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Thread: halobenzene nitration

  1. #1 halobenzene nitration 
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    Here's an interesting fact!

    The Fluorobenzene nitration has a reaction speed fourth time superior then the chloro and Bromobenzene but! the nitration of the iodobenzene is a lot faster then the chloro and bromobenzene nitration but slower then the fluorobenzene reaction.
    Could you explain the variation of reactivity of the halobenzene please.

    Thank you very much, even my teacher don't know!


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  3. #2  
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    To my knowledge the nitration of benzenes is a electrophylic substitution reaction. NO2(+) will react with the benzene.
    Hence the benzene will be more reactive if it has an electron surplus.
    Different effects can influence this charge distribution
    -Mesomere effects: bringing a negative charge in the benzene ring and thus will enhance the reaction.
    -Iductieve effects: pulling the electron (electron negativity toward itself – out of the ring) and slowing the reaction down.


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  4. #3  
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    I knew these factors,

    but here's the rapidity, from faster to slower, of the nitration of a benzene with an halogene: Fluorobenzene>Iodobenzene>>chlorobenzene>bromobenz ene

    Anybody know why the iodobenzene is faster than the chlorobenzene and the bromobenzene by a large margin?
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  5. #4  
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    F has the same engery orbitals (correct in English?) as C so the electron translocation will happens more easily when F is bound to the Benzene => positive effect => F-benzene reacts the quickest and mesomere are then greater then inducitve.

    But not if the orbitals do not overlap as easily the inductive effect get greater this can ecplain for the faster I compared to Cl en Br. But not why Br is slower compared to Cl

    So indeed there’s still missing something.
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