a
\(\mathop {{\mkern 1mu} {\text{C}}{{\text{H}}_{\text{3}}}C{H_2}I{\mkern 1mu} }\limits_{ethyl\,{\kern 1pt} iodide} {\mkern 1mu} \xrightarrow{{NaCN}}{\mkern 1mu} \) \(\mathop {C{H_3}C{H_2}CN}\limits_{propen{\kern 1pt} \,nitrile} {\mkern 1mu} {\mkern 1mu} \xrightarrow{{O{H^{ - 1}}}}\) \({\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \mathop {C{H_2}C{H_2}CON{H_2}}\limits_{propen\,amide} {\mkern 1mu} {\mkern 1mu} \) \(\xrightarrow{{B{r_2}/4NaOH}}{\mkern 1mu} \mathop {C{H_3}C{H_2}N{H_2}}\limits_{ethen\,amine} {\mkern 1mu} \)