Synthesis method of tetra (2-ethoxyl) furan diamide

Abstract

The invention discloses a synthesis method of tetra (2-ethoxyl) furan diamide, which comprises the following specific implementation processes: mixing furandicarboxylic acid and a strong acid solid resin catalyst, adding absolute methanol to generate furandimethanol, replenishing absolute methanol after reaction, completing esterification reaction, cooling, filtering, recovering the catalyst, adding 2-hydroxyethylamine into filtrate, and reacting at the temperature of between 20 and 30 DEG C to obtain the tetra (2-ethoxyl) furan diamide. Controlling the temperature to react, and performing post-treatment to obtain the tetra (2-ethoxyl) furan diamide. The reaction steps are simple, the catalyst has good chemical stability and can be repeatedly used, and the reaction has high conversion rate and selectivity.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis, specifically relating to a method for synthesizing tetra(2-hydroxyethyl)furandiamide. Background Technology

[0002] Tetra(2-hydroxyethyl)furandiamide is an organic compound with a unique chemical structure and properties, showing broad application prospects in many fields. In the field of polymer materials, it can be used as a modifier to improve the mechanical properties and thermal stability of materials; in the pharmaceutical field, its potential biological activity makes it a potential lead compound for novel drugs; and in the fields of coatings and adhesives, it can also be used as a curing agent to improve the curing performance and overall quality of products.

[0003] Currently, there are several main technologies for synthesizing tetra(2-hydroxyethyl)furandiamide, but each has its own advantages, disadvantages, and challenges: 1) Traditional Chemical Synthesis Method: This method is based on common organic chemical reactions, with widely available raw materials, a relatively clear reaction principle, and mature technology, enabling large-scale production to a certain extent. However, it typically requires large amounts of organic solvents, which not only pollute the environment but also pose safety hazards. Furthermore, the reaction process often requires highly corrosive and toxic catalysts, such as concentrated sulfuric acid and concentrated hydrochloric acid, increasing the risk of equipment corrosion and posing a threat to the health of operators. Moreover, these catalysts are difficult to separate and recover, leading to high production costs. This method also requires harsh reaction conditions, generally high temperature and high pressure, which places extremely high demands on the reaction equipment, increasing equipment investment and operating costs. In addition, the reaction selectivity is low, with numerous side reactions, and the separation and purification of the product are complex, making it difficult to guarantee product purity and yield. 2) Biosynthesis: This method offers advantages such as mild reaction conditions, high selectivity, and environmental friendliness, aligning with the development advantages of green chemistry. However, current research on this method is still in the laboratory stage. The activity and stability of biocatalysts are relatively poor, resulting in low reaction efficiency and making industrial-scale production difficult. Furthermore, the biosynthetic process is influenced by many factors, such as the microbial growth environment and substrate concentration, making process control challenging. The screening and optimization of biocatalysts are crucial for biosynthesis, but currently, the available biocatalysts are limited, and research on their catalytic mechanisms is insufficient, making it difficult to find highly efficient and stable biocatalysts. In addition, byproducts generated during biosynthesis also require separation and purification.

[0004] 3) Microwave-assisted synthesis: Microwave heating can accelerate the reaction rate, shorten the reaction time, and improve the reaction efficiency. Simultaneously, this method features selective heating, which can reduce side reactions and improve product purity and yield. However, microwave equipment has a high investment cost, and localized overheating can occur during microwave heating, easily leading to reactant decomposition and side reactions. Furthermore, microwave-assisted synthesis has high requirements for reactants; some reactants may not react or react poorly under microwave conditions. Controlling microwave power, frequency, and heating time to achieve efficient and stable reaction is one of the challenges of microwave-assisted synthesis. In addition, the interaction mechanism between microwaves and reactants is not yet fully understood and requires further in-depth research.

[0005] In terms of applications, tetra(2-hydroxyethyl)furandiamide has unique advantages as a curing agent. In the field of epoxy resin curing, traditional curing agents such as amines and acid anhydrides have some shortcomings. For example, amine curing agents have a fast curing speed but are highly toxic, and the cured product is relatively brittle. Acid anhydride curing agents produce products with good heat resistance, but the curing speed is too slow and requires high-temperature curing. Tetra(2-hydroxyethyl)furandiamide, as a curing agent, has the following special advantages: 1) Good reactivity: Multiple active groups in its molecular structure can react with epoxy resin, and the curing speed is moderate. It can achieve rapid curing at room temperature or lower temperature, thereby improving production efficiency. 2) Excellent flexibility: Multiple active groups in its molecular structure can react with epoxy resin, and the curing speed is moderate. It can achieve rapid curing at room temperature or lower temperature, thereby improving production efficiency. 3) High chemical corrosion resistance: It endows the cured material with good chemical corrosion resistance, enabling it to maintain stable performance in harsh chemical environments; 4) Good environmental performance: Compared with traditional curing agents, tetra(2-hydroxyethyl)furandiamide has lower toxicity and less harm to the environment and human body, meeting environmental protection requirements.

