Tests for Phenols - Discussion

Phenol

Catechol

Resorcinol

2-napthol

Solubility

Some phenols (Ex: Phenol,catechol,resorcinol) are soluble in water and others are sparingly soluble or insoluble in water because of the increasing molecular weight and hydrophobic nature. But all the phenols are capable of reacting with NaOH solution and dissolve.

C₆H₅OH + NaOH ----> C₆H₅ONa + H₂O

Reaction with Sodium carbonate

Phenols give no reaction with sodium carbonate but as the aqueous solution of it was used,phenols dissolved in it giving the same colourations given when testing the solubility in water.As Phenols do not produce gas from sodium carbonate it should be a very weak acid.

Benzoylation

To react with benzoyl chloride, phenol should be modified to make the reaction possible.the -COCl group is bounded directly to the benzene ring. Therefore it's less reactive.phenol is first dissolved in NaOH in order to get the phenoxide. Later it's reacted with the Benzoyl chloride.