Preparation method and device of 2-phenylimidazoline and obtained product

Abstract

The invention relates to a preparation method and device of 2-phenylimidazoline and an obtained product. The method comprises the following steps: adding benzonitrile, ethidene diamine and a catalyst into a reaction kettle, heating the reaction kettle to a reaction temperature in an inert gas atmosphere, starting a reaction, timing from 80 DEG C when the temperature is automatically increased to 155-180 DEG C, preferably 160-170 DEG C and is not increased any more, and reacting for 4-12 hours, preferably about 5-10 hours, after the reaction is finished, carrying out vacuum distillation on the reaction kettle, the product is obtained from the bottom of the reaction kettle (1), the material ratio is that the molar ratio of benzonitrile to ethylenediamine is 1: (1.03-1.20), and the molar ratio of the addition amount of the catalyst to ethylenediamine is (0.004-0.01): 1. The cyanobenzene is almost completely converted, the conversion rate is greater than 99.9%, and the residual quantity of cyanobenzene in the product is less than 0.01%, which is far superior to that of the existing production process.

Description

Technical Field

[0001] The invention relates to a preparation method and device of 2-phenylimidazoline and the obtained product. Background Art

[0002] 2-Phenylimidazoline, also known as 2-phenyl-2-imidazoline, molecular formula C 9 H 10 N 2 , can be used as epoxy resin powder coating curing agent, pharmaceutical raw material or for organic synthesis. Its chemical structure contains tertiary nitrogen atoms and active hydrogen, which can polymerize epoxy groups at relatively low temperatures, and the cured product has excellent mechanical and physical properties and chemical stability. It has the appearance of white or light yellow crystals, and the melting point of pure substances is 101 ℃, which is exactly the same as common solid epoxy resins (domestic E-12, American DOW663U, Japanese YD-013, etc.), and has good compatibility and processability. It meets the requirements of powder coatings based on epoxy resins, so it is developed as a low-temperature fast curing agent and curing accelerator for epoxy powder coatings.

[0003] In 2002, Wang Shensheng et al. published a paper titled "Synthesis of 2-phenylimidazoline and its application in epoxy powder coatings" in the journal "Thermosetting Resins", with the publication date of September 2002. The reaction time, the ratio of benzonitrile and ethylenediamine, the amount of catalyst added and the reaction stability were investigated, and 2-phenylimidazoline can be stably synthesized, and the product quality meets the standards, but the product color is yellowish and has an odor, and the product yield is low at 92%-96%. The product refining consumes a large amount of solvent, and the impurities in the solvent cannot be recovered after accumulation, resulting in large losses.

[0004] In 2009, Wang Jialin et al. published a paper titled "Synthesis and Characterization of 2-Phenylimidazole" in the journal "Guangzhou Chemical Industry". The method for synthesizing 2-phenylimidazoline in the paper was consistent with Wang Shensheng's method, and toluene was selected as the refining solvent. Because impurities in the refining solvent will accumulate, the solvent loss is large, the material consumption is high, and the product yield is low and there is a solvent odor. Summary of the invention

[0005] According to the invention, raw materials benzonitrile and ethylenediamine are transferred to a reaction kettle, and 2-phenylimidazoline is synthesized by heating under the action of a certain amount of catalyst. Under the selected reaction time, reaction temperature, material ratio of ethylenediamine and benzonitrile, and catalyst addition amount, the reaction conversion rate of benzonitrile can reach more than 99.9%, no solvent is added in the whole process, the yield of the product 2-phenylimidazoline is more than 99.3%, the material loss is small, ammonia produced by the reaction is sucked into an ammonia absorption tower through a vacuum system, transparent and high-grade ammonia water is produced as a by-product, and the efficiency is increased. A slicer, a silo, and a packaging machine are equipped with an exhaust gas absorption system to remove a small amount of odor in the product. The product finally produced is snow-white in color and has no obvious odor. Compared with the prior art, the product has high purity, light white color, is colorless and transparent, and has little odor.

