Concise CuI-Catalyzed Azide–Alkyne 1,3-Dipolar Cycloaddition Reaction Ligation Remarkably Enhances the Corrosion Inhibitive Potency of Natural Amino Acids for Mild Steel in HCl

Abstract

Despite natural amino acids having been proposed as the green surrogate of currently used corrosion inhibitors that are generally toxic to both nature and human body during the everyday industrial processing of metallic equipments, their structural simplicity yet lowers the inhibitive potency, thereby hampering their further industrialization. We disclose here that a concise chemical ligation (CuI-catalyzed azide–alkyne 1,3-dipolar cycloaddition reaction [Cue-AAC]) between two l-amino acids that are weak or noncorrosion inhibitors may result in their largely improved protective effect for mild steel in HCl. A series of 1,4-disubstituted 1,2,3-triazolyl bis-amino acid derivatives constituted by l-serine, l-threonine, l-phenylalanine, and l-tyrosine were efficiently synthesized via Cue-AAC and deprotection reactions in high yields. Subsequently performed electrochemical impedance spectroscopy (EIS) evidenced that the inhibitive effect of these compounds for mild steel in 1 M HCl is markedly better than that...