Question

Write the reactions involved in the following:

Hint:

Reimer–Tiemann adds –CHO at ortho; Kolbe adds –COOH to ortho position of phenol under heat and pressure.

Answer 1

(a) Reimer–Tiemann reaction:
This is used to convert phenol to salicylaldehyde using chloroform and NaOH. \[ \text{C}_6\text{H}_5\text{OH} + \text{CHCl}_3 + 3\text{NaOH} \xrightarrow{\Delta} \text{OH–C}_6\text{H}_4\text{–CHO} + 3\text{NaCl} + 2\text{H}_2\text{O} \] (b) Kolbe’s reaction:
Sodium phenoxide reacts with CO\(_2\) under pressure to form salicylic acid. \[ \text{C}_6\text{H}_5\text{ONa} + \text{CO}_2 \xrightarrow{473\,K,\,6\,atm} \text{OH–C}_6\text{H}_4\text{–COONa} \xrightarrow{\text{H}^+} \text{OH–C}_6\text{H}_4\text{–COOH} \]