A process for the manufacture of 3-aminomethyl-3,5,5-trimethylcyclohexylamine

Abstract

The present application relates to a kind of preparation methods of 3-aminomethyl-3,5,5-trimethylcyclohexane.The preparation method includes: isophorone nitrile, ammonia and hydrogen peroxide occur in the presence of modified titanium silicon catalyst and generate intermediate 1, and the obtained intermediate 1 occurs in the presence of hydrogenation catalyst and hydrogenation reaction generates 3-aminomethyl-3,5,5-trimethylcyclohexylamine.The method described in the present application can be operated at lower reaction pressure, reaction step is simple, yield is high, product is easy to purify and separate, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine, belonging to the field of organic synthesis. BACKGROUND

[0002] 3-aminomethyl-3,5,5-trimethylcyclohexylamine, referred to as IPDA for short, is an alicyclic diamine, which is applied in various industries, for example, can be used as a curing agent in epoxy resin production, can be used as a crosslinking agent, a coupling agent and a hydroxyl stabilizer and a special monomer in polyurethane production, and can be used as a raw material for synthesizing isophorone diisocyanate.

[0003] The mainstream production process of IPDA at present is isophorone nitrile amination and hydrogenation: first, isophorone nitrile and ammonia are reacted to generate isophorone nitrile imine through dehydration, and then the isophorone nitrile imine is hydrogenated to generate IPDA:

[0004]

[0005] DuPont (US5491264), BASF (US5371292A, CN1561260A) use liquid ammonia as an imination reactant and as a hydrogenation reaction solvent at the same time. Since liquid ammonia is introduced into the whole system, the ammonia partial pressure in the hydrogenation reaction system is relatively high, and therefore a relatively high reaction pressure needs to be adopted to ensure the hydrogenation reaction effect.

[0006] Deggusa (US5679860, US4429157A), Sumitomo (US5395972A, US5589596A) introduce a solvent methanol into the reaction system to solve the problem of high reaction pressure caused by ammonia partial pressure, thereby reducing the operating pressure, reducing the material requirement grade, and reducing the equipment investment. At the same time, it is found that since the methanol solvent is introduced, a methylated product of IPDA appears in the hydrogenation product, which is difficult to separate from IPDA, increases the energy consumption of separation, and reduces the product quality. Considering that ammonia still has a certain partial pressure, the reaction pressure is still relatively high.

[0007] In summary, the existing methods for preparing IPDA have problems such as high pressure, or high content of difficult-to-separate impurities (IPDA methylated product) (introduction of methanol as a solvent). SUMMARY

[0008] The purpose of the present application is to provide a method for preparing IPDA, by which a reaction liquid with a relatively low content of difficult-to-separate impurities can be obtained at a relatively low reaction pressure, the reaction steps are simple, the yield is high, and the product is easy to purify and separate.

[0009] The analysis of the process which has realized industrial production can see that the imination reaction of isophorone nitrile and ammonia is an equilibrium reaction, in order to move the imination reaction to the direction of the positive reaction, the use amount of ammonia is greatly excessive, which will lead to the high ammonia partial pressure in the whole reaction system, and the reaction pressure is increased. Similarly, we have studied the introduction of methanol solvent, and found that both the N-methylated product and the methylated product are generated in the imination stage, in which the methanol and liquid ammonia generate methylamine in the presence of imination catalyst, the methylamine and IPN generate the N-methylated product of IPDA in the presence of imination catalyst by imination reaction and further hydrogenation reaction; the methylated product of IPN is generated by the alkylation reaction of IPN and methanol in the presence of imination catalyst, and then the methylated product of IPNI is generated by the imination reaction of the methylated product of IPN and liquid ammonia, and further hydrogenation reaction generates the methylated product of IPDA. The specific reaction process is shown as follows:

[0010]

[0011]

[0012] Since the N-methylated product and the methylated product of IPDA are similar to the structure of IPDA, it is difficult to separate in the actual operation process, and therefore the generation of the two compounds needs to be avoided.

[0013] According to the research results, in order to achieve the above purpose, the C=O group is changed into C-NO2 by reaction, the influence of the imination reaction balance on the reaction does not need to be considered, the content of ammonia is low or does not contain ammonia in the hydrogenation reaction stage, the ammonia partial pressure is low or even zero, the reaction pressure is greatly reduced, and in addition, since the imination reaction is not involved, the N-alkylated product and the alkylated product of IPDA are avoided to be generated, and the separation difficulty is reduced.

[0014] The application adopts the following technical scheme:

[0015] A preparation method of IPDA, comprising the following steps:

[0016] (1) isophorone nitrile, ammonia and hydrogen peroxide react in the presence of a modified titanium-silicon catalyst to generate an intermediate 1;

[0017] (2) the obtained intermediate 1 generates 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine by hydrogenation reaction in the presence of a hydrogenation catalyst.

