DEPENDENCE OF THE ANTIOXIDANT PROPERTIES OF SOME SPATIALLY SUBSTITUTED PHENOLS ON THE CALCULATED PARAMETERS OF THE STRUCTURE OF ANTIOXIDANT MOLECULES

The choice and optimization of antioxidants and their amount depends on many factors, including the composition of the fuel, the technical characteristics of the fuel and the storage conditions. During the operation of engines and mechanisms, they come into contact with air, often at elevated temperatures. Under these conditions and under the catalytic action of metals, lubricating oils and fuels are oxidized. Traditionally, the search for compounds with high antioxidant activity is relevant. In this paper, the possibilities of software packages for quantum-chemical calculations of spatially substituted phenols (SSP) were studied. A structural series of SSPs were synthesized, their antioxidant activity was studied, and then quantum chemical calculations of the structures were carried out in order to identify the dependence of their activity on certain parameters. At the stage of literature analysis, only a few calculated parameters were identified, on which the antiradical activity of the compound depends. However, when studying the dependencies, it was found that the activity of phenols as antioxidants depends on a slightly larger number of parameters, such as the ionization potential, LUMO energy, enthalpy, total energy of the molecule and the C-O-H valence angle. The structure of phenols prevents their solubility in oil, which makes it difficult to test compounds such as antioxidants. It was decided to first dissolve the compound in a hydrocarbon solvent, and then add the concentrate to the oil. The antioxidant activity of the compounds was measured by the acid number of the oxidized oil containing the studied compound. The results of this work allowed us to determine the dependence of antioxidant activity on various parameters of the phenol structure. In the future, it is planned to expand the above-mentioned series, similar to the structure, as well as to conduct tests for antioxidant activity in oils and fuels of various brands. Antioxidants or inhibitors of oxidation processes play a major role in various spheres of human life: oil refining, food and cosmetics industry, drug manufacturing and many others.

Automated summary

The selection and optimization of antioxidants depend on various factors such as fuel composition, technical characteristics, and storage conditions. Studies have shown that the activity of phenols as antioxidants is related to parameters like ionization potential, LUMO energy, enthalpy, total energy, and the C-O-H valence angle.