Preparation method of sterically hindered amine

Abstract

The invention belongs to the technical field of amine compounds, particularly relates to the field of IPC C07C213, and more particularly relates to a preparation method of steric hindrance amine. Comprising the following steps: step 1, ammoniating alcohol: carrying out ammoniation reaction on alcohol and amine under the condition of hydrogen in the presence of a heterogeneous catalyst to obtain a secondary amine intermediate; 2, secondary amine alkylation: carrying out a hydrogenation reaction on the secondary amine intermediate and an alkylation reagent in the presence of a heterogeneous catalyst in the presence of hydrogen to obtain a crude product; and step 3, rectification: removing water and light fractions from the crude product to obtain the product. Compared with a traditional tertiary amine catalyst, such as bis (dimethylamino) ethyl ether, pentamethyldiethylenetriamine and triethylene diamine, the steric hindrance amine prepared by the preparation method disclosed by the invention has excellent catalytic activity and ageing resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of amine compounds, and more specifically, to a method for preparing a sterically hindered amine. Background Art

[0002] Traditional tertiary amine catalysts are widely used in a variety of organic transformation reactions in organic synthetic chemistry. Its molecular structure contains ether units and tertiary amine groups, has significant alkalinity and strong nucleophilicity, and is easily oxidized by oxidants to form nitrogen oxides. In addition, it can also undergo nucleophilic substitution reactions with alkyl halides to generate corresponding quaternary ammonium salt compounds. However, this type of catalyst is prone to a significant decrease in activity after storage and aging, which limits its application. Steric hindered amines are organic amine compounds with an amino group connected to a tertiary carbon atom or a secondary carbon atom and having a steric hindered amine effect. The steric hindrance effect is used to effectively adjust its application performance, making it have better stability, activity and selectivity.

[0003] Chinese invention patent CN118239848A discloses a sterically hindered amine and its preparation method and application. The sterically hindered amine has a group with a strong steric effect, has a good removal effect on hydrogen sulfide and thiol organic sulfur, has a low CO2 co-absorption rate, and has a high desulfurization selectivity, but does not involve research on stability in the catalytic field. Summary of the invention

[0004] The present invention provides a method for preparing a sterically hindered amine, comprising the following steps:

[0005] Amination of alcohols: alcohols and amines undergo amination reaction in the presence of a heterogeneous catalyst under hydrogen conditions to obtain secondary amine intermediates;

[0006] Secondary amine alkylation: A secondary amine intermediate and an alkylating agent are subjected to a hydrogenation reaction under hydrogen conditions in the presence of a heterogeneous catalyst to obtain a crude product;

[0007] Distillation: Remove water and light fractions from the crude product to obtain.

[0008] The research in this application found that by selecting the process routes of alcohol amination and secondary amine alkylation, the presence of steric hindrance groups is formed through non-linear substituent groups with steric hindrance structures, which limits the reactivity of the hydrogen atoms connected to the nitrogen atoms of the hindered amines, ensures the stability of the structure and performance, improves the storage stability under special environments, and broadens the application scenarios.

[0009] The step 1 comprises: mixing amine with alcohol within 1-5 hours.

[0010] Preferably, the step 1 comprises: mixing the amine with the alcohol within 3-5 hours.

[0011] The amination reaction time is 3-8h, the temperature is 70-140°C, and the pressure is 3-7MPa.

[0012] Preferably, the amination reaction time is 5-8 h, the temperature is 70-120° C., and the pressure is 5-7 MPa.

[0013] The present application has found that in step 1, the amine is mixed with the alcohol within 1-5 hours, and the amination reaction time is 3-8 hours, the temperature is 70-140°C, and the pressure is 3-7MPa, which can reduce the content of by-products. It may be that the specific feeding method reduces the occurrence of violent amine-alcohol reaction and avoids the temperature fluctuation caused by it.

