Question

Identify the reagent involved in Sandmeyer reaction.

• A. CuCN/KCN
• B. Cu (Powder) /HBr
• C. $\text{H}_3\text{PO}_3$
• D. $\text{CH}_3\text{CH}_2\text{OH}$

Hint:

Sandmeyer = Cuprous SALT ($CuCl, CuBr, CuCN$). Gattermann = Copper POWDER ($Cu + HCl/HBr$).

Answer 1

The Correct Option is A

Step 1: Concept
The Sandmeyer reaction replaces a diazonium group on an aromatic ring with a nucleophile (like $\text{Cl}^-$, $\text{Br}^-$, or $\text{CN}^-$) using copper(I) salts.

Step 2: Meaning
Reagents involve a Cuprous salt ($CuX$) where $X$ is the group to be introduced.

Step 3: Analysis
- $\text{CuCN/KCN}$ is the reagent for introducing a nitrile group into a diazonium salt (Sandmeyer). - Note: Option (B) using Copper powder instead of a salt is called the Gattermann reaction.

Step 4: Conclusion
Reagent (A) is the correct Cuprous salt combination for the Sandmeyer reaction. Final Answer: (A)