Question

Which of the following method gives better yield of p-nitrophenol?

• A. $Phenol\underset{{20}^{o}C}{\overset{dil.H{NO}_3}{\to }}p-Nitrophenol$
• B. $Phenol\underset{H{NO}_3}{\overset{\left(i\right)Na{NO}_2+H_2{SO}_4,7-8^{o}C}{\to }}p-Nitrophenol$
• C. $Phenol\underset{\left(ii\right)Conc.H{NO}_3}{\overset{\left(i\right)NaOH}{\to }}$
• D. None of these

Answer 1

Answer: (B)

$Phenol\underset{H{NO}_3}{\overset{\left(i\right)Na{NO}_2+H_2{SO}_4,7-8^{o}C}{\to }}p-Nitrophenol$

The following method gives better yield of p-nitrophenol.

$Phenol\underset{H{NO}_3}{\overset{\left(i\right)Na{NO}_2+H_2{SO}_4,7-8^{o}C}{\to }}p-Nitrophenol$

The oxidation of phenol is minimised by forming p-nitrosophenol.
When phenol is treated with dil nitric acid at ${20}^{0}C$, a mixture of ortho (40%) and para (10%) nitro phenol is obtained.