ISSN 2305-6894

New copper corrosion inhibitors in chloride environments based on benzo-[1,2,4]-triazolo-[1,2]-triazinones

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1 Voronezh State University, 1 Universitetskaya pl., 394018 Voronezh, Russian Federation
2 Voronezh State Agricultural University named after Emperor Peter I, 1 ul. Michurina, 394087 Voronezh, Russian Federation
3 National Institute of Technology Kurukshetra, 136119 Kurukshetra, India

Abstract: New compounds based on benzo[1,2,4]-triazolo[1,2,4]-triazinones have been synthesized in yields above 78%. The structures were confirmed by IR and 1H NMR spectroscopy. For structures that can exist in tautomeric forms, the calculation of the total energy of the molecule shows the predominant realization of the keto form. A set of field tests, electrochemical, and quantum-chemical methods was used to evaluate the inhibition of copper corrosion in chloride environments. The lack of an inhibitory effect of benzo[e][1,2,4]triazolo[5,1-c][1,2,4]triazin-6-ol can be explained by excessive acidity due to the strong electron-acceptor properties of the triazolotriazine cycle. There was an increase in the degree of protection of up to 68% in 3% HCl solution for the modified 8,8-dimethyl-8,9-dihydrobenzo[e][1,2,4]triazolo[5,1-c][1,2,4]triazin-6(7H)-ones at a concentration of 1.00 mM in the series of substituents: “ethylsulfinyl–methyl–methylmercapto” with a maximum degree of protection observed for the structure without a substituent. In the neutral chloride solution, the highest degree of protection (93%) was obtained for 8,8-dimethyl-8,9-dihydrobenzo[e][1,2,4]triazolo[5,1-c][1,2,4]triazin-6(7H)-one. The difference in the results between the experiments when immersed in a neutral solution and in the salt fog chamber is explained by the possible mechanical washing away of the inhibitor from the metal surface during surface irrigation, which is typical of a salt fog chamber. It was suggested that the inhibitory effect is associated with the formation of chelate complexes due to the hydroxybenzotriazine fragments in the studied compounds.

Keywords: copper, corrosion inhibitors, chlorides, triazole derivatives, triazolotriazines

Int. J. Corros. Scale Inhib., , 10, no. 1, 228-244 PDF (790 K)
doi: 10.17675/2305-6894-2021-10-1-13

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