Synthesis And Application Of Functional Ionic Liquids

Ionic liquid is a green organic material with the advantages of low volatility,non-flammability,recyclability,good thermal stability,and adjustable physical and chemical properties.It has been successfully used in organic synthesis,biocatalysis,separation and extraction,electrochemistry,etc.field.In the concept,Ionic liquids are similar in composition to"salts",but their melting points are usually lower than room temperature.Therefore,ionic liquids are also called"room-temperature molten salts".Organic salts with melting points below 100?are now commonly referred to as room-temperature ions liquid.The primary goal of this paper is green chemistry.Ionic liquids and water as solvents or catalysts are applied to Baylis-Hillman reactions.The Baylis-Hillman reaction is a very classic C-C bond formation reaction in the name reaction.Under the action of tertiary amines,activated olefins usually react with aromatic aldehydes to form compounds with multiple functional groups,and multiple functional groups contained in the product can be further converted.So this type of reaction has received widespread attention in organic synthesis.This thesis starts with the synthesis of ionic liquids.Then we studies the optimization and purification processes of several ionic liquids,and in-depth explores the applications of these ionic liquids as solvents and catalysts in Baylis-Hillman reactions.(1)We first synthesized ten ionic liquids of imidazole salts,quaternary ammonium salts,and DABCOs.The preparation process of ionic liquids is easy to operate.The reaction types are all quaternization reactions on N atoms,and the yields are all above 90%.We pre-processed the raw materials,protected the reaction with inert gas,and explored the effect of the feed ratio and temperature on the reaction yield.The ionic liquid was diluted with the solvent of acetone,and activated carbon was added for decolorization treatment.The product was washed several times with purified water.And no precipitation was detected in Ag NO₃ solution.(2)The quaternary ammonium salt ionic liquid and DABCO jointly promoted the Baylis-Hillman reaction.When the quaternary ammonium salt ionic liquid[N₂₂₂₄]Br is combined with the catalyst DABCO,the yield adding 100mol%DABCO reached 80.1%,and when the amount of DABCO is reduced to 80mol%,the yield also reached 80.4%.When the quaternary ammonium salt ionic liquid[N₂₂₂₄]Br and water were used as the composite solvent,the reaction time was shortened to 2 h with the catalyst DABCO,and when the amount of DABCO was reduced to 80 mol%,the yield also reached 80.6%.[N₂₂₂₄]Br was recycled 4 times after simple treatment,and still had catalytic activity.(3)Through quaternization reaction,DABCO obtains DABCO-based ionic liquid.Its structure contains a tertiary amine and a quaternary ammonium salt.The ionic liquid has better water solubility,and the structure of tertiary amine has strong basicity,which can speed up the reaction.Applying it to the Baylis-Hillman reaction,it was found that[C₄dabco]BF₄ has the best catalytic effect through screening of catalysts and solvents.With the addition of 1 ml of water,the yield was as high as 90.2%.After expanding the reaction substrate,it was found that[C₄dabco]BF₄ is suitable for aromatic aldehydes with electron-withdrawing groups,and also has good catalytic effect on aromatic aldehydes without groups.After 6 cycles of DABCO-based ionic liquids,the reactivity did not decrease.The reaction was completed within 5 to 6 hours,and the yield was about 90%.(4)The effects of quaternary ammonium,DABCO ionic liquids and solvent water on the Baylis-Hillman reaction were investigated using an ultrasonic-assisted method.When the quaternary ammonium ionic liquid and water were used as a composite solvent,the reaction time was shortened from 1.5 h to 1.2 h,and the yield is 85.7%.The reaction time of[C₄dabco]BF₄ catalyzed by ultrasound was shortened from 5 h to 4.5 h.Compared with other reactions,the yield was highest,and it was 90.9%.The substrate range was further expanded,and the results showed that aromatic aldehydes with electron-withdrawing groups were more reactive than those without or with electron-donating groups.