


$C{{H}_{3}}-C{{H}_{2}}-COOH\xrightarrow{PC{{l}_{3}}}I\xrightarrow{{{C}_{6}}{{H}_{6}}/AlC{{l}_{3}}}II\xrightarrow[\text{base/heat}]{N{{H}_{2}}-N{{H}_{2}}}III$
$\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-OH+C{{H}_{3}}-OH\overset{cat.}{\longleftrightarrow} \\
\end{matrix}\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-O-C{{H}_{3}}+{{H}_{2}}O \\
\end{matrix}$


$(A)\, CH_3CO_2H$ $(B)\, MeOCH_2CO_2H$
$(C)\,CF_2CO_2H$ $(D)\,$