$C{H_3}COOH + PC{l_5} \to A\mathop {\xrightarrow{{{C_6}{H_6}}}}\limits_{anh.\,AlC{l_3}} $ $B\mathop {\xrightarrow{{{C_2}{H_5}MgBr}}}\limits_{ether} C$
$C{{H}_{3}}-C{{H}_{2}}-COOH\xrightarrow{PC{{l}_{3}}}I\xrightarrow{{{C}_{6}}{{H}_{6}}/AlC{{l}_{3}}}II\xrightarrow[\text{base/heat}]{N{{H}_{2}}-N{{H}_{2}}}III$
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