Preparation method of L-aminopropanol
L-aminopropanol is prepared by gas-solid phase reaction using modified perlite-supported zirconia catalyst, which solves the problems of complex operation, high risk and environmental pollution in the existing technology and realizes the production of L-aminopropanol with high purity and high yield.
Patent Information
- Application Number
- CN202510291810.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2045-03-12
AI Technical Summary
The existing preparation methods of L-aminopropanol have the problems of complex operation, high risk, high cost and serious environmental pollution, especially in the preparation process of 2-methylaziridine.
Modified perlite-supported zirconia catalyst was used to prepare 2-methylaziridine through a gas-solid phase reaction, which was then hydrolyzed to obtain L-aminopropanol. The catalyst was composed of zirconium oxide, strontium, nickel, and tin, and its acid-base dual functional sites were used to stabilize the reaction, thereby improving activity and selectivity.
The high-purity and high-yield preparation of L-aminopropanol is achieved, the process route is simplified, the production cost is reduced, and environmental pollution is reduced.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of preparation of aminopropanol, and specifically relates to a preparation method of L-aminopropanol. Background Art
[0002] L-aminopropanol is a key intermediate in the synthesis of the third-generation quinolone antibiotic levofloxacin, which boasts a broad antimicrobial spectrum, strong antimicrobial activity, minimal toxicity, and no cross-resistance with other antibiotics. Furthermore, as a chiral modifier, L-aminopropanol is widely used in racemate resolution, resulting in significant market demand.
[0003] Research on the synthesis method of L-aminopropanol can be mainly divided into three methods. One is the chiral separation method, in which the main process is to prepare DL-aminopropanol and then obtain L-aminopropanol by chiral separation. However, due to the higher industrial difficulty of chiral separation, the second method is generally adopted in industrial production, in which the corresponding optically active alanine or its derivatives are reduced. The industrial production mainly uses reducing agents such as KBH4, LiBH4, NaBH4 or LiAlH4, but these reducing agents are expensive, dangerous, and have a complicated post-processing process, large environmental pollution, and great limitations. The third method is to first prepare 2-methylaziridine, and then prepare L-aminopropanol by hydrolysis of 2-methylaziridine. The difficulty of this method is the preparation of 2-methylaziridine.
[0004] For the preparation of 2-methylaziridine, concentrated sulfuric acid is first added to generate 2-aminosulfuric acid isopropyl ester intermediate, which is stable and soluble in water. Subsequently, the concentrated sulfuric acid intermediate is reacted with concentrated sodium hydroxide aqueous solution to finally generate methylaziridine. First, the operation of this liquid phase production method is quite complicated, involving the control of multiple steps and reaction conditions, which increases the technical difficulty of production. Secondly, due to the use of strong acids and bases such as concentrated sulfuric acid, the operation process has a high risk and needs to take strict safety measures. In addition, due to the complex production process, the production cost is relatively high, which limits the scale and efficiency of production to a certain extent. This production method also has the problem of environmental pollution. Especially when treating wastewater, it is necessary to process the inorganic salts produced. Therefore, although the liquid phase kettle method for producing methylaziridine has certain advantages, such as higher yield, its complicated operation, high risk, high production cost and environmental pollution problems make it urgent to seek a safer, more economical and environmentally friendly production method.
[0005] Therefore, it is necessary to explore a novel preparation method of L-aminopropanol. Summary of the Invention
[0006] The present invention aims to provide a method for preparing L-aminopropanol. The method has a simple process route, is environmentally friendly, and has high yield and purity of the prepared L-aminopropanol.
[0007] The preparation method of L-aminopropanol of the present invention comprises the following steps:
[0008] (1) Dissolve zirconium oxychloride in deionized water, heat it to 70-73°C, add ammonia water dropwise thereto to prepare a sol, then add expanded perlite to the sol and stir to dissolve, age, dry and calcine at room temperature to prepare a perlite-loaded zirconium oxide carrier;
[0009] (2) Strontium nitrate, nickel chloride and stannous chloride are dissolved in deionized water to prepare a mixed solution, and an equal volume of the mixed solution is impregnated on a perlite-supported zirconia support. After the impregnation is completed, the water is evaporated, dried and calcined to prepare a modified perlite-supported zirconia catalyst;
[0010] (3) isopropanolamine is pumped into a preheating vaporizer through a flow meter and mixed with nitrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. The fixed bed reactor is filled with a modified perlite-supported zirconia catalyst. After the reaction, the material is condensed and the gas-liquid is separated. The resulting liquid phase is subjected to reduced pressure distillation to prepare 2-methylaziridine;
[0011] (4) 2-Methylaziridine and tetrabutylammonium bromide are mixed evenly, cooled to 0°C, and then water is added dropwise to carry out a hydrolysis reaction. After the hydrolysis is completed, L-aminopropanol is prepared by post-treatment.