[0018] The reaction equation of the reaction is shown as follows:

[0019]

[0020] Considering that intermediate 1 is insoluble in water, in order to ensure that the reaction system does not separate into phases, step (1) of the present invention needs to be carried out in the presence of a solvent. The preferred solvent is a C1-4 alcohol, and more preferably methanol or ethanol.

[0021] Furthermore, in step (1), the mass ratio of isophorone nitrile to solvent is 1:1 to 20, preferably 1:5 to 10.

[0022] Furthermore, the reaction temperature used in step (1) is 30 to 90°C, preferably 40 to 70°C; the reaction pressure used is 0.1 to 1.0 MPa, preferably 0.1 to 0.3 MPa.

[0023] Furthermore, in step (1), the ammonia is liquid ammonia, and the molar ratio of isophorone nitrile, ammonia and hydrogen peroxide is 1:1 to 3:1.2 to 2.5, preferably 1:1.1 to 2.0:2 to 2.5.

[0024] Furthermore, the reaction in step (1) is carried out in a fixed bed packed with modified titanium-silicon catalyst. Isophorone nitrile, liquid ammonia, hydrogen peroxide and solvent are mixed and continuously passed from bottom to top through the fixed bed packed with modified titanium-silicon catalyst.

[0025] The modified titanium-silicon catalyst is a zinc- and rare-earth-modified titanium-silicon catalyst. Its preparation method can be found in patent CN115845915A, for example:

[0026] (1) Hydrolysis: Titanium source, silicon source, template agent and water are mixed and hydrolyzed to obtain hydrolysis products;

[0027] (2) Rare earth metal and zinc modification: Add rare earth metal source and zinc source to the hydrolysis product obtained in step (1) and carry out hydrothermal crystallization reaction to obtain crystallized product;

[0028] (3) Alkali metal modification: Add an alkali metal source to the crystallized product obtained in step (2), mix evenly to obtain an alkali metal modified product;

[0029] (4) Molding: The alkali metal modified product obtained in step (3) is dried and shaped to obtain the catalyst shaped product;

[0030] (5) Calcination: The catalyst forming product obtained in step (4) is calcined to obtain the modified titanium silicon catalyst.

[0031] The molar ratio of zinc to rare earth elements is 0.1–10 (e.g., 0.2, 0.5, 0.6, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, etc.). Other conditions can be found in CN115845915A, and will not be described in detail here. The catalyst of this invention significantly improves the conversion rate of the reaction in step (1).

[0032] Furthermore, in step (1) of the present invention, the amount of modified titanium-silicon catalyst is 0.01 to 1 g isophorone nitrile / (g catalyst·hour), preferably 0.1 to 0.2 g isophorone nitrile / (g catalyst·hour).

[0033] Furthermore, the reaction solution obtained in step (1) of this invention can be separated by distillation to obtain intermediate 1 for use in step (2) of the reaction, or the reaction solution containing intermediate 1 can be used directly in step (2) of the reaction without separation. From the perspective of energy saving and reducing investment, it is preferable that the reaction solution containing intermediate 1 is used directly in step (2) of the reaction without separation.

[0034] In step (2) of the present invention, the reaction temperature is 60-150℃, preferably 100-120℃, and the reaction pressure is 1-12MPa, preferably 5-8MPa.

[0035] Furthermore, in step (2) of the present invention, the molar ratio of intermediate 1 to hydrogen is 1:10 to 200, preferably 1:40 to 100.

[0036] Furthermore, in step (2) of the present invention, the hydrogenation catalyst is a nickel-based or cobalt-based catalyst, selected from a supported catalyst or a Raney catalyst or a combination of both; preferably, the catalyst is a Raney nickel catalyst.

[0037] Preferably, the hydrogenation reaction in step (2) is carried out in a fixed bed packed with a hydrogenation catalyst, and the reaction liquid containing intermediate 1 and hydrogen obtained in step (1) pass from top to bottom through the fixed bed packed with the hydrogenation catalyst.

[0038] Furthermore, in step (2) of the present invention, the amount of hydrogenation catalyst is 0.01 to 1 g intermediate 1 / (g catalyst·hour), preferably 0.05 to 0.2 g intermediate 1 / (g catalyst·hour).

[0039] In the preparation method of this invention, the hydrogenation reaction solution can be purified to obtain IPDA product. In a specific embodiment, the specific separation steps are as follows: the hydrogenation reaction solution is first completely or partially separated from hydrogen, inert gas, ammonia, solvent, low-boiling impurities, and a portion of water in one or more distillation columns, wherein the solvent and liquid ammonia (in small amounts) can be recycled; other low-boiling impurities, water, and high-boiling impurities are completely or partially separated in the distillation columns to obtain IPDA.

