\({\text{C}}{{\text{H}}_{\text{3}}}{\text{N}}{{\text{H}}_{\text{2}}}{\text{ + COC}}{{\text{l}}_{\text{2}}}{\text{ }}\xrightarrow{{ - HCl}}\,{\text{[C}}{{\text{H}}_{\text{3}}}{\text{NH - CO - Cl] }}\mathop {\xrightarrow{\Delta }}\limits_{ - HCl} \,{\text{C}}{{\text{H}}_{\text{3}}}{\text{ - N = C = O}}\)