[0006] However, the application of tetratetra(2-hydroxyethyl)furandiamide as a curing agent currently faces some challenges. For example, its synthesis process is complex and costly, limiting its large-scale application; research on its curing mechanism and performance regulation is not yet in-depth, making it difficult to fully realize its advantages. Therefore, developing an efficient, environmentally friendly, and economical method for synthesizing tetratetra(2-hydroxyethyl)furandiamide is of significant practical importance. Summary of the Invention

[0007] To address the above problems, the present invention aims to provide a method for synthesizing tetrakis(2-hydroxyethyl)furandiamide.

[0008] The specific technical solution is as follows: A method for synthesizing tetra(2-hydroxyethyl)furandiamide includes the following steps: In a reaction vessel, furanyl dicarboxylic acid and a strong acid solid resin catalyst are added, followed by the initial addition of anhydrous methanol. Stirring is started, and the reaction temperature is controlled to generate furanyl dimethyl. After the reaction, anhydrous methanol is added again, and the reaction temperature is controlled. The water generated in the reaction is carried away by the evaporation of methanol, which promotes the forward esterification reaction. The acid value of the reaction system is measured. When the acid value is less than 10 mg KOH / g, the esterification reaction is considered to be complete. The catalyst is recovered by cooling and filtration. The filtrate is a mixed solution of dimethyl furanyl dicarboxylic acid and methanol. 2-Hydroxyethylamine was added dropwise to the filtrate while controlling the temperature. After the addition was complete, the mixture was stirred to allow the reaction to proceed fully. After the reaction was completed, the product was post-treated to obtain tetra(2-hydroxyethyl)furandiamide.

[0009] The above reaction process is as follows: furanyl dicarboxylic acid reacts with methanol to produce dimethyl furanyl dicarboxylate and water, and dimethyl furanyl dicarboxylate reacts with 2-hydroxyethylamine to produce tetra(2-hydroxyethyl)furandiamide and methanol.

[0010] Furthermore, in step 1), the mass of the strong acid solid resin catalyst added is 5-10% of the mass of furanyl dicarboxylic acid.

[0011] Furthermore, in step 1), the molar ratio of anhydrous methanol to furanyl dicarboxylic acid added before stirring is 2-10:1. During the process of replenishing anhydrous methanol after the reaction, the mass of anhydrous methanol added per hour is 10-20% of the initial mass of anhydrous methanol added.

[0012] Further, in step 1), add initial anhydrous methanol, start stirring, control the reaction temperature at 65°C, and react for 2 hours. During the subsequent addition of anhydrous methanol, control the reaction temperature at 85-90°C.

[0013] Initially, furanyl dicarboxylic acid has not completely reacted to form dimethyl furanyl dicarboxylate. The temperature is set at 65℃, mainly due to the boiling point of methanol. As the reaction continues, the amount of dimethyl furanyl dicarboxylate produced increases, and the boiling point of the solution rises accordingly. Increasing the temperature causes methanol and water to azeotropically react, and the water produced in the reaction can be discharged in time, which is conducive to the reaction proceeding towards the formation of dimethyl furanyl dicarboxylate.

[0014] Furthermore, in step 2), the total molar amount of 2-hydroxyethylamine and the molar ratio of furanyldicarboxylic acid in step 1) are 2.0-3.5:1.

[0015] Further, in step 2), the dropping rate of 2-hydroxyethylamine is 0.3-2% of the total mass of 2-hydroxyethylamine per minute.

[0016] Furthermore, in step 2), the temperature is controlled at 55-60℃.

[0017] Further, in step 2), the post-treatment process is to centrifuge the reaction solution after the reaction is completed, and place the solid product after centrifugation and filtration in an oven and dry it at 60-80℃ to constant weight to obtain tetra(2-hydroxyethyl)furandiamide.