[0014] Further studies have found that by limiting the molar ratio of alcohol to amine to 1:(4-8), the reaction rate can be increased while the purity of the secondary amine intermediate can be increased to more than 80%, avoiding the impact of by-products on the subsequent secondary amine alkylation. It may be that the amination rate and the temperature rise of the system are balanced under a specific ratio of reactants, avoiding excessive amination and thus controlling the reaction equilibrium to move toward the direction of forming secondary amine intermediates.

[0015] The step 2 comprises: mixing an alkylating agent with a secondary amine intermediate within 1-6 hours.

[0016] Preferably, step 2 comprises: mixing the alkylating agent with the secondary amine intermediate within 4-6 hours.

[0017] Further preferably, the step 2 comprises: mixing the alkylating agent with the secondary amine intermediate within 5-6 hours.

[0018] The temperature of the hydrogenation reaction is 100-140° C. and the pressure is 1-5 MPa.

[0019] Preferably, the temperature of the hydrogenation reaction is 100-120° C. and the pressure is 2-5 MPa.

[0020] Further preferably, the temperature of the hydrogenation reaction is 120° C. and the pressure is 2-3 MPa.

[0021] In step 2, the alkylating agent is mixed with the secondary amine intermediate within 1-6 hours, and the temperature of the hydrogenation reaction is 100-140° C. and the pressure is 1-5 MPa, which can increase the purity of the sterically hindered amine to more than 80%, and the by-product is less than 10%. It may be that the specific reaction conditions reduce the reaction between the by-products produced in the alcohol amination step and the reaction products such as the alkylating agent.

[0022] The molar ratio of the alcohol to the amine is 1:(4-8).

[0023] Preferably, the molar ratio of the alcohol to the amine is 1:(4-7).

[0024] More preferably, the molar ratio of the alcohol to the amine is 1:(5-7).

[0025] The molar ratio of the secondary amine intermediate to the alkylating agent is 1:(1.5-7).

[0026] Preferably, the molar ratio of the secondary amine intermediate to the alkylating agent is 1:(1.5-5).

[0027] Further preferably, the molar ratio of the secondary amine intermediate to the alkylating agent is 1:(1.5-4).

[0028] The alcohol includes at least one of ethylene glycol, diethylene glycol, ethanolamine, diethanolamine, N-methyldiethanolamine, and N,N-dimethylethanolamine.

[0029] Preferably, the alcohol includes at least one of diethylene glycol, N-methyldiethanolamine, and N,N-dimethylethanolamine.

[0030] The amine includes at least one of anhydrous ammonia, methylamine, ethylamine, propylamine and butylamine.

[0031] Preferably, the amine includes at least one of methylamine, ethylamine and propylamine.

[0032] The alkylating agent includes at least one of formaldehyde, acetaldehyde, acetone, isobutyraldehyde and methyl ethyl ketone.

[0033] Preferably, the alkylating agent comprises at least one of formaldehyde, acetaldehyde and acetone.

[0034] The heterogeneous catalyst includes one of metal-loaded activated carbon, metal-loaded alumina, metal-loaded silicon oxide, and metal-loaded molecular sieve carrier.

[0035] Preferably, the metal includes at least one of copper, nickel, zinc, magnesium, ruthenium, palladium and platinum.

[0036] Further preferably, the metal includes at least one of ruthenium, palladium, platinum, and copper-nickel.

[0037] Beneficial Effects

[0038] 1. The process routes of alcohol amination and secondary amine alkylation are selected to prepare sterically hindered amines with excellent catalytic activity.

[0039] 2. In step 1, the amine is mixed with the alcohol within 1-5 hours, and the amination reaction time is 3-8 hours, the temperature is 70-140° C., and the pressure is 3-7 MPa, which can reduce the content of by-products.

[0040] 3. By limiting the molar ratio of alcohol to amine to 1:(4-8), the reaction rate can be increased while the purity of the secondary amine intermediate can be increased to more than 80%.

