A process for the preparation of 2-amino-2-methyl-1-propanol

Abstract

The application discloses a preparation method of 2-amino-2-methyl-1-propanol, which comprises the following steps: preparing 2-amino-2-methyl-1-propanol by performing ring-opening reaction of methyl epoxide propyl and liquid ammonia under the condition of an acid catalyst. The preparation method is favorable for controlling the reaction in the mono-substitution stage of ammonia, that is, 2-amino-2-methyl-1-propanol is generated, and almost no di-substitution product di(1-hydroxy-2,2'-dimethyl)amine of ammonia is generated, the product has high selectivity, raw materials are easy to obtain, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of 2-amino-2-methyl-1-propanol production, and more specifically to a method for preparing 2-amino-2-methyl-1-propanol from methyl propylene oxide. Background Technology

[0002] 2-Amino-2-methyl-1-propanol is a white crystalline or colorless viscous liquid, usually prepared as a 95% aqueous solution. It is an important organic synthesis raw material, widely used in coatings, inks, metalworking fluids, personal care products, and pharmaceutical intermediates. Its molecular formula is as follows:

[0003]

[0004] The classic synthetic route of 2-amino-2-methyl-1-propanol uses 2-nitropropane as the starting material, which is hydroxymethylated with formaldehyde to obtain 2-nitro-2-methyl-1-propanol. Then, catalytic reduction yields 2-amino-2-methyl-1-propanol. This route uses propane nitration to prepare the starting material 2-nitropropane, but the nitration selectivity is low and it is extremely prone to explosion.

[0005] Patent CN1911899A uses isobutylene as the main raw material and chlorine and acetonitrile as auxiliary materials. It utilizes the Ritter reaction to carry out a series of reactions such as chlorination, cyclization, ring opening, hydrolysis, and acid-base neutralization. The product 2-amino-2-methyl-1-propanol is then obtained by distillation. This reaction has many preparation steps and the overall yield is low (50-69%).

[0006] Patent CN105418440A uses isopropylamine and syngas as raw materials to synthesize the target product through a hydroformylation reaction with specific catalysts and ligands, achieving a yield of up to 93%. However, this reaction requires harsh conditions, including high temperature and pressure, and specific catalysts, ligands, and solvents.

[0007] Patent CN1810767A describes a reaction between isopropanol, sodium nitrite, and paraformaldehyde at 0–25°C, followed by extraction, washing, and distillation to obtain 2-nitro-2-methyl-1-propanol, which is then catalytically hydrogenated to yield the final product. However, this patent does not specify the exact reaction conditions or yield. The disadvantages of this route include complex synthesis conditions, long reaction time, and difficult post-processing.

[0008] Existing methods for preparing 2-amino-2-methyl-1-propanol suffer from various problems, including demanding raw material sources, complex processes, low yields, and high costs. There is an urgent need to find a new method for preparing 2-amino-2-methyl-1-propanol. Summary of the Invention

[0009] To address the above problems, this invention proposes a method for preparing 2-amino-2-methyl-1-propanol. The acidic molecular sieve catalyst used in this invention employs 2-amino-2-methyl-1-propanol as a structure directing agent or template agent, which is beneficial for controlling the reaction at the mono-substitution stage of ammonia, i.e., generating 2-amino-2-methyl-1-propanol, while producing almost no di-substituted product of ammonia, di(1-hydroxy-2,2'-dimethyl)amine. This method offers high product selectivity, readily available raw materials, and low cost.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for preparing 2-amino-2-methyl-1-propanol includes the following steps: preparing 2-amino-2-methyl-1-propanol by ring-opening reaction of methyl propylene oxide and liquid ammonia under acidic catalyst conditions.

[0012] Its synthetic route is as follows:

[0013]

[0014] In this invention, the liquid ammonia is anhydrous liquid ammonia, and the mass ratio of liquid ammonia to methyl propylene oxide is (2-5):1, preferably (2.5-3.5):1.

[0015] In this invention, the reaction temperature is 90–200°C, preferably 120–140°C.

