Method for preparing 2, 2-bis (4-aminocyclohexyl) propane through hydroamination

Abstract

The invention belongs to the technical field of fine chemical engineering, and discloses a method for preparing 2, 2-bis (4-aminocyclohexyl) propane through hydroamination, which comprises the following steps: taking ruthenium as an active component, combining with a ligand to synthesize a ruthenium homogeneous catalyst, and under the condition of the ruthenium homogeneous catalyst, catalytically hydrogenating a bisphenol A solution and liquid ammonia to generate hydroamination reaction to prepare the 2, 2-bis (4-aminocyclohexyl) propane. The catalyst is 1, 2-bis (4-aminocyclohexyl) propane. According to the method provided by the invention, the activity of the catalyst and the selectivity of primary amine can be effectively improved, and the proportion of isomers in the product can be adjusted by adjusting the type of the Ru ligand.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamylation. Background Technology

[0002] 2,2-Bis-(4-aminocyclohexyl)propane, as a monomer for the preparation of novel polyimides, is mainly used as a chain extender or crosslinking agent for polyether-type polyurethane elastomers, and has important applications in the elastomer industry. In addition, it can be used to synthesize transparent plastics with optical transmittance and polyamides. Polyamides prepared from 2,2-bis-(4-aminocyclohexyl)propane have higher glass transition temperatures than those prepared using linear diamines, and maintain good mechanical properties and dimensional stability even at high temperatures. Different isomer ratios of 2,2-bis-(4-aminocyclohexyl)propane lead to a wide range of downstream applications. For example, the cis isomer enhances intermolecular hydrogen bonding and is used to prepare highly crystalline optical materials or as a corrosion inhibitor; the trans isomer exhibits strong intermolecular forces, improving polymer thermal stability and is suitable for high-temperature lubricants or radiation-resistant materials. Therefore, the controllable adjustment of the isomer ratio of 2,2-bis-(4-aminocyclohexyl)propane has significant application value.

[0003] The hydroammoniation of alicyclic alcohols to prepare the corresponding alicyclic amines typically uses supported Ni or Co catalysts. To improve catalyst performance, the reaction needs to be carried out at higher temperatures (150–200 °C) and higher pressures (12–25 MPa), resulting in lower product yields. For example, patent US3551485 reports a method using a Co-based catalyst for the hydroammoniation of 2,2-bis-(4-hydroxycyclohexyl)alkanes in a batch process to prepare 2,2-bis-(4-aminocyclohexyl)alkanes. With a 2,2-bis-(4-hydroxycyclohexyl)alkan / ammonia molar ratio of 1 / 3 to 1 / 6, a hydrogen pressure of 10–40 MPa, and a reaction temperature of 170–200 °C, the yield of 2,2-bis-(4-aminocyclohexyl)alkanes is 86–92%. CN118142528A provides a method for the hydroammoniation of cyclohexanol to prepare cyclohexylamine using a nickel catalyst supported on alumina. The reaction was carried out at a pressure of 0.8–2.0 MPa, a temperature of 160–200 °C, and a cyclohexanol space velocity of 0.3–1.2 h⁻¹. -1 The ammonia / alcohol molar ratio was 4–11, the hydrogen / alcohol molar ratio was 12–16, and the reaction time was 24 h. The conversion rate of cyclohexanol was >95%, and the selectivity of cyclohexylamine was >86%. Both the conversion rate and selectivity were not high enough. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroammoniation, in order to solve the problem mentioned in the background art that the yield of the corresponding alicyclic amines prepared by hydroammoniation of alicyclic alcohols is usually low.

[0005] To achieve the above objectives, the present invention provides a method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination, comprising the following steps: using ruthenium as the active component, combining it with a ligand to synthesize a homogeneous ruthenium catalyst, and under the conditions of the homogeneous ruthenium catalyst, catalyzing the hydrogenation of bisphenol A solution and liquid ammonia to undergo a hydroamination reaction to obtain 2,2-bis(4-aminocyclohexyl)propane.

[0006] In one specific embodiment, the homogeneous ruthenium catalyst is a homogeneous Ru catalyst solution, and the preparation method of the homogeneous Ru catalyst solution is as follows: under anaerobic conditions, the ruthenium source and ligand are dissolved in a solvent and kept at a certain temperature to obtain a homogeneous Ru catalyst solution.

