Synthesis and Mechanosynthesis of N, N?-bis (2-thyenilethyl)-2,3-butanodiimine with corrosion inhibitor properties

In this work, we report the conventional and mechanochemical synthesis of the a-diimine derivate of 2, 3-butanedione and the primary amine 2-aminoethanethiol designated DD-DC and DD-DC/MS respectively. The products were characterized by 1H and 13C-NMR, FT-IR, MS-EI and elemental analysis. The products were also electrochemically evaluated by potentiodynamic polarization technique in order to measure their corrosion inhibition efficiency on AISI 1018 steel, immersed in a corrosive solution type NACE TM 0177. The results indicate that the compound obtained under mechanosyntesis conditions, DD-DC/MS, presents better inhibitory properties with 53% efficiency at 10 ppm concentration. On the other hand, the compound obtained by conventional synthesis (DD-DC) presented efficiency of 29% at 10 ppm concentration. Also, the DFT results show that a-diimine derivatives possesses corrosion inhibition properties, consisting of the transfer of high-charge density which in the delocalization region (N=C?C=N) is formed by p (C=N) and SH, these moiety play an important role, because their electron lone pairs help to form a protective coating to form an adsorption layer. The results showed that cysteamine compound turns out to be a good corrosion inhibitor for the steel iron surface in an acid medium forming an adsorption film over metallic surface.