Wurtz reaction is used to prepare:

**Wurtz reaction**: $2 R X + 2 Na \xrightarrow{\text{dry ether}} R{-}R + 2 NaX$. Two alkyl halide molecules combine, with sodium metal as the reducing agent, to give a higher symmetric alkane with double the carbon chain. Example: $\mathrm{CH_3 I + CH_3 I \xrightarrow{2Na} CH_3 CH_3}$ (ethane). Limitation: doesn't work well for asymmetric alkanes — mixing two different RX gives a statistical mixture of R-R, R'-R' and R-R', hard to separate. So Wurtz is best for symmetric products.