[0007] In one specific implementation, the ruthenium source is Ru3(CO). 12 The ruthenium source is one of RuHCl(CO)(PPh3)3, and the ligand is one of DPEphos, Xantphos, Thixantphos, DPPE, DPPB, and 4,5-bis-(bis-isopropylphosphinomethyl)acridine; the molar ratio of the ruthenium source to the ligand is 1 / 1 to 2 / 1.

[0008] In one specific embodiment, the homogeneous Ru catalyst solution is prepared under a nitrogen atmosphere, with a holding temperature of 60–100°C and a holding time of 1–8 h, and the solvent is one or two of toluene, xylene, and tert-amyl alcohol.

[0009] In one specific embodiment, the hydrogenated bisphenol A solution comprises hydrogenated bisphenol A and a solvent, wherein the solvent is one or two of toluene, xylene, tert-amyl alcohol, cyclohexane, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and tetrahydrofuran, and the mass fraction of hydrogenated bisphenol A is 3-15 wt%.

[0010] In one specific embodiment, a solution of hydrogenated bisphenol A, liquid ammonia, and a ruthenium homogeneous catalyst are pumped into a tubular reactor to react and prepare 2,2-bis(4-aminocyclohexyl)propane. The molar ratio of the catalyst active component ruthenium to hydrogenated bisphenol A is 0.5 / 100 to 5 / 100, the molar ratio of hydrogenated bisphenol A to liquid ammonia is 1 / 4 to 1 / 16, the reaction temperature is 100 to 150°C, and the reaction pressure is 2 to 5 MPa.

[0011] In one specific embodiment, the reaction solution is treated by membrane filtration, and the homogeneous ruthenium catalyst is backflushed, concentrated, and recycled. The membrane filtration pressure is 0.1 to 1.0 MPa.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1) The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydrogenation of bisphenol A provided by the present invention uses a homogeneous catalyst to catalyze the alcohol amination reaction. Compared with heterogeneous catalysis, the homogeneous catalyst has a high degree of dispersion of active components and can effectively avoid mass transfer resistance. The catalyst has high activity, which can significantly reduce reaction temperature and pressure, reduce energy consumption, and, due to the mild reaction conditions and single active center, the selectivity of the target product is high.

[0014] 2) The amination reaction uses a tubular reactor. The hydrogenation liquid is treated by a membrane, which intercepts the homogeneous catalyst and allows it to be recycled. At the same time, it can avoid the enrichment of water in the reaction system and increase the stability of the homogeneous catalyst.

[0015] 3) In addition, since the types of ligands in homogeneous catalysts can be adjusted, there is a large range of options for adjusting the isomer selectivity of the product.

[0016] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The present invention will now be described in further detail. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of the ligand DPEphos according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the ligand Xantphos according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the ligand Thixantphos according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of ligand DPPE according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the structure of ligand DPPB according to an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the structure of ligand 4,5-bis-(bis-isopropylphosphinomethyl)acridine according to an embodiment of the present invention. Detailed Implementation

[0024] The embodiments of the present invention will be described in detail below. The specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0025] This invention provides a method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination, comprising the following steps: using ruthenium as the active component, combining it with a ligand to synthesize a homogeneous ruthenium catalyst, and under the conditions of the homogeneous ruthenium catalyst, catalyzing the hydrogenation of bisphenol A solution and liquid ammonia to undergo a hydroamination reaction to obtain 2,2-bis(4-aminocyclohexyl)propane.

[0026] The homogeneous ruthenium catalyst is a homogeneous Ru catalyst solution. The preparation method of the homogeneous Ru catalyst solution is as follows: under anaerobic conditions, the ruthenium source and ligand are dissolved in a solvent and kept at a certain temperature to obtain a homogeneous Ru catalyst solution.

[0027] The ruthenium source is Ru3(CO). 12 The ruthenium source is one of RuHCl(CO)(PPh3)3, and the ligand is one of DPEphos, Xantphos, Thixantphos, DPPE, DPPB, and 4,5-bis-(bis-isopropylphosphinomethyl)acridine; the molar ratio of the ruthenium source to the ligand is 1 / 1 to 2 / 1.

