
(figure) $\xrightarrow[CC{{l}_{4}}]{B{{r}_{2}}}(A)\xrightarrow[(ii)\,NaN{{H}_{2}}]{(i)\,alc.\,KOH}(B)\xrightarrow[(ii)\,C{{H}_{3}}-Cl]{(i)\,NaN{{H}_{2}}}(C)$
${H_2}C\, - \,\,\mathop C\limits_{\mathop |\limits_D } H\, - \,\,\mathop C\limits_{\mathop |\limits_{C{H_3}} } H\, - \,\,C{H_3}\, + \,\,Br\,\, \to \,\,'X'\,\, + \,\,HBr$