Synthesis of asymmetric secondary amines and their anticorrosive properties

Abstract

Given the need to protect metal structures and equipment from the destructive effects of aggressive media, the search for new corrosion inhibitors constitutes a relevant and important area of development in the modern chemical industry. Corrosion significantly reduces the durability and reliability of metal products, which increases maintenance costs and the risk of failures, while also negatively affecting environmental safety. Therefore, it is relevant to synthesize compounds with potential anticorrosive properties. In order to expand the range of such substances, secondary amines were obtained by condensing cyclic aldehydes and primary amines, as well as by reducing condensation products. The structure of the synthesized compounds was confirmed via infrared spectroscopy and nuclear magnetic resonance spectroscopy (¹H and ¹³C). The infrared spectra of the synthesized azomethines reveal imine-characteristic C=N stretch absorption bands at 1650–1570 cm^-1. In the ¹H nuclear magnetic resonance spectra, the protons of the azomethine group resonate at 8.15–8.25 ppm; the ¹³C nuclear magnetic resonance spectra reveal the carbon atoms of the imine group at δ_c of 158.00–161.00 ppm. The ability of the obtained compounds to inhibit corrosion in a model medium was tested using a gravimetric method. Their protective properties were evaluated using an electrochemical method. The properties of the obtained compounds are consistent with data presented in bibliographic sources. The best result was obtained for the secondary amine 2-((2-((4-chlorobenzyl) amino)ethyl)amino)ethan-1-ol, which exhibits anticorrosive properties in a hydrogen sulfide medium and provides a 97% protection level.