[0028] The homogeneous Ru catalyst solution was prepared under a nitrogen atmosphere, with a holding temperature of 60–100°C and a holding time of 1–8 h. The solvent was one or two of toluene, xylene, and tert-amyl alcohol.

[0029] The hydrogenated bisphenol A solution comprises hydrogenated bisphenol A and a solvent, wherein the solvent is one or two of toluene, xylene, tert-amyl alcohol, cyclohexane, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and tetrahydrofuran, and the mass fraction of hydrogenated bisphenol A is 3-15 wt%.

[0030] 2,2-bis(4-aminocyclohexyl)propane was prepared by pumping a solution of hydrogenated bisphenol A, liquid ammonia, and a ruthenium homogeneous catalyst into a tubular reactor. The molar ratio of the catalyst active component ruthenium to hydrogenated bisphenol A was 0.5 / 100 to 5 / 100, the molar ratio of hydrogenated bisphenol A to liquid ammonia was 1 / 4 to 1 / 16, the reaction temperature was 100 to 150 °C, and the reaction pressure was 2 to 5 MPa.

[0031] The reaction solution is treated by membrane filtration, and the homogeneous ruthenium catalyst is backwashed, concentrated and recycled. The membrane filtration pressure is 0.1 to 1.0 MPa, and the catalyst recovery rate reaches 90 to 100%.

[0032] Example A1

[0033] Weigh 3.05g of RuHCl(CO)(PPh3)3 and 1.81g of DPEphos into a flask, purge with nitrogen 3-5 times, inject 50g of oxygen-free toluene in a nitrogen atmosphere, and keep warm at 80℃ for 2h to obtain a homogeneous catalyst solution.

[0034] Weigh 30.0g of hydrogenated bisphenol A and 270g of toluene into a reaction vessel, purge with nitrogen three times, and heat to 120℃ to dissolve, thus obtaining a hydrogenated bisphenol A solution.

[0035] Liquid ammonia was added at a rate of 0.17 g / min under a pressure of 5 MPa. Hydrogenated bisphenol A solution and homogeneous catalyst solution were pumped into a tubular reactor at rates of 3.0 g / min and 0.64 g / min, respectively. The resulting hydrogenated liquid was treated with a membrane filter at a pressure of 1 MPa. The catalyst was backwashed, concentrated, and then recycled.

[0036] Example A2

[0037] Example A2 is the same as Example A1, except that the structure of the added ligand is different. In order to ensure that the molar ratio of ligand to Ru is fixed at 1.05, 1.95g of Xantphos ligand is weighed in Example A2.

[0038] Example A3

[0039] Example A3 is the same as Example A1, except that the only difference is the structure of the added ligand. In order to ensure that the molar ratio of ligand to Ru is fixed at 1.05, 2.01g of Thixantphos ligand is weighed in Example A3.

[0040] Example A4

[0041] Example A4 is the same as Example A1, except that the only difference is the structure of the added ligand. In order to ensure that the molar ratio of ligand to Ru is fixed at 1.05, Example A4 weighs 1.48g of 4,5-bis-(bis-isopropylphosphinomethyl)acridine as the ligand.

[0042] Comparative Example B1

[0043] 3.68 g of magnesium nitrate was dissolved in 7 mL of deionized water and impregnated onto 9.0 g of alumina (20-40 mesh) by an equal volume for 24 h. After impregnation, the alumina was dried at 80 °C for 12 h and calcined at 600 °C for 3 h in an air atmosphere in a muffle furnace to obtain a MgO-Al2O3 support. 1.35 g of ruthenium chloride hydrate was dissolved in 7 mL of deionized water and impregnated onto 9.5 g of the MgO-Al2O3 support for 24 h. After drying at 80 °C for 12 h, the alumina was reduced at 350 °C for 2 h in a hydrogen atmosphere to obtain a 5% Ru / MgO-Al2O3 catalyst.

[0044] 6.0 g of the sample was loaded into a fixed-bed reactor and reacted. The mixture was heated to 210 °C under a hydrogen atmosphere and subjected to a volume hourly space velocity (VHSV) of 0.5 h⁻¹. -1 The catalyst will be evaluated below.

