Acidity of acids?

[ciestar]

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I'm looking over this in TBR. I think I get it more when it comes to benzene and whatnot..

But with acidity, a molecule with EWG is stronger and a molecule with EDG are weaker.

In the book it gives a few examples with their pka's.

Why is an alkoxide a weaker acid? Maybe I'm thinking incorrectly, but since O is EN, wouldn't it be withdrawing? I think I just need some clarification on this topic. And a phenol is more acidic than an alkoxide due to it's resonant effects and stability?

The list in the book include; carboxylic acid > phenol = (approximately) alkyl ammonium cation > alkoxide > carbonyl alpha-proton.

Ranked in order of acidity from stronger to weakest.

A cation obviously is electron withdrawing. I understand that much.

Thanks!

 

[ciestar]

I may have answered my own question...

Does it have to do with the stability of the acid's conjugate base? Following the rule the more stable the conjugate base the stronger the acid?

Please correct me if I'm wrong!

 

[ReggieD6868]

I may have answered my own question...

Does it have to do with the stability of the acid's conjugate base? Following the rule the more stable the conjugate base the stronger the acid?

Please correct me if I'm wrong!

The relative strength of a conjugate base determines the conjugate acids strength and vice versa. In terms of acidity, the weaker the conjugate base is, the stronger the conjugate acid is. A conjugate base is "weakened" with increasing stability of that said conjugate base. Resonance and inductive effects weaken the conjugate base by stabilizing the negative charge.

 

[brood910]

I may have answered my own question...

Does it have to do with the stability of the acid's conjugate base? Following the rule the more stable the conjugate base the stronger the acid?

Please correct me if I'm wrong!

Yes.
Think about it this way.
Acids tend to give H away.
Which one do you think will be more likely to give up H?
When acids give up H, they become conj bases. If the bases are more stable, acids will LOVE to be bases = more likely to give H away.