[0012] in:
[0013] In step (1), the mass ratio of zirconium oxychloride to deionized water is 1:10.
[0014] In step (1), the molar ratio of zirconium oxychloride to ammonia water is 1:2.5-2.7.
[0015] In step (1), the mass ratio of zirconium oxychloride to expanded perlite is 1.2-1.3:1.
[0016] The stirring and dissolving time in step (1) is 1.5-1.8 hours, and the stirring and dissolving temperature is 50-55°C.
[0017] In step (1), the aging temperature is room temperature and the aging time is 24 hours.
[0018] In step (1), the drying temperature is 100-103°C and the drying time is 12 hours.
[0019] In step (1), the calcination temperature is 640-645° C. and the calcination time is 2.5 h.
[0020] In step (2), the temperature for evaporating water is 85°C, the drying temperature is 110-113°C, the drying time is 16 hours, the roasting temperature is 465-470°C, and the roasting time is 4.8 hours.
[0021] In the modified perlite-supported zirconia catalyst prepared in step (2), the mass of strontium oxide accounts for 22-24% of the total mass of the catalyst, the mass of nickel oxide accounts for 8-10% of the total mass of the catalyst, the mass of tin oxide accounts for 11-13% of the total mass of the catalyst, and the mass of perlite-supported zirconia accounts for 55-57% of the total mass of the catalyst.
[0022] The volume space velocity of the modified perlite-supported zirconia catalyst in the fixed bed reactor in step (3) is 0.53-0.55h -1 .
[0023] In step (3), nitrogen is used as circulating gas to maintain the reaction pressure in the fixed bed reactor at normal pressure and the reaction temperature at 450°C.
[0024] In step (3), the distillation temperature is 50° C. and the distillation pressure is 0.03 MPa.
[0025] In step (4), the mass ratio of 2-methylaziridine, tetrabutylammonium bromide and water is 1:0.038:4.3.
[0026] In step (4), the water was added dropwise for 4 h, and the temperature of the system was controlled to be 0° C. After the addition was completed, the hydrolysis reaction was carried out at room temperature for 20 h.
[0027] The post-treatment in step (4) is to allow the reaction to stand for separation after completion of the reaction, extract the aqueous layer with dichloromethane and combine it with the organic layer, then distill under reduced pressure to remove the dichloromethane, and finally perform vacuum distillation to collect the fraction at 72-73° C. to prepare L-aminopropanol.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] (1) The method for preparing L-aminopropanol of the present invention comprises the following steps: first, using isopropanolamine as a reaction raw material and nitrogen as a circulating gas to carry out a gas-solid phase reaction to prepare 2-methylaziridine; then, hydrolyzing the 2-methylaziridine to prepare L-aminopropanol. When preparing 2-methylaziridine, modified perlite-supported zirconia is used as a catalyst, and perlite-supported zirconia is used as a catalyst carrier. The introduced zirconia can improve the thermal stability of the expanded perlite carrier at high temperatures and further increase the surface area of the carrier through its own porous structure, thereby improving the dispersibility of the active components and making the catalyst carrier have both acidic and basic sites. Strontium, nickel, and tin are used as the active components of the catalyst. The acid-base dual-functional sites in the catalyst can stably generate methylaziridine. The addition of strontium can effectively prevent the occurrence of deamination reaction or intermolecular condensation reaction. The addition of nickel can effectively prevent the acidic sites from promoting intermolecular dehydration. The presence of tin can promote the conversion of isopropanolamine. The interaction between strontium and nickel promotes the synthesis of methylaziridine. The presence of zirconia in the carrier can effectively prevent the loss of active components. Therefore, the support and active components in the catalyst work synergistically to exert good catalytic activity on the direct cyclization reaction of isopropanolamine.
