Question

Which alkanes cannot be prepared by Wurtz reaction ?

Answer 1

1. Alkyl halides on reaction with sodium metal in dry ether give higher alkanes. This is known as the Wurtz reaction.
2. This reaction is used for the preparation of higher alkanes containing an even number of carbon atoms.
3. The alkanes with an odd number of carbon atoms are not prepared by this method.
4. $$\begin{gathered} {\mathrm{CH}}_3\mathrm{Br}+2\mathrm{Na}+{\mathrm{BrCH}}_3\stackrel{\mathrm{dry}\mathrm{ether}}{\to }{\mathrm{CH}}_3-{\mathrm{CH}}_3+2\mathrm{NaBr} \\ \mathrm{Bromomethane}\mathrm{Ethane} \end{gathered}$$