[0018] The beneficial effects of this invention are as follows: 1) This invention uses a strong acid solid resin as a catalyst. This catalyst has good chemical and thermal stability and can be reused multiple times, which reduces catalyst consumption and waste generation, lowers production costs, and also meets the requirements of green chemistry development. 2) Throughout the synthesis process, the reaction temperature is kept within a relatively low range, avoiding harsh conditions such as high temperature and high pressure, reducing equipment requirements, reducing energy consumption, and improving production safety; 3) The reaction steps are simple and clear, the operating conditions of each step are easy to control, the catalyst can be separated by simple filtration, and the product separation and purification adopts conventional operations such as centrifugation, filtration and drying, without the need for complicated separation technology, which is convenient for industrial production. 4) The conversion rate of raw materials and the selectivity of target products have reached a high level. The conversion rate of furanyl dicarboxylic acid is 99%, the selectivity of dimethyl furanyl dicarboxylate is 99%, the conversion rate of dimethyl furanyl dicarboxylate is 99.5%, and the selectivity of tetra(2-hydroxyethyl)furandiamide is 99%. The raw materials are fully utilized, there are few side reactions, the product purity is high, and the difficulty and cost of subsequent separation and purification are reduced. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0020] Example 1

[0021] Step 1: Preparation of dimethyl furanate 1) In a 500mL three-necked flask, add 50g (0.31mol) furanyl dicarboxylic acid and 3g strong acid solid resin catalyst (Amberlyst 15). 2) Add 60g (1.87mol) of anhydrous methanol to a three-necked flask, turn on the stirrer and keep the reaction temperature at 65℃ for 2 hours; 3) After 2 hours, anhydrous methanol was added at a rate of 6g per hour, while the reaction temperature was raised to 85℃. The water generated in the reaction was continuously separated out using a water separator. A small amount of the reaction solution was taken every 30 minutes to measure the acid value. The reaction was stopped when the acid value dropped to 8 mgKOH / g. 4) After the reaction is completed, the reaction solution is cooled to room temperature and the solid catalyst is recovered by filtration. The solid catalyst can be reused after simple treatment. The filtered solution (a mixed solution of dimethyl furanate and methanol) is analyzed by gas chromatography. The conversion rate of furanate is 99.1% and the selectivity of dimethyl furanate is 99.2%.

[0022] Step 2: Preparation of tetra(2-hydroxyethyl)furandiamide 1) Transfer the above-obtained mixed solution of dimethyl furanate and methanol to another 500 mL three-necked flask; 2) Under catalyst-free conditions, 62g (1.01mol) of 2-hydroxyethylamine was slowly added dropwise at a rate of 0.6g per minute through a dropping funnel. During the addition, the reaction temperature was controlled at 55℃ using a constant temperature water bath. After the addition was completed, the reaction was stirred for 1.5h. 3) After the reaction was completed, the reaction solution was transferred to a centrifuge tube and centrifuged at 4000 r / min for 10 minutes. The centrifuged solid product was dried in an oven at 60℃ to constant weight to obtain tetra(2-hydroxyethyl)furandiamide white solid powder. The conversion rate of dimethyl furanate was 99.6% and the selectivity of tetra(2-hydroxyethyl)furandiamide was 99.1% by high performance liquid chromatography.

[0023] Example 2

[0024] Step 1: Preparation of dimethyl furanate 1) In a 500mL three-necked flask, add 50g (0.31mol) furanyl dicarboxylic acid and 4g strong acid solid resin catalyst (Nafion-NR50). 2) Add 90g (2.81mol) of anhydrous methanol to a three-necked flask, turn on the stirrer and keep the reaction temperature at 65℃ for 2 hours; 3) After 2 hours, anhydrous methanol was added at a rate of 9g per hour, while the reaction temperature was raised to 85℃. The water generated in the reaction was continuously separated out using a water separator. A small amount of the reaction solution was taken every 30 minutes to measure the acid value. The reaction was stopped when the acid value dropped to 7 mgKOH / g. 4) After the reaction is completed, the reaction solution is cooled to room temperature and the solid catalyst is recovered by filtration. The solid catalyst can be reused after simple treatment. The filtered solution (a mixed solution of dimethyl furanate and methanol) is analyzed by gas chromatography. The conversion rate of furanate is 99.3% and the selectivity of dimethyl furanate is 99.3%.

