Có các chất sau: C_2H_5OH,,CH_3rmCOOH,,C_6H_5ONa (natri phenolat), C_6H_5NH_2

${C_2}{H_5}OH\, + C{H_3}{\rm{COOH}}\, \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} \,{\rm{C}}{{\rm{H}}_3}{\rm{COO}}{{\rm{C}}_2}{H_5} + {H_2}O$
$C{H_3}COOH\, + {C_6}{H_5}ONa\, \to \,{C_6}{H_5}OH\, + \,C{H_3}COONa$
$C{H_3}COOH\, + \,{C_6}{H_5}N{H_2} \to \,{C_6}{H_5}N{H_3}OOCC{H_3}$