Adsorption properties and inhibition of carbon steel corrosion in hydrochloric acid solution by Ethyl 3-hydroxy-8-methyl-4-oxo-6-phenyl-2-(p-toly)-4,6-dihydropyrimido[2,1-b] [1,3]thiazine-7-carboxylate

Ethyl 3-hydroxy-8-methyl-4-oxo-6-phenyl-2-(p-toly)-4,6-dihydropyrimido[2,1-b] [1,3]thiazine-7-carboxylate. (pt) was examined as a corrosion inhibitor for carbon steel in 1.0 m hcl by using electrochemical impedance spectroscopy (eis) and potentiodynamic polarization (pdp). results show that pt is a good inhibitor and its inhibition efficiency reaches 95 % at 10-3 m. the percentage inhibition efficiency (η) was found to increase with increase of the inhibitor concentration due to the adsorption of the inhibitor molecules on the metal surface. tafel polarisation study revealed that (pt) acts as a mixed type inhibitor. in addition it was established the adsorption follows langmuir adsorption isotherm. moreover,the thermodynamic activation parameters for the corrosion reaction were calculated and discussed in relation to the stability of the protective inhibitor layer. quantum chemical parameters are calculated using the density functional theory method (dft). correlation between theoretical and experimental results is discussed.