Organic synthesis and inhibition action of novel hydrazide derivative for mild steel corrosion in acid solutions

• One-pot synthesis of novel hydrazinyl hydrazide (HDOP) derivative is described.
• Both spectral and elemental analyses are used for characterization of the HDOP.
• EIS, Tafel plots, SEM and EDX are used in the corrosion study in HCl and H2SO4.

A new derivative of hydrazide family, 2-(2-hydrazinyl-1,6-dihydro-6-oxopyrimidin-4-yl) acetohydrazide (HDOP) is synthesized and used as a corrosion inhibitor for mild steel both in 1 M HCl and 0.5 M H2SO4 solutions. A facial synthesis of a novel hydrazinyl hydrazide derivative is accomplished via a one-pot synthesis. Reaction of ethyl 2-(1,2,3,6-tetrahydro-6-oxo-2-thiopyrimidin-4-yl)acetate (1) with hydrazine hydrate in an ethanol refluxing produces the target hydrazinyl hydrazide derivative in a good yield. Different techniques such as IR, NMR and mass spectroscopy are used for characterization of the obtained products. The inhibition of mild steel corrosion using HDOP in different concentrations is studied by electrochemical impedance spectroscopy and polarization measurements. The inhibition efficiency (IE) of HDOP is found to be higher in HCl than that in H2SO4 solution. This is attributed to the stronger adsorption of Cl− on the iron surface which enables better synergism between Cl− and the protonated inhibitor. The HDOP acts mainly as a cathodic inhibitor (in both acid solutions) and an inhibition efficiency of ∼89% was obtained in the HCl solution. The free energy of adsorption obtained by applying Langmuir adsorption isotherm predicts physisorption of HDOP on the iron surface in the HCl solution.