The Properites Of Lewis Acidic Ionic Liquids And The Study On Using Its As Catalyst For The Synthesis Of Diisoocty Terephthalate

Diocty terephthalate (DOTP), a new type of non-toxic plasticizer, is used toreplace the Diocty1phthalate(DOP) which is widely used as the primary plasticier onthe market, on account of its excellent performance. At present, the synthetic methodof DOTP in industry is the derict esterification method by using titanate as catalyst,but the greatest disatvantages of this method are that the reaction time is long,theseparation of catalyst and product is so hard, so the seaking of more efficient andcheaper catalyst became the main reaserch direction in this field with the purpose ofimproving the esterification efficiency.The ionic liquids have many excellent features. In the feild of catalysis, ionicliquids have many advantages wich other traditional catalysts can’t compare with. Theionic liquids have received widespread attention due to showing good catalytic effectby using ionic liquids as catalytic esterification synthesis of plasticizer.In this article,15kinds of lewis acid ionic liquids have been synthesized as thecatalyst of syntheticing DOTP, the main purpose is to find the better compoundLewis acidic liquids, and study its heat atability, catalytic performance and effect lawof technological parameter. At last, the reaction system is gradually enlarged so as toreview product yield and change rule of acid value. The specific research contentsand results are as follows:1、The synthesis and characterization of lewis ionic liquids:15kinds of lewisacid ionic liquids were synthesized, respectively,[bpy]Cl/nSnCl2(n=0.5、0.8、1、2、3)、[bpy]Cl/nZnCl2(n=0.5、0.8、1、2、3)、[bpy]Cl/nZnBr2(n=0.5、0.8、1、2、3). The qualitative analysis was assisted by the FTIR spectra,NMR, the result showthat synthetiic ionic liquids is the target ionic liquids. 2、After the thermal stability analysis of ionic liquids by TGA-DTA, theresult show that decomposition temperature is over300℃, indicating that heatstability of ionic liquids is fine, so it could be used as catalyst of preparation ofDOTP.3、15kinds of ionic were characterized by pyidine probe method and acetonitrrileprobe method. The experiment result indicate that the acidity of ionic liquids build upas the halide content increase; When the halide content is same, the order of ionicliquids acidity is [bpy]Cl/nZnCl2>[bpy]Cl/nZnBr2>[bpy]Cl/nSnCl2.4、Using the PTA and isooctyl alcohol as raw material and ionic liquids[bpy]Cl/3SnCl2、[bpy]Cl/3ZnCl2、[bpy]Cl/3ZnBr2、compound each other syntheticcatalystand last we inspect the yield and acidic value of product. The result show theorder of yield and conversion rate by using the single liquids as catalyst is that[bpy]Cl/3SnCl2>[bpy]Cl/3ZnBr2>[bpy]Cl/3ZnCl2, the conversation rate and yiledof [bpy]Cl/3SnCl2is91.95%,89.32%. While the catalytic effect of [bpy]Cl/3ZnBr2,[b p y] C l/3Z n C l2i s p o o r, t h e a c i d i c o r d e r i s [bpy]Cl/3ZnCl2>[bpy]Cl/3ZnBr2>[bpy]Cl/3SnCl2,the reason may be caused by solubility, surface activity and soon, it is also to be further studyed. Obviously, the latter two kinds of ionic liquidscould not be used as catalyst of preparation of DOTP. The catalytic effect of somecompound ionic liquids are better than single ionic liquid, in all of ionic liquids, thecatalytic effect of n[bpy]Cl/3SnCl2:n[bpy]Cl/3ZnCl2=3:1is the best, respectively98.96%and95.46%, the reason is also to be further studyed. Because the price ofZnCl2is cheaper than SnCl2, so through comprehensive consideration of catalyticeffect and cost factor, we choose the cooperative ionic liquids as catalyst of DOTP.When the ionic liquids were recycled6times, the yield of DOTP also could research more the90%. It show that the ionic liquids also have strong activity after being used6times.5、When the reaction ststem was ealarged to1L gradully, we found that yield ofproduct still reach91.10%after comparing the yield and acid value with previous, butthe acid value of product has rising. We need further optimize the reaction time andprocess condition in order to improve the production rate and reduce the acid value.6、To improve the washing process, it is that hot dilute solution is replaced bysaturated salt water to washing the product, avoiding the saponification and smulsionphenomenon of product. After washing4times, The product acid value reduced to1mgKOH/g, reaching the quality requirements which GB/T6489.2-2001hasstipulated. After washing process, isooctyl alcohol was distilled from the product, andthe product was characterzed by FT-IR and NMR, the resuilt show htat traget productis DOTP.