Quantum Chemical Studies on the Inhibiting Effect of Bipyrazoles on Steel Corrosion in HCl

K Laarej,S Kertit,M Bouachrine,B Hammouti,S Radi

doi:10.1155/2010/273206

Abstract

Correlation of the efficacy of some bipyrazoles,N,N-bis(3,5-dimethyl-pyrazol-1-ylmethyl)-cyclohexylamine (Bip 1),N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-ethanolamine (Bip 2),N,N-bis(3,5-dimethylpyrazol-1-ylmethyl) allylamine (Bip 3) andN,N-bis(3-carboethoxy-5-methylpyrazol-1-ylmethyl)-cyclohexylamine (Bip 4), against the corrosion of mild steel in HCl is discussed using density functional approach B3LYP/6-31G(d) calculations. The bipyrazole inhibitors exhibited the highest inhibition efficiency. The quantum chemical parameters calculated are, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the gap energy (ΔE), the dipole moment (μ), the softness (σ) and the total energy (TE).

Highlights

The protection of metals against corrosion may be achieved by adding inhibitors in small concentrations to its environment
The restrictions caused by the high computational effort of the calculations mean that quantum chemical methods will not in the foreseeable future be able to replace experimental corrosion studies or computationally less expensive methods for the processes related to corrosion inhibition
According to the frontier molecular orbital theory, the formation of a transition state is due to an interaction between the frontier orbitals (HOMO and lowest unoccupied molecular orbital (LUMO)) of reactants[16]

Summary

Introduction

The protection of metals against corrosion may be achieved by adding inhibitors in small concentrations to its environment. Numerous studies were performed on the pyrazolic molecules which exhibited good inhibiting effect on corrosion of metallic materials[1,2,3,4,5,6,7,8]. The molecular structure, including the electronic parameters, can be obtained by means of the theoretical calculations by using the computational methodologies of quantum-chemistry.

Objectives

Results

Conclusion