Synthesis Of Gemini Ionic Liquid And It's Application In Cross-coupling Reaction

An intermediate,1-cyanoethyl imidazole,was synthesized with imidazole and acrylonitrile as raw materials,and the optimum reaction conditions were determined as follows:molar rate of imidazole and acrylonitrile 1.00:1.35,reaction temperature 50?,reaction time 8 h,methanol as solvent.The final yield and the purity reached up to 92.8%and98.5%,respectively.The optimum synthesis conditions for symmetrical gemini ionic liquid1,4-Bis?1-cyanoethylimidazolium-1-yl?butylene brominates?[C₄?NEim?₂][Br]₂?were that molar rate of cyanoethyl imidazole and 1,4-dibromobutane 3.0:1.0,reaction temperature80?,reaction time 2 h,benzyl alcohol as solvent.The yield was 96.2%and the purity was99.0%.Furemore,another intermediate,1-?1-methylpyrrolidine?-4-bromine butylene brominate?[BrC₄Pyr][Br]?was prepared and its preparation conditions can be described as follows:the molar rate of N-methylpyrrolidine and 1,4-dibromobutane 1.0:7.0,reaction temperature 30?,reaction time 4 h,solvent-free,N-methylpyrrolidine added successively dropwise to the solution in 2³ h.The control experiment resulted in 87.5%yield and 99.7%purity.Then,the optimum synthesis conditions of asymmetrical gemini ionic liquid1-?1-methylpyrrolidine?-4-?1-cyanoethylimidazolium-1-yl?butylenebrominate[PyrC₄?NEim?][Br]₂ were investigated and can be described as follows:molar rate of[BrC₄Pyr][Br]and cyanoethylimidazole 1.0:1.1,reaction temperature 70?,reaction time 10h,isopropanol as solvent.The final yield of[PyrC₄?NEim?][Br]₂ was 72.8%and the purity was 99.4%.Moreover,the structures of all those ionic liquids were characterized by IR,¹H NMR and all the data of characterizations were in accordance with the expected structures.The excess molar volume?V^E?of the[PyrC₄?NEim?][Br]₂+H₂O binary mixture was calculated using the experimental values such as densities???that were measured over the whole compositions range at temperature range of 293.15K³23.15K and atmospheric pressure.The excess molar volume was positive value and presented a slight positive deviation compared the ideal solution while the mole fraction???of[PyrC₄?NEim?][Br]₂ less than 0.4.Besides,the excess molar volume presented a maxmium positive deviation at??0.3,which was contributions from the a strong hydrogen bonding in the binary mixture.The excess molar volume was negative value and presented a negative deviation while the?>0.4.The excess molar volume presented a minmium deviation at??0.55 and it indicated that there was a strong ion-dipole interaction and packing efficiency between the ionic liquid and water molecules.The thermal decomposition kinetics of[C₄?NEim?₂][Br]₂ was studied using non-isothermal thermogravimetric analysis?TGA?under the atmosphere of highly pure nitrogen.The heating curves at different rates were correlated with ASTM,Ozawa-Flynn-Wall and Friedman methods,and the results of the three methods were same basically.The activation energy E and logarithmic pre-exponential factor lgA were obtained.The mechanism function of the thermal decomposition process was also obtained,which can be defined as:f???=?1-??^1.3767,where?was the conversion of mass and 1.3767 was reaction order.The ionic liquid[C₄?NEim?₂][Br]₂ that has been synthetized previous can cleated with palladium chloride to form a catalyst applied in bromobenzene and phenylboronic acid Suzuki cross-coupling reaction.Besides,it can catalyze that Suzuki crossing-coupling reactions between phenylboronic acid and aromatic hydrocarbons,such as iodobenzene,p-bromotoluene.The results indicated that 1-bromo-4-nitrobenzene can react with phenylboronic acid in the yield of 85%in the presence of sodium carbonate,5 mol‰catalyst and dimethylformamide as solvent.After recycling 4 times,the catalyst still has activity and the yield of bipheny was still up to 52%.