C2H5-CHO → C2H5-COOH → CH3-CHCl-COOH → CH3-CHNH2-COOH → CH3-CHNH2-COOCH3
C2H5-CHO + Ag2O ⇒ C2H5-COOH + 2Ag↓
C2H5-COOH + Cl2 ⇒ CH3-CHCl-COOH +HCl↑
CH3-CHCl-COOH + NH3 ⇒ CH3-CHNH2-COOH + HCl↑
CH3-CHNH2-COOH + HO-CH3 ⇒ CH3-CHNH2-COOCH3 + H2O
