Question

A new carbon-carbon bond formation is possible in:
I. Cannizzaro reaction II. Friedel-Crafts reaction III. Clemmensen reduction IV. Reimer-Tiemann reaction

• A. I, II and III
• B. II, III and IV
• C. I and III
• D. II and IV

Hint:

Friedel-Crafts = C–C bond formation reaction.

Answer 1

The Correct Option is D

To determine in which reactions a new carbon-carbon bond formation is possible, let's examine each of the given reactions:

1. Cannizzaro Reaction: This reaction involves the disproportionation of a non-enolizable aldehyde to give a primary alcohol and a carboxylic acid. There is no formation of a new carbon-carbon bond in this reaction.
2. Friedel-Crafts Reaction: There are two types of Friedel-Crafts reactions, namely Friedel-Crafts alkylation and Friedel-Crafts acylation. Both types involve the formation of a new carbon-carbon bond by introducing an alkyl or acyl group into an aromatic ring. Hence, a new C-C bond formation occurs here.
3. Clemmensen Reduction: This reaction reduces ketones or aldehydes to alkanes using zinc amalgam and hydrochloric acid. There is no formation of a new carbon-carbon bond.
4. Reimer-Tiemann Reaction: This reaction is used to form ortho- and para-hydroxybenzaldehyde from phenols. It involves the formation of a new carbon-carbon bond between the phenolic compound and a dichlorocarbene (:CCl₂), which then rearranges.

From the analysis above, we can conclude that new carbon-carbon bond formation is possible in the Friedel-Crafts reaction and the Reimer-Tiemann reaction.

Correct Answer: II and IV