[0030] (2) The method for preparing L-aminopropanol of the present invention is simple in process, wherein isopropanolamine is directly dehydrated and cyclized to synthesize 2-methylaziridine, and then directly hydrolyzed to obtain L-aminopropanol. This is a green chemical synthesis method, and the purity and yield of the prepared L-aminopropanol are high. DETAILED DESCRIPTION
[0031] The present invention will be further described below with reference to the examples.
[0032] Example 1
[0033] The preparation method of L-aminopropanol described in this embodiment 1 consists of the following steps:
[0034] (1) Dissolve zirconium oxychloride in deionized water, heat it to 71°C, add ammonia water dropwise thereto to prepare a sol, then add expanded perlite to the sol and stir to dissolve, age, dry and calcine at room temperature to prepare a perlite-loaded zirconium oxide carrier;
[0035] (2) Strontium nitrate, nickel chloride and stannous chloride are dissolved in deionized water to prepare a mixed solution, and an equal volume of the mixed solution is impregnated on a perlite-supported zirconia support. After the impregnation is completed, the water is evaporated, dried and calcined to prepare a modified perlite-supported zirconia catalyst;
[0036] (3) isopropanolamine is pumped into a preheating vaporizer through a flow meter and mixed with nitrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. The fixed bed reactor is filled with a modified perlite-supported zirconia catalyst. After the reaction, the material is condensed and the gas-liquid is separated. The resulting liquid phase is subjected to reduced pressure distillation to prepare 2-methylaziridine;
[0037] (4) 2-Methylaziridine and tetrabutylammonium bromide are mixed evenly, cooled to 0°C, and then water is added dropwise to carry out a hydrolysis reaction. After the hydrolysis is completed, L-aminopropanol is prepared by post-treatment.
[0038] in:
[0039] In step (1), the mass ratio of zirconium oxychloride to deionized water is 1:10.
[0040] The molar ratio of zirconium oxychloride to ammonia water in step (1) is 1:2.6.
[0041] In step (1), the mass ratio of zirconium oxychloride to expanded perlite is 1.25:1.
[0042] The stirring and dissolving time in step (1) is 1.6 h, and the stirring and dissolving temperature is 53°C.
[0043] The aging temperature in step (1) is room temperature and the aging time is 24 hours.
[0044] In step (1), the drying temperature is 102°C and the drying time is 12 hours.
[0045] In step (1), the calcination temperature is 643° C. and the calcination time is 2.5 h.
[0046] In step (2), the temperature for evaporating water is 85°C, the drying temperature is 112°C, the drying time is 16 hours, the roasting temperature is 467°C, and the roasting time is 4.8 hours.
[0047] In the modified perlite-supported zirconia catalyst prepared in step (2), the mass of strontium oxide accounts for 23% of the total mass of the catalyst, the mass of nickel oxide accounts for 9% of the total mass of the catalyst, the mass of tin oxide accounts for 12% of the total mass of the catalyst, and the mass of perlite-supported zirconia accounts for 56% of the total mass of the catalyst.
[0048] The volume space velocity of the modified perlite-supported zirconia catalyst in the fixed bed reactor in step (3) is 0.54 h -1 .
[0049] In step (3), nitrogen is used as circulating gas to maintain the reaction pressure in the fixed bed reactor at normal pressure and the reaction temperature at 450°C.
[0050] In step (3), the distillation temperature is 50° C. and the distillation pressure is 0.03 MPa.
[0051] In step (4), the mass ratio of 2-methylaziridine, tetrabutylammonium bromide and water is 1:0.038:4.3.
[0052] In step (4), the water was added dropwise for 4 h, and the temperature of the system was controlled to be 0° C. After the addition was completed, the hydrolysis reaction was carried out at room temperature for 20 h.
[0053] The post-treatment in step (4) is to allow the reaction to stand for separation after completion of the reaction, extract the aqueous layer with dichloromethane and combine it with the organic layer, then distill under reduced pressure to remove the dichloromethane, and finally perform vacuum distillation to collect the fraction at 72-73° C. to prepare L-aminopropanol.
[0054] According to analysis, the conversion rate of isopropanolamine in the preparation of 2-methylaziridine in step (3) was 95.32%, and the selectivity of 2-methylaziridine was 93.28%. The yield of L-aminopropanol prepared in step (4) was 86.46%, and the purity of L-aminopropanol was 99.63%.
