THEORETICAL STUDY ON CORROSION INHIBITION PROPERTIES OF 2-ISOPROPYL-5-METHYLPHENOL

Abstract

Corrosion inhibitors of 2-isopropyl-5-methylphenol and its derivatives has been elucidated by means of density functional theory at B3LYP/6-31G(d) level of theory. Effect of electron donating and withdrawing groups such as NH_2, SH, CHCH₂, CH₃, OH, CHO, COOH, F and NO₂ on the corrosion inhibitor of 2-isopropyl-5-methylphenol derivatives also have been studied. The quantum chemical parameters such as the frontier orbital energies (E_HOMO), ionization potential (I), electron affinity (A) and electronegativity (χ) are closely related to the corrosion inhibition efficiency (IE %) of 2-isopropyl-5-methylphenol derivatives. The presence of electron donating groups increase IE % values meanwhile electron with drawing groups reduce IE % values. The enhancement of IE % follows NO₂ < CHO < COOH < SH < F < CH₃ < CHCH₂ < OH < NH₂. Electron donating NH₂ group gives 96.38 % of IE %, pure 2-isopropyl-5-methylphenol IE % = 82.70 %. In contrast, electron withdrawing NO₂ group gives IE % only 68.66 %. This theoretical study would have a significantly contribution for accelerating corrosion inhibitor experimental to gain optimum results.