Question

Assertion: Reimer-Tiemann reaction of phenol with ${\mathrm{CCl}}_4$ in $\mathrm{NaOH}$ at $340\mathrm{K}$ gives Salicylic acid as the major product.

Reason: The reaction occurs through intermediate formation of dichlorocarbene.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is C

Assertion is correct but Reason is incorrect

The explanation for Assertion statement

• When phenol $\left({\mathrm{C}}_6{\mathrm{H}}_5\mathrm{OH}\right)$ is treated with chloroform $\left({\mathrm{CCl}}_4\right)$ in the presence of aqueous sodium hydroxide $\left(\mathrm{NaOH}\right)$ or Potassium hydroxide $\left(\mathrm{KOH}\right)$ at $340\mathrm{K}$, followed by the hydrolysis of the resulting products, salicylaldehyde $\left({\mathrm{OHC}}_6{\mathrm{H}}_4\mathrm{CHO}\right)$ is produced.
• The reaction is as follows:

The explanation for Reason statement

• The chloroform carbanion is formed when the chloroform is deprotonated by the highly basic aqueous hydroxide solution.
• This chloroform carbanion quickly undergoes alpha elimination, producing dichlorocarbene.
• The primary reactive species is dichlorocarbene.
• The aqueous hydroxide also deprotonates the phenol reactant, resulting in a negatively charged phenoxide.
• This negative charge has now been delocalized within the benzene ring, making it significantly more nucleophilic.
• This causes a nucleophilic attack on the dichlorocarbene, resulting in the formation of an intermediate dichloromethyl substituted phenol.
• This intermediate is then treated with basic hydrolysis to get the required ortho-hydroxybenzaldehyde.
• The mechanism is as follows:

Therefore, the correct option is (C) Assertion is correct but Reason is incorrect.