Studies on the Effect of Some Pyrimidine Derivatives on the Corrosion of Iron in 1M Hydrochloric Acid

The effect of three pyrimidine derivatives namely, 6-amino-3,4-dihydropryimidin-2(1H)-thione (Pyr-3) , ethyl (R)-2-mercapto-4-methyl-6-phenyl-1,6-dihydropyrimidine-5-carboxylate (Pyr-7) and ethyl (R)-6-(4-chlorophenyl)-2-mercapto-4-methyl-1,6- dihydropyrimidine-5-carboxylate (Pyr-9) on the corrosion of iron in 1.0 M HCl in absence and presence of various concentrations ranging from 10-3 to 10-7 M has been studied. Both electrochemical (potentiodynamic, electrochemical impedance spectroscopy and electrochemical frequency modulation) and computational studies (quantum chemical calculations and molecular dynamic simulations) have been used in this study. Electrochemical investigations show the effectiveness of the studied pyrimidine derivatives as corrosion inhibitors. The best inhibition efficiency reached 98% for Pyr-9 at 10-3 M. The studied pyrimidine derivatives were of mixed type inhibitor. Equivalent circuit for the studied system was determined. The studied pyrimidine derivatives follow Langumir adsorption isotherm. Computational study confirms the experimental investigation.