Effect of the substituent nature on the efficiency of isoquinolines

• A.G. Berezhnaya, A.D. Zagrebaev, V.V. Chernyavina, I.I. Krotkii and V.V. Chernyavskaya

Southern Federal University, ul. Zorge 7, 344090 Rostov-on-Don, Russian Federation

Abstract: 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 effect – calculated characteristics” decrease with an increase in temperature.

Keywords: inhibitor, acid corrosion, isoquinoline derivatives, steel

Int. J. Corros. Scale Inhib., 2024, 13, no. 2, 962-974
doi: 10.17675/2305-6894-2024-13-2-17

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