Oxidation of phenol with chromic acid produces benzoquinone. In the presence of air, phenols undergo slow oxidation, forming dark-colored mixtures containing quinones.
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Phenoxide ion, produced by treating phenol with sodium hydroxide, undergoes electrophilic substitution with carbon dioxide in Kolbe’s reaction, forming ortho hydroxybenzoic acid as the main product. The phenoxide ion is more reactive than phenol due to its enhanced nucleophilicity.
Picric acid is obtained by treating phenol first with concentrated sulfuric acid, converting it to phenol-2,4-disulphonic acid, and then with concentrated nitric acid to yield 2,4,6-trinitrophenol. The modern method is preferred for improved yield in the preparation of picric acid.
Phenol reacts with dilute nitric acid at low temperature, producing a mixture of ortho and para nitrophenols. Steam distillation is used to separate the isomers; o-nitrophenol is steam volatile due to intramolecular hydrogen bonding, while p-nitrophenol is less volatile due ...