[0040] Using the method described in this patent, isophorone nitrile can be efficiently converted into IPDA under relatively low reaction pressure, with a total conversion rate of 99.9% and a total selectivity of not less than 95.0% (based on isophorone nitrile).

[0041] The advantages of the preparation method of this invention are mainly reflected in:

[0042] It can be operated at relatively low reaction pressure, the reaction steps are simple, and the yield is high; it does not generate N-alkylation and alkylation products, the product is easy to purify and separate, and it is suitable for industrial production. Detailed Implementation

[0043] The present invention will be further described below with reference to the embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0044] The main raw materials involved in this invention were all purchased through commercial channels.

[0045] The testing instruments used in this embodiment are: Agilent 7820 for GC testing, and the sample is diluted 3 times with chromatographic methanol.

[0046] [Preparation Example 1] Preparation of Modified Titanium-Silicon Catalyst

[0047] The preparation process of the modified titanium-silicon catalyst is as follows: 2083.0 g of tetraethyl silicate and 91.0 g of tetraethyl titanate were mixed evenly and then added dropwise to a solution containing 51.0 g of tetrapropylammonium hydroxide (TPAOH) and 3600.0 g of water. Hydrolysis was carried out at 45 °C for 3 hours. Then, 22 g of Ce(NO3)3·6H2O and 10 g of Zn(NO3)2·6H2O were added, and the mixture was stirred at 40 °C for 36 hours. The solution was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 2 hours to obtain a crystallized reaction product. The crystallized reaction product was transferred to a beaker, and 3.5 g of KNO3 was added. The mixture was stirred at 50 °C for 8 hours. Finally, the modified crystallized product was dried, shaped, and calcined at 550 °C for 4 hours to obtain the modified microsphere titanium-silicon catalyst.

[0048] [Preparation Example 2] Preparation of Modified Titanium-Silicon Catalyst

[0049] The difference between the preparation of the modified titanium-silicon catalyst and Example 1 is that Zn(NO3)2·6H2O is not added.

[0050] Example 1

[0051] (1) Prepare a stainless steel tubular fixed bed reactor with an inner diameter of 15 mm and a length of 500 mm; and fill it with 50 g of the modified titanium-silicon catalyst prepared in the aforementioned preparation example 1.

[0052] The mass ratio of isophorone nitrile to methanol was controlled at 1:5. A mixed solution of isophorone nitrile and methanol was prepared and continuously fed into the reactor along with liquid ammonia and hydrogen peroxide aqueous solution via separate feed pumps. The feed flow rates were: isophorone nitrile methanol solution 30 g / h, liquid ammonia 0.57 g / h, and hydrogen peroxide aqueous solution (35 wt%) 5.89 g / h. The reaction temperature was controlled at 40℃, and the reaction pressure at 0.1 MPa. Intermittent sampling was performed on the reaction solution for GC analysis. After 6 hours of reaction, the reaction reached a steady state, with a conversion rate of 99.9% and a selectivity of 97.2% for intermediate 1.

[0053] (2) Prepare a stainless steel tubular fixed bed reactor with an inner diameter of 15 mm and a length of 500 mm; and fill it with 50 g of Raney nickel catalyst (purchased from Grace).

[0054] The reaction solution containing intermediate 1 obtained in step (1) was continuously fed into the reactor at a rate of 15.78 g / h using a feed pump. The hydrogen flow rate was controlled at 11.4 L / h, the reaction temperature at 100 °C, and the reaction pressure at 5 MPa. Intermittent sampling was performed on the reaction solution for GC analysis. It was found that the reaction reached a steady state after 4 h, with a conversion rate of 99.9% and an IPDA selectivity of 99.2%. No N-alkylation or alkylation products were detected.

[0055] The crude hydrogenation reaction liquid was separated by distillation. The distillation column had 30 trays. First, methanol, water and other low-boiling-point compounds were separated under a pressure of 20 kPa. Then, the pressure was reduced to 2.0 kPa, and the product with a purity of ≥99.7% was collected.

[0056] Example 2

[0057] (1) Same as in Example 1, prepare a stainless steel tubular fixed bed reactor with an inner diameter of 15 mm and a length of 500 mm; and fill it with 50 g of the modified titanium-silicon catalyst prepared in the aforementioned Example 1.

[0058] The mass ratio of isophorone nitrile to ethanol was controlled at 1:10. A mixed solution of isophorone nitrile and ethanol was prepared and continuously fed into the reactor along with liquid ammonia and hydrogen peroxide aqueous solution using separate feed pumps. The feed flow rates were: isophorone nitrile methanol solution 110 g / h, liquid ammonia 2.05 g / h, and hydrogen peroxide aqueous solution (35 wt%) 14.66 g / h. The reaction temperature was controlled at 70℃, and the reaction pressure at 0.3 MPa. Intermittent sampling was performed on the reaction solution for GC analysis. After 6 hours of reaction, the reaction reached a steady state, with a conversion rate of 99.9% and a selectivity of 97.8% for intermediate 1.

