Electrophilic Aromatic Substitution

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The discussion revolves around the electrophilic aromatic substitution (EAS) reactions of compounds P, Q, and S with a nitrating mixture. For compounds P and Q, the ortho positions are favored for substitution due to the activating effects of -OH and -OCH3 groups, respectively. The confusion arises with compound S, where the -OC=O group is debated as either electron-withdrawing or donating. It is clarified that despite resonance stabilization with the carbonyl, the group acts as a +R substituent, leading to a preference for substitution at the ortho position rather than meta. Ultimately, the correct product for S is identified as being influenced by the electron-rich nature of the substituent.
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Homework Statement


The compounds P, Q and S, were separately subjected to nitration using HNO3/H2SO4mixture. The major product formed in each case respectively, is :
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Homework Equations

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?
 
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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?
 
Suraj M said:
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

Oh ok!
No meta then. I was thinking -I kind of thing. But got it!
 
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