| Deep eutectic solvents(DESs)refer to the eutectic substances composed of two or three cheap and green components in combination with each other through hydrogen bonds.DESs with high purity can be obtained by one-step method without using other organic solvents.Therefore,DESs are considered as non-toxin,renewable,biodegradable,and environmentally friendly green solvents,catalysts,and extractants.In this thesis,a series of new acidic DESs and three-component metal deep eutectic solvents(MDESs)were designed and synthesized,and the physicochemical properties of some DESs were studied.Then the catalytic properties of acidic DESs for Biginelli reaction and Pechmann reaction were investigated.The extraction properties of MDESs for dibenzothiophene were also investigated.Firstly,different acidic DESs and three-component MDESs were designed and synthesized.Choline chloride(ChCl),tetrabutyl ammonium chloride(TBAC),and other quaternary ammonium salts were chosen as hydrogen bond acceptors(HBAs);p-toluene sulfonic acid(PTSA),trichloroacetic acid(TCA),monochloroacetic acid(MCA),and propionic acid(PA)were chosen as hydrogen bond donors(HBDs).The physicochemical properties of acidic DESs(ChCl/2PTSA,ChCl/2TCA,ChCl/2MCA,and ChCl/2PA)and three-component MDESs(TBAC/PEG/FeCl3,TBAC/PEG/ZnCl2,TBAC/PEG/NiCl2,and TBAC/PEG/CuCl2),including density,electrical conductivity,dynamic viscosity,and refractive index were determined.The results showed that the density,viscosity,and refractive index decreased with the increase of temperature,whereas the electrical conductivity increased with the increase of temperature.The VFT equation could be used for fitting the electrical conductivity and dynamic viscosity to temperature very well.However,The relationship between conductivity,dynamic viscosity,and temperature did not well accord with Arrhenius equation.The acidities of acidic DESs were characterized by calculating the Hammett acid function H0,and the results obtained indicated that acidic intensity of the acidic DESs in the following order:ChCl/2PTSA>ChCl/2TCA>ChCl/2MCA>ChCl/2PA.Then,the catalytic properties of acidic DESs for Biginelli reaction and Pechmann reaction were studied.The DESs with high catalytic activity was screened out and the reaction conditions were optimized.Meanwhile,the scope of the substrates was investigated and the reaction mechanism was studied.The catalytic activities of DESs increased with the increase of acidic intensity of the hydrogen bond donors.Among the acidic DESs,ChCl/2PTSA exhibited the highest catalytic activity in Biginelli reaction.The efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones was achieved in ChCl/2PTSA without other solvent.ChCl/2PTSA was suitable for various substrates,affording the corresponding products in 42%-92%yields.Furthermore,ChCl/2PTSA could be recycle used for six times without significant loss of its catalytic activity,exhibiting excellent stability.Pechmann condensation reaction with ChCl/PTSA as both solvent and catalyst was studied.The results obtained showed that the best reaction condition was as follows:phenol,acetoacetate,and ChCl/PTSA with 1:1:0.1 of molar ratio at 80℃.The reactivities of diphenol and trihydric phenol were higher than that of monophenol.ChCl/PTSA could be recycle used for four times without significant loss of its catalytic activity.In the last part,the extraction of dibenzothiophene from simulated oil by MDESs was investigated.Over 88%of extraction efficiency was achieved by MDESs(TBAC/PEG/FeCl3 and TBAC/PEG/ZnCl2)for one time extraction.After second times extractions,the extraction efficiency could reach up to 100%,and thereby deep desulfurization was realized.The extraction efficiency remained unchanged after recycling five times of MDESs.Infrared and ultraviolet spectra showed that there was strong interaction between MDESs and DBT.The main reasons for the high extraction efficiency were the π-complexation between metal ions and aromatic rings and the hydrogen bonds between MDESs and DBT. |
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