Mannich bases: Chemical structure, chemistry, coordination bonding and application in aqueous phase corrosion protection

Corrosion remains a significant concern due to its detrimental impact on structures and equipment's integrity, safety, and performance. The economic and environmental corrosion costs are substantial, necessitating the development of effective corrosion prevention strategies. Among these strategies, corrosion inhibitors have emerged as a promising approach to mitigate corrosion damage and prolong the lifespan of metals and alloys. Among the various types of corrosion inhibitors, Mannich bases (MBs; β-amino-ketone) have emerged as promising candidates due to their unique chemical properties and high inhibitory effectiveness. The majority of research shows that MBs exhibit more than 90 % efficiency and can be employed as powerful inhibitors for electrolytes with practical applications in industry. Designing and optimizing MBs as corrosion inhibitors requires an understanding of the mechanisms by which they prevent corrosion. The different ways that MBs reduce corrosion are highlighted in this article along with a thorough explanation of how they work. This encompasses the actions of MBs in coordination bonds and during adsorption in aqueous electrolytes. More particular, the effects of different substituents are discussed together with the adsorption and bonding activities of MBs. Through their adsorption at the metal-electrolyte interface using their electron-rich amino (–NH₂) and carbonyl (>C = O) sites, MBs become effective by creating chemical bonds. The final section examines the difficulties and opportunities of using MBs in corrosion protection.