[0041] 4. Step 2: Mix the alkylating agent with the secondary amine intermediate within 1-6 hours, and the temperature of the hydrogenation reaction is 100-140°C and the pressure is 1-5MPa, which can increase the purity of the sterically hindered amine to more than 80% and the by-products to less than 10%.

[0042] 5. Compared with traditional tertiary amine catalysts, such as bis(dimethylaminoethyl)ether, pentamethyldiethylenetriamine, and triethylenediamine, the sterically hindered amine prepared in the present application has both excellent catalytic activity and aging resistance. DETAILED DESCRIPTION

[0043] Example 1

[0044] A method for preparing a sterically hindered amine comprises the following steps:

[0045] Step 1, amination of alcohol: The reaction equation is shown in Formula 1. The experiment was carried out in a 500mL stirred autoclave. 100g of diethylene glycol was placed in an autoclave filled with the corresponding copper-nickel metal-loaded catalyst (SNCAT-1805TE of Shanghai Xunkai New Materials Technology Co., Ltd.), and the reactor was purged with nitrogen. The reactor was pressurized to 5.0MPa with hydrogen, and the mixture was heated to a reaction temperature of 120°C by an electric heating system. Under the conditions of reaching the reaction temperature and pressure, 220g of ethylamine was added at a rate of 44g / h in 5h with the help of a high-pressure peristaltic pump, and the stirring speed was 800rpm. After the addition was completed, the reaction temperature was 120°C and the reaction pressure was 5.0MPa, and the reaction was performed for 8h to obtain diethylaminoethyl ether. The catalyst used was copper-nickel-loaded alumina, and the amount was 8wt% (based on diethylene glycol).

[0046]

[0047] Step 2, secondary amine alkylation: The reaction equation is shown in Formula 2. The experiment was carried out in a 500mL stirred autoclave. 100g of diethylaminoethyl ether was placed in an autoclave filled with the corresponding palladium-loaded activated carbon catalyst, and the reactor was purged with nitrogen. The reactor was pressurized to 2.0MPa with hydrogen, and the mixture was heated to a reaction temperature of 120°C by an electric heating system. When the reaction temperature and pressure conditions were reached, 220g of 40wt% acetaldehyde aqueous solution was added at a uniform rate within 5h by means of a high-pressure peristaltic pump until the reaction no longer absorbed hydrogen, and the reaction was terminated. During the period, the stirring speed was 800rpm, the reaction temperature was 120°C, and the reaction pressure was 2.0MPa. The amount of catalyst was 0.1wt% (based on diethylaminoethyl ether).

[0048]

[0049] Step 3, distillation: The reaction solution obtained in step 2 is filtered and the crude product is fed into a glass tower distillation column. In the first step, the water in the reaction is removed by atmospheric distillation at a temperature of 100°C. In the second step, the light fraction is removed at a temperature of 90°C under vacuum at -0.1MPa. The temperature is then continued to rise to 130°C to obtain a 97.8% pure product of diethylaminoethyl ether from the top of the distillation column.

[0050] Example 2

[0051] A method for preparing a sterically hindered amine comprises the following steps:

[0052] Step 1, amination of alcohol: The reaction equation is shown in Formula 3. The experiment was carried out in a 500mL stirred autoclave. 100g of diethylene glycol was placed in an autoclave filled with the corresponding copper-nickel loaded silica catalyst, and the reactor was purged with nitrogen. The reactor was pressurized to 5.0MPa with hydrogen, and the mixture was heated to a reaction temperature of 80°C by an electric heating system. When the reaction temperature and pressure conditions were reached, 180g of anhydrous amine was added at a rate of 36g / h for 5h with the help of a high-pressure peristaltic pump. The stirring speed was 800rpm. The reaction temperature was 80°C and the reaction pressure was 5.0MPa. The reaction was carried out for 8h to obtain dimethylaminoethyl ether. The catalyst used was 12wt% (based on diethylene glycol).

