$C{H_2} = C{H_2} + \mathop {KMn{O_4}}\limits_{\begin{array}{*{20}{c}}
\,\\
{\begin{array}{*{20}{c}}
{{\rm{Alk}}{\rm{. Pink}}}\\
{}
\end{array}}
\end{array}} \mathop {\mathop {\mathop {C{H_2}}\limits_{|\,\,\,\,\,\,\,} }\limits_{OH\,} - \xrightarrow{H_2O} \mathop {\mathop {C{H_2}}\limits_{|\,\,\,\,\,\,\,} }\limits_{OH\,} \, + Mn{O_2}}\limits_{{\rm{Colourless}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} $