A process for the preparation of dibenzylamine

Abstract

The application relates to the technical field of organic synthesis intermediates, and particularly discloses a preparation method of high-purity dibenzylamine. First, Schiff base reaction is carried out on benzaldehyde, liquid ammonia and benzyl chloride to generate a Schiff base product N-benzylidene benzylamine; then, under the action of a hydrogenation catalyst, the N-benzylidene benzylamine reacts with hydrogen to generate dibenzylamine. Compared with the method of benzyl chloride and other methods, the preparation method of high-purity dibenzylamine provided by the application has the advantages of mild reaction conditions, high activity and stability of the catalyst, high product selectivity, high atomic utilization rate, reusability of the catalyst and solvent and other substances, less waste, and conformity to the environmental protection theme of green and clean production.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis intermediates, specifically a method for preparing high-purity dibenzylamine. Background Technology

[0002] Dibenzylamine is a secondary amine compound consisting of two benzyl groups linked to an amino group. It typically appears as a colorless or pale yellow oily liquid with an ammonia odor. It is readily soluble in organic solvents such as ethanol, ether, and chloroform, and slightly soluble in water. It can be used as a reagent for determining cobalt, iron, and cyanate. Dibenzylamine is also an important organic synthesis intermediate, commonly used in the synthesis of penicillin and curing agents for rubber and plastics, or in the production of tetrabenzylthiuram disulfide (TBZTD) and zinc dibenzyl dithiocarbamate (ZBEC), two highly effective and non-toxic vulcanization accelerators. Furthermore, derivatives of dibenzylamine and pharmaceutical compositions containing these derivatives can be used to treat some cardiovascular diseases, such as atherosclerosis.

[0003] There are many methods for synthesizing dibenzylamine, such as the benzyl chloride method and the benzaldehyde method. The benzyl chloride method involves the condensation reaction of benzyl chloride with aniline under the action of a catalyst to produce dibenzylamine and the byproduct hydrogen chloride. This method uses inexpensive raw materials and is simple to operate, but the yield of the main product is low, while the yield of the byproduct trichlorobenzyl is high, and the production process generates a large amount of waste, causing serious environmental pollution. The benzaldehyde method utilizes the reductive hydrogenation theory of aldehydes or chlorine to prepare a single secondary amine under the catalysis of a hydrogenation catalyst. Benzaldehyde, ammonia, and hydrogen are reacted with a hydrogenation catalyst to produce dibenzylamine and the byproduct water. This method has a short reaction time, high product selectivity, and high product recovery rate, but the production process requires pressurized hydrogenation, which places strict requirements on the reaction equipment and the skill level of the operators. Therefore, developing a simple, high-purity, and high-yield method for producing dibenzylamine is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-purity dibenzylamine, which has a simple reaction process, low environmental pollution, and high atom utilization, thus solving the problems of low dibenzylamine product yield and low dibenzylamine product output.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing high-purity dibenzylamine, specifically as follows:

[0007] Step 1: Mix benzaldehyde, liquid ammonia and benzyl chloride evenly, and react at 60-80℃ and 10-15MPa for 4-6 hours. After the reaction is completed, add deionized water to terminate the reaction, let stand and separate the layers, wash the oil phase with deionized water to obtain N-benzylbenzylamine.

[0008] Step 2: Mix N-benzylbenzylamine, ethanol, and Raney nickel catalyst evenly, introduce hydrogen gas, and react at 90-120℃ for 0.5-2 hours. After the reaction is complete, cool and filter. Distill the filtrate to remove ethanol, benzylamine, and benzyl alcohol. Finally, heat to 300-310℃, distill, and cool to obtain high-purity dibenzylamine.

[0009] As a limitation of the present invention, the mass ratio of benzaldehyde, liquid ammonia and benzyl chloride is (3-7):(0.5-1.5):(4-8).

[0010] As a limitation of the present invention, the mass ratio of N-benzylbenzylamine, ethanol, and Raney nickel catalyst is (8-10):(4-8):(0.05-0.2).

[0011] As a limitation of the present invention, in step 1, the mass ratio of deionized water to liquid ammonia to terminate the reaction is 1:(0.8~1.2). Deionized water can be replaced by an equal volume of ammonia water, which is obtained by distillation of the aqueous phase after standing and layering, and then condensation.

[0012] As a limitation of the present invention, the Raney nickel catalyst contains 90% to 100% nickel, and the Raney nickel catalyst in step 2 can be filtered out and reused.