[0006] Therefore, the present invention provides a preparation method of 2-phenylimidazoline, and the process flow is as follows: benzonitrile, ethylenediamine and a catalyst are put into a reactor, and the reactor is heated to a reaction temperature in an inert gas atmosphere to start a reaction, and when the temperature rises to 155-180°C, preferably 160-175°C, and further to 160-170°C, for example, a maximum reaction temperature of 161, 162, 163, 164, 165, 166, 167, 168, 169°C, the temperature does not rise any more, and the timing is started from 80°C, the reaction time is 4-12 hours, preferably about 5-10h or 6-9h, and more preferably about 7-8h, the reaction is finished, the reactor is vacuum distilled, and a product is obtained from the bottom of the reactor, The material ratio is: the molar ratio of benzonitrile to ethylenediamine is 1:1.03-1.20, preferably 1:1.08-1.20, and more preferably 1:1.10-1.17; and / or The molar ratio of the catalyst added to ethylenediamine is 0.004-0.01:1, preferably 0.006-0.008:1.

[0007] In the present application, the temperature is raised to the highest point by self-heating, which may be any temperature of 140-180°C. It needs to be manually controlled to the highest temperature that needs to be controlled. After the temperature is kept for a certain period of time, the reaction is completed.

[0008] Furthermore, ammonia is continuously released during the reaction, which enters a reflux vacuum buffer tank after condensation, and is sucked into an ammonia absorption tower by a vacuum pump for absorption, producing ammonia water as a by-product. During the reaction, excess ethylenediamine is refluxed to the reactor through a condenser to continue the reaction.

[0009] Furthermore, the excess ethylenediamine is distilled into a reflux vacuum buffer tank for storage by vacuum distillation to be used as a raw material for the next reaction.

[0010] The method of the present invention may further include discharging the product from the reactor into a slicer for slicing, the sheet product is discharged from the slicer and then stored in a silo, the product in the silo is packaged in a packaging machine, and finally stacked and stored.

[0011] Furthermore, during the slicing process, dust and exhaust gas generated by the slicer, silo and packaging machine enter the exhaust gas spray tower through the fan for absorption.

[0012] The catalyst can be selected from one or more of thioacetamide, N-bromosuccinimide, zirconium oxychloride, silicotungstic acid, p-toluenesulfonic acid, and anhydrous magnesium sulfate, preferably thioacetamide and / or anhydrous magnesium sulfate, and more preferably anhydrous magnesium sulfate.

[0013] Furthermore, the ammonia generated during the reaction enters the reflux vacuum buffer tank from the top of the reactor through a pipeline, and then is transported to the ammonia absorption tower through a vacuum pump for absorption to form by-product ammonia water. The by-product is transparent, high-grade ammonia water, which increases efficiency. After the sampling and analysis of the ammonia water tower are qualified, they are transferred to the dump tank area, and the desalted water is replenished to resume the ammonia water absorption process, and a new round of production begins.

[0014] Furthermore, the inert gas atmosphere is nitrogen, argon, helium or the like, preferably nitrogen atmosphere; the vacuum degree of the vacuum distillation is above 95 KPa, and the time of the vacuum distillation is 1-2 hours, preferably 1.5-2 hours.

[0015] In the present invention, ethylenediamine and benzonitrile are heated under the action of a catalyst to react with each other to generate 2-phenylimidazoline, while releasing ammonia as a gaseous byproduct. The reaction formula is: .

[0016] The condensation is carried out by a primary condenser and a secondary condenser, the operating temperature of the primary condenser is 30-50°C, preferably 35-40°C, and the operating temperature of the secondary condenser is 10-30°C, preferably 15-25°C.

[0017] After the product is packaged, samples are taken for analysis of benzonitrile and ethylenediamine residues and chromaticity black and white value (L value). The product 2-phenylimidazoline of the present invention has high purity, wherein the residual amounts of benzonitrile and ethylenediamine of the raw materials are both less than 0.01%, and there is no solvent residue. The product is colorless, transparent and has no obvious odor.

