Non-soluble chalcones and their potential application as corrosion coatings on carbon steel exposed to 1 M HCl solutions

Abstract

Chalcones are secondary metabolites of great interest in chemistry due to their broad biological activities. In recent years, the versatility of this class of molecules has been demonstrated, especially in several synthetic analogs, which have shown behavior as corrosion inhibitors. In this article, a series of chalcone analogs were synthesized using the Claisen-Schmidt methodology in both conventional and microwave-assisted irradiation methodologies. The obtained compounds are non-soluble, which widens the window of chalcones with the possibility of being used as anticorrosive. These were analyzed by electrochemical impedance spectroscopy, potentiodynamic polarization, weight loss measurements and scanning electron microscopy. The results suggest that the chalcone compounds such as the trans-4-(N,N-diphenylamino)chalcone (CH11), (E)-1-phenyl-3-(thiophen-2-yl)prop-2-en-1-one (CH15) and (E)-1-phenyl-3-(thiophen-3-yl)prop-2-en-1-one (CH16) have anticorrosive activity for carbon steel in HCl solutions. The electrochemical techniques showed that increasing the mass of the three chalcone on carbon steel increases the efficiency of the inhibition. A mass amount of 1.4 mg of CH15 or CH16 was shown to have the maximum inhibition from corrosion, but for CH11 the maximum inhibition was 3.0 mg on carbon steel. The percentage inhibition that reached these three compounds was about 95 % at 20 °C. Theoretical calculations by Density Functional Theory (DFT) were performed to explain the measured corrosion decrease assisted by compounds CH11, CH15, and CH16.