11. ALCOHOLS, PHENOLS AND ETHERS (HM)
Explanation:
$\begin{matrix}
C{{H}_{2}}OH \\
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{2}}OH \\
\end{matrix}$ $+$ $PI_3\,\,\to $ $\begin{matrix}
C{{H}_{2}}I\,\,\,\,\,\,\,\, \\
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{2}}I\,\,\,\,\,\, \\
\end{matrix}$ $\xrightarrow[-{{I}_{2}}]{{}}$ $C{{H}_{2}}=C{{H}_{2}}$