!
     
  7. jjw822

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    D cannot be anti or aromatic because it does NOT have shared conjugated system. see the Carbon in the bottom?? that C is sp3 so it cannot be consider to be anti or aromatic.
     
  8. 211183

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    there are three terms:
    aromatic, anti aromatic, and non aromatic. I used to get the latter two mixed up as well.

    aromatic is if it follow ALL the aromaticity rules
    planar, conjugated system, ring, and sp2 AND is 4n+2 (you knew that)

    if it FOLLOWS ALL of those..... BUT is 4n = antiaromatic

    if it violates any one of those = nonaromatic
    so if its not planar, not conjugated, not a ring, or has anything but sp2 carbons...

    I forget which rings are nonplanar.... there are some higher #carbon ones that are and aren't. I don't know if they'd test those exceptions though.

    Sorry if you knew that already- just trying to help!
     
  9. jjw822

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    Thanks i was just trying to explain in simple terms.lol

    my DAT is in wed..... don't know what to do now.. think i am pretty ready.. but little nervous.
     
  10. 211183

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    Mine is Tuesday. I'm the same... still reviewing though...but at this point everything I review feels like a movie i've watched 10 times adn I can recite all the words.

    I think it might be smart to do some QR practice and RC .... GOD I HATE TRIG! I don't think I will ever understand it.
     
  11. jjw822

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    I feel you on TRIG.. I was so good at math in high school and didnt take any math course in college.. and forgot everything.. for trig, you just have to memorize those stupid identities..

    best luck for both of us!!!
     

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