Method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan
阅读说明：本技术 一种光催化生物质呋喃制备2,5-二甲氧基-2,5-二氢呋喃的方法 (Method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan ) 是由 杨晓琴 喻艳华 于敬晖 叶金枝 康美琦 于 2019-12-06 设计创作，主要内容包括：本发明公开了一种光催化生物质呋喃制备2,5-二甲氧基-2,5-二氢呋喃的方法。目前的传统合成方法有两种,一种为化学合成法,通过呋喃与单质溴发生卤代反应实现,该方法反应过程生产成本高,对环境污染严重,已被逐渐淘汰；另一种为电解法,通过呋喃在甲醇溶液中电解氧化制备,该方法也存在生产成本高,电解质处理复杂等缺点。本发明以生物质呋喃、甲醇为原料,在可见光照射下,于室温、常压的空气气氛中,通过光催化剂作用合成2,5-二甲氧基-2,5-二氢呋喃。本发明方法操作简单,极大降低了生产成本,避免了环境污染,是一种具有工业开发价值、高效环保的合成方法。(The invention discloses a method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan. The existing traditional synthesis methods comprise two methods, one is a chemical synthesis method, and is realized by the halogenation reaction of furan and elemental bromine, and the method has high production cost in the reaction process, has serious environmental pollution and is gradually eliminated; the other method is an electrolytic method, and the furan is prepared by electrolytic oxidation in a methanol solution, and the method also has the defects of high production cost, complex electrolyte treatment and the like. The invention takes biomass furan and methanol as raw materials, and synthesizes 2,5-dimethoxy-2,5-dihydrofuran under the irradiation of visible light in air atmosphere at room temperature and normal pressure through the action of a photocatalyst. The method disclosed by the invention is simple to operate, greatly reduces the production cost, avoids environmental pollution, and is a high-efficiency and environment-friendly synthesis method with industrial development value.)
1. A method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalysis of biomass furan is characterized in that under the irradiation of visible light, the biomass furan and methanol are synthesized into the 2,5-dimethoxy-2,5-dihydrofuran under the action of a photocatalyst at room temperature and normal pressure in the air atmosphere, the catalyst is removed by filtration after the reaction is finished, and the filtrate is separated by reduced pressure distillation, wherein the reaction formula is as follows:
2. the method for preparing 2,5-dimethoxy-2,5-dihydrofuran by using photocatalytic biomass furan as claimed in claim 1, wherein: in the above reaction, biomass furan, methanol, catalyst were added to a three-necked round bottom flask equipped with a stirrer.
3. The method for preparing 2,5-dimethoxy-2,5-dihydrofuran by using photocatalytic biomass furan as claimed in claim 1, wherein: in the above reaction, the catalyst is a photocatalyst comprising one or more of an organic ruthenium (ii) complex, an organic iridium (iii) complex, eosin Y, rose bengal.
4. The method for preparing 2,5-dimethoxy-2,5-dihydrofuran by using photocatalytic biomass furan as claimed in claim 2, wherein: the usage amount of the biomass furan and the methanol is 1: 2-1: 10 in molar ratio, and the mass of the photocatalyst is 0.3-1.5 wt% of the mass of the furan.
5. The method for preparing 2,5-dimethoxy-2,5-dihydrofuran by using photocatalytic biomass furan as claimed in claim 1, wherein: the reaction conditions are visible light, room temperature, normal pressure and air.
6. The method for preparing 2,5-dimethoxy-2,5-dihydrofuran by using photocatalytic biomass furan as claimed in claim 5, wherein: the wavelength range of the visible light is 380-780 nm.
Technical Field
The invention relates to the field of organic chemical synthesis, in particular to a method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan.
Background
2,5-Dimethoxy-2,5-dihydrofuran (2,5-Dimethoxy-2,5-dihydrofuran, DHF) is a C4 synthetic block which is very useful in organic synthesis reaction, is an intermediate for synthesizing anticholinergic drug atropine sulfate and anisodamine hydrobromide, and is hydrolyzed by hydrochloric acid to generate 2-hydroxy-1, 4-butanedialdehyde; hydrogenation and hydrolysis to obtain succinaldehyde.
