Question

Which compound undergoes Cannizzaro reaction: Formaldehyde, Acetaldehyde, or Benzophenone?

• A. Formaldehyde
• B. Acetaldehyde
• C. Benzophenone
• D. Both (A) and (B)

Hint:

Cannizzaro reaction occurs only in aldehydes without \(\alpha\)-hydrogen atoms. Examples include formaldehyde and benzaldehyde.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to identify which of the given chemical compounds will undergo a Cannizzaro reaction when treated with a strong concentrated base.
Step 2: Key Formula or Approach:
The fundamental requirement for a molecule to undergo a Cannizzaro reaction is that it must be an aldehyde that lacks an \(\alpha\)-hydrogen atom.
Molecules lacking \(\alpha\)-hydrogens undergo self-oxidation-reduction (disproportionation) instead of an aldol condensation.
Step 3: Detailed Solution:
Let's analyze each of the given options:
1. Formaldehyde (\(HCHO\)): The carbonyl carbon is attached only to hydrogen atoms. There is no \(\alpha\)-carbon, and thus zero \(\alpha\)-hydrogens. It fits the criteria perfectly.
2. Acetaldehyde (\(CH_3CHO\)): The \(\alpha\)-carbon (the \(CH_3\) group) contains three \(\alpha\)-hydrogen atoms. Therefore, it will undergo aldol condensation instead of Cannizzaro.
3. Benzophenone (\(Ph-CO-Ph\)): While it does lack \(\alpha\)-hydrogens, it is a ketone, not an aldehyde. The Cannizzaro reaction is a characteristic reaction of aldehydes.
Therefore, only Formaldehyde will undergo the Cannizzaro reaction.
Step 4: Final Answer:
Formaldehyde is the correct compound.