Synthesis and Study of Diphenyl and 4-(Phenyldiazenyl)phenyl Based Tetrasubstituted Imidazoles in the Presence of Ionic Liquid Catalysts

In this study, 4,5-diphenyl-1-(4-(phenyldiazenyl)phenyl)-1H-imidazole derivatives were synthesized from benzyl, ammonium acetate, p-aminoazobenzene and aromatic aldehydes, in the presence of ionic type, N-methylpyrrolidone perchlorate and 1-butyl-3-methylimidazolium hydrogen sulfate catalysts.Ethanol was used as a solvent.In the synthesis, optimization was carried out depending on the amount of 1,4-dimethylpiperazine dihydrogen sulfate catalyst and temperature.It is determined that, the optimal amount of the catalyst is 10% (mol) and the optimal temperature is 78 o C. Other ionic liquid catalysts for comparison were tested under the same conditions as the 1,4dimethylpiperazine dihydrogen sulfate catalyst.The theoretical mechanism of the 1,4-dimethylpiperazine dihydrogen sulfate catalyst's impact on the reaction was investigated.It was found that the catalyst activates the carbonyl group of aldehyde and diketone to form imine intermediate compound.The reaction mechanism of other catalysts is the same as 1,4-dimethylpiperazine dihydrogen sulfate catalyst.The conditions' results were compared and the 1,4-dimethylpiperazine dihydrogen sulfate catalyst was determined to be more effective due to its high yield (67.0-80.2%)and short reaction time (25-38 min.).The image of visible surface of the synthesized substances was obtained and the homogeneity of the surface was determined using "LUMOS FT-IR Microscope" spectrometer. 1 H, 13 C NMR, and IR spectroscopy were used to confirm the structures of the obtained compounds.Two-dimensional HSQC NMR experiment was used to investigate H-C correlations and hydrogen-free carbon atoms in the molecule.Chromophoric groups in the compounds were studied by UV spectrophotometer.It was determined that hypsachromic and bathachromic shifts are observed in π→π* and n→π* transitions depending on the joining radicals, auxomes affect the intensity of chromophore groups Keywords: imidazole, benzyl, p-aminoazobenzene, 1,4-dimethylpiperazine dihydrogen sulfate, N-methylpyrrolidone perchlorate, 1-butyl-3-methylimidazolium hydrogen sulfate