Synthesis method of bio-based 1, 5-pentamethylene diamine derivative curing agent

Abstract

The invention discloses a synthesis method of a bio-based 1, 5-pentanediamine derivative curing agent, which comprises the following steps: S1, heating 1, 5-pentanediamine to 20-120 DEG C under the condition of nitrogen, then dropwise adding acrylonitrile, and reacting for 0.5-24 hours to obtain N, N '-poly (2-cyanoethyl)-1, 2-pentanediamine; s2, forming a reaction system by the N, N '-poly (2-cyanoethyl)-1, 2-pentamethylene diamine obtained in the S1, Raney nickel, inorganic alkali and a methanol ammonia solution, and reacting for 1-24 hours at the pressure of 0.1-10.0 MPa and the temperature of 50-80 DEG C to obtain a crude product; and S3, rectifying the crude product obtained in S2 to obtain a pure product. A series of biomass curing agents with brand new structures are synthesized, a synthesis scheme with mild and efficient conditions and low production cost is provided, and the problems of long reaction time, low reaction efficiency and high cost in the prior art are solved.

Description

Technical Field

[0001] The invention relates to a chemical raw material synthesis technology, in particular to a method for synthesizing a bio-based 1,5-pentanediamine derived curing agent. Background Art

[0002] Epoxy resins and polyureas prepared with organic amines as curing agents are widely used in civil fields such as coatings, adhesives and composite materials. At the same time, there are also many product applications in the fields of concrete, cement-based or ceramic-based building materials. With people's attention to environmental protection and biomass materials, in the context of sustainable development, the preparation of amine-based curing agents using biomass compounds as raw materials has a very broad market prospect.

[0003] 1,5-Pentanediamine is a substance widely found in nature, also known as cadaverine. At present, it has achieved large-scale industrialization of biomass synthesis method, and the raw materials used have gradually evolved from glucose to corn today, which greatly reduces the manufacturing cost. As a typical diamine, 1,5-pentanediamine has many advantages in use as a curing agent, such as high activity, high amine value, and relatively small usage, but it has a very unpleasant odor. Even if the curing reaction is carried out thoroughly, the resulting cured product still retains some taste, which greatly limits people's acceptance of 1,5-pentanediamine-based products.

[0004] Therefore, it is very important to modify 1,5-pentanediamine to reduce the odor without reducing the amine value of the modified compound. It is a common synthetic method to add diamine compounds to acrylonitrile through Michael addition and then obtain chain-extended diamine compounds through reduction.

[0005] DE2446489 document discloses that acrylonitrile and ethylenediamine react in a molar ratio of about 2:1, and acetic acid is used as a catalyst to obtain the desired product within 2 hours. After distillation, N, N'-bis (2-cyanoethyl) -1, 2-ethylenediamine with a yield of 98.1% can be obtained. U5434262 prepared N, N'-bis (cyanoethyl) -1, 2-diamine compounds by adding 3 moles of acrylonitrile to 1 mole of diamine within 3 hours, and hydrogenated in ethanol by Raney-type catalyst to obtain N, N'-bis (3-aminopropyl) -1, 2-diamine compounds, and the desired product can be obtained by distillation with a yield of about 60%. Although the above two schemes both obtain related addition products and hydrogenation products, their corrosion to equipment pipelines (acetic acid) and yield are relatively low, which greatly limits their industrial application.

[0006] The US005869653A document discloses that a series of Michael addition products of diamines and acrylonitrile are synthesized using diamines of different carbon chain lengths as raw materials, and the above addition products are reduced using Raney cobalt / hydrogen to obtain the corresponding extended chain diamine compounds. Experiments have shown that the hydrogenated product contains not only the desired disubstituted reduction product, but also a large amount of monosubstituted and imine by-products under the reaction conditions. The CN 116003268A document discloses that the addition product of 1,3-propylenediamine and acrylonitrile can undergo a hydrogenation reaction under the action of Ru / C to obtain the corresponding high-purity hydrogenated product. However, its high catalyst cost is not suitable for industrial application.

[0007] The above existing technologies do not involve bio-based 1,5-pentanediamine, and the research on its related curing agents still needs to be further deepened. The successful development and large-scale use of high-biomass content curing agents will greatly reduce human consumption of earth resources and environmental damage. Summary of the invention

[0008] The present invention aims to solve the existing problems and provide a method for synthesizing a bio-based 1,5-pentanediamine derived curing agent.