[0013] As a limitation of the present invention, in step 2, the ethanol can be distilled from the filtered filtrate for reuse, and the distillation temperature is controlled at 75-90°C.

[0014] As a limitation of the present invention, the distillation temperature is controlled at 185-200°C during the removal of benzylamine.

[0015] As a limitation of the present invention, the distillation temperature is controlled at 205-220°C during the removal of benzyl alcohol.

[0016] The reaction mechanism of this invention is as follows: Under conditions of excess ammonia, benzaldehyde first reacts with ammonia to generate benzylimine (a Schiff base intermediate) and water. Benzylimine then reacts with benzyl chloride under alkaline conditions to generate N-benzylbenzylamine and hydrogen chloride. N-benzylbenzylamine reacts with hydrogen gas under the action of Raney nickel catalyst to generate dibenzylamine.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention provides a method for preparing high-purity dibenzylamine. The method uses benzaldehyde and benzyl chloride as raw materials and synthesizes dibenzylamine by catalytic hydrogenation under the action of Raney nickel catalyst. The reaction conditions are mild, the product selectivity is high, the atom utilization rate is high, and the waste generated is low, which is in line with the environmental protection theme of green and clean production.

[0019] This invention uses Raney nickel catalyst to catalyze the hydrogenation reaction of intermediate N-benzylbenzylamine. It has high catalytic activity and stable properties, generates few byproducts (benzylamine, benzyl alcohol) during the reaction, and has high selectivity for the product dibenzylamine, which is beneficial to the formation of dibenzylamine. This catalyst can catalyze the reaction at lower temperatures and pressures, with low reaction energy consumption, which is conducive to large-scale production.

[0020] In addition to the reusable Raney nickel catalyst, the preparation method provided by this invention also allows excess ammonia and solvent ethanol in the raw materials to be recovered and reused through distillation and other methods, reducing resource waste and waste generation, and lowering production costs. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Raney nickel catalyst (purity: Ni≥90%).

[0023] Example 1: A method for preparing high-purity dibenzylamine, specifically as follows:

[0024] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0025] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 150g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill out benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill out benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0026] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 97.7%.

[0027] Example 2: A method for preparing high-purity dibenzylamine, specifically as follows:

[0028] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0029] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 130g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0030] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 97.6%.

[0031] Example 3: A method for preparing high-purity dibenzylamine, specifically as follows:

[0032] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0033] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 80g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0034] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 97.3%.

[0035] Example 4: A method for preparing high-purity dibenzylamine, specifically as follows:

[0036] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0037] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 50g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill out benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill out benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0038] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 96.8%.

[0039] Example 5: A method for preparing high-purity dibenzylamine, specifically as follows:

[0040] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0041] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 95℃ for 1.5h. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill out benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill out benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0042] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 96.5%.

[0043] Example 6: A method for preparing high-purity dibenzylamine, specifically as follows:

[0044] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0045] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 95℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0046] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 95.2%.

[0047] Example 7: A method for preparing high-purity dibenzylamine, specifically as follows:

[0048] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0049] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 0.5h. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill out benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill out benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0050] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 95.6%.

[0051] Example 8: A method for preparing high-purity dibenzylamine, specifically as follows:

[0052] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0053] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 95℃ for 0.5h. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 75℃ and distill to remove the reusable solvent ethanol. Then heat to 185℃ and distill benzylamine from the solvent-free filtrate. Then heat to 205℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0054] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 100% and the selectivity of dibenzylamine was 92.2%.

[0055] Example 9: A method for preparing high-purity dibenzylamine, specifically as follows:

[0056] Step 1: Add 500g benzaldehyde, 100g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0057] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0058] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 98.8%, and the selectivity of dibenzylamine was 96.9%.

[0059] Example 10: A method for preparing high-purity dibenzylamine, specifically as follows:

[0060] Step 1: Add 500g benzaldehyde, 90g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0061] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0062] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 96.4%, and the selectivity of dibenzylamine was 93.7%.

[0063] Example 11: A method for preparing high-purity dibenzylamine, specifically as follows:

[0064] Step 1: Add 550g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0065] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0066] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 99.2%, and the selectivity of dibenzylamine was 97.2%.

