The reactions which cannot be applied to prepare an alkene by elimination, are: A.

B. mathrmCH_3 - CH_2 - undersetoverset|mathrmBrmathrmCH - CH_3 xrightarrowmathrmKOH\ (aq.)$\mathrm{CH_3 - CH_2 - \underset{\overset{|}{\mathrm{Br}}}{\mathrm{CH}} - CH_3 \xrightarrow{\mathrm{KOH\ (aq.)}}}$ C.

D.

E.

Choose the correct answer from the options given below:

### Related Formula textR-X + textAgCN rightarrow textR-NC + textAgX$$\text{R-X} + \text{AgCN} \rightarrow \text{R-NC} + \text{AgX}$$ ### Core Logic Cyanide (CN^-$CN^-$) is an ambident nucleophile that can attack through either carbon or nitrogen: * textKCN$\text{KCN}$ and textNaCN$\text{NaCN}$ are predominantly ionic compounds, leaving the carbon atom free and highly nucleophilic to yield alkyl cyanides (textR-CN$\text{R-CN}$) as the major product. * Silver cyanide (textAgCN$\text{AgCN}$) is predominantly covalent. Because the silver-carbon bond is strong, the lone pair on nitrogen acts as the primary nucleophilic site, leading to the formation of alkyl isocyanides (textR-NC$\text{R-NC}$). ### Step 1: Selection Therefore, reacting an alkyl halide with textAgCN$\text{AgCN}$ selectively produces an alkyl isocyanide. ### Pattern Recognition Ionic cyanides like textKCN$\text{KCN}$ yield nitriles, whereas covalent cyanides like textAgCN$\text{AgCN}$ yield isocyanides due to the availability of the nitrogen lone pair. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Organic Compounds Containing Halogens