[0009] In order to achieve the above object, the technical solution adopted by the present invention includes a method for synthesizing a bio-based 1,5-pentanediamine-derived curing agent, comprising the following steps:

[0010] S1, under nitrogen, 1,5-pentanediamine is heated to 20-120°C, and then acrylonitrile is added dropwise, and the reaction is carried out for 0.5-24 hours to obtain N,N'-poly(2-cyanoethyl)-1,2-pentanediamine;

[0011] S2, in an autoclave, the N,N'-poly(2-cyanoethyl)-1,2-pentanediamine obtained in S1 is reacted with Raney nickel, an inorganic base, and a methanol ammonia solution to form a reaction system at a pressure of 0.1 to 10.0 MPa and a temperature of 50 to 80° C. for 1 to 24 hours to obtain a crude product of N,N'-poly(3-aminopropyl)-1,2-pentanediamine;

[0012] S3, distilling the crude product obtained in S2, and when the GC purity of the distillate reaches more than 99%, receiving the product to obtain a pure product.

[0013] Preferably, in S1, the temperature is heated to 50-80°C.

[0014] Preferably, in S1, the molar ratio of pentamethylenediamine to acrylonitrile is 1:0.8 to 1:10, more preferably 1:1 to 1:4. Preferably, in S2, the mass ratio of Raney nickel catalyst to raw material is 1% to 100%, more preferably 5% to 20%. Preferably, in S2, the inorganic base is KOH, NaOH, LiOH, Cs 2 CO3 or Li 2 CO 3 , preferably KOH and NaOH.

[0015] Preferably, in S2, the mass ratio of the inorganic base to the Raney nickel is 1% to 100%, more preferably 5% to 20%. Preferably, in S2, NH 3 The concentration of the methanol solution is 10 to 30 wt%.

[0016] Preferably, in S2, the mass ratio of N,N'-poly(2-cyanoethyl)-1,2-pentanediamine to ammonia methanol is 1% to 100%, more preferably 10% to 70%.

[0017] Preferably, in S2, the reaction system H 2 The pressure is 0.2~2.0MPa.

[0018] Preferably, in S2, the reaction time is 1 to 3 hours.

[0019] Compared with the prior art, the present invention prepares N,N'-poly(2-cyanoethyl)-1,2-pentanediamine by reacting 1,5-pentanediamine and acrylonitrile, and then performs a hydrogenation reaction under the action of a Raney nickel catalyst to obtain the desired product, and finally synthesizes a series of biomass curing agents with new structures, providing a synthesis scheme with mild conditions, high efficiency and low production cost, and solving the problems of long reaction time, low reaction efficiency and high cost in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 GC test curve diagram of the product prepared in Example 1;

[0021] Figure 2 GC test curve diagram of the product prepared in Example 2;

[0022] Figure 3 This is the GC test curve of the product prepared in Example 5. DETAILED DESCRIPTION

[0023] The above scheme is further described below in conjunction with specific examples. The present invention provides a method for synthesizing a bio-based 1,5-pentanediamine derivative curing agent, and the structure of the bio-based N,N'-poly(3-aminopropyl)-1,2-pentanediamine to be prepared is as follows:

[0024]

[0025] Furthermore, the embodiment specifically includes the following steps:

[0026] S1: Add 1,5-pentanediamine to the flask under nitrogen and heat to the target temperature. Use a constant flow pump to drop acrylonitrile into the flask. After the dropwise addition is completed, react for a period of time to obtain the desired N,N'-poly(2-cyanoethyl)-1,2-pentanediamine.

[0027] S2 adds Raney nickel, inorganic base, N,N'-poly(2-cyanoethyl)-1,2-pentanediamine and methanol ammonia solution obtained in S1 into an autoclave. Set the pressure and temperature of the reaction system. After a certain reaction time, cool the autoclave, filter with diatomaceous earth, and spin dry to obtain the desired crude N,N'-poly(3-aminopropyl)-1,2-pentanediamine. S3 distills the crude product obtained in S2, and when the GC purity of the distillate reaches more than 99%, start to receive the product to obtain a pure product.

[0028] Furthermore, the target temperature in S1 is 20°C to 120°C, more preferably 50-80°C.