[0067] Example 12: A method for preparing high-purity dibenzylamine, specifically as follows:

[0068] Step 1: Add 600g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 70℃ and 12MPa for 5h. After 4-6h of reaction, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain recyclable ammonia water.

[0069] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0070] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 97.8%, and the selectivity of dibenzylamine was 94.9%.

[0071] Example 13: A method for preparing high-purity dibenzylamine, specifically as follows:

[0072] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well and react at 60℃ and 10MPa for 6h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0073] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0074] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 94.6%, and the selectivity of dibenzylamine was 91.4%.

[0075] Example 14: A method for preparing high-purity dibenzylamine, specifically as follows:

[0076] Step 1: Add 500g benzaldehyde, 110g liquid ammonia and 650g benzyl chloride to a high-pressure reactor, mix well, and react at 80℃ and 12MPa for 4h. After the reaction is completed, add 100g deionized water to terminate the reaction, let stand and separate the layers. Wash the oil phase with deionized water to obtain N-benzylbenzylamine. Distill the aqueous phase at 100℃ and cool to obtain ammonia water that can be recycled.

[0077] Step 2: Transfer the N-benzylbenzylamine prepared in Step 1 to another reactor. At the same time, add 500g of ethanol and 100g of Raney nickel catalyst to the reactor, mix well, and then introduce hydrogen gas. React at 110℃ for 1 hour. After the reaction is complete, cool, filter, and filter out the reusable Raney nickel catalyst. Heat the filtrate to 80℃ and distill to remove the reusable solvent ethanol. Then heat to 190℃ and distill benzylamine from the solvent-free filtrate. Then heat to 210℃ and distill benzyl alcohol from the solvent-free filtrate. Finally, heat to 300℃, distill, and cool to obtain high-purity dibenzylamine.

[0078] The product after the reaction in step 2 was sampled and analyzed by gas chromatography. The conversion rate of benzaldehyde was 95.6%, and the selectivity of dibenzylamine was 93.4%.

[0079]

[0080] Conclusion: Gas chromatography analysis of the mixtures obtained after the reactions in each embodiment shows that the method for preparing high-purity dibenzylamine proposed in this invention can efficiently synthesize dibenzylamine using raw materials such as benzaldehyde, liquid ammonia, and benzyl chloride. Furthermore, due to the selective catalytic activity of the catalyst, the main product exhibits strong selectivity, with almost no byproducts such as benzylamine and benzyl alcohol generated. In addition, the catalysts and solvents used in the production process can be separated from the mixture and reused through filtration and distillation, resulting in high atom utilization and aligning with the theme of green and environmentally friendly production.

[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for the preparation of dibenzylamine, characterized in that: Specifically, Step 1: uniformly mix benzaldehyde, liquid ammonia and benzyl chloride, and then react at 60-80℃ and 10-15MPa for 4-6h; after the reaction is completed, add deionized water to terminate the reaction, stand to separate layers, wash the oil phase with deionized water, and obtain N-benzylidene benzylamine; Step 2: uniformly mix N-benzylidene benzylamine, ethanol and Raney nickel catalyst, and then introduce hydrogen, and react at 90-120℃ for 0.5-2h; after the reaction is completed, cool, filter, distill the filtrate after filtration to remove ethanol, benzylamine and benzyl alcohol, finally heat to 300-310℃, rectify, cool, and obtain dibenzylamine.

2. A process for the preparation of dibenzylamine according to claim 1, characterized in that: The mass ratio of benzaldehyde, liquid ammonia and benzyl chloride is (3-7):(0.5-1.5):(4-8).

3. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: The mass ratio of N-benzylidene benzylamine, ethanol and Raney nickel catalyst is (8-10):(4-8):(0.05-0.2).

4. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: In step 1, the mass ratio of deionized water used to terminate the reaction to liquid ammonia is 1:(0.8-1.2), and the deionized water is replaced by ammonia water, which is obtained by distilling the water phase after standing to separate layers and condensing.

5. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: In the Raney nickel catalyst, the content of nickel is 90%-100%, and the Raney nickel catalyst filtered out in step 2 is reused.

6. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: In step 2, the ethanol distilled from the filtrate after filtration is reused, and the distillation temperature is controlled at 75-90℃.

7. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: When removing benzylamine, the distillation temperature is controlled at 185-200℃.

8. The process for the preparation of dibenzylamine as claimed in claim 1, wherein: When removing benzyl alcohol, the distillation temperature is controlled at 205-220℃.

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