Acidic Protons

[flin5845]

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Why is a carboxylic acid proton more acidic than phenol proton?

I would have thought that the conjugate base of the phenol has more resonance through the benzene ring, making it more acidic, since the CB is more stable.

 

[wired202808]

Why is a carboxylic acid proton more acidic than phenol proton?

I would have thought that the conjugate base of the phenol has more resonance through the benzene ring, making it more acidic, since the CB is more stable.

I believe is the electronegativity of the carbonyl carbon that provides for a higher Ka value on a carboxylic structure vs. a benzene ring.

 

[JohnnnyD]

Why is a carboxylic acid proton more acidic than phenol proton?

I would have thought that the conjugate base of the phenol has more resonance through the benzene ring, making it more acidic, since the CB is more stable.

the benzene ring would rather keep its aromaticity. the loss of aromaticity results in a decrease in stabilization.

take the H+ off the phenol and drop your electrons down from the phenolate into the benzene ring. you'll find that all the resonance forms are going have result in a carbanion on either the ortho or para position, which is not stable (and is also the reason why the oxygen is a ortho para director on the benzene ring).

let me know if this doesnt help and ill try again haha. im not very good at explaining **** haha

 

[mh0000]

The resonance structures of a carboxylate anion distribute the negative charge across two electronegative oxygen atoms. In a phenoxide anion, the negative charge is distributed across less electronegative carbon atoms (and on the oxygen itself) of the aromatic ring. So while there are more resonance structures in phenoxide, they are not able to stabilize the anion as well due to carbon being less electronegative than oxygen.

 

[JohnnnyD]

The resonance structures of a carboxylate anion distribute the negative charge across two electronegative oxygen atoms. In a phenoxide anion, the negative charge is distributed across less electronegative carbon atoms (and on the oxygen itself) of the aromatic ring. So while there are more resonance structures in phenoxide, they are not able to stabilize the anion as well due to carbon being less electronegative than oxygen.

👍 better said than mine

 

[LetsGo2DSchool]

The resonance structures of a carboxylate anion distribute the negative charge across two electronegative oxygen atoms. In a phenoxide anion, the negative charge is distributed across less electronegative carbon atoms (and on the oxygen itself) of the aromatic ring. So while there are more resonance structures in phenoxide, they are not able to stabilize the anion as well due to carbon being less electronegative than oxygen.

If I can remember correctly, Chad said this in his videos.

 

[JohnnnyD]

If I can remember correctly, Chad said this in his videos.

then it is definitely better said than mine haha

 

[flin5845]

Thanks guys that makes more sense!