Question

An alkyl isocyanide is prepared by -

• A. Heating an amide with $P_2{O}_5$
• B. Reacting an alcohol with $N{H}_3$
• C. The action of $AgCN$ on alkyl halide
• D. The action of $KCN$ on alkyl halide

Answer 1

The correct option is C The action of $AgCN$ on alkyl halide

An alkyl isocyanide is prepared by the action of $AgCN$ on alkyl halide
$C{H}_{3}C{H}_2-Br+AgCN\to C{H}_{3}C{H}_{2}CN+C{H}_{3}C{H}_2{N}^{-}{C}^{+}+NaBr\text{Ethyl cyanide}\text{Ethyl isocyanide}\text{Minor}\text{Major}$

In $AgCN$, the bond between Ag and C is predominantly covalent in nature, thus, C site is not available in case of AgCN. Hence, the lone pair of N attacks the ethyl bromide, and isocyanide is formed as the major product.

Alcohol with ammonia give primary amine and amide on heating with $P_2{O}_5$ gives cyanide.

Hence, option (c) is correct.