JEE Advanced 2021 · Paper 2, Chemistry question 2

Identify each compound.

• $\mathbf P=\ce{PhCH2Br}$, from bromination of toluene in light.
• S is foul smelling, so it is an isocyanide from the carbylamine reaction. R must therefore be a primary amine: $\mathbf R=\ce{PhCH2NH2}$, phenylmethanamine.
• P→R: $\mathbf Q=\ce{AgNO2}$ gives $\ce{PhCH2NO2}$, which $\ce{H2}$/Pd reduces to the amine. ($\ce{KNO2}$ would give mainly the nitrite ester.)
• $\mathbf T=$ benzoic acid, and $\mathbf U=$ benzamide (from $\ce{NH3}$, then heat). $\mathbf W=\ce{LiAlH4}$ reduces the amide to $\ce{PhCH2NH2}$.
• P→S directly: $\mathbf V=\ce{AgCN}$ gives $\ce{PhCH2NC}$.

Check each option.

• (A) Q is not $\ce{KNO2}$. False.
• (B) R is not benzenamine (aniline), and V is not KCN. False.
• (C) True.
• (D) True.

(C), (D)