[0029] Furthermore, the molar ratio of pentamethylenediamine to acrylonitrile in S1 is 1:0.8 to 1:10, more preferably 1:1 to 1:4.

[0030] Furthermore, the dropwise addition of acrylonitrile in S1 is completed and the reaction is carried out for 0.5 to 24 hours.

[0031] Furthermore, the mass ratio of the Raney nickel catalyst to the raw material in S2 is 1% to 100%, more preferably 5% to 20%.

[0032] Furthermore, the inorganic base in S2 is KOH, NaOH, LiOH, Cs 2 CO 3 , Li 2 CO 3 wait.

[0033] Furthermore, the mass ratio of the inorganic base to the Raney nickel in S2 is 1% to 100%, more preferably 5% to 20%. 3 The concentration of the methanol solution is 10 to 30 wt %; the mass ratio of N,N'-poly(2-cyanoethyl)-1,2-pentanediamine to ammonia methanol is 1 to 100%, more preferably 10 to 70%.

[0034] Furthermore, in S2, the reaction system H is set 2 The pressure is 0.1 to 10.0 MPa, more preferably 0.2 to 2.0 MPa.

[0035] Furthermore, the reaction time in S2 is 1 to 24 hours, more preferably 1 to 3 hours.

[0036] The process of the above preparation method is as follows:

[0037] (1) Preparation of N,N'-poly(2-cyanoethyl)-1,2-pentanediamine:

[0038]

[0039] (2) Preparation of N,N'-poly(3-aminopropyl)-1,2-pentanediamine (taking disubstituted cyanoethyl as an example):

[0040] The preferred embodiments of the present invention are as follows:

[0041] Embodiment 1:

[0042] Add 1,5-pentanediamine (510 g, 5 mol) to a 2L three-necked flask, seal it with a rubber stopper, insert a thermometer to observe the temperature, and heat the reaction system to 50°C. Take another 1L flask, add acrylonitrile (530 g, 10 mol), and blow N into the two raw materials at the same time. 2 To remove dissolved O 2 . Adjust the constant flow pump to drip acrylonitrile into 1,5-pentanediamine. The system temperature will rise after the dripping begins. Control the dripping speed so that the internal temperature of the system does not exceed 60°C. After the acrylonitrile is dripped, continue stirring for 30 minutes to obtain the intermediate product N,N'-di(2-cyanoethyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 95% (yield: 95%).

[0043] Subsequently, 3.5 g of methanol-substituted Raney nickel catalyst, 0.5 g of NaOH, and 150 mL of NH 3 18wt%, 7mol / L methanol solution and 50g of N,N'-di(2-cyanoethyl)-1,2-pentanediamine. After the addition, seal the mixture. 2 After two substitutions, keep p(H 2 )=1.0MPa,T=80℃, stir and react for 2 hours.

[0044] After the reaction is completed, the reactor is placed in an ice bath to quickly cool down. After the system temperature drops to room temperature, the reactor cover is opened, the supernatant is poured out, and the catalyst solids remaining in the supernatant are removed by diatomaceous earth filtration, and the residue is washed with methanol (50 mL × 3), the liquid phase is collected, and the solvent is dried to obtain the crude product. The purity of the product detected by GC gas chromatography is about 95% (yield: 90%). Figure 1 , is the GC test curve of the product prepared in Example 1 (analysis period: 20.3min slope / peak width: 100:1), after distillation, N,N'-di(3-aminopropyl)-1,2-pentanediamine with a GC purity of 99.5% can be obtained. After testing, the amine value of the obtained product is 1050, which is very close to the amine value of 1,5-pentanediamine (1100), indicating that the scheme has a very high feasibility.

[0045] Embodiment 2:

[0046] Add 1,5-pentanediamine (510 g, 5 mol) to a 2L three-necked flask, seal it with a rubber stopper, insert a thermometer to observe the temperature, and heat the reaction system to 50°C. Take another 1L flask, add acrylonitrile (530 g, 10 mol), and blow N into the two raw materials at the same time. 2 To remove dissolved O 2 . Adjust the constant flow pump to drip acrylonitrile into 1,5-pentanediamine. The system temperature will rise after the dripping begins. Control the dripping speed so that the internal temperature of the system does not exceed 60°C. After the acrylonitrile is added, continue stirring for 30 minutes to obtain the intermediate product N,N'-di(2-cyanoethyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 95% (yield: 95%). Subsequently, 3.5g of methanol-substituted Raney nickel catalyst, 0.3g of NaOH, and 150mL of NH 3 18wt%, 7mol / L methanol solution and 40g of N,N'-di(2-cyanoethyl)-1,2-pentanediamine. After the addition, seal the mixture. 2 After two substitutions, keep p(H 2 )=0.8MPa,T=50℃, stir and react for 4 hours.

