Question

Identify the products $(A)$ and $(B)$ in the reactions.
$RX+AgCN\to \frac{(A)}{}+Agx$
$RX+KCN\to \frac{(B)}{}+Kx$

• A. $(A)-RCN$, $(B)-RCN$
• B. $(A)-RCN$, $(B)-RNC$
• C. $(A)-RNC$, $(B)-RCN$
• D. $(A)-RNC$, $(B)-RNC$

Answer 1

Answer: (C)

$RX+AgCN\to \underset{\text{(A)}}{\mathrm{RNC}}+AgX$
$RX+KCN\to \underset{\text{(B)}}{\mathrm{RCN}}+KX$
Both $C$ and $N$ can donate electron pairs. Since $KCN$ is predominantly ionic and $C—C$ bond is more stable than $C—N$ bond in case of $KCN$, attack takes place through carbon atom.
$AgCN$ is predominantly covalent hence only nitrogen pair is available for bonding resulting in formation of isocyanide.