This book consist three parts;I)The synthesis of four new heterocyclic compounds by domino reactions,II)The identification of the synthesis compounds by several techniques such as, (FT - IR),(1HNMR),( 13C NMR), (GC-Mass), and(CHNS). III)The study of the prepared compounds as corrosion inhibitors for carbon steel alloy (N-80)in aqueous solution of 0.5 M hydrochloric acid ,and brine water was used as a corrosive media. Several techniques was employed such as weight loss method, potentiodynamic polarization (Tafel Plot), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray fluorescence spectroscopy(EDX), and Atomic force microscopy(AFM).