Study Of Synthesis Of Dialkyl Carbonates By Using Basic Ionic Liquids As Catalysts

Ionic liquids(ILs) are salts below100℃composed of organic cations and inorganic or organic anions. Ionic liquids known as "designer solvents" are the perfect substitute of conventional solvents owing to its highly conductivity, wide electrochemical widow, neglectable vapor tension and amenable to diverse solutes, porper viscosity. Ionic liquids have been widely used in many fields such as electrochemistry,organic synthesis, catalyst and separation. Recently, almost of reserchs are focus on acidic Ionic liquid compared with basic ionic liquid. The application of basic ionic liquids localized on preparation of biodiesel、 Knoevenagel condensation、Mannich condensation^Perkin reaction and Markovnikov additional reaction, but few of transesterification is reported.Diaryl Carbonates of higher alcohols are synthesised by transesterification with short-chain dialkyl carbonates from higher alcohols. Diaryl Carbonates which can be used in formulating lubricants is a species of important raw material of organic synthesis with low pour points, excellent lubricating properties, high thermo-oxidative stability, and completely miscible with hydrocarbon oils. Nowdays,most of Diaryl Carbonates were obtained by transesterification of DMC by aliphatic alcohols using Lewis acid and alkali as catalysts. The mixture using solid alkali as catalysts were separated easily, but the process of synthesis and reuse of catalysts were complex, moreover, the catalysts were reacted to H2O and CO2easily. Further more, the yeild of Diaryl Carbonates was low and the reutilization of raw materials were impossible. So, finding some new green catalysts to heightening the yeild and selectivity of Diaryl Carbonates is one of the most urgent technology synthesis Diaryl Carbonates.In the thesis, we investigated the synthesis of three basic ionic liquids with different alkalescence. Then catalyze the transesterification of DMC and aliphatic alcohols to obtained Diaryl Carbonates. The catalysts were low pollution and high efficiency.The major works are as follows:(1)Three basic ionic liquids [Bmim]OH、[Bmim]OAc and [Bmim]Im were synthesized, their structure were unambiguously confirmed by FT-IR spectrometry.(2)Diaryl Carbonates were synthesis by transesterification of DMC by aliphatic alcohols using these three basic ionic liquids.(3)The structure of Dibutyl Carbonate, Di-2-methylproryl Carbonate, Dipentyl Carbonate, Di-3-methylbutyl Carbonate, Dihexyl Carbonate, Dioctyl Carbonate, Didodecyl Carbonate were charactered by FT-IR spectrometry. The structure of Di-2-ethylhexyl Carbonate was confirmed by1HNMR spectrometry.(4)Physical properties of Di-2-ethylhexyl Carbonate were tested. Kinematic viscosity (40℃) of4.49mm2/s, acid number of0mgKOH/g, pour point below-57℃, flash point of168℃, density of0.8958g/cm3, sapoonification number of189mgKOH/g, which indicate that the Diaryl Carbonates synthesis by transesterification using basic ionic liquid as catalyst have potential application in the fild of synthetical lubricanting oils.