What is the Difference Between Gattermann and Gattermann Koch Reaction?

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The Gattermann and Gattermann-Koch reactions are both organic substitution reactions used to formylate aromatic compounds. However, there are key differences between the two reactions:

  1. Use of Carbon Monoxide: The Gattermann reaction does not use carbon monoxide, while the Gattermann-Koch reaction involves the use of carbon monoxide instead of hydrogen cyanide (HCN).
  2. Substrate Applicability: The Gattermann-Koch reaction cannot be applied to phenol and phenol ether substrates, unlike the Gattermann reaction.
  3. Catalysts: The Gattermann-Koch reaction usually uses zinc chloride as the catalyst and requires the presence of a trace amount of copper(I) chloride as a co-catalyst. In contrast, the Gattermann reaction may use other catalysts, such as aluminum chloride.
  4. Product Formation: The Gattermann reaction forms aryl aldehydes, while the Gattermann-Koch reaction forms aromatic aldehydes from aromatic hydrocarbons.

In summary, the main difference between the Gattermann and Gattermann-Koch reactions lies in the use of carbon monoxide and the type of catalysts employed in each reaction. Additionally, the Gattermann-Koch reaction cannot be applied to phenol and phenol ether substrates, unlike the Gattermann reaction.

Comparative Table: Gattermann vs Gattermann Koch Reaction

The Gattermann and Gattermann-Koch reactions are both methods for synthesizing aromatic aldehydes from benzene or its derivatives. The main difference between the two reactions lies in the reagents and catalysts used:

Gattermann Reaction Gattermann-Koch Reaction
Uses a mixture of HCN (hydrogen cyanide) and HCl (hydrochloric acid) as reagents Uses carbon monoxide as a reagent instead of hydrogen cyanide
The Lewis acid catalyst is typically AlCl3 The reaction usually uses zinc chloride as the catalyst, and requires the presence of a trace amount of copper(I) chloride as a co-catalyst
Developed by German chemist Ludwig Gattermann Developed by Ludwig Gattermann and Julius Arnold Koch

Both reactions aim to attach a -CHO (formyl group) to an aromatic system, but the Gattermann-Koch reaction is a variation of the Gattermann reaction and uses carbon monoxide instead of hydrogen cyanide as the reagent.