Question

Write the chemical equations of the following reactions:
i) Reaction of dilute HNO$_3$ with phenol
ii) Reaction of phenol with chloroform in the presence of NaOH (aq.)

Hint:

Dilute nitration of phenol mainly gives ortho and para products. Reimer-Tiemann reaction (phenol + CHCl$_3$/NaOH) is a key method to introduce a $-CHO$ group at the ortho-position of phenol.

Answer 1

i) Reaction of dilute HNO$_3$ with phenol:
Phenol undergoes nitration with dilute HNO$_3$ to form ortho- and para-nitrophenol.
\[ C_6H_5OH + HNO_3 \; \rightarrow \; o\text{-}C_6H_4(OH)(NO_2) + p\text{-}C_6H_4(OH)(NO_2) + H_2O \]
ii) Reaction of phenol with chloroform in the presence of NaOH (aq.):
This is the Reimer-Tiemann reaction. Phenol reacts with chloroform and NaOH to give salicylaldehyde (o-hydroxybenzaldehyde).
\[ C_6H_5OH + CHCl_3 + 3NaOH \;\rightarrow\; o\text{-}OH\text{-}C_6H_4CHO + 3NaCl + 2H_2O \]