[0055] Example 2
[0056] The preparation method of L-aminopropanol described in this embodiment 2 consists of the following steps:
[0057] (1) Dissolve zirconium oxychloride in deionized water, heat it to 70°C, add ammonia water dropwise thereto to prepare a sol, then add expanded perlite to the sol and stir to dissolve, age, dry and calcine at room temperature to prepare a perlite-loaded zirconium oxide carrier;
[0058] (2) Strontium nitrate, nickel chloride and stannous chloride are dissolved in deionized water to prepare a mixed solution, and an equal volume of the mixed solution is impregnated on a perlite-supported zirconia support. After the impregnation is completed, the water is evaporated, dried and calcined to prepare a modified perlite-supported zirconia catalyst;
[0059] (3) isopropanolamine is pumped into a preheating vaporizer through a flow meter and mixed with nitrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. The fixed bed reactor is filled with a modified perlite-supported zirconia catalyst. After the reaction, the material is condensed and the gas-liquid is separated. The resulting liquid phase is subjected to reduced pressure distillation to prepare 2-methylaziridine;
[0060] (4) 2-Methylaziridine and tetrabutylammonium bromide are mixed evenly, cooled to 0°C, and then water is added dropwise to carry out a hydrolysis reaction. After the hydrolysis is completed, L-aminopropanol is prepared by post-treatment.
[0061] in:
[0062] In step (1), the mass ratio of zirconium oxychloride to deionized water is 1:10.
[0063] In step (1), the molar ratio of zirconium oxychloride to ammonia water is 1:2.5.
[0064] In step (1), the mass ratio of zirconium oxychloride to expanded perlite is 1.3:1.
[0065] The stirring and dissolving time in step (1) is 1.8 h, and the stirring and dissolving temperature is 50°C.
[0066] The aging temperature in step (1) is room temperature and the aging time is 24 hours.
[0067] In step (1), the drying temperature is 100°C and the drying time is 12 hours.
[0068] In step (1), the calcination temperature is 645° C. and the calcination time is 2.5 h.
[0069] In step (2), the temperature for evaporating water is 85°C, the drying temperature is 110°C, the drying time is 16 hours, the roasting temperature is 470°C, and the roasting time is 4.8 hours.
[0070] In the modified perlite-supported zirconia catalyst prepared in step (2), the mass of strontium oxide accounts for 24% of the total mass of the catalyst, the mass of nickel oxide accounts for 8% of the total mass of the catalyst, the mass of tin oxide accounts for 11% of the total mass of the catalyst, and the mass of perlite-supported zirconia accounts for 57% of the total mass of the catalyst.
[0071] The volume space velocity of the modified perlite-supported zirconia catalyst in the fixed bed reactor in step (3) is 0.53 h -1 .
[0072] In step (3), nitrogen is used as circulating gas to maintain the reaction pressure in the fixed bed reactor at normal pressure and the reaction temperature at 450°C.
[0073] In step (3), the distillation temperature is 50° C. and the distillation pressure is 0.03 MPa.
[0074] In step (4), the mass ratio of 2-methylaziridine, tetrabutylammonium bromide and water is 1:0.038:4.3.
[0075] In step (4), the water was added dropwise for 4 h, and the temperature of the system was controlled to be 0° C. After the addition was completed, the hydrolysis reaction was carried out at room temperature for 20 h.
[0076] According to analysis, the conversion rate of isopropanolamine in the preparation of 2-methylaziridine in step (3) was 94.37%, and the selectivity of 2-methylaziridine was 92.09%; the yield of L-aminopropanol prepared in step (4) was 83.68%, and the purity of L-aminopropanol was 99.55%.
[0077] Example 3
[0078] The preparation method of L-aminopropanol described in this embodiment 3 consists of the following steps:
[0079] (1) Dissolve zirconium oxychloride in deionized water, heat it to 73°C, add ammonia water dropwise thereto to prepare a sol, then add expanded perlite to the sol, stir and dissolve it, age, dry and calcine it at room temperature to prepare a perlite-loaded zirconium oxide carrier;
[0080] (2) Strontium nitrate, nickel chloride and stannous chloride are dissolved in deionized water to prepare a mixed solution, and an equal volume of the mixed solution is impregnated on a perlite-supported zirconia support. After the impregnation is completed, the water is evaporated, dried and calcined to prepare a modified perlite-supported zirconia catalyst;
[0081] (3) isopropanolamine is pumped into a preheating vaporizer through a flow meter and mixed with nitrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. The fixed bed reactor is filled with a modified perlite-supported zirconia catalyst. After the reaction, the material is condensed and the gas-liquid is separated. The resulting liquid phase is subjected to reduced pressure distillation to prepare 2-methylaziridine;
[0082] (4) 2-Methylaziridine and tetrabutylammonium bromide are mixed evenly, cooled to 0°C, and then water is added dropwise to carry out a hydrolysis reaction. After the hydrolysis is completed, L-aminopropanol is prepared by post-treatment.