[0016] In this invention, the reaction pressure needs to be set above the saturated vapor pressure of liquid ammonia, generally maintained at 6 to 14 MPa, preferably 9 to 12 MPa.

[0017] In this invention, the reaction time is 30 to 90 minutes, preferably 50 to 70 minutes.

[0018] In this invention, the acidic catalyst includes a solid acid catalyst. More specifically, the solid acid catalyst includes acidic molecular sieves, heteropoly acids, acidic ion exchange resins, metal oxides, or sulfides. More preferably, the acidic catalyst is an acidic molecular sieve.

[0019] Preferably, the preparation method of the acidic molecular sieve mainly includes the following steps:

[0020] S1: A gel mixture is obtained by mixing aluminum source, silicon source, 2-amino-2-methyl-1-propanol, NaOH and water at 25-60°C;

[0021] S2: The gel mixture obtained in step S1 is placed into a hydrothermal synthesis vessel and crystallized at 160-250°C for 10-80 hours.

[0022] S3: After complete crystallization, the molecular sieve is obtained by filtration, washing, and calcination.

[0023] In this invention, the aluminum source in step S1 includes one or more of activated alumina, aluminum isopropoxide, boehmite, and aluminum sulfate; the silicon source includes one or more of amorphous silica gel, orthosilicate, and activated silica.

[0024] In this invention, the molar ratio of SiO2 in the silicon source, Al2O3 in the aluminum source, 2-amino-2-methyl-1-propanol, and NaOH:H2O in step S1 is 100:(0.2~1):(5~20).

[0025] (5~10):(200~300).

[0026] In this invention, the calcination temperature in step S3 is 400–700°C, and the calcination time is 5–15 h.

[0027] In this invention, the amount of acidic catalyst added is 2% to 20% of the mass of methyl propylene oxide, preferably 5% to 10%.

[0028] Preferably, after the reaction is completed, a mother liquor containing 2-amino-2-methyl-1-propanol is obtained. The mother liquor is then subjected to catalyst removal treatment, deammoniation treatment, and purification treatment to obtain 2-amino-2-methyl-1-propanol.

[0029] In this invention, the solid catalyst obtained from the catalyst removal process can be recycled.

[0030] In this invention, the ammonia removal process employs conventional separation methods in the art, such as multi-stage flash evaporation and / or distillation.

[0031] In this invention, the ammonia obtained from the deammoniation treatment can be reused after compression and condensation.

[0032] In this invention, the refining process mainly includes light-weight removal, which employs conventional separation methods in the art, such as distillation, rectification, or adsorption.

[0033] The beneficial effects of this invention are:

[0034] (1) A new route for preparing 2-amino-2-methyl-1-propanol is provided. The route uses methyl propylene oxide and anhydrous liquid ammonia as raw materials. The three-membered ring in methyl propylene oxide has a large ring strain and is protonated under the action of an acidic catalyst. The protonated methyl propylene oxide tends to generate tertiary carbocations and primary carbocations. The tertiary carbocation is more stable than the primary carbocation. The three-membered ring of methyl propylene oxide is broken between the tertiary carbooxy bonds. At this time, liquid ammonia acts as a nucleophile to attack the protonated methyl propylene oxide, thereby undergoing a nucleophilic substitution reaction similar to SN1 to obtain the main product 2-amino-2-methyl-1-propanol.

[0035] (2) The present invention uses methyl propylene oxide and liquid ammonia as raw materials, and the product can be obtained by synthesis in one step. The raw materials are readily available and the cost is low.

[0036] (3) The acidic molecular sieve catalyst provided by the present invention uses 2-amino-2-methyl-1-propanol as a structure directing agent or template agent, which is beneficial to control the structure of the reaction channels in the molecular sieve, so that the reaction is controlled at the mono-substitution stage of ammonia, that is, 2-amino-2-methyl-1-propanol is generated, while almost no di-substitution product of ammonia, di(1-hydroxy-2,2'-dimethyl)amine, is produced.

[0037] (4) The reaction of the present invention has high safety, generates less waste, and the equipment involved is all conventional equipment, making it more suitable for industrial-scale production. Detailed Implementation

[0038] The present invention will be further illustrated by specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0039] Raw material sources: Unless otherwise specified, all preparation examples and embodiments below were purchased from the market.

