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Homework Help: Electrophilic Aromatic Substitution

  1. Jan 15, 2016 #1
    1. The problem statement, all variables and given/known data
    The compounds P, Q and S, were separately subjected to nitration using HNO3/H2SO4mixture. The major product formed in each case respectively, is :



    2. Relevant equations

    3. The attempt at a solution
    This is a standard EAS reaction. I know the answer will be either C or D, because in case of (P) -OH is more activating so the substitution will be with at ortho with respect to -OH (as para is blocked), similarly in case of (Q), it will be oath with respect to -OCH3 (more activating).
    I don't understand what with respect to S. Is the -OC=O group electron withdrawing or donating? I thought it was withdrawing because the lone pair on oxygen is in resonance with the C=O bond (not with the benzene as the resonance with C=O is much more stable due to equivalent resonance structures (the reason why carboxylic acids are so stable). So, I thought the answer would be D and the substitution would occur at the meta position. But the answer is C. Help?
  2. jcsd
  3. Jan 15, 2016 #2

    Suraj M

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    Gold Member

    Though O might undergo resonance with Carbonyl carbon, it's still a +R group for the second benzene ring making it more electron Rich and promoting Electrophile approach
    How would you justify meta position?
  4. Jan 15, 2016 #3
    Oh ok!
    No meta then. I was thinking -I kind of thing. But got it!
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