[0018] In a specific embodiment, the method of the present invention comprises sequentially putting a certain amount of benzonitrile (1000-3000kg), ethylenediamine (600-1800kg), circulating ethylenediamine (50-100kg) and catalyst (5-15kg) into a reactor with a volume of 2000-5000L and heating to 150-180°C. After reacting for 5-10 hours, a decompression reaction is carried out, and the vacuum is slowly increased until the vacuum degree reaches above 95Kpa. The process is changed to remove the solvent. After removing the solvent for 1-2 hours, the vacuum is broken with nitrogen and slicing is started. Before slicing, the slicer, silo, and packaging machine exhaust fan are turned on in advance to reduce the product odor and on-site dust. After the sampling and analysis of the ammonia tower are qualified, the tank area is transferred to the desalted water area, and the ammonia absorption process is restored to start a new round of production. The circulating ethylenediamine is temporarily stored in the reflux vacuum buffer tank for feeding the next kettle of raw materials.

[0019] The present invention also relates to a 2-phenylimidazoline product obtained by the preparation method, wherein the product is colorless and transparent, and the residual amounts of the raw materials benzonitrile and ethylenediamine are both less than 0.01wt%.

[0020] The present invention further provides a preparation device for 2-phenylimidazoline, comprising a reaction kettle, a primary condenser, a secondary condenser, a reflux vacuum buffer tank, a vacuum pump, a centrifugal pump, a slicer, a silo, a fan, and a packaging machine. The top outlet of the reactor is connected to a primary condenser, a secondary condenser, and a reflux vacuum buffer tank in sequence, the gas phase outlet of the reflux vacuum buffer tank is connected to a vacuum pump, and the vacuum pump is further connected to an ammonia absorption tower; The liquid phase outlet of the reflux vacuum buffer tank is connected to a centrifugal pump, which is further connected to a reactor; The lower outlet of the reactor is connected to a slicer, the slicer is connected to a silo, the discharge port of the silo is connected to a packaging machine, the exhaust port of the silo is connected to a fan, and the fan is further connected to an exhaust gas spray tower.

[0021] Advantages and effects of the present invention: The benzonitrile conversion of the present invention is nearly complete, with a conversion rate greater than 99.9%, and the residual benzonitrile in the product is less than 0.01%, which is far superior to the existing production process; The present invention does not require the addition of a third solvent, and has an obvious effect of removing excess raw material ethylenediamine, with the residual ethylenediamine in the product being less than 0.01%; The product of the present invention is white or colorless and transparent, and the black and white value of the tested chromaticity is above 92, preferably greater than 94, for example, it can reach 95, which is better than the existing process, wherein the black and white values ​​of the existing products on the market are all less than 90; The yield of the product of the present invention reaches more than 99.3%, and the highest is 99.6%, which is better than the existing production process; The ammonia generated during the reaction enters the reflux vacuum buffer tank through a pipeline from the top of the reactor, and is then transported to the ammonia absorption tower through a vacuum pump for absorption to form by-product ammonia water. After the reaction is completed, the reactor is vacuum distilled, and excess ethylenediamine enters the condenser from the top of the reactor for condensation and then enters the reflux vacuum buffer tank through a pipeline to be used as the raw material for the next reaction. Therefore, this method produces almost no waste, that is, it achieves "zero waste discharge" and meets the requirements of "green chemistry". BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the preparation device of 2-phenylimidazoline. DETAILED DESCRIPTION

[0023] In the following examples, the residual amounts of benzonitrile and ethylenediamine were analyzed by the following method: The internal standard method is used to analyze the residual amount of benzonitrile and ethylenediamine in the product. Preparation method of standard solution: weigh about 1g of the sample (accurate to 0.1mg), dissolve 20g of dilution solvent DMF (accurate to 0.1mg), dilute and place in the sample preparation bottle, shake well and set aside.

