Solution

The Wurtz reaction is used to prepare symmetrical alkanes: $R-X + 2Na + X-R \xrightarrow{dry\ ether} R-R + 2NaX$ If $R_1$ and $R_2$ are different, a mixture of alkanes ($R_1-R_1$, $R_1-R_2$, $R_2-R_2$) is obtained. n-Heptane (odd number of carbons, $C_3 + C_4$) is unsymmetrical, so it cannot be made in good yield. 2,3-Dimethylbutane, n-butane and n-hexane are symmetrical.

Concept alkanes obtainable by Wurtz reaction

Hydrocarbons in past papers

75 questions from this chapter have appeared across 26 exam years.