$\mathop {{C_2}{H_5}OH}\limits_{\left( I \right)} $ $\mathop {{C_2}{H_5}Cl}\limits_{\left( {II} \right)} $ $\mathop {{C_2}{H_5}C{H_3}}\limits_{\left( {III} \right)} $ $\mathop {{C_2}{H_5}OC{H_3}}\limits_{\left( {IV} \right)} $
${C_3}{H_7}OH\,\xrightarrow{{{H_2}S{O_4}}}X\,\xrightarrow{{B{r_2}}}\,Y\xrightarrow{{KOH}}Z$