[0024] 0.4 μL of the sample prepared above was injected into the gas chromatograph, the chromatogram was recorded, and then the content of the tested compound in the sample was calculated according to formula (1).

[0025]

[0026] Where: w 1 :--the content of the tested compound i in the sample, in milligrams per kilogram (mg / kg); A 1 --The peak area of ​​the tested compound i in the sample; A--Peak area of ​​calibration compound s in standard working solution; W--the content of calibration compound s in the standard working solution, in milligrams per kilogram (mg / kg); m 1 ,--The mass of the dilution solvent r, in grams (g); m 2 ,--The mass of the sample, in grams (g).

[0027] In the following examples, the product chromaticity L value is determined by the following method: The PS2010 "Chubby Girl" spectrophotometer produced by Guangdong Sanenshi Intelligent Technology Co., Ltd. was used to analyze the color of the samples. The L value is the black and white value, and the black and white value range is 0-100. The closer to 100, the whiter the product, and the closer to 0, the darker the product. Please refer to the product manual for details.

[0028] like Figure 1 As shown, a preparation device for 2-phenylimidazoline includes a reaction kettle 1, a primary condenser 2, a secondary condenser 3, a reflux vacuum buffer tank 4, a vacuum pump 5, a centrifugal pump 6, a slicer 7, a silo 8, a fan 9, and a packaging machine 10. The top outlet of the reactor is connected to the primary condenser 2, the secondary condenser 3, and the reflux vacuum buffer tank 4 in sequence, the gas phase outlet of the reflux vacuum buffer tank 4 is connected to the vacuum pump 5, and the vacuum pump 5 is further connected to the ammonia absorption tower; The liquid phase outlet of the reflux vacuum buffer tank 4 is connected to a centrifugal pump 6, and the centrifugal pump 6 is further connected to the reactor; The lower outlet of the reactor 1 is connected to a slicer 7, the slicer is connected to a silo 8, the discharge port of the silo is connected to a packaging machine 10, the exhaust port of the silo is connected to a fan 9, and the fan is further connected to an exhaust gas spray tower.

[0029] The connection described in this application includes direct connection or connection via a pipeline.

[0030] The benzonitrile used in the following examples is industrial grade with a purity of more than 99 wt %; ethylenediamine is industrial grade with a purity of more than 99 wt %; thioacetamide is industrial grade with a purity of 99 wt %; anhydrous MgSO 4 It is industrial grade with purity above 99wt%. Example 1

[0031] According to the designed amount of the formula, benzonitrile and ethylenediamine are transferred to the reactor through a pump, and the catalyst is added from the hand hole of the reactor. After nitrogen is turned on to replace the air for 10-20 minutes, steam is turned on to start heating the reactor. After 80°C, the steam is turned off to start the reaction. During the reaction, ammonia is continuously released, which enters the reflux vacuum buffer after condensation by the primary condenser and the secondary condenser, passes through the vacuum pump, and finally enters the ammonia absorption tower for absorption, and ammonia water is produced as a by-product. During the reaction, excess ethylenediamine is refluxed to the reactor through the condenser to continue the reaction. When the temperature rises to the reaction temperature by itself, it no longer rises. The timing starts from 80°C, the reaction time is about 10h, and the reaction is completed. The reactor is changed to vacuum distillation, and the excess ethylenediamine is distilled to the reflux vacuum buffer tank for storage, which is used as the raw material for the next reaction. The product is discharged from the reactor to the slicer for slicing. The flaky product is discharged from the slicer and enters the silo for storage. The product in the silo enters the packaging machine for packaging, and finally stacked and stored. During the slicing process, the dust and tail gas generated by the slicer, silo and packaging machine enter the tail gas spray tower for absorption through the fan.

