Question

Which of the following reactions is shown by aldehydes that do not have alpha H-atom?

• A. Aldol condensation
• B. Cross aldol condensation
• C. Cannizzaro reaction
• D. Kolbe’s reaction

Answer 1

The Correct Option is C

The Cannizzaro reaction is characteristic of aldehydes that lack an alpha hydrogen atom. This reaction involves the simultaneous reduction and oxidation of two aldehyde molecules that do not possess an alpha hydrogen. In essence, one aldehyde molecule is reduced to an alcohol, while the other is oxidized to a carboxylate.

Process Description:

1. An aldehyde, represented as RCHO, without an alpha hydrogen is the reactant.

2. Two molecules of this aldehyde participate in a disproportionation, a type of redox reaction.

3. The outcome is the formation of an alcohol (RCH₂OH) from one molecule and a carboxylate (RCOO^-) from the other.

Reaction Equation:

2RCHO → RCH₂OH + RCOO^-

Therefore, aldehydes devoid of an alpha hydrogen atom undergo the Cannizzaro reaction.