\(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\begin{array}{*{20}{c}}
  {\,\,\,\,C{H_3}\,\,} \\ 
  {|\,\,\,\,} 
\end{array}} \\ 
  {C{H_3} - C - X + } \\ 
  {\,\,\,\,\,|\,\,\,\,} \\ 
  {\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,} 
\end{array}\)   \(NaOC_2H_5\,\to \) \(\mathop {\begin{array}{*{20}{c}}
  {\,\,\,\,\,C{H_3}} \\ 
  {|\,} \\ 
  {C{H_3} - C = C{H_2}} 
\end{array}}\limits_{2\, - \,methyl\,propane} \)