The New Material Of Environmentally Friendly-Synthesis And Applications Of Room Temperature IonicLiquids

In recent times, the use of room temperature ionic liquids as green solvents foruse in organic synthetic processes has gained considerable importance due to itsnegligible vapour pressure, solvating ability and easy recyclibility. Many recationshave been reported recently using ionic liquids as a reaction medium and as rateenchancens.In this paper, a series of RTILs were synthesized by a one-step or two-stepmethod,which was identfied by FT-IR, ¹H-NMR spectroscopy.These RTILs areimidazolium composition ionic liquids, like the four fluoroborate and its sixhexafluorophosphoric acid salt series ionic liquids, the imidazolyl amino acid seriesionic liquids and the lactic acid ionic liquids.This paper is dealing with detailed investigations on the hydroesterification ofstyrene catalyzed by palladium compounds in room temperature ionic liquids. Wehave also studied the asymmetric hydroesterification of styrene using chiralphosphines and palladium complexes.1.Styrene was converted into esters of 2-phenyl propionic acid in the presenceof a PdCl₂-CuCl₂-PPh₃ catalyst system and in room temperature ionic liquids. Typicalreaction conditions are: temperature, 80℃; Pco=4.0～6.0Mpa; reaction time: 24h.The experimental results showed that PdCl₂-CuCl₂-PPh₃ was the best catalyst systemand the best solvent was [BMIM]BF₄.Very good regioselectivity and a high yieldwere obtained when styrene was used as a substrate.2.PdCl₂-CuCl₂-Chiral phosphine catalyst systems have good enantioselectivitiesand regioselectivities to hydroesterification of styene in room temperature ionicliquids. High optical purity and good chemical yields have been obtained by usingthe ligand DDPPI for PdCl₂-CuCl₂ catalyzed reaction. The effects of P/Pd ratio, thereaction pressure, and solvent have also been investigated with this catalyst system. 3.The final products could be easily separated from the reaction system bysimple extraction with anhydrous ether, which solved the problem in the traditional.homogeneous phase catalyst system the catalyst and the product were not easy toseparate. The ionic liquids were reused several times, and found decrease in theconversion and regioselectivity of styrene with the number of times increase.In addition, due to the characteristics of gas adsorption, using the roomtemperature ionic liquid as the absorbent to SO₂ absorbs. Under the experimentcondition, each milliliter of ionic liquids absorbed about 50 mL SO₂, volume of ionicliquids show no obvious change.