Ochem Help???

Discussion in 'Pre-Dental' started by Beagle, Jul 21, 2002.

  1. Beagle

    Beagle Meet BEAGLE

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    Can someone explain Huckal's rule to me?
    I have no idea how to find out of a molecule is aromatic or not.
    Kaplans book isn't of much help with this stuff(to me anyway)
    Thanks !!!
     
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  3. DesiDentist

    DesiDentist G. S. Khurana, DMD, MBA
    Moderator Emeritus Exhibitor

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    From my understanding you can use huckles rule if you see all of the aromatic compounds are cyclic (joined) and conjugated then you can use 4n+2 (Huckles rule) so if you had a benzene ring with 3 double bonds you know that those three double bonds have 6 e- so you can put the equation like this:

    6=4n+2
    -2 -2
    ________
    4=4n

    4/4 =n

    n = 1

    so benzene is aromatic since n= a whole number

    If there was a cyclic compound with 8 e- or 4 double bonds then the equation would be:


    8=4n+2
    -2 -2
    ________

    6=4n

    6/4 =n which is not a whole number, thus not aromatic. But use huckles rule only after ruling out the first two criteria:

    1.) cyclic
    2.) conjugation

    Hope this helps,

    DesiDentist
     

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