Question

Question: Possible resonance structures for p-nitrophenol

Predict which will be the stronger acid. (Hint: Consider possible resonance

structures analogous to those given in the text for phenol.

Short answer

Answer

The compound p-nitrophenol is more acidic than m-nitrophenol.

Step-by-step solution

The resonance structure of p-nitrophenol

Possible resonance structures for p-nitrophenol

The resonance structure of m-nitrophenol

Possible resonance structures for m-nitrophenol

Result

The stronger acid is p-nitrophenol because it has more resonance structures than

m-nitrophenol and the negative charge is delocalized onto the oxygens of the nitro

group, which are highly electro negative and therefore stabilize the charge

effectively. In the case of m-nitrophenol, the stabilization is possible because there is

no opportunity via resonance for delocalization onto the nitro group.