Synthesis Of Cyclic Carbonates By Epoxidation Of Olefin And CO₂ Cycloaddition In Situ

Carbon dioxide is well known as a kind of greenhouse gas.It can also be used as C1 resource,which is cheap,environmental and with rich reserves.Cyclic carbonates have considerable add value and are widely used as polar solvent,organic synthetic intermediates,electrolyte of lithium battery and polymer monomer.Using carbon dioxide to synthesize cyclic carbonate is one of the most effective way to achieve the CO2 resource utilization,and many synthesis methods have been created and developed.Among them,cycloaddition reaction using CO2 and epoxide as substrate is the most popular way.So far,however,almost all reported catalysis reactions have halogen anion,which can cause the corrosion of the production equipment and reactors.As a result,developing non-halogen catalyst has wide industrial application prospect.Moreover we considered that if we can use olefin,which has little toxicity and lower price,as substrate for the synthesis of cyclic carbonate directly,the preparation and separation of epoxide can be skipped.This synthesis method could have bright application.Carbene-CO2 adducts(NHC-CO2)is one of non-halogen catalyst for the cycloaddition between CO2 and epoxide,but the synthesize condition of traditional NHC-CO2 is strict and it is unstable.So,it is necessary to develop catalyst which is similar to NHC-CO2 with high stability,low price and good retrievability.In previous research,we discovered that simple imidazolium hydrogen carbonate ILs([CnCm-IM][HCO3])can also convert to NHC-CO2 spontaneously.Based on this point,a set of[CnCm-IM][HCO3]were used to catalyze the cycloaddition reaction of CO2 and epoxide.Moreover,we inspected the effect of temperature,pressure,time and load of catalyst to the reaction result.Using[C1C6-IM][HCO3]and styrene oxide under the best condition,yield of cyclic carbonate can reach 94%.Besides,this catalysis system can also be effective to many different terminal epoxides.The catalyst can be easily recycled at least five times without significant reduction of catalytic activity.As heteropolyphosphatotungstate can catalyze both the epoxidation of olefin and cycloaddition reaction between CO2 and epoxide,in the chapter three,we prepared a set of quaternary ammonium heteropoly-phosphatotungstate catalysts for the synthesis of cyclic carbonates from CO2 and olefins directly.We first investigated the performance of catalysts in the epoxidation of olefin and cycloaddition reaction between CO2 with epoxide.Then,we explored the effect of solvent,reaction temperature,adding method of H2O2,pressure of CO2,catalyst load,reaction time and other condition.Under the best condition,the conversion of 1-hexene reaches 96%,and the yield of cyclic carbonate is 71%.It is interesting to find that this catalytic system show good catalytic activity to straight chain olefins,but the conversion rate and yield of aromatic and cyclic olefins can be regulate by the selection of oxidant.Above all,this paper developed a green and effective method for the cyclic carbonate synthesis.We used epoxide or olefin as substrate and CO2 as carbon source to synthesize the cyclic carbonate,and achieved the CO2 utilization.