A theoretical study of some barbiturates as corrosion inhibitors for mild steel

P. Udhayakala, T. V. Rajendira

Abstract

The Density functional theory (DFT) study was performed on three barbiturates namely, 5-(3-phenylallylidene) pyrimidine-2,4,6-trione (PPT), 5-(2-hydroxybenzylidene) pyrimidine-2,4,6-trione (HPT) and 5-benzlidene pyrimidine-2,4,6-trione (BPT) at the B3LYP/6-31G(d,p) basis set level to investigate the relationship between their molecular and electronic structure and inhibition efficiency. The quantum chemical properties such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), energy gap (ΔE), dipole moment (μ), hardness (η), softness (S), the absolute electronegativity (χ), the fractions of electrons transferred (ΔN) and the electrophilicity index (ω) were calculated. The local reactivity is analyzed through the Fukui function and condensed softness indices in order to compare the possible sites for nucleophilic and electrophilic attacks. The obtained correlations and theoretical conclusions agree well with the experimental data reported.