[0053]

[0054] Step 2, secondary amine alkylation: The reaction equation is shown in Formula 4. The experiment was carried out in a 500mL stirred autoclave. 100g of dimethylaminoethyl ether was placed in an autoclave filled with the corresponding ruthenium-loaded activated carbon catalyst, and the reactor was purged with nitrogen. The reactor was pressurized to 2.5MPa with hydrogen, and the mixture was heated to a reaction temperature of 120°C by an electric heating system. When the reaction temperature and pressure conditions were reached, 220g of acetone was added within 5h with the help of a high-pressure peristaltic pump. The reaction was terminated until the reaction no longer absorbed hydrogen. The stirring speed was 800rpm. The reaction temperature was 120°C and the reaction pressure was 2.5MPa. The amount of catalyst was 0.1wt% (based on dimethylaminoethyl ether).

[0055]

[0056] Step 3, distillation: The reaction solution obtained in step 2 is filtered and the crude product is fed into a glass tower distillation column. In the first step, the water in the reaction is removed by atmospheric distillation at a temperature of 100°C. In the second step, the light fraction is removed at a temperature of 90°C under vacuum at -0.1MPa. The temperature is then continued to rise to 130°C to obtain a 96.5% pure product, diisopropylmethylaminoethyl ether, from the top of the distillation column.

[0057] Example 3

[0058] A method for preparing a sterically hindered amine comprises the following steps:

[0059] Step 1, amination of alcohol: The reaction equation is shown in Formula 5. The experiment was carried out in a 500 mL stirred autoclave. 100 g of N-methyldiethanolamine was placed in an autoclave filled with the corresponding copper-nickel loaded molecular sieve catalyst, and the reactor was purged with nitrogen. The reactor was pressurized to 7.0 MPa with hydrogen, and the mixture was heated to a reaction temperature of 120°C by an electric heating system. When the reaction temperature and pressure conditions were reached, 340 g of isopropylamine was added at a rate of 68 g / h for 5 h by means of a high-pressure peristaltic pump. The stirring speed was 800 rpm. The reaction temperature was 70°C and the reaction pressure was 7.0 MPa. The reaction was carried out for 8 h to obtain diisopropylmethyldiethylenetriamine.

[0060] The amount of the catalyst used was 5 wt% (based on N-methyldiethanolamine).

[0061]

[0062] Step 2, secondary amine alkylation: The reaction equation is shown in Formula 6. The experiment was carried out in a 500mL stirred autoclave. 100g of diisopropylmethyldiethylenetriamine was placed in an autoclave filled with the corresponding platinum-loaded activated carbon catalyst, and the reactor was purged with nitrogen. The reactor was pressurized to 3.0MPa with hydrogen, and the mixture was heated to a reaction temperature of 120°C by an electric heating system. When the reaction temperature and pressure conditions were reached, 310g of 44wt% formaldehyde aqueous solution was added within 5h by means of a high-pressure peristaltic pump. The reaction was terminated when the reaction no longer absorbed hydrogen. The stirring speed was 800rpm. The reaction temperature was 120°C and the reaction pressure was 3.0MPa.

[0063] The amount of the catalyst used was 0.1 wt% (based on diisopropylmethyldiethylenetriamine).

[0064]

[0065] Step 3, distillation: The reaction liquid obtained in step 2 is filtered and the crude product is fed into a glass tower distillation column. In the first step, the water in the reaction is removed by atmospheric distillation at a temperature of 100°C. In the second step, the light fraction is removed at a temperature of 90°C under vacuum at -0.1MPa. The temperature is then raised to 130°C to obtain a 98.1% pure product, diisopropyltrimethyldiethyltriamine, from the top of the distillation column.

