The inhibition ability of ethyl 6-amino-5-cyano-2-methyl-4-phenyl-4H-pyran-3-carboxylate (Pr3) on low low carbon steel (LCS) in 1.0 M HCl solution was studied by electrochemical techniques. Pr3 inhibited low low carbon steel corrosion in 1.0 M HCl solution significantly and the inhibition efficiency increased with Pr3 concentration. Polarization measurements indicated that, the studied inhibitor acts as mixed-type inhibitor. Phenomenon of physical and chemical adsorption is proposed for the inhibition and the process followed the Langmuir adsorption isotherm and kinetic / thermodynamic model of El-Awady et al. Correlations between the quantum chemical parameters (EHOMO, ELUMO, the energy gap, global hardness, global softness, Mulliken charges were calculated and Fukui index) and experimentally determined inhibition efficiency have been carried out and discussed.
