The protective effect of 3-mercaptoalkyl derivatives of 5-amino-1H-1,2,4-triazole against corrosion of α-brass in a chloride media was studied using polarization curves, electrochemical impedance spectroscopy, and full-scale corrosion testing. The brass electrode remains passive up to the activation potential, which is much higher than in solutions without organic additives, and it increases with the concentration of the inhibitor. The protection degree of all the studied inhibitors reaches its maximum of over 99% in solutions with the concentration of the inhibitor Cinh ≥ 0.10 mM. The protective effect increases with the length of the alkyl chain. All the studied derivatives are effective against atmospheric corrosion of α-brass. A protective film is formed on the brass surface, and it most probably includes oxides as well as complex compounds of zinc and copper with the molecules of the inhibitors. The impedance spectroscopy demonstrated that the presence of the inhibitor results in a decrease in the double-layer capacitance and an increase in the polarization resistance, which proves that the protective film actually forms on the brass surface. The quantum chemical analysis of the optimized molecular structures demonstrates that all the studied inhibitors should have a similar protective effect, which agrees with the experimental results.
In this study we investigated the cascade heterocyclisation reactions of 1,2-diamino-4H-phenylimidazole with dimethylaminomethylidene (ethoxymethylidene) by the derivatives of acetoacetic ester, acetyl acetone, and aryl(hetaryl)butane-1,3diones. As a result of the studied processes 7-amino-2-R-3-R1-5phenylimidazo[1,5-b]pyridazines were obtained, whose structures were proved by means of 1 H NMR, 13 C NMR, XRS, and NOESY spectroscopy. Heterocyclisation conditions were opti-mised to obtain target products with high yields. A probable mechanism for regioselective processes was suggested. It was found that three-component processes with initial diamine, 1,3-dicarbonyl compounds and triethyl orthoformate or dimethylformamide dimethylacetal result in similar products. The yield of these reactions was slightly reduced in comparison to the two-component processes.
It is possible to obtain products with a wide range of useful properties as a result of the modification of epoxidized vegetable oils and their derivatives. The aim of this work was to develop methods for the synthesis of new products by the reaction of epoxidized sunflower oil fatty acid methyl esters (FAME) with dihydric alcohols: ethylene glycol, butanediol-1,4, diethylene glycol, as well as in the study of their structure and properties. Dependences of the structure of the obtained products on the conditions of the process and the type of the modifier have been established. It was shown that carrying out the modification at a higher temperature (100 ° C) leads to the formation of crosslinked products as a result of intermolecular dehydration with the participation of both hydroxyl groups of the diol molecule. In addition to the opening of the oxirane ring, the transesterification process with the participation of the ester fragment is realized. Certain characteristics of the obtained products, including the acid number, saponification number, were determined, and the emulsifying effect was evaluated. In addition, the solidification temperature and pour point were determined for the products obtained. It was found that the products of modification of epoxy derivatives of FAME of sunflower oil obtained at 50 ° C have the greatest emulsifying effect.
Methyl (2Z)-[2[(diaminomethylene)amino]-4-oxothiazol-5(4H)-ylidene]acetate was obtained by the reaction of N-amidinothiourea and dimethyl acetylenedicarboxylate (DMAD) under various conditions: methanol, ethanol, acetonitrile, ethyl acetate, dioxane, acetic acid, ethanol/TsOH. The structure of the product has been proven by X-ray diffraction analysis. A series of new N-(5-R-1,3,5-triazinan-2-ylidene)-N-1,3-thiazol-2-amines was obtained as a result of the multicomponent condensation of methyl (2Z)-[2[(diaminomethylene)amino]-4oxothiazol-5(4H)-ylidene]acetate with alkylamines and formaldehyde.
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