[0083] in:
[0084] In step (1), the mass ratio of zirconium oxychloride to deionized water is 1:10.
[0085] The molar ratio of zirconium oxychloride to ammonia water in step (1) is 1:2.7.
[0086] In step (1), the mass ratio of zirconium oxychloride to expanded perlite is 1.2:1.
[0087] The stirring and dissolving time in step (1) is 1.5 h, and the stirring and dissolving temperature is 55°C.
[0088] The aging temperature in step (1) is room temperature and the aging time is 24 hours.
[0089] In step (1), the drying temperature is 103°C and the drying time is 12 hours.
[0090] In step (1), the calcination temperature is 640° C. and the calcination time is 2.5 h.
[0091] In step (2), the temperature for evaporating water is 85°C, the drying temperature is 113°C, the drying time is 16 hours, the roasting temperature is 465°C, and the roasting time is 4.8 hours.
[0092] In the modified perlite-supported zirconia catalyst prepared in step (2), the mass of strontium oxide accounts for 22% of the total mass of the catalyst, the mass of nickel oxide accounts for 10% of the total mass of the catalyst, the mass of tin oxide accounts for 13% of the total mass of the catalyst, and the mass of perlite-supported zirconia accounts for 55% of the total mass of the catalyst.
[0093] The volume space velocity of the modified perlite-supported zirconia catalyst in the fixed bed reactor in step (3) is 0.55 h -1 .
[0094] In step (3), nitrogen is used as circulating gas to maintain the reaction pressure in the fixed bed reactor at normal pressure and the reaction temperature at 450°C.
[0095] In step (3), the distillation temperature is 50° C. and the distillation pressure is 0.03 MPa.
[0096] In step (4), the mass ratio of 2-methylaziridine, tetrabutylammonium bromide and water is 1:0.038:4.3.
[0097] In step (4), the water was added dropwise for 4 h, and the temperature of the system was controlled to be 0° C. After the addition was completed, the hydrolysis reaction was carried out at room temperature for 20 h.
[0098] According to analysis, the conversion rate of isopropanolamine in the preparation of 2-methylaziridine in step (3) was 94.85%, and the selectivity of 2-methylaziridine was 92.73%. The yield of L-aminopropanol prepared in step (4) was 85.13%, and the purity of L-aminopropanol was 99.60%.
[0099] Comparative Example 1
[0100] The method for preparing L-aminopropanol described in Comparative Example 1 is the same as that in Example 1, except that, in step (1), the expanded perlite is no longer modified with zirconium oxide, but is directly used as the catalyst support. Analysis shows that in step (3), the conversion of isopropanolamine in the preparation of 2-methylaziridine is 81.56%, and the selectivity of 2-methylaziridine is 77.61%. The yield of L-aminopropanol prepared in step (4) is 61.55%, and the purity of L-aminopropanol is 80.31%.
[0101] Comparative Example 2
[0102] The method for preparing L-aminopropanol described in Comparative Example 2 is the same as that in Example 1, except that strontium nitrate is not added in step (2). Analysis shows that the conversion of isopropanolamine in preparing 2-methylaziridine in step (3) is 83.72%, and the selectivity of 2-methylaziridine is 80.56%. The yield of L-aminopropanol prepared in step (4) is 65.58%, and the purity of L-aminopropanol is 83.43%.
[0103] Comparative Example 3
[0104] The method for preparing L-aminopropanol described in Comparative Example 3 is the same as that in Example 1, except that nickel chloride is not added in step (2). Analysis shows that the conversion of isopropanolamine in preparing 2-methylaziridine in step (3) is 90.93%, and the selectivity of 2-methylaziridine is 86.85%. The yield of L-aminopropanol prepared in step (4) is 76.79%, and the purity of L-aminopropanol is 90.45%.
[0105] Comparative Example 4
[0106] The method for preparing L-aminopropanol described in Comparative Example 4 is the same as that in Example 1, except that stannous chloride is not added in step (2). Analysis shows that the conversion of isopropanolamine in preparing 2-methylaziridine in step (3) is 87.91%, and the selectivity of 2-methylaziridine is 85.20%. The yield of L-aminopropanol prepared in step (4) is 72.83%, and the purity of L-aminopropanol is 88.69%.
