Effect of the substituent nature on the efficiency of isoquinolines

The protective effect of seven new isoquinoline derivatives as inhibitors of acid corrosion of low-carbon steel in 1 M hydrochloric acid has been studied.At a temperature of 298 K and a concentration of 0.1 mmol/L, the protective effect of the compounds was found to be 93-98.8%depending on the nature of the substituent.When the temperature increases to 353 K, the efficiency decreases to 80-93%.The compounds studied change the effective activation energy of corrosion, affect the structure of the double electric layer, and block a fraction of the steel surface upon adsorption.The compounds reduce the rates of cathodic and anodic processes.A satisfactory correlation of efficiency with the calculated parameters of molecules obtained within the scope of the density functional theory (DFT) B3LYP/6-311+G(d) has been found.It has been shown that the correlation coefficients of the linear relationships "protective effectcalculated characteristics" decrease with an increase in temperature.