[0040] A) Preparation of acidic molecular sieve catalysts

[0041] Preparation Example 1

[0042] Component A was prepared by mixing boehmite (0.7g, Al2O3 content 71.2%), NaOH (2.8g), and distilled water (45g). Component B was prepared by mixing silica sol (200g, SiO2 content 30wt%) and 2-amino-2-methyl-1-propanol (13.4g). Component A was then added dropwise to component B at 30°C. The mixture was stirred at room temperature to form a gel, aged for 1 hour, and then placed in a stainless steel reactor. The mixture was heated to 170°C and allowed to crystallize for 80 hours until complete crystallization. After filtration, washing, and drying, the mixture was calcined in a muffle furnace at 500°C for 10 hours to obtain molecular sieve I.

[0043] Preparation Example 2

[0044] According to specific ingredient requirements, alumina (1g), NaOH (4g), and distilled water (54g) were prepared as component A, and tetraethyl orthosilicate (214.3g) and 2-amino-2-methyl-1-propanol (17.8g) were prepared as component B. Component A was then added dropwise to component B at 45°C. The mixture was stirred at room temperature to form a gel, aged for 1 hour, and then placed in a stainless steel reactor. The mixture was heated to 200°C and allowed to crystallize (for 15 hours). After complete crystallization, the mixture was filtered, washed, and dried, and then calcined in a muffle furnace at 600°C for 9 hours to obtain molecular sieve II.

[0045] Preparation Example 3

[0046] According to specific ingredient requirements, aluminum isopropoxide (0.8g), NaOH (2g), and distilled water (36g) were prepared as component A, and silica (60g) and 2-amino-2-methyl-1-propanol (4.5g) were prepared as component B. Component A was then added dropwise to component B at 50°C. The mixture was stirred at room temperature to form a gel, aged for 1 hour, and then placed in a stainless steel reactor. The mixture was heated to 250°C and allowed to crystallize (for 10 hours) until complete crystallization. After filtration, washing, and drying, the mixture was calcined in a muffle furnace at 400°C for 15 hours to obtain molecular sieve III.

[0047] Preparation Example 4

[0048] According to specific ingredient requirements, aluminum sulfate (1.6g), NaOH (3.2g), and distilled water (52.2g) were prepared as component A, and silica sol (200g) and 2-amino-2-methyl-1-propanol (11.6g) were prepared as component B. Component A was then added dropwise to component B at 60℃. The mixture was stirred at room temperature to form a gel, aged for 1 hour, and then placed in a stainless steel reactor. The mixture was heated and allowed to crystallize (170℃, 14 hours) until complete crystallization. After filtration, washing, and drying, the mixture was calcined in a muffle furnace at 700℃ for 5 hours to obtain molecular sieve IV.

[0049] Preparation Example 5

[0050] According to specific ingredient requirements, alumina (0.71g), NaOH (2.4g), and distilled water (36g) were prepared as component A, and silicon dioxide (60g) and 2-amino-2-methyl-1-propanol (7.1g) were prepared as component B. Component A was then added dropwise to component B at 25°C. The mixture was stirred at room temperature to form a gel, aged for 1 hour, and then placed in a stainless steel reactor. The mixture was heated and allowed to crystallize (190°C for 13 hours) until complete crystallization. After filtration, washing, and drying, the mixture was calcined in a muffle furnace at 500°C for 15 hours to obtain molecular sieve V.

[0051] B) Example

[0052] Analytical method: Agilent 7890A (FID) detector, INNOWAX column, injection port 300℃, detector 300℃; temperature program: 100℃, hold for 1 min, then increase to 200℃ at a rate of 20℃ / min and hold for 8 min.

