The structure of the major product formed in the following reaction is :

### Core Logic The substrate contains two distinct carbon-halogen bonds: an aryl-bromide bond (mathrmAr-Br$\mathrm{Ar-Br}$) on the ring and an aliphatic alkyl-chloride bond (mathrmCH_2-Cl$\mathrm{CH_2-Cl}$) on the side chain. 1. **Aryl Halide Site (mathrmC_sp^2mathrm-Br$\mathrm{C}_{sp^2}\mathrm{-Br}$):** The bromine atom attached directly to the aromatic ring does not undergo standard nucleophilic substitution (S_N2$S_N2$ or S_N1$S_N1$) under normal conditions due to resonance stabilization, which gives the bond partial double-bond character. 2. **Alkyl Halide Site (mathrmC_sp^3mathrm-Cl$\mathrm{C}_{sp^3}\mathrm{-Cl}$):** The side-chain aliphatic carbon bond undergoes smooth, unhindered nucleophilic substitution. When reacting with silver cyanide (mathrmAgCN$\mathrm{AgCN}$): mathrmAgCN$\mathrm{AgCN}$ is predominantly covalent. The lone pair on the nitrogen atom acts as the primary nucleophilic center rather than the carbon atom. Consequently, substitution at the aliphatic site yields an **isonitrile (-mathrmNC$-\mathrm{NC}$)** derivative as the major product, leaving the aryl bromide group completely untouched. ### Step 1: Structural Resolution The reaction progresses cleanly at the side-chain carbon:

### Pattern Recognition Remember the key selectivity rule for cyanide nucleophiles: * mathrmKCN / mathrmNaCN ightarrow$\mathrm{KCN} / \mathrm{NaCN} ightarrow$ ionic reagents ightarrow$ ightarrow$ attacks via carbon to form a **Nitrile (-mathrmCN$-\mathrm{CN}$)**. * mathrmAgCN ightarrow$\mathrm{AgCN} ightarrow$ covalent reagent ightarrow$ ightarrow$ attacks via nitrogen to form an **Isonitrile (-mathrmNC$-\mathrm{NC}$)**. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Haloalkanes and Haloarenes