If we use carbon tetrachloride in Reimer- Tiemann reaction in place of chloroform, the product formed is

Reimer-Tiemann Reaction with Carbon Tetrachloride

When carbon tetrachloride (CCl₄) is substituted for chloroform (CHCl₃) in the Reimer-Tiemann reaction, the product formed is salicylic acid (2-hydroxybenzoic acid) when phenol is used as the substrate. This modification shifts the reaction outcome from producing an aldehyde (e.g., salicylaldehyde) to generating a carboxylic acid.

Key Differences in Reaction Mechanism

• Standard Reimer-Tiemann (with CHCl₃): Generates dichlorocarbene (:CCl₂), which attacks phenol to form an ortho-substituted aldehyde after hydrolysis.
• Modified Reaction (with CCl₄): Produces trichloromethyl carbene (:CCl₃) instead. This intermediate undergoes hydrolysis to form a carboxylic acid group at the ortho position of the phenol ring.

Example Reaction

The product is salicylic acid, not salicylaldehyde.

Selectivity and Limitations

The reaction retains ortho-selectivity due to the electrophilic nature of the carbene intermediate. However, yields are often lower compared to the standard Reimer-Tiemann reaction, and copper catalysts may improve efficiency.

This variant demonstrates how reagent choice fundamentally alters the reaction pathway and product class in electrophilic aromatic substitution.