[0053] Example 1

[0054] 6.5g of molecular sieve I was added to the reactor. After purging with nitrogen three times, 390g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 120℃ using a programmed temperature rise method. The pressure was then adjusted to 10MPa using high-pressure nitrogen, and 130g of methyl propylene oxide was pumped in, maintaining the temperature for 60 minutes. After the reaction was completed, the mixture was filtered, subjected to pressure relief flash evaporation, deammoniated under reduced pressure, and distilled to obtain the product. Gas chromatography analysis of the product and mass balance showed that the conversion rate of methyl propylene oxide was 98.8%, and the purity of the product 2-amino-2-methyl-1-propanol was 96.7%.

[0055] Example 2

[0056] 15g of molecular sieve II was added to the reactor. After purging with nitrogen three times, 300g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 100℃ using a programmed temperature rise method. The pressure was then adjusted to 9MPa using high-pressure nitrogen, and 150g of methyl propylene oxide was pumped in and maintained for 40 minutes. After the reaction was completed, the mixture was filtered, subjected to pressure relief flash evaporation, deammoniation under reduced pressure, and demethyl propylene oxide under vacuum. The product was analyzed by gas chromatography, and mass balance was performed. The results showed that the conversion rate of methyl propylene oxide was 99.5%, and the purity of the product 2-amino-2-methyl-1-propanol was 95.1%.

[0057] Example 3

[0058] 6g of molecular sieve III was added to the reactor. After purging with nitrogen three times, 200g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 150℃ using a programmed temperature rise method. The pressure was then adjusted to 13MPa using high-pressure nitrogen, and 40g of methyl propylene oxide was pumped in and maintained for 30min. After the reaction was completed, the mixture was filtered, subjected to pressure relief flash evaporation, deammoniation under reduced pressure, and demethyl propylene oxide under vacuum. The product was analyzed by gas chromatography, and mass balance was performed. The results showed that the conversion rate of methyl propylene oxide was 99.4%, and the purity of the product 2-amino-2-methyl-1-propanol was 97.2%.

[0059] Example 4

[0060] 6g of molecular sieve IV was added to the reactor. After purging with nitrogen three times, 135g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 200℃ using a programmed temperature rise. The pressure was then adjusted to 14MPa using high-pressure nitrogen, and 30g of methyl propylene oxide was pumped in and maintained for 30min. After the reaction was completed, the mixture was filtered, subjected to pressure relief flash evaporation, deammoniation under reduced pressure, and demethyl propylene oxide under vacuum. The product was analyzed by gas chromatography, and mass balance was performed. The results showed that the conversion rate of methyl propylene oxide was 99.4%, and the purity of the product 2-amino-2-methyl-1-propanol was 96.9%.

[0061] Example 5

[0062] 3.12 g of molecular sieve V was added to the reactor. After purging with nitrogen three times, 390 g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 90 °C using a programmed temperature rise method. The pressure was then adjusted to 6 MPa using high-pressure nitrogen, and 156 g of methyl propylene oxide was pumped in and maintained for 70 min. After the reaction was completed, the mixture was filtered, subjected to pressure relief flash evaporation, deammoniation under reduced pressure, and demethyl propylene oxide under vacuum. The product was analyzed by gas chromatography, and mass balance was performed. The results showed that the conversion rate of methyl propylene oxide was 97.5%, and the purity of the product 2-amino-2-methyl-1-propanol was 95.8%.

[0063] Example 6

[0064] 6.5g of HZSM-5 was added to the reactor. After purging with nitrogen three times, 390g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 120℃ using a programmed temperature rise. The pressure was then adjusted to 10MPa using high-pressure nitrogen, and 130g of methyl propylene oxide was pumped in and maintained for 60 minutes. After the reaction was completed, the pressure was released and flash evaporated, followed by deammoniation under reduced pressure and demethyl propylene oxide removal under vacuum. The product was analyzed by gas chromatography and the mass balance was calculated. The results showed that the conversion rate of methyl propylene oxide was 92.2%, and the purity of the product 2-amino-2-methyl-1-propanol was 75.3%.