Claims
1. A method for preparing L-aminopropanol, characterized in that: It consists of the following steps: (1) Dissolve zirconium oxychloride in deionized water, heat it to 70-73°C, add ammonia water dropwise thereto to prepare a sol, then add expanded perlite to the sol and stir to dissolve, age, dry and calcine at room temperature to prepare a perlite-loaded zirconium oxide carrier; (2) Strontium nitrate, nickel chloride and stannous chloride are dissolved in deionized water to prepare a mixed solution, and an equal volume of the mixed solution is impregnated on a perlite-supported zirconia support. After the impregnation is completed, the water is evaporated, dried and calcined to prepare a modified perlite-supported zirconia catalyst; (3) isopropanolamine is pumped into a preheating vaporizer through a flow meter and mixed with nitrogen for preheating and vaporization, and then enters a fixed bed reactor for reaction. The fixed bed reactor is filled with a modified perlite-supported zirconia catalyst. After the reaction, the material is condensed and the gas-liquid is separated. The resulting liquid phase is subjected to reduced pressure distillation to prepare 2-methylaziridine; (4) 2-Methylaziridine and tetrabutylammonium bromide are mixed evenly, cooled to 0°C, and then water is added dropwise to carry out a hydrolysis reaction. After the hydrolysis is completed, L-aminopropanol is prepared by post-treatment.
2. The preparation method of L-aminopropanol according to claim 1, wherein: In step (1), the mass ratio of zirconium oxychloride to deionized water is 1:10; In step (1), the molar ratio of zirconium oxychloride to ammonia water is 1:2.5-2.7; In step (1), the mass ratio of zirconium oxychloride to expanded perlite is 1.2-1.3:
1.
3. The preparation method of L-aminopropanol according to claim 1, wherein: The stirring and dissolving time in step (1) is 1.5-1.8 hours, and the stirring and dissolving temperature is 50-55°C; In step (1), the aging temperature is room temperature and the aging time is 24 hours; In step (1), the drying temperature is 100-103°C and the drying time is 12 hours; In step (1), the calcination temperature is 640-645° C. and the calcination time is 2.5 h.
4. The method for preparing L-aminopropanol according to claim 1, wherein: In step (2), the temperature for evaporating water is 85°C, the drying temperature is 110-113°C, the drying time is 16 hours, the calcination temperature is 465-470°C, and the calcination time is 4.8 hours; In the modified perlite-supported zirconia catalyst prepared in step (2), the mass of strontium oxide accounts for 22-24% of the total mass of the catalyst, the mass of nickel oxide accounts for 8-10% of the total mass of the catalyst, the mass of tin oxide accounts for 11-13% of the total mass of the catalyst, and the mass of perlite-supported zirconia accounts for 55-57% of the total mass of the catalyst.
5. The preparation method of L-aminopropanol according to claim 1, wherein: The volume space velocity of the modified perlite-supported zirconia catalyst in the fixed bed reactor in step (3) is 0.53-0.55h -1 .
6. The method for preparing L-aminopropanol according to claim 1, wherein: In step (3), nitrogen is used as circulating gas to maintain the reaction pressure in the fixed bed reactor at normal pressure and the reaction temperature at 450°C.
7. The method for preparing L-aminopropanol according to claim 1, wherein: In step (3), the distillation temperature is 50° C. and the distillation pressure is 0.03 MPa.
8. The method for preparing L-aminopropanol according to claim 1, wherein: In step (4), the mass ratio of 2-methylaziridine, tetrabutylammonium bromide and water is 1:0.038:4.
3.
9. The method for preparing L-aminopropanol according to claim 1, wherein: In step (4), the water was added dropwise for 4 h, and the temperature of the system was controlled to be 0° C. After the addition was completed, the hydrolysis reaction was carried out at room temperature for 20 h.
10. The method for preparing L-aminopropanol according to claim 1, wherein: The post-treatment in step (4) is to allow the reaction to stand for separation after completion of the reaction, extract the aqueous layer with dichloromethane and combine it with the organic layer, then distill under reduced pressure to remove the dichloromethane, and finally perform vacuum distillation to collect the fraction at 72-73° C. to prepare L-aminopropanol.
Citation Information
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