[0045] The effect of Ru ligands on the reaction is shown in Table 1.

[0046] Table 1. Effect of Ru ligands on the reaction

[0047] T / ℃ <![CDATA[n Ru / n HBPA ]]> Conversion rate % Selectivity % Trans% Example A1 140 0.03 96.9 89.4 38.6 Example A2 140 0.03 96.1 93.4 55.5 Example A3 140 0.03 91.8 88.3 72.9 Example A4 140 0.03 95.3 94.2 71.5 Comparative Example B1 210 / 95.1 88.7 39.4

[0048] As shown in Table 1, compared with the heterogeneous catalyst of Comparative Example B1, the homogeneous catalyst has higher catalyst activity, can significantly reduce reaction temperature and energy consumption, and can effectively improve the selectivity of the target product.

[0049] A comparison of Examples A1 to A4 shows that adjusting the structure of the Ru ligand can regulate the ratio of isomers in the product. Example A1 exhibits high catalytic activity due to the ligand's large electron-donating ability, which enhances the activity of the metal center. However, its relatively low steric hindrance hinders the improvement of catalytic selectivity. In contrast, the ligand in Example A4 has a moderate electron-donating ability and relatively large steric hindrance, effectively improving the reaction selectivity and the proportion of the trans isomer in the product.

[0050] Examples A5-A7

[0051] Examples A5 to A7 are the same as example A4, except that the molar ratio of the active component ruthenium to the reactant (HBPA) is changed during the feeding process.

[0052] Table 2 Effect of catalyst dosage on the reaction

[0053] <![CDATA[n Ru / n HBPA ]]> Conversion rate % Selectivity % Trans% Example A5 0.02 91.1 81.5 58.8 Example A4 0.03 95.3 94.2 71.5 Example A6 0.04 96.1 95.0 73.5 Example A7 0.05 96.8 92.2 76.4

[0054] As can be seen from the comparison data of Examples A4 to A7 in Table 2, n Ru / n HBPA At a concentration of 0.02, the reaction is incomplete, resulting in a significant amount of monoamine byproducts in the hydrogenation solution, leading to low selectivity. As n increases... Ru / n HBPA With the increase of n, the yield of the target product and the proportion of the trans product in the product increase significantly. Ru / n HBPA When the concentration is ≥0.05, the amount of byproducts in the hydrogenation solution increases significantly, and the selectivity of the target product decreases. Optimal n Ru / n HBPA The value is between 0.03 and 0.05. Considering cost, n is preferred. Ru / n HBPA =0.03 for further optimization.

[0055] Examples A8 to A10

[0056] Examples A8 to A10 are the same as example A4, except that the molar ratio of reactant (HBPA) to ammonia is changed by adjusting the ammonia feed rate during the reaction process.

[0057] Table 3 Effect of the molar ratio of ammonia to hydrogenated bisphenol A

[0058] <![CDATA[n Ru / n HBPA ]]> <![CDATA[n 氨气 / n HBPA ]]> Conversion rate % Selectivity % Trans% Example A8 0.03 4:1 85.6 65.7 56.2 Example A4 0.03 8:1 95.3 94.2 71.5 Example A9 0.03 12:1 96.6 94.9 70.8 Example A10 0.03 16:1 93.5 90.7 63.7

[0059] A comparison of Examples A4 and A8-A10 shows that, under the same reaction conditions, n 氨气 / n HBPA When the ratio of ammonia to nitrogen is 4:1, the conversion rate is low, the reaction rate is slow, resulting in a large accumulation of byproducts and intermediates. Simultaneously, due to insufficient ammonia, the proportion of the trans form in the product decreases significantly. With increasing n... 氨气 / n HBPA An increase in the ratio of n to n, within a certain range, helps to form more active intermediates, thereby improving the conversion rate and selectivity of the HBPA hydroamination reaction. 氨气 / n HBPA When the ratio is ≥16, the catalytic activity is significantly inhibited.

