INHIBITING PROPERTIES OF CONJUGATED UNSATURATED KETONES IN THE ACIDIC MEDIUM

Corrosion inhibitors are effective against corrosion in various aggressive environments. The actual scientific task is the search for the relationship between the molecules structure and their inhibiting properties. The authors studied the inhibiting properties of some cross-conjugated and linearly conjugated enynones in the process of protection of carbon steel against corrosion in the 1M chlorohydric acid medium using various methods. The electrochemical study was carried out on the complex of potentiostat and impedancemeter devices with the software developed by the A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the RAS, Moscow. The experiments were conducted in the standard electrochemical cell. The edge of carbon steel cylinder, the side surface of which is isolated from the corrosive environment exposure, was used as the working electrode. The experiments were carried out at ambient temperature. The surface tension was investigated by the Rehbinder method (the method of maximum pressure in the air bubble) using the special laboratory facility. The data of electrochemical impedance spectroscopy of the compounds studied allowed determining the equivalent circuit of the corrosion process and the effectiveness of protective action. The potentiodynamic methods at the medium and large overstresses gave the information about the mechanism of corrosion protection and the effectiveness of corrosion currents reduction. The functional substituents in the benzene ring influence the mechanism of inhibition and the efficiency of the protective action. The experimental substances have mixed and cathode mechanism of the protective action. All studied compounds showed the satisfactory and good inhibiting activity. The method of determining the surface activity of the solutions in the corrosive environment did not identify any strict relationship between the surface activity of inhibitors at the “solution – electrolyte” interface and the ability to inhibit iron corrosion within the acidic medium. However, the authors identified the relationship between the inhibiting effect and the dipole moment of the molecules under the study, which was obtained by the calculation method based on the results of quantum chemical calculations.