[0032] The formula and reaction conditions are as follows: 1700 kg of benzonitrile, 1080 kg of ethylenediamine, 7 kg of catalyst thioacetamide, 50 kg of recycled ethylenediamine (benzonitrile / ethylenediamine molar ratio = about 1:1.14, catalyst to ethylenediamine molar ratio is about 0.0050), maximum reaction temperature 160-165°C, reaction time 10 hours, decompression and excess ethylenediamine removal for 2 hours. After the product was sliced ​​and sampled for analysis, the residual benzonitrile was 0.0055%, ethylenediamine was 0.0015%, the product chromaticity L value was 96, and the yield of the product 2-phenylimidazoline was 99.45%. Example 2

[0033] The preparation process is the same as in Example 1, except that the formulation and conditions are changed as follows: Benzonitrile 2000 kg, ethylenediamine 1260 kg, anhydrous MgSO 4 15 kg, 100 kg of recycled ethylenediamine (benzonitrile / ethylenediamine molar ratio = about 1:1.17, catalyst to ethylenediamine molar ratio is about 0.0055), maximum reaction temperature 170-175 ° C, reaction time 8 hours, decompression and excess ethylenediamine removal for 1.5 hours. The experimental results showed that the residual benzonitrile content was 0.0085%, ethylenediamine was 0.0025%, the product chromaticity L value was 95, and the yield of the product 2-phenylimidazoline was 99.35%.

[0034] Comparative Example 1 The preparation process is the same as in Example 1, except that the formulation and conditions are changed as follows: 1700 kg of benzonitrile, 1080 kg of ethylenediamine, 7 kg of thioacetamide, 50 kg of recycled ethylenediamine, maximum reaction temperature 145-150 ° C, reaction time 8h, decompression and excess ethylenediamine removal for 1.5 hours. Experimental results: benzonitrile residue 0.09%, ethylenediamine 0.0025%, product chromaticity L value 89, product 2-phenylimidazoline yield 98.90%. In Comparative Example 1, the reaction temperature is low, resulting in low conversion rate, high benzonitrile residue, and low product chromaticity black and white value.

[0035] Comparative Example 2 The preparation process is the same as in Example 1, except that the formulation and conditions are changed as follows: Benzonitrile 2000 kg, ethylenediamine 1260 kg, anhydrous MgSO 4 15 kg, 100 kg of circulating ethylenediamine, the maximum reaction temperature is 170-175 ° C, the reaction time is 14h, and the excess ethylenediamine is removed under reduced pressure for 1.5 hours. The experimental results show that the residual amount of benzonitrile is 0.0065%, the ethylenediamine is 0.0009%, the product chromaticity L value is 88, and the product 2-phenylimidazoline yield is 99.35%. In Comparative Example 2, the reaction time is too long, resulting in an overly violent reaction, and the product chromaticity L value is low.

[0036] Comparative Example 3 The preparation process is the same as in Example 1, except that the formulation and conditions are changed as follows: Benzonitrile 2300 kg, ethylenediamine 1260 kg, anhydrous MgSO 4 15 kg, 100 kg of recycled ethylenediamine, the highest reaction temperature is 170-175 ° C, the reaction time is 8 hours, and the excess ethylenediamine is removed under reduced pressure for 1.5 hours. The experimental results show that the residual benzonitrile is 0.3206%, the ethylenediamine is 0.0025%, the product chromaticity black and white value is 86, the product 2-phenylimidazoline yield is 94.32%, and the product benzonitrile has a distinct odor. In Comparative Example 3, due to the high ratio of benzonitrile to ethylenediamine (benzonitrile / ethylenediamine molar ratio 1:1.015), benzonitrile cannot be completely converted, affecting the residual benzonitrile and product chromaticity.

[0037] Comparative Example 4 The preparation process is the same as in Example 1, except that the formulation and conditions are changed as follows: 2000 kg of benzonitrile, 1260 kg of ethylenediamine, 6 kg of thioacetamide, 100 kg of circulating ethylenediamine, maximum reaction temperature 170-175 degrees Celsius, reaction time 8 hours, decompression and removal of excess ethylenediamine for 1.5 hours. Experimental results benzonitrile residue 0.2036%, ethylenediamine 0.0025%, product chromaticity black and white value 90, product 2-phenylimidazoline yield 98.60%, product has benzonitrile smell. In comparative example 4, due to the catalyst content being lower than the scope specified in the present invention, the conversion rate is low, the benzonitrile residue is high, the product has an odor, and the chromaticity L value is low.

