Evaluation of Changes in Bond Parameters in Sulfolane Under the Influence of Electron Donating Substituents

Sulfolane is a promising solvent for electrolytes in lithium-ion batteries, because it possesses high thermal and oxidative stability, high flash point, well dissolves lithium salts. However, sulfolane has a high melting point (27.5 °C) and viscosity (0.01029 Pa • s at 30 °C). High melting point and viscosity due to the tendency of sulfolane to self-association. To reduce the degree of self-association is possible by introducing various substituents into the sulfolane molecule. The aim of the work was to investigate how the introduction of substituents into the sulfolane molecule affects its chemical stability. Chemical resistance was judged by changes in bond orders. Presented work summarizes the results of quantum-chemical calculations of the bond orders in the sulfolane molecule and its substituted analogs, including methyl-, ethyl-, propyl-, vinyl- and allylsulfolanes (Figure 2). Quantum chemical calculations were performed using the Gaussian09 software package. The optimization procedure was performed using the TPSS/cc-pVTZ method. Analysis of wave functions and calculation of bond orders by “fuzzy” method were performed in MultiWfn software package. The objects of study were sulfolane and analogs with electron donor substituents. A total of 21 structures. The nature of the change in bond orders shows the influence of the position of substituents on electron density distribution. It has been established that the substitution of hydrogen atoms for this groups has the greatest influence on the order of the C – S and C – C bonds, reducing it, and the smallest on the S = O bond. This is especially clearly observed when hydrogen atoms attached to carbons connected to sulfur are substituted. These data show the possible paths of reduction reactions. This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7) Russia and was also financially supported by the Russian Science Foundation (project No 17-73-20115). Figure 1