$C{{H}_{3}}-C{{H}_{2}}-COOH\xrightarrow{PC{{l}_{3}}}I\xrightarrow{{{C}_{6}}{{H}_{6}}/AlC{{l}_{3}}}II\xrightarrow[\text{base/heat}]{N{{H}_{2}}-N{{H}_{2}}}III$

${CH}_{3} {COOH}+{SOCl}_{2} \longrightarrow {A} \xrightarrow[AlCl_3]{Benzene} {B} \xrightarrow[-OH]{KCN} {C}$
