\(\begin{array}{*{20}{c}}
{\,\,\,\,\,\begin{array}{*{20}{c}}
{\,\,\,\,C{H_3}\,\,} \\
{|\,\,\,\,}
\end{array}} \\
{C{H_3} - C - X + } \\
{\,\,\,\,\,|\,\,\,\,} \\
{\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,}
\end{array}\) \(NaOC_2H_5\,\to \) \(\mathop {\begin{array}{*{20}{c}}
{\,\,\,\,\,C{H_3}} \\
{|\,} \\
{C{H_3} - C = C{H_2}}
\end{array}}\limits_{2\, - \,methyl\,propane} \)
$\begin{align}
(A)\,Nu+R-L\to \overset{\oplus }{\mathop{Nu}}\,-R+{{L}^{-}} \\
(B)\,R-{{L}^{\oplus }}\to {{R}^{\oplus }}+:L \\
\end{align}$