[0038] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for preparing 2-phenylimidazoline, characterized in that The following steps are involved: Benzonitrile, ethylenediamine and a catalyst are placed in a reaction kettle. In an inert gas atmosphere, the temperature of the reaction kettle is raised to the reaction temperature to start the reaction. When the temperature rises to a maximum reaction temperature of 155-180°C, preferably 160-170°C, it stops rising. The time is started from 80°C. The reaction time is 4-12 hours, preferably about 5-10 hours, and more preferably 7-8 hours. After the reaction is completed, the reaction kettle is subjected to vacuum distillation to obtain the product from the bottom of the reaction kettle (1). The material ratio is: the molar ratio of benzonitrile / ethylenediamine is 1:1.03-1.20, preferably 1:1.08-1.20, and more preferably 1:1.10-1.

17. The molar ratio of the catalyst added to ethylenediamine is 0.004-0.01:1, preferably 0.006-0.008:

1.

2. The preparation method according to claim 1, characterized in that During the reaction, ammonia is continuously released, which enters the reflux vacuum buffer tank after condensation, passes through the vacuum pump, and finally enters the ammonia absorption tower for absorption, producing ammonia water as a by-product. During the reaction, excess ethylenediamine is refluxed to the reactor through the condenser to continue the reaction.

3. The preparation method according to claim 1, characterized in that: The excess ethylenediamine is distilled into a reflux vacuum buffer tank for storage as a raw material for the next reaction.

4. The preparation method according to any one of claims 1 to 3, characterized in that The method further includes discharging the product from the reactor into a slicer for slicing; the sheet product is discharged from the slicer and then stored in a silo; the product in the silo is packaged in a packaging machine and finally stacked and stored.

5. The preparation method according to claim 4, characterized in that: During the slicing process, the dust and exhaust gas generated by the slicer, silo and packaging machine enter the exhaust gas spray tower through the fan for absorption.

6. The preparation method according to claim 5, characterized in that: The catalyst is selected from one or more of thioacetamide, N-bromosuccinimide, zirconium oxychloride, silicotungstic acid, p-toluenesulfonic acid, and anhydrous magnesium sulfate, preferably thioacetamide and / or anhydrous magnesium sulfate, and more preferably anhydrous magnesium sulfate.

7. The preparation method according to claim 3 or 4, characterized in that: The dust and exhaust gas generated by the slicer, silo and packaging machine enter the exhaust gas spray tower through the fan for absorption.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The inert gas is selected from one of nitrogen, argon and helium, preferably nitrogen.

9. The 2-phenylimidazoline product obtained according to the preparation method described in any one of claims 1 to 8, wherein the product is colorless and transparent, the residual amounts of raw material benzonitrile and ethylenediamine are both less than 0.01wt%, and the test chromaticity black and white value is more than 92, preferably greater than 94.

10. A preparation device for 2-phenylimidazoline, comprising a reaction kettle, a primary condenser, a secondary condenser, a reflux vacuum buffer tank, a vacuum pump, a centrifugal pump, a slicer, a silo, a fan, and a packaging machine. The top outlet of the reactor is connected to a primary condenser, a secondary condenser, and a reflux vacuum buffer tank in sequence, the gas phase outlet of the reflux vacuum buffer tank is connected to a vacuum pump, and the vacuum pump is further connected to an ammonia absorption tower; The liquid phase outlet of the reflux vacuum buffer tank is connected to a centrifugal pump, which is further connected to a reactor; The lower outlet of the reactor is connected to a slicer, the slicer is connected to a silo, the discharge port of the silo is connected to a packaging machine, the exhaust port of the silo is connected to a fan, and the fan is further connected to an exhaust gas spray tower.

Images