[0060] Examples A11 to A15

[0061] Examples A11 to A15 are the same as Example A4, except that the reactants are adjusted to 1,4-cyclohexanediol, 1,4-butanediol, ethylene glycol, propylene glycol, and pentanediol during the feeding process.

[0062] Table 4 Expansion of reaction substrates

[0063] <![CDATA[n 氨气 / n 原料 ]]> reaction temperature Conversion rate % Selectivity % Trans% 1,4-Cyclohexanediethanol 8:1 140 94.2 91.9 67.4 1,4-Butanediol 8:1 130 89.2 84.1 / Ethylene glycol 8:1 120 78.6 68.1 / Propylene glycol 8:1 120 86.8 78.3 / Pentylene glycol 8:1 130 93.8 86.2 /

[0064] Note: n Ru / n 原料 =0.03;

[0065] Examples A11-A15 show that applying this process to the hydroamination reactions of diols such as 1,4-cyclohexanediol, 1,4-butanediol, ethylene glycol, propylene glycol, and pentanediol yields high conversion rates and selectivity. However, in ethylene glycol and propylene glycol, the close proximity of their two hydroxyl groups makes it difficult for them to simultaneously approach the active sites of the catalyst during the reaction, resulting in low reaction rates and a tendency to generate cyclization and other byproducts.

[0066] Compared with traditional supported catalysts, the homogeneous catalyst of the present invention has the following advantages: 1. The metal active center is dispersed in the form of single atoms, which greatly enhances the intrinsic catalytic activity, thereby significantly reducing the reaction temperature and reaction pressure; 2. The synergistic effect of a single active site and mild conditions ensures high selectivity of the target product; 3. The designability of the ligand structure provides the possibility for isomer selectivity regulation.

[0067] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination, characterized in that, Includes the following steps: A ruthenium homogeneous catalyst was synthesized by combining ruthenium as the active component with ligands. Under the conditions of the ruthenium homogeneous catalyst, the hydrogenation of bisphenol A solution and liquid ammonia was catalyzed to produce 2,2-bis(4-aminocyclohexyl)propane.

2. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 1, characterized in that, The homogeneous ruthenium catalyst is a homogeneous Ru catalyst solution. The preparation method of the homogeneous Ru catalyst solution is as follows: under anaerobic conditions, the ruthenium source and ligand are dissolved in a solvent and kept at a certain temperature to obtain a homogeneous Ru catalyst solution.

3. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 2, characterized in that, The ruthenium source is Ru3(CO). 12 The ruthenium source is one of RuHCl(CO)(PPh3)3, and the ligand is one of DPEphos, Xantphos, Thixantphos, DPPE, DPPB, and 4,5-bis-(bis-isopropylphosphinomethyl)acridine; the molar ratio of the ruthenium source to the ligand is 1 / 1 to 2 / 1.

4. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 2, characterized in that, The homogeneous Ru catalyst solution was prepared under a nitrogen atmosphere, with a holding temperature of 60–100°C and a holding time of 1–8 h. The solvent was one or two of toluene, xylene, and tert-amyl alcohol.

5. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 1, characterized in that, The hydrogenated bisphenol A solution comprises hydrogenated bisphenol A and a solvent, wherein the solvent is one or two of toluene, xylene, tert-amyl alcohol, cyclohexane, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and tetrahydrofuran, and the mass fraction of hydrogenated bisphenol A is 3-15 wt%.

6. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 1, characterized in that, 2,2-bis(4-aminocyclohexyl)propane was prepared by pumping a solution of hydrogenated bisphenol A, liquid ammonia, and a ruthenium homogeneous catalyst into a tubular reactor. The molar ratio of the catalyst active component ruthenium to hydrogenated bisphenol A was 0.5 / 100 to 5 / 100, the molar ratio of hydrogenated bisphenol A to liquid ammonia was 1 / 4 to 1 / 16, the reaction temperature was 100 to 150 °C, and the reaction pressure was 2 to 5 MPa.

7. The method for preparing 2,2-bis(4-aminocyclohexyl)propane by hydroamination according to claim 1, characterized in that, The reaction solution is treated by membrane filtration, and the homogeneous ruthenium catalyst is backflushed, concentrated and recycled. The membrane filtration pressure is 0.1 to 1.0 MPa.

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