I am assuming that the -I inductive effect in 2,3-dinitrophenol is stronger than in 2,4-dinitrophenol since it operates through less bonds, therefore on inductive grounds it should have a lower $\mathrm{p}K_\mathrm{a}$?

However it's unclear to me whether there are any differences in π-resonance effects. Any help?

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    $\begingroup$ Can you draw resonance structures for the conjugate base? $\endgroup$ Nov 25, 2019 at 19:09
  • $\begingroup$ @orthocresol I got 3 resonance forms for the conjugate bases of each. Is this correct? $\endgroup$
    – Anne
    Nov 25, 2019 at 19:19
  • $\begingroup$ You seems to forgot to include nitro groups. Try again and see. $\endgroup$ Nov 25, 2019 at 20:02
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    $\begingroup$ @MathewMahindaratne the conjugate base of 2,4-nitrophenol would be more stable and therefore it would be more acidic. Thank you for your guidance. $\endgroup$
    – Anne
    Nov 25, 2019 at 20:59
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    $\begingroup$ You got it! :-) $\endgroup$ Nov 25, 2019 at 21:32


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