between C6H5CO2H AND C204H2 which is stronger acid?

Question

anonymous · Answer

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andrefontex · Answer

think its the first . more resonance. but second has more probability to lose H+
almost sure that is the first

anonymous · Answer

ALWAYS draw the conjugate bases! Then draw resonance for the conjugate base and find out which one is more stable.

andrefontex · Answer

yes , ofc doing that is the first.
but consider that u have 3 or 4 hydrogens that u can take from a specie, and only 1 from the other with resonance, the one with 1 hydrogen is always more acid?

anonymous · Answer

The upper structure's conjucate base is resonance stabilised and so does the conjucate base of lower one.

anonymous · Answer

Hmm this is tough actually. You're right, they have the same resonance. Oxalic acid (second one) has a pka of 1.23 and benzoic acid (first one) has a pka of 4.2 so the answer is definetely the second one. The question is why?

anonymous · Answer

Maybe because the second one has inductive effect?

anonymous · Answer

But andrefontex hydrogens attached to electronegative element are acidic|dw:1358108657752:dw|