[0066] Performance Testing Methods

[0067] 1. During the reaction, the compositions of the products of step 1 and step 2 in Examples 1-3 were monitored by gas chromatography. The analysis procedure was as follows: chromatographic column DB-5, length: 60 m; inner diameter: 0.32 mm; carrier gas: helium; temperature program: 80° C., then increased to 260° C. at 5° C. / min, and finally maintained at 260° C. for 10 min. The results are listed in Tables 1-6, wherein Table 1 is the composition of the product of step 1 in Example 1, Table 2 is the composition of the product of step 2 in Example 1, Table 3 is the composition of the product of step 1 in Example 2, Table 4 is the composition of the product of step 2 in Example 2, Table 5 is the composition of the product of step 1 in Example 3, and Table 6 is the composition of the product of step 2 in Example 1.

[0068] 2. Take 1 part of the product of Example 1, the product of Example 2, the product of Example 3, BDMAEE (bis(dimethylaminoethyl)ether), PMDETA (pentamethyldiethylenetriamine), and TEDA (triethylenediamine) respectively and mix them with 207 parts of product liquid to obtain 6 test samples, which are named as serial numbers 1-6 respectively. The product liquid consists of 133 parts of toluene isocyanate, 74 parts of n-butanol, and 100 parts of toluene.

[0069] Catalytic activity test: The above 6 test samples were placed at a rated temperature of 40°C and a rotation speed of 1000 rpm. After a rated time of 1 minute, the isocyanate content (-NCOwt%) was tested. The test results are shown in Table 7.

[0070] Test method:

[0071] Accurately weigh about 3g of sample and put it in a clean conical flask. Add 10mL of anhydrous toluene to dissolve the sample. Use a pipette to add 20.0mL of di-n-butylamine toluene solution and shake to mix the solution in the flask evenly. Let it stand at room temperature for 30mins. Add 50mL of isopropanol and use bromocresol green as an indicator. Titrate with 0.5mol / L HCL standard solution. The end point is when the solution changes from blue to yellow and there is no color change for 15s.

[0072] W NCO =(V0-V S )*C*42 / (1000m)*100%

[0073] Where:

[0074] V0- Volume of hydrochloric acid standard solution consumed in blank titration mL

[0075] V S - Volume of hydrochloric acid standard solution consumed in sample titration mL

[0076] C- is the concentration of hydrochloric acid solution mol / L

[0077] m-sampling volume g

[0078] 42- constant NCO group molar mass g / mol

[0079] 3. Take 1 part of the product of Example 1, the product of Example 2, the product of Example 3, BDMAEE (bis(dimethylaminoethyl)ether), PMDETA (pentamethyldiethylenetriamine), TEDA (triethylenediamine), 74 parts of n-butanol and 10 parts of aging agent-1-chlorotrifluoropropylene to form component A, and obtain 6 test samples, which are named as serial numbers 1-6, and aged in a 50°C oven for 48h. 133 parts of p-toluene isocyanate and 100 parts of toluene form component B. Storage stability determination: Mix component A and component B at a rated temperature of 40°C, test the content of isocyanate (-NCOwt%), obtain the initial (-NCOwt%), record it as W0, the speed is 1000rpm, and the content of isocyanate (-NCOwt%) is tested again after a rated time of 1 minute to obtain the content of isocyanate (-NCOwt%) after the change, record it as W1, change = W1-W0, and the test results are shown in Table 8.

[0080] Performance test data

[0081] Table 1

[0082] Serial number Amine addition time / h Reaction time / h Diethylene glycol Ethylamine Bisethylaminoethyl ether By-products 1 1 3 22.3％ 3.2％ 68.9％ 5.6％ 2 3 5 13.6％ 4.8％ 74.9％ 6.7％ 3 5 6 4.3％ 3.6％ 85.0％ 7.1％ 4 5 8 1.2％ 2.5％ 88.1％ 8.2％

[0083] Table 2

[0084] Serial number Add acetaldehyde time / h Bisethylaminoethyl ether Acetaldehyde Bis(diethylaminoethyl)ether By-products 1 1 61.3％ 1.2％ 20.3％ 17.2％ 2 3 18.2％ 2.4％ 65.6％ 13.8％ 3 5 5.5％ 2.5％ 85.1％ 6.9％ 4 End of reaction 0.3％ 0.1％ 93.9％ 5.7