[0047] After the reaction is completed, the reactor is placed in an ice bath to quickly cool down. After the system temperature drops to room temperature, the reactor cover is opened, the supernatant is poured out, and the catalyst solids remaining in the supernatant are removed by diatomaceous earth filtration, and the residue is washed with methanol (50 mL × 3), the liquid phase is collected, and the solvent is dried to obtain the crude product. The purity of the product detected by GC gas chromatography is about 95% (yield: 85%). Figure 2 , which is the GC test curve of the product prepared in Example 2 (analysis period: 20.3 min slope / peak width: 100:1). After distillation, N,N'-di(3-aminopropyl)-1,2-pentanediamine with a GC purity of 99.5% can be obtained.

[0048] Embodiment 3:

[0049] Add 1,5-pentanediamine (510 g, 5 mol) to a 2L three-necked flask, seal it with a rubber stopper, insert a thermometer to observe the temperature, and heat the reaction system to 50°C. Take another 1L flask, add acrylonitrile (260 g, 5 mol), and blow N into the two raw materials at the same time. 2 To remove dissolved O 2. Adjust the constant flow pump to drip acrylonitrile into 1,5-pentanediamine. The system temperature will rise after the dripping begins. Control the dripping speed so that the internal temperature of the system does not exceed 60°C. After the acrylonitrile is added, continue stirring for 30 minutes to obtain the intermediate product N,N'-mono(2-cyanoethyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 90% (yield: 95%). Subsequently, 3.5g of methanol-substituted Raney nickel catalyst, 0.35g of NaOH, and 150mL of NH 3 18wt%, 7mol / L methanol solution and 80g of N,N'-mono(2-cyanoethyl)-1,2-pentanediamine. After the addition, seal the mixture. 2 After two substitutions, keep p(H 2 )=1.0MPa,T=80℃, stir and react for 2 hours.

[0050] After the reaction is completed, the reactor is placed in an ice bath to quickly cool down. After the system temperature drops to room temperature, the reactor cover is opened, the supernatant is poured out, the catalyst solids remaining in the supernatant are removed by diatomaceous earth filtration, and the residue is washed with methanol (50mL×3), the liquid phase is collected, and the solvent is dried to obtain a crude product. The purity of the product detected by GC gas chromatography is about 92% (yield: 95%). After distillation, N,N'-mono(3-aminopropyl)-1,2-pentanediamine with a GC purity of 99.5 can be obtained.

[0051] Embodiment 4:

[0052] Add 1,5-pentanediamine (510 g, 5 mol) to a 2L three-necked flask, seal it with a rubber stopper, insert a thermometer to observe the temperature, and heat the reaction system to 50°C. Add acrylonitrile (840 g, 15 mol) to another 2L flask, and blow N 2 To remove dissolved O 2 . Adjust the constant flow pump to drip acrylonitrile into 1,5-pentanediamine. The system temperature will rise after the dripping begins. Control the dripping speed so that the internal temperature of the system does not exceed 60°C. After the acrylonitrile is added, continue stirring for 30 minutes to obtain the intermediate product N,N'-tri(2-cyanoethyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 96% (yield: 95%). Subsequently, 3.5g of methanol-substituted Raney nickel catalyst, 0.35g of KOH, and 150mL of NH 3 18wt%, 7mol / L methanol solution and 30g of N,N'-tri(2-cyanoethyl)-1,2-pentanediamine. After the addition, seal the container and 2 After two substitutions, keep p(H 2 )=1.0MPa,T=80℃, stir and react for 2 hours.