[0065] Example 7

[0066] 6.5g of perfluorosulfonic acid resin was added to the reactor. After purging with nitrogen three times, 390g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 120℃ using a programmed temperature rise method. The pressure was then adjusted to 10MPa using high-pressure nitrogen, and 130g of methyl propylene oxide was pumped in and maintained for 60min. After the reaction was completed, the pressure was released and flash evaporated, followed by deammoniation under reduced pressure and demethyl propylene oxide removal under vacuum. The product was analyzed by gas chromatography and the mass balance was calculated. The results showed that the conversion rate of methyl propylene oxide was 93.5%, and the purity of the product 2-amino-2-methyl-1-propanol was 74.9%.

[0067] Comparative Example 1

[0068] 6.5g of inert ceramic balls were added to the reactor. After purging with nitrogen three times, 390g of liquid ammonia was pumped in, stirring was started, and the temperature was raised to 120℃ using a programmed temperature rise method. The pressure was then adjusted to 10MPa using high-pressure nitrogen, and 130g of methyl propylene oxide was pumped in and maintained for 60min. After the reaction was completed, the pressure was released and flash evaporated, followed by deammoniation under reduced pressure and demethyl propylene oxide removal under vacuum. The product was analyzed by gas chromatography and the mass balance was calculated. The results showed that the conversion rate of methyl propylene oxide was 75.1%, and the purity of the product 2-amino-2-methyl-1-propanol was 54.6%.

Claims

1. A method for preparing 2-amino-2-methyl-1-propanol, characterized in that, Includes the following steps: 2-Amino-2-methyl-1-propanol was prepared by ring-opening reaction of methyl propylene oxide and liquid ammonia under acidic catalyst conditions. The acidic catalyst is an acidic molecular sieve, and the preparation method of the acidic molecular sieve mainly includes the following steps: S1: A gel mixture is obtained by mixing aluminum source, silicon source, 2-amino-2-methyl-1-propanol, NaOH and water at 25~60℃; S2: The gel mixture obtained in step S1 is placed into a hydrothermal synthesis vessel and crystallized at 160~250 ℃ for 10~80 h. S3: After complete crystallization, the molecular sieve is obtained by filtration, washing, and calcination.

2. The preparation method according to claim 1, characterized in that, The liquid ammonia is anhydrous liquid ammonia, and the mass ratio of liquid ammonia to methyl propylene oxide is (2~5):

1.

3. The preparation method according to claim 2, characterized in that, The liquid ammonia is anhydrous liquid ammonia, and the mass ratio of liquid ammonia to methyl propylene oxide is (2.5~3.5):

1.

4. The preparation method according to claim 1, characterized in that, The reaction temperature is 90~200 ℃.

5. The preparation method according to claim 4, characterized in that, The reaction temperature is 120~140 ℃.

6. The preparation method according to claim 1, characterized in that, The reaction pressure is 6~14 MPa.

7. The preparation method according to claim 6, characterized in that, The reaction pressure is 9~12 MPa.

8. The preparation method according to claim 1, characterized in that, The reaction time is 30-90 min.

9. The preparation method according to claim 8, characterized in that, The reaction time is 50-70 min.

10. The preparation method according to claim 1, characterized in that, The aluminum source mentioned in step S1 includes one or more of activated alumina, aluminum isopropoxide, boehmite, and aluminum sulfate; the silicon source includes one or more of amorphous silica gel, orthosilicate, and activated silica.

11. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of SiO2 in the silicon source, Al2O3 in the aluminum source, 2-amino-2-methyl-1-propanol, and NaOH:H2O is 100:(0.2~1):(5~20):(5~10):(200~300).

12. The preparation method according to claim 1, characterized in that, In step S3, the roasting temperature is 400~700℃ and the roasting time is 5~15 h.

13. The preparation method according to claim 1, characterized in that, The amount of acidic catalyst added is 2% to 20% of the mass of methyl propylene oxide.

14. The preparation method according to claim 13, characterized in that, The amount of acidic catalyst added is 5-10% of the mass of methyl propylene oxide.

15. The preparation method according to claim 1, characterized in that, After the reaction is complete, a mother liquor containing 2-amino-2-methyl-1-propanol is obtained. The mother liquor is then subjected to catalyst removal treatment, deammoniation treatment, and purification treatment to obtain 2-amino-2-methyl-1-propanol.

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