[0085] Table 3

[0086] Serial number Amine addition time / h Reaction time / h Diethylene glycol Methylamine Bismethylaminoethyl ether By-products 1 1 3 16.3％ 5.6％ 74.8％ 3.3％ 2 3 5 12.6％ 3.2％ 80.3％ 3.9％ 3 5 6 8.2％ 3.1％ 83.5％ 5.2％ 4 5 8 3.6％ 2.7％ 86.9％ 6.8％

[0087] Table 4

[0088] Serial number Acetone addition time / h Bismethylaminoethyl ether acetone Bis(diisopropyl)methylaminoethyl ether By-products 1 1 54.3％ 3.6％ 28.7％ 13.4％ 2 3 25.7％ 3.1％ 61.4％ 9.8％ 3 5 8.2％ 2.4 83.1％ 6.3％ 4 End of reaction 0.5％ 1.2％ 92.4％ 5.9％

[0089] Table 5

[0090]

[0091] Table 6

[0092]

[0093] Table 7

[0094]

[0095]

[0096] Table 8

[0097] Code Initial (-NCOwt%) change% 1 30.9％ +15.3％ 2 25.3％ +5.0％ 3 32.1％ +5.6％ 4 42.5％ +96.7％ 5 49.1％ +108.9％ 6 52.3％ +155.1％

[0098] According to the comparison between Table 7 and Table 8: The catalyst activity of the compounds of Examples 1-3 showed excellent stability before and after aging, while the traditional products (BDMAEE, PMDETA, TEDA) had high initial catalytic activity but suffered serious losses after aging. In summary, the embodiments of the present invention have good storage stability and catalytic activity.

Claims

1. A method for preparing a sterically hindered amine, characterized in that: The following steps are involved: Amination of alcohols: alcohols and amines undergo amination reaction in the presence of hydrogen and a heterogeneous catalyst to obtain secondary amine intermediates; Secondary amine alkylation: a secondary amine intermediate and an alkylating agent are subjected to a hydrogenation reaction in the presence of hydrogen and a heterogeneous catalyst to obtain a crude product; Distillation: Remove water and light fractions from the crude product to obtain.

2. The method for preparing a sterically hindered amine according to claim 1, characterized in that: The step 1 comprises: mixing amine with alcohol within 1-5 hours.

3. The method for preparing the sterically hindered amine according to claim 2, characterized in that: The amination reaction time is 3-8h, the temperature is 70-140°C, and the pressure is 3-7MPa.

4. The method for preparing the sterically hindered amine according to claim 3, characterized in that: The step 2 comprises: mixing an alkylating agent with a secondary amine intermediate within 1-6 hours.

5. The method for preparing the sterically hindered amine according to claim 4, characterized in that: The temperature of the hydrogenation reaction is 100-140° C. and the pressure is 1-5 MPa.

6. The method for preparing the sterically hindered amine according to claim 1 or 5, characterized in that: The molar ratio of the alcohol to the amine is 1:(4-8).

7. The method for preparing a sterically hindered amine according to claim 6, characterized in that: The alcohol includes at least one of ethylene glycol, diethylene glycol, ethanolamine, diethanolamine, N-methyldiethanolamine, and N,N-dimethylethanolamine.

8. The method for preparing the sterically hindered amine according to claim 7, characterized in that: The amine includes at least one of anhydrous ammonia, methylamine, ethylamine, propylamine and butylamine.

9. The method for preparing a sterically hindered amine according to claim 8, characterized in that: The alkylating agent includes at least one of formaldehyde, acetaldehyde, acetone, isobutyraldehyde and methyl ethyl ketone.

10. The method for preparing a sterically hindered amine according to claim 9, characterized in that: The heterogeneous catalyst includes one of metal-loaded activated carbon, metal-loaded alumina, metal-loaded silicon oxide, and metal-loaded molecular sieve carrier.

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