[0059] (2) Same as in Example 1, prepare a stainless steel tubular fixed bed reactor with an inner diameter of 15 mm and a length of 500 mm; and fill it with 50 g of Raney nickel catalyst (purchased from Grace).

[0060] The reaction solution containing intermediate 1 obtained in step (1) was continuously fed into the reactor using a 109 g / h feed pump. The hydrogen flow rate was controlled at 114 L / h, the reaction temperature at 120 °C, and the reaction pressure at 8 MPa. Intermittent sampling was performed on the reaction solution for GC analysis. It was found that the reaction reached a stable state after 2 hours, with a conversion rate of 99.9%, an IPDA selectivity of 99.3%, and no N-alkylation or alkylation products detected.

[0061] The crude hydrogenation reaction liquid was separated by distillation. The distillation column had 30 trays. First, methanol, water and other low-boiling-point compounds were separated under a pressure of 20 kPa. Then, the pressure was reduced to 2.0 kPa, and the product with a purity of ≥99.7% was collected.

[0062] Comparative Example 1

[0063] The only difference from Example 1 is that the catalyst in step (1) is the modified titanium-silicon catalyst prepared in Example 2, and the final conversion rate of intermediate 1 is 86.5%.

[0064] Comparative Example 2

[0065] The imidization reactor and the hydrogenation reactor are fixed beds with a diameter of 25 mm and a length of 1000 mm. The imidization reactor is filled with 100 g of activated alumina pellets (purchased from Dalian Haixin), and the hydrogenation reactor is filled with 200 g of Raney cobalt catalyst (purchased from Grace).

[0066] The raw materials IPN, liquid ammonia, and methanol were mixed and continuously fed into the imidization reactor at a feed rate of 20 g / h. The mass ratio of liquid ammonia, IPN, and methanol was 3:1:4. The imidization reaction temperature was controlled at 30℃, and the reaction pressure at 12 MPa. The imidized reaction solution from the imidization reactor outlet entered the hydrogenation reactor, where the hydrogenation reaction temperature was controlled at 130℃, and the reaction pressure at 12 MPa. GC analysis was performed on samples taken during the feeding process. After 9 hours, the reaction reached equilibrium. The conversion rate of IPN amination and hydrogenation to IPDA was calculated to be 99.9%, with an IPDA selectivity of 97.3%, of which the content of IPDA methylation products was 0.785%.

Claims

1. A process for the preparation of 3-aminomethyl-3,5,5-trimethylcyclohexylamine, characterized in that, The method comprises the following steps: (1) isophoronenitrile, ammonia and hydrogen peroxide react in the presence of a zinc and rare earth element modified titanium-silicon catalyst to form an intermediate 1; (2) the obtained intermediate 1 is subjected to a hydrogenation reaction in the presence of a hydrogenation catalyst to form 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine.

2. The method of claim 1, wherein, The step (1) is carried out in the presence of a solvent.

3. The method of claim 2, wherein, The solvent is a C1-4 alcohol.

4. The method of claim 3, wherein, The mass ratio of isophoronenitrile to the solvent is 1:1-20.

5. The method according to any one of claims 1 to 2, characterized in that, The reaction temperature of step (1) is 30-90℃, and the reaction pressure is 0.1-1.0 MPa.

6. The method according to any one of claims 1 to 3, characterized in that, The ammonia of step (1) is liquid ammonia, and the molar ratio of isophoronenitrile, ammonia and hydrogen peroxide is 1:1-3:1.2-2.

5.

7. The method according to any one of claims 1 to 4, characterized in that, The processing capacity of the modified titanium-silicon catalyst of step (1) is 0.01-1 g of isophoronenitrile / (g of catalyst·hour).

8. The method of claim 1, wherein, The reaction temperature of step (2) is 60-150℃, and the reaction pressure is 1-12 MPa.

9. The method according to claim 1 or 8, characterized in that, The molar ratio of intermediate 1 to hydrogen in step (2) is 1:10-200.

10. The method of claim 9, wherein, The molar ratio of intermediate 1 to hydrogen in step (2) is 1:40-100.

11. The method of claim 1, wherein, The hydrogenation catalyst of step (2) is a nickel-based or cobalt-based catalyst.

12. The method of claim 11, wherein, The hydrogenation catalyst of step (2) is selected from a supported catalyst, a Raney catalyst or a combination of the two.

13. The method of claim 12, wherein, The hydrogenation catalyst of step (2) is a Raney catalyst.

14. The method of any one of claims 1, 11-13, wherein, The processing capacity of the catalyst of step (2) is 0.01-1 g of intermediate 1 / (g of catalyst·hour).

Images