[0025] Step 2: Preparation of tetra(2-hydroxyethyl)furandiamide 1) Transfer the above-obtained mixed solution of dimethyl furanate and methanol to another 500 mL three-necked flask; 2) Under catalyst-free conditions, 65g (1.06mol) of 2-hydroxyethylamine was slowly added dropwise at a rate of 0.9g per minute through a dropping funnel. During the addition, the reaction temperature was controlled at 60℃ using a constant temperature water bath. After the addition was completed, the reaction was stirred for 1.5h. 3) After the reaction was completed, the reaction solution was transferred to a centrifuge tube and centrifuged at 4000 r / min for 10 minutes. The solid product after centrifugation and filtration was dried in an oven at 60℃ to constant weight to obtain tetra(2-hydroxyethyl)furandiamide white solid powder. The conversion rate of dimethyl furanate was 99.7% and the selectivity of tetra(2-hydroxyethyl)furandiamide was 99.3% by high performance liquid chromatography analysis.

[0026] Comparative Example Synthesis of tetra(2-hydroxyethyl)furandiamide using traditional concentrated sulfuric acid as a catalyst Step 1: Preparation of dimethyl furanate 1) Add 50 g (0.31 mol) furanyl dicarboxylic acid and 5 mL concentrated sulfuric acid to a 500 mL three-necked flask; 2) Add 60 g (1.87 mol) of methanol, heat to 65°C, and reflux for 4 hours; 3) After the reaction was completed, the reaction solution was cooled and neutralized to neutral with sodium carbonate solution. Then, methanol and water were distilled, and dimethyl furanate was distilled off. Gas chromatography analysis showed that the conversion rate of furanate was 90% and the selectivity of dimethyl furanate was 92%. Step 2: Preparation of tetra(2-hydroxyethyl)furandiamide 1) The above-obtained dimethyl furanate was mixed with 60g of fresh methanol and transferred to a three-necked flask. A small amount of sodium hydroxide was added as a catalyst, and 62 g (1.01 mol) of 2-hydroxyethylamine was added dropwise (at a rate of 0.6g per minute). The mixture was reacted at 70°C for 2 hours. 2) After the reaction was completed, post-processing was performed. High performance liquid chromatography analysis showed that the conversion rate of dimethyl furanate was 95% and the selectivity of tetrakis(2-hydroxyethyl)furandiamide was 93%.

Claims

1. A method for synthesizing tetrakis(2-hydroxyethyl)furandiamide, characterized in that, Includes the following steps: 1) In a reaction vessel, add furan dicarboxylic acid and a strong acid solid resin catalyst, then add the initial anhydrous methanol, start stirring, control the reaction temperature to generate furan dimethyl methanol, add anhydrous methanol after the reaction, control the reaction temperature, and use the methanol evaporation to remove the water generated in the reaction to promote the forward esterification reaction. Measure the acid value of the reaction system. When the acid value is less than 10 mgKOH / g, the esterification reaction is determined to be complete. Cool and filter to recover the catalyst. The filtrate is a mixed solution of dimethyl furanate and methanol. 2) Add 2-hydroxyethylamine dropwise to the filtrate, control the temperature, and stir after the addition is complete to allow the reaction to proceed fully. After the reaction is complete, perform post-treatment to obtain tetra(2-hydroxyethyl)furandiamide.

2. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 1, characterized in that, In step 1), the mass of the strong acid solid resin catalyst added is 5-10% of the mass of furanyl dicarboxylic acid.

3. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 1, characterized in that, In step 1), the molar ratio of anhydrous methanol to furanyl dicarboxylic acid added before stirring is 2-10:

1. During the process of replenishing anhydrous methanol after the reaction, the mass of anhydrous methanol added per hour is 10-20% of the initial mass of anhydrous methanol added.

4. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 1, characterized in that, In step 1), add initial anhydrous methanol, start stirring, control the reaction temperature at 65℃, and react for 2 hours. During the subsequent addition of anhydrous methanol, control the reaction temperature at 85-90℃.

5. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 1, characterized in that, In step 2), the total molar amount of 2-hydroxyethylamine is 2.0-3.5:1 compared with the molar ratio of furanyldicarboxylic acid in step 1).

6. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 5, characterized in that, In step 2), the dropping rate of 2-hydroxyethylamine is 0.3-2% of the total mass of 2-hydroxyethylamine per minute.

7. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 6, characterized in that, In step 2), the temperature is controlled at 55-60℃.

8. The method for synthesizing tetrakis(2-hydroxyethyl)furandiamide as described in claim 1, characterized in that, The post-processing in step 2) is to centrifuge the reaction solution after the reaction is completed, and place the solid product after centrifugation and filtration in an oven to dry at 60-80℃ to constant weight to obtain tetra(2-hydroxyethyl)furandiamide.