Study On Catalytic Synthesis Of Vitamin E By Acidic Ionic Liquid

Vitamin E is an important research object in the field of vitamins.It has good physiological activity and is also an antioxidant with good pharmaceutical value.Due to its wide application value in food,feed,cosmetics and other fields,the market demand for vitamin E is constantly increasing.At present,chemically synthesized vitamin E accounts for more than 80%of the market,and it is of great significance to increase the production and production efficiency of vitamin E.At present,chemical synthesis is the main source of vitamin E in the market.Its traditional synthetic methods have many drawbacks:1.It requires the use of a large amount of acidic catalyst,which is easy to cause corrosion to the production equipment;2.The catalyst cannot be recycled,which increases the production cost;3.The reaction time is too long,which affects the production efficiency;4.A large amount of wastewater is generated in the post-treatment process,which pollutes the environment.With the promotion of green chemistry concepts,reducing environmental pollution is a top priority for modern industrial production.In recent years,ionic liquids have received great attention as an environmentally friendly new material.It has the advantages of good stability,non-volatilization,adjustable organic compatibility and high catalytic activity.In the process of synthesizing vitamin E,the ionic liquid as a catalyst can solve the problems of poor selectivity of the catalyst,poor catalytic activity,and incapability of recycling.Therefore,ionic liquid applications have broad prospects in the synthetic vitamin E industry.First,in this paper,the preparation of four different Lewis acidic ionic liquids is described.The prepared acidic ionic liquids are:[TEA-PS][ZnCl₃]、[TEA-PS][ZnBr₂Cl]、[BMIM][ZnCl₂Br]、[BMIM][ZnBr₃],and applied to the catalytic synthesis of vitamin E.After a large number of experiments,it was found that[BMIM][ZnBr₃]has high catalytic activity.Then,the optimal conditions for the synthesis of vitamin E were obtained by single factor variable method:reaction temperature 70°C,reaction time 5 h,isophytol:2,3,5-trimethylhydroquinone diethyl ester:Ionic liquid=1:1.02:0.25（molar ratio）.Finally,the yield of catalytically synthesized vitamin E can reach 95.54%.At the same time,the ionic liquid was tested for circulation performance,and the ionic liquid was used for 6 times.The catalytic effect did not change much,and the ionic liquid was characterized by infrared spectrometer and nuclear magnetic resonance spectrometer.Since the ionic liquid is exhibits a viscous liquid state,a large amount of catalyst remains easily during the recycling of the catalyst,and the synthesized acidic ionic liquid is immobilized in order to solve the problem of residual catalyst.In this thesis,the immobilized acidic ionic liquid[BMIM][ZnBr₃]/silica gel was prepared by ionic liquid loading on silica gel,and applied to the catalytic synthesis of vitamin E,and then the optimal conditions for the vitamin E condensation reaction were determined by orthogonal test:reaction temperature 70°C,reaction time 7 h,isophytol:2,3,5-trimethylhydroquinone diethyl ester=1:1（molar ratio）,and the amount of the catalyst used is 20%of the total mass of the raw materials.Finally,the yield of the reaction was 91.85%.At the same time,the catalyst was also subjected to recycling experiments,and the silica-supported ionic liquid was characterized by infrared and thermogravimetry.The research in this thesis shows that the application of acidic ionic liquids to the catalytic synthesis of vitamin E has a good effect,which provides a new idea for the industrial production of vitamin E in ionic liquids.