At present, two common methods for synthesizing 2,5-dimethoxy-2,5-dihydrofuran are mainly used, namely a chemical synthesis method and an electrolytic method. (1) Chemical synthesis method: the method is realized by the halogenation reaction of furan and elemental bromine, and 1.6kg of elemental bromine is consumed for producing 1kg of products. The method needs to be carried out at a low temperature, reaction equipment needs to be corrosion-resistant, the bromine consumption is high, the used liquid bromine is extremely easy to volatilize to form toxic and corrosive gas, a large amount of three wastes are generated in the whole reaction process, the production cost is high, the environmental pollution is serious, and the method is basically not adopted at present. (2) An electrolytic method: the method is realized by using furan indirect oxidation, using methanol as electrolyte and halide as supporting electrolyte to directly generate a product on an anode, and is the main method for synthesizing 2,5-dimethoxy-2,5-dihydrofuran at present. Although the electrolytic method reduces the consumption of bromine and the discharge of three wastes, the electrolytic method still has the defects of electrolyte waste, complex electrolyte post-treatment, low production efficiency of the traditional electrochemical reactor caused by low electrolyte conductivity, need of developing a special reactor and the like.
Chinese patent application with the application number of 201610774331.X and the application date of 2016, 8, 31 discloses a method for preparing 2,5-dimethoxy-2,5-dihydrofuran, which adopts the technical scheme that methanol and furan are used as raw materials, chlorine replaces bromine under the condition of adding a catalyst, sodium methoxide is added as alkali to neutralize acid generated by reaction, and the reaction temperature is kept at 25-50 ℃; the catalyst is one or more of sodium bromide, zinc bromide and potassium bromide. Although the by-product is sodium chloride, the technical scheme is simple in treatment, but still has the following major defects: (1) chlorine gas is a toxic and harmful gas, and the risk of escaping or leaking can exist in the experimental process; (2) because chlorine gas is introduced to generate acid, in order to avoid the influence of acidity on the reaction in the reaction process, sodium methoxide solution is used as an acid-binding agent, so that the production cost is increased; (3) the amount of chlorine as gas is not easy to control, a sealing device is needed, the whole reaction temperature needs to be controlled at 25-50 ℃, the production control link is increased, and the requirement of the reaction environment is improved; (4) the catalyst is one or more of sodium bromide, zinc bromide and potassium bromide containing bromine, and toxic and harmful pollution is possible. In conclusion, the technical scheme also has the safety defect, and does not achieve the technical aims of strict environmental protection, high efficiency and conservation.
Disclosure of Invention
The invention aims to provide a method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan, which further reduces the production cost, improves the resource utilization rate, effectively reduces or avoids the use and generation of environmental toxicants and pollutants in the synthesis process while realizing the high-efficiency synthesis of the 2,5-dimethoxy-2,5-dihydrofuran, and solves the defect problems of the prior art in scientific research and actual production.
In order to achieve the above object, the present invention provides a method for preparing 2,5-dimethoxy-2,5-dihydrofuran by photocatalytic biomass furan, under the irradiation of visible light, biomass furan and methanol are synthesized into 2,5-dimethoxy-2,5-dihydrofuran under the action of a photocatalyst at room temperature and normal pressure in an air atmosphere, after the reaction is finished, the catalyst is removed by filtration, and the filtrate is separated by reduced pressure distillation, wherein the reaction formula is as follows:
preferably, in the above reaction, biomass furan, methanol, catalyst are added to a three-necked round bottom flask equipped with a stirrer.
Preferably, in the above reaction, the catalyst is a photocatalyst comprising one or more of an organic ruthenium (ii) complex, an organic iridium (iii) complex, eosin Y, rose bengal.
Preferably, the usage amount of the biomass furan and the methanol is 1: 2-1: 10 in molar ratio, and the photocatalyst is 0.3-1.5 wt% of furan by mass.
Preferably, the reaction conditions are visible light, room temperature, normal pressure and air.
Preferably, the wavelength range of the visible light is 380-780 nm.
Compared with the prior art, the invention has the beneficial results that:
1. the reaction raw materials and the external energy source are green and renewable, the production cost can be further reduced, the resource utilization rate is improved, and the aim of efficiently synthesizing the 2,5-dimethoxy-2,5-dihydrofuran is fulfilled.
2. The reaction process is green and pollution-free, and the use and generation of environmental poisons and pollutants in the synthesis process are effectively reduced or avoided, so that the technical purposes of safety, environmental protection and no pollution are achieved.
3. The reaction condition is mild and easy to realize, the reaction device has no special requirement on corrosion resistance, the production condition limitation is further reduced, and the method is economical and practical and has industrial development value.
Drawings
FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of a
FIG. 2 shows the
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying examples, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.