Acids and Bases - Organic Chemistry Concepts: An EFL Approach - page 96

B Possible resonance forms include:
In the case of ethanol and its ethoxide conjugate base, resonance forms are not likely.
This is because carbon is less likely than oxygen to have a negative charge. Therefore,
we can say that neither ethanol nor the ethoxide conjugate base is resonance stabilized.
The resonance forms for ethanoic acid and the ethanoate anion are much more likely.
Between these two options, the resonance forms for the ethanoate anion are better.
This is because these resonance forms are equal and the resonance is symmetrical.
One of the resonance forms for ethanoic acid has charge separation, and this is a
relatively high energy form. The presence of resonance stabilization in ethanoic acid
( pK a 4.7) shows why it is a stronger acid than ethanol ( pK a 16).
The same method can be used with base strength. Study the example of aniline
( phenylamine ) and its saturated counterpart cyclohexylamine.
Use possible resonance forms to show which you expect to be the stronger base?
C To compare these molecules, you should have drawn resonance forms similar to:
We can easily draw resonance forms for the aromatic aniline. However, there is no
similar resonance for cyclohexylamine. The delocalization stabilizes the aniline and