Preparation Of Five Membered Cyclic Carbonate And Its Application

Cyclic carbonates have been widely used in extraction separation of mixture,spinning,electrochemistry,organic synthesis and the preparation of high polymer.This is attributed to its excellent physical and chemical properties such as high solubility,high boiling point,low toxicity and biodegradablity,etc.Thereby,cyclic carbonates are an important kind compounds.Glycerol carbonate(GC)is an important cyclic carbonate,and has been widely used in solvent,cosmetic,coatings,polyester and polycarbonte,etc.By converting biodiesel byproduct(glycerol)into GC,not only improves the values of glycerol,but also promotes the development of bio-diesel industry.Besides,non-isocyanate polyurethanes(NIPU)synthesized by GC not only avoid the harm of isocyanate to human health and environment during the preparation process,but also has better performance than the traditional polyurethane in hydrolytic stability and machinability.Consequently,the NIPU synthesized by GC has attracted many researchers during the last years.In view of the difficult recovery and rapid loss of catalytic activity in the catalytic synthesis of GC,this paper mainly attempted to find a catalyst with efficient,easy separation and better re-usability for synthesis of GC.First,several anhydrous silicates were prepared by calcination at 400?,and the effect of the catalysts on the transesterification of glycerol with dimethyl carbonate(DMC)were investigated.Among them,calcined sodium silicate showed the best catalytic activity.In addition,the glycerol conversion,GC selectivity and GC yield can reached up to 97.7%,94.0% and 91.8%,respectively.The solid base catalyst was prepared with Na2SiO3·9H2O by calcination,and then was ground,sieved and used in the catalytic synthesis of GC from glycerol and DMC.Then,a series of sodium silicates were calcined at different temperatures and characterized by TG-DTG,BET,XRD,FT-IR,FESEM and Hammett indicator method.It was found that the basicity and amount of strong basic sites of sodium silicates are highly depended on the calcination temperature.The increased amount of strong basic sites resulted in the formation of glycidol,a by-product,resulted in the decreasing of the GC yield and GC selectivity.Moreover,it was found that anhydrous Na2 Si O3 prepared by the simple calcination of at 200? for 2 h and with the particle size of 120 meshes,has the highest catalytic activity.The glycerol conversion and GC selectivity can be reached 97.8% and 97.6%,respectively.When the catalyst Na2SiO3-200 dosage was used,the reaction time,reaction temperature and DMC/glycerol molar ratio is 5%,2.5h,75? and 4:1,respectively.This catalyst can be re-used five times without a noticeable drop in catalytic activity.In addition,sebacic acid reacted with glycerol carbonate with using of4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide as catalysts at room temperature for 16 h leading to the formation 1,10-bis[(2-oxo-1,3-dioxolan-4-yl)methyl] ester.The dicarbonate reacted with polyamines over organic base at 150? for 4h obtained NIPU.By comparing the NIPU synthesised from dicarbonate and diamine with NIPU prepared by dicarbonate and melamine,it was found that NIPU synthesised by melamine has better properties.