Study On Synthesis Process Of Hydroxybutyl Vinyl Ether

Vinyl ethers are an important intermediate in organic synthesis and polymer monomers,and can also be used as reactive diluents.The huge market demand for downstream products has caused the synthesis of vinyl ethers to receive much attention.As a kind of vinyl ether,it is synthesized by etherification of acetylene and butanediol in industry at present.The reaction needs to be carried out under high temperature and high pressure,Acetylene has great safety hazards under high pressure conditions,so the development of acetylene etherification under normal pressure conditions is more meaningful for the industrial production of HBVE.This dissertation explored the process conditions for the synthesis of HBVE under normal pressure by the acetylene method through the improvement of the basic catalytic system,the selection of the reaction solvent,and the introduction of the strongly basic ionic liquid catalytic system.First of all,using BDO and acetylene as the reaction raw materials and KOH as the catalyst,the single factor experiments were used to explore the reaction law of HBVE synthesis under normal pressure.Under the optimal process conditions:the reaction liquid was subjected to vacuum distillation and water removal treatment before the reaction,The reaction temperature was 160℃,the acetylene flow rate was 0.06 L/min,m(KOH)/m(BDO)=10%,and the reaction time was 8 h.The conversion rate of BDO was 41.6%,and the yield of HBVE was 32.1%.Afterwards,high-boiling point solvents and basic catalysts were screened,in the screening of eight high-boiling solvents such as DMI,DMSO and HMPA,it was found that DMI had the best promotion effect on the synthesis of HBVE under normal pressure,Under the solvent ratio of m(DMl)/m(BDO)=250%,the conversion rate of BDO and the yield of HBVE reached 82.5%and 48.9%,respectively.Then the basic catalysts such as KOtBu,CH3ONa,KOH and solid alkali were screened,it was found that KOH had the best catalytic effect.And optimized the compound of a single catalyst,it was found that the composite catalytic system of PPh3+KOH,PPh3+CH3ONa and CH3ONa+KOH had a good effect.In the screening of synthetic K/ZrO23 K/Al2O3,Na2O/ZrO2,KF/CaO and other 6 solid base catalysts,the catalytic effect of K/ZrO2 was relatively good.Through the design of L9(34)orthogonal test,under the optimal process conditions:KOH loading was 30%,m(K/ZrO2)/m(BDO)=25%,reaction temperature was 160℃,reaction time was 8 h,stirring speed was 350 r/min.The yield of HBVE reached 32.2%.And after K/ZrO2 was repeatedly used for five times,the HBVE yield still reached 24.2%.Then,based on the characteristics of alkaline ionic liquids that have both high temperature melting point and alkaline catalysis,through the synthesis of nine kinds of basic ionic liquids such as[Bmim]OH,[Emim]OH,[Bmim]Ac,[Emim]Ac,CH,CMe and CEt,to explore the influence of ionic liquid as a catalyst on the reaction.The results showed that the overall catalytic effect of basic ionic liquids was not good.Only[Bmim]OH had relatively good catalytic effect.Under the best experimental conditions:reaction time was 8 h,m(DMI)/m(BDO)=250%,acetylene flow rate was 0.06 L/min,reaction temperature was 180℃,m(ILs)/m(BDO)=8%.The yield of HBVE was 9.2%.The comparison of the alkalinity intensity of the selected ionic liquids by ultraviolet spectrophotometry showed that there was no positive correlation between the alkalinity of the ionic liquids and the catalytic performance.Finally,we added additives to the system to further optimize the reaction,through the screening of seven cocatalysts such as PPh3/ZnO,octadecyltrimethylammonium chloride,cetyltrimethylammonium chloride and so on,it was found that cetyltrimethylammonium chloride had the best promotion effect on HBVE synthesis reaction.The best process conditions were obtained:reaction time was 9 h,m(DMI)/m(BDO)=200%,m(KOH)/m(BDO)=12%,reaction temperature was 170℃,acetylene flow rate was 0.06 L/min,m(cocatalyst)/m(BDO)=3%.Under these reaction conditions,the BDO conversion rate was 85.4%,and the HBVE yield was 54.8%.In consideration of whether there was interaction between the various factors and the order of the primary and secondary effects on the reaction,a L16(45)orthogonal experiment was designed for optimization.The experimental results showed that there was no interaction between the various factors,and the order of the primary and secondary effects of each factor on the reaction was:reaction temperature>reaction time>cocatalyst dosage>catalyst dosage.Through a series of studies,the thesis constructed an atmospheric reaction system with acetylene and BDO as the reaction raw materials,KOH as the catalyst,DMI as the solvent,and cetyltrimethylammonium chloride as the cocatalyst,which avoided the harshness of the high-pressure reaction conditions to the equipment,and achieved a higher conversion rate and yield under normal pressure,BDO conversion rate was 85.4%,HBVE yield was 54.8%.In addition,the synthesized alkaline ionic liquids were used as a catalyst in the synthesis of HBVE by the acetylene method for the first time,and the influence of alkaline strength and catalytic performance of the alkaline ionic liquids were explored.