Quantum chemical studies on inhibition activities of 2,3-dihydroxypropyl-sulfanyl derivative on carbon steel in acidic media

• A.K. Oyebamiji¹ and B.B. Adeleke²

¹ Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo State, Nigeria
² Department of Chemistry, University of Ibadan, P.M.B. 5116, Ibadan, Oyo State, Nigeria

Abstract: The inhibiting activity of 3 sets of organic compounds ([2-[(2,3-dihydroxypropyl)sulfanyl]-N-octylacetamide (DSO), 2-[(2,3-dihydroxypropyl)sulfanyl]-N-decylacetamide (DSD) and 2-[(2,3-dihydroxypropyl)sulfanyl]-N-dodecylacetamide (DSDD)) were studied. The studied anti-corrosion compounds i.e. 2,3-dihydroxypropyl-sulfanyl derivatives were calculated using quantum chemical calculation and several descriptors (highest occupied molecular orbital energy (E_HOMO), lowest unoccupied molecular orbital energy (E_LUMO) and chemical reactivity indices (global electrophilicity index (ω), chemical hardness (η), electronegativity (χ), local reactivity index, electron affinity and ionization potential) which described the anti-corrosion properties of the studied compounds were obtained. Fukui Indices for nucleophilic and electrophilic Attacks for inhibitors i.e. [2-[(2,3-dihydroxypropyl)sulfanyl]-N-octylacetamide (DSO), 2-[(2,3-dihydroxypropyl)sulfanyl]-N-decylacetamide (DSD) and 2-[(2,3-dihydroxypropyl)¬sulfanyl]-N-dodecylacetamide (DSDD) were observed and sites for nucleophilic and electrophilic attacks for DSO were C6 (0.047) and O3 (0.170); for DSD, the utmost value for f_k⁺ was found on C6 (0.047), and the highest value for f_k^- was located on C5 with 0.099 while the greatest value for f_k⁺ was situated on C6 with 0.047 and the highest value for f_k^- is found on C3 and C4 with 0.053 each for the DSDD molecule. The molecules used in this study was calculated using quantum chemical calculation and it was achieved using Spartan 14. More so, the QSAR study using multiple linear regression method was executed using Gretl 1.9.8. The selected descriptors among the entire calculated descriptors were used in the development of quantitative structural activity relationship (QSAR) model and the developed model replicated the observed %IE. The correlation coefficient (R2) was calculated to be 0.926, cross validation (CV.R²) was 0.963 and adjusted R² was 0.852. Also, E_LUMO was the predominating parameter in the corrosion inhibition property of the studied compounds.

Keywords: 2,3-dihydroxypropyl-sulfanyl derivatives, corrosion inhibition, molecular descriptors, carbon steel, DFT, QSAR

Int. J. Corros. Scale Inhib., 2018, 7, no. 4, 498-508 PDF (1 044 K)
doi: 10.17675/2305-6894-2018-7-4-2

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