[0053] After the reaction is completed, the reactor is placed in an ice bath to quickly cool down. After the system temperature drops to room temperature, the reactor cover is opened, the supernatant is poured out, and the catalyst solids remaining in the clear liquid are removed by diatomaceous earth filtration, and the residue is washed with methanol (50 mL×3). The liquid phase is collected and the solvent is dried to obtain the crude product N,N'-tris(3-aminopropyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 94% (yield: 90%).

[0054] Embodiment 5:

[0055] Add 1,5-pentanediamine (510 g, 5 mol) to a 3L three-necked flask, seal it with a rubber stopper, insert a thermometer to observe the temperature, and heat the reaction system to 50°C. Add acrylonitrile (1040 g, 20 mol) to another 2L flask, and blow N 2 To remove dissolved O 2 . Adjust the constant flow pump to drip acrylonitrile into 1,5-pentanediamine. The system temperature will rise after the dripping begins. Control the dripping speed so that the internal temperature of the system does not exceed 60°C. After the acrylonitrile is dripped, continue stirring for 30 minutes to obtain the intermediate product N,N'-tetra(2-cyanoethyl)-1,2-pentanediamine. The purity detected by GC gas chromatography is about 96% (yield: 95%).

[0056] Subsequently, 3.5 g of methanol-substituted Raney nickel catalyst, 0.35 g of KOH, and 150 mL of NH 3 18wt%, 7mol / L methanol solution and 25g of N,N'-tetra(2-cyanoethyl)-1,2-pentanediamine. After the addition, seal the mixture. 2 After two substitutions, keep p(H 2 )=1.0MPa,T=80℃, stir and react for 2 hours.

[0057] After the reaction is completed, the reactor is placed in an ice bath to quickly cool down. After the system temperature drops to room temperature, the reactor cover is opened, the supernatant is poured out, and the catalyst solids remaining in the supernatant are removed by diatomaceous earth filtration. The residue is washed with methanol (50 mL × 3), the liquid phase is collected, and the solvent is dried to obtain the crude product N,N'-tetrakis(3-aminopropyl)-1,2-pentanediamine; see Figure 3 , which is the GC test curve of the product prepared in Example 5 (analysis period: 20.3 min slope / peak width: 100:1), and the purity detected by GC gas chromatography is about 96% (yield: 90%).

Claims

1. A method for synthesizing a bio-based 1,5-pentanediamine-derived curing agent, characterized in that The steps include: S1, under nitrogen, 1,5-pentanediamine is heated to 20-120°C, and then acrylonitrile is added dropwise, and the reaction is carried out for 0.5-24 hours to obtain N,N'-poly(2-cyanoethyl)-1,2-pentanediamine; S2, in an autoclave, the N,N'-poly(2-cyanoethyl)-1,2-pentanediamine obtained in S1 is reacted with Raney nickel, an inorganic base, and a methanol ammonia solution to form a reaction system at a pressure of 0.1 to 10.0 MPa and a temperature of 50 to 80° C. for 1 to 24 hours to obtain a crude product of N,N'-poly(3-aminopropyl)-1,2-pentanediamine; S3, distilling the crude product obtained in S2 to obtain a pure product.

2. The method according to claim 1, characterized in that: In S1, the temperature is heated to 50-80°C.

3. The method according to claim 1, characterized in that: In S1, the molar ratio of pentamethylenediamine to acrylonitrile is 1:0.8 to 1:10 or 1:1 to 1:

4.

4. The method according to claim 1, characterized in that: In S2, the mass ratio of the Raney nickel catalyst to the raw material is 1% to 100% or 5% to 20%.

5. The method according to claim 1, characterized in that: In S2, the inorganic base is KOH, NaOH, LiOH, Cs2CO3 or Li2CO3.

6. The method according to claim 1, 4 or 5, characterized in that: In S2, the mass ratio of the inorganic base to the Raney nickel is 1% to 100% or 5% to 20%.

7. The method according to claim 1, characterized in that: In S2, the concentration of the methanol ammonia solution is 10 to 30 wt%.

8. The method according to claim 1, characterized in that: In S2, the mass ratio of N,N'-poly(2-cyanoethyl)-1,2-pentanediamine to ammonia methanol is 1% to 100% or 10% to 70%.

9. The method according to claim 1, characterized in that: In S2, the pressure of the reaction system H2 is 0.2 to 2.0 MPa.

10. The method according to claim 1, characterized in that: In S2, the reaction time is 1 to 3 hours.

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