(a) How is ethane prepared by Wurtz reaction?
(b) How can we prepare ethane by reduction of a halogen compound?

(a) In preparation of ethane by Wurtz reaction, methyl bromide (BrH₃Br) or methyl iodide (CH₃I) and sodium are heated in the presence of dry ether to obtain ethane (CH₃CH₃).

​2CH₃I + 2Na $\stackrel{\mathrm{Dry}\mathrm{ether}}{\to }$ CH₃CH₃ + 2NaI

(b) Reduction of halogen compound (like ethyl iodide) in the presence of the combination of Zn + Cu in alcohol yields ethane:

$$\begin{gathered} {\mathrm{CH}}_3{\mathrm{CH}}_3\mathrm{I}+2\left[\mathrm{H}\right]\to {\mathrm{C}}_2{\mathrm{H}}_6+\mathrm{HI} \\ {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br}+2\left[\mathrm{H}\right]\to {\mathrm{C}}_2{\mathrm{H}}_6+\mathrm{HBr} \end{gathered}$$