which one is more acidic, phenol, carboxylic acid or benzoic acid, why?

Asked by  | 28th Dec, 2012, 03:53: PM

Expert Answer:

Phenols are less (pKa»10) acidic than carboxylic acids (pKa»5)

Figure 1.  The anion resulting from deprotonation of phenol.

 

Figure 2.  The anion resulting from deprotonation of benzoic acid.

  • In phenol, the anion formed by loss of a proton is delocalized. Resonance structures show the negative charge can be shared between the oxygen atom and three of the carbons in the benzene ring.
  • In benzoic acid, the anion is also delocalized. This time the negative charge is shared between two different oxygen atoms.

Answered by  | 28th Dec, 2012, 04:17: PM

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