## 3 Results and Discussion
Table 1 also shows the refractive indices of the diesel fraction after extraction of SCC with extraction systems. The refractive index of the desulfurized samples of diesel fraction is reduced, which indirectly indicates a decrease in the content of aromatic hydrocarbons in the desulfurized sample. To confirm this assumption, the \({}^{13}\)C NMR and PMR spectra were registered for the initial and desulfurized diesel fraction (Figures 2 and 3). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Compounds, Molecular Ratio**} & \multicolumn{8}{c}{**Chemical Shifts, ppm**} \\ \cline{2-9}  & \multicolumn{3}{c}{**DMF**} & \multicolumn{3}{c}{**Aliphatic Protons and Protons in Aromatic Rings**} \\ \cline{2-9}  & **CH3 ** & **CH3 ** & **CH2 ** & **CH2 ** & **CH3 ** & **CH3 ** & **CH3 ** & **Ring** \\ \hline \multirow{2}{*}{Dibenzothiophene (DBT)} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} 8.14–7.98 & \multirow{2}{*}{} \\  & & & & & & & 7.90–7.60 \\ \cline{1-1} \cline{5-5}  & & & & & & & 7.50–7.20 \\ \hline \multirow{2}{*}{DBT-DMF} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} & \multirow{2}{*}{} 8.40–8.14 & \multirow{2}{*}{} \\  & & & & & & & 8.04–7.80 \\ \cline{1-1} \cline{5-5}  & & & & & & 7.55–7.80 \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 2: \({}^{13}\)C NMR spectra of the diesel fraction boiling at 200–350 \({}^{\circ}\)C.  
In the \({}^{13}\)C NMR spectrum a signal of carbon atoms corresponding to saturated structures in the range 0-70 ppm with an integrated intensity I\({}_{\rm sat}\) = 19.51 and a signal of carbon atoms corresponding to aromatic structures with an integrated intensity I\({}_{\rm a}\) = 1.81 are observed. The aromaticity factor is  
\[\rm{F_{a}=I_{a}/(I_{a}+I_{sat})=0.08489}. \tag{1}\]  
In the PMR spectrum the signals of protons of aromatic nuclei (region 6.5-8.5 ppm), protons of CH, CH\({}_{2}\), and CH\({}_{3}\) groups located in the \(\alpha\)-positions of aromatic nuclei (1.8-4 ppm) are observed. Protons of hydrocarbon radicals more distant from the aromatic nucleus are partially superimposed on signals of protons of aliphatic hydrocarbons (0.8-1.8 ppm). In the \({}^{13}\)C NMR spectrum the signal of carbon atoms corresponding to saturated structures in the range 0-70 ppm with an integrated intensity I\({}_{\rm sat}\) = 14.62 and a signal of carbon atoms corresponding to aromatic structures with an integrated intensity I\({}_{\rm a}\) = 0.87 are observed. The aromaticity factor is  
\[\rm{F_{a}=I_{a}/(I_{a}+I_{sat})=0.05616}. \tag{2}\]  
In the PMR spectrum the signals of protons of aromatic nuclei in the range 6.5-8.5 ppm and protons of CH, CH\({}_{2}\), CH\({}_{3}\) groups located in the \(\alpha\)-positions of aromatic nuclei (1.8-4 ppm) are observed. Protons of hydrocarbon radicals more distant from the aromatic nucleus are partially superimposed on signals of protons of aliphatic hydrocarbons (0.8-1.8 ppm). All these data indicate a decrease in the content of aromatic hydrocarbons in the diesel fraction approximately by 33%. Extraction of SCC by DMF-CdCl\({}_{2}\), CoCl\({}_{2}\), CuCl\({}_{2}\), MnCl\({}_{2}\), CrCl\({}_{3}\), Co(TFA)\({}_{2}\), Mn(TFA)\({}_{2}\), Cu(TFA)\({}_{2}\) Extraction Systems  
Table 3 shows the results of extraction of the sulfur-containing fraction boiling in the temperature range of 200-350 \({}^{\circ}\)C with solutions of chlorides and metal trifluoroacetates in DMSO. Figure 3: \({}^{13}\)C NMR spectra of the desulfurized diesel fraction 200–350 \({}^{\circ}\)C.  
It is difficult to evaluate the interaction of metal salts with DMSO, since it is both a soft and hard base. DMSO is an ambidentate ligand, i.e., it contains a lone electron pair both with an oxygen atom and with a sulfur atom, but only one atom of either oxygen or sulfur can participate in the coordination to the metal ion.