In this paper, we investigated the sterically hindered bisphenols used as antioxidant additives to lubricating oils and having bulky α-methylbenzyl radicals in the o-position and disulfide bridges in the o- and p-positions. The influence of the structure of sterically hindered phenols and the presence of various substituents in the benzene ring on their antioxidant activity is considered and the expediency of introducing of α-methylbenzyl radicals into the composition of sterically hindered phenols is proved to increase their antioxidant activity by enhancing the donor activity of the radicals and increasing sterical hindrance, and the expediency of introducing of sulfur atoms to obtain the effect of auto-synergism is shown. The mechanism of oxidation of lubricating oils is shown, as well as the mechanism of inhibiting of the oxidation process by spatially-hindered phenols. The performed synthesis of sterically -hindered bisphenols containing disulfide bridges between benzene rings in o- and p-positions is considered. In addition, in this paper, geometric parameters (lengths of hydroxyl O-H bonds of sterically -hindered bisphenols) were calculated using the quantum-chemical calculations within the framework of the B3LYP/6-31++G(d, p) method. The same methods were used to calculate the distribution of electron density (partial charges according to Mulliken) on the oxygen atoms of the hydroxyl group and carbon atoms directly related to the phenolic group of the studied sterically-hindered bisphenols. On the basis of the work done, an estimated substantiation of the influence of the length of the hydroxyl bond and of the partial charges on oxygen atoms and the carbon atom directly related to it (which directly depend on the structure of the studied spatially-hindered bisphenols) on their antioxidant activity, is given.Forcitation:Tukhvatullin R.F., Kolchina G.Yu., Movsumzade E.M., Mamedova P.Sh., Babaev E.R. Synthesis and research of geometry and electronic density of hindered phenols used as antioxidant additives for lubricating oils. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 84-92
Evaluation of some functionalized imidazoles and 1,2,4-triazoles as antioxidant additives for industrial lubricating oils and correlating the results with the structures of additives using empirical AM1 calculations
