Purification method of 2-amino-2-methyl-1-propanol

Abstract

The invention discloses a purification method of 2-amino-2-methyl-1-propanol, which comprises the following steps: (1) cooling molten impurity-containing 2-amino-2-methyl-1-propanol to 35-37 DEG C, cooling to 27-30 DEG C at a rate of 0.5-1.5 DEG C / h, preserving heat for 0.5-2 hours for crystallization, and separating out uncondensed liquid; and (2) after the uncondensed liquid is separated out, heating the remaining material to 33-34 DEG C at the rate of 0.5-1.5 DEG C / h, preserving heat for 6-12 hours, sweating, and separating sweat, thereby obtaining the purified 2-amino-2-methyl-1-propanol. Through the crystallization sweating process, the effect of purifying the AMP product is achieved under the condition that new impurities are not introduced.

Description

Technical Field

[0001] The invention relates to the field of purification and separation of organic matter, and in particular to a method for purifying 2-amino-2-methyl-1-propanol. Background Art

[0002] 2-amino-2-methyl-1-propanol (AMP) is an important organic synthesis raw material. The multifunctional coating additive AMP-95 (95% aqueous solution of 2-amino-2-methyl-1-propanol) of Angus Company of the United States is made of 2-nitro-2-methyl-1-propanol (NMP) as raw material, and is prepared by catalytic hydrogenation reduction, and its product purification adopts distillation process. However, 4,4-dimethyl-1,3-oxazolidine will be generated during the hydrogenation reaction, and part of this impurity will be further hydrogenated to generate 2-methylamino-2-methyl-1-propanol (MAMP), and AMP, 4,4-dimethyl-1,3-oxazolidine, and MAMP are difficult to be completely separated by distillation process, especially MAMP. Usually, the AMP-95 product as a coating additive controls the content of MAMP within 5%. However, in high-value fields, such as the cosmetics field, the content of MAMP in AMP is required to be less than 0.5wt%, which greatly limits the application of conventional AMP products with high MAMP content in these fields. Therefore, improving the purity of AMP can not only broaden the application scope of the product, but also increase the economic added value of AMP.

[0003] US20110224460A1 discloses a process for preparing AMP from NMP by hydrogenation, that is, after 1-12 hours of hydrogenation reaction, the obtained hydrogenated liquid is first subjected to vacuum distillation to remove the solvent, AMP is obtained by distillation, and then the obtained AMP is dissolved in a solvent and adsorbed on activated carbon to obtain a product of higher purity. However, this method can only remove odorous heavy components and colored substances, and cannot reduce the amount of MAMP generated. The patent points out that the amount of MAMP generated is mainly related to the residual formaldehyde in the raw material. By reducing the formaldehyde content in the raw material, the selectivity of MAMP can be reduced to 0.17%, but it still does not involve the separation of MAMP and AMP. Summary of the invention

[0004] In view of the market demand for high-purity AMP products, the inventors found that the melting point of high-purity AMP is 33-34°C. When the MAMP content in the AMP product increases, its melting point will also decrease. It is worth noting that AMP containing MAMP has a wide melting range and does not completely melt at a certain temperature, that is, during the solidification and melting process of AMP, its composition is constantly changing. Based on this, the present invention has developed a crystallization sweating process to achieve the effect of purifying AMP products without introducing new impurities.

[0005] Therefore, one of the objects of the present invention is to provide a method for purifying 2-amino-2-methyl-1-propanol.

[0006] The second object of the present invention is to obtain the 2-amino-2-methyl-1-propanol obtained by the above purification method.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for purifying 2-amino-2-methyl-1-propanol, comprising the following steps:

[0009] (1) cooling the molten impure 2-amino-2-methyl-1-propanol (AMP) to 35-37° C., then cooling to 27-30° C. at a rate of 0.5-1.5° C. / h and keeping the temperature for 0.5-2 h to crystallize, and separating the uncondensed liquid;

[0010] (2) After the uncondensed liquid is separated, the remaining material is heated to 33-34°C at a rate of 0.5-1.5°C / h and kept at this temperature for 6-12h to induce sweating, and the sweat is separated to obtain purified 2-amino-2-methyl-1-propanol.

[0011] In some embodiments, in step (1), the impure 2-amino-2-methyl-1-propanol (AMP) is derived from an AMP product directly obtained from an AMP preparation process, a commercially available AMP crystal product, or a commercially available product containing AMP and other ingredients (e.g., water), for example, it can be derived from the multifunctional additive AMP-95 of ANGUS Corporation in the United States, which contains about 5% water.

[0012] In some embodiments, in step (1), the water content of the 2-amino-2-methyl-1-propanol (AMP) used for melting is less than 0.01%, preferably less than 0.005%. Too high a water content of AMP will reduce the melting range and have an adverse effect on the purification of AMP. When the water content of 2-amino-2-methyl-1-propanol (AMP) is higher than 0.01%, it needs to be dehydrated. For example, it can be distilled in a dehydration distillation tower under reduced pressure conditions (for example, a vacuum degree of -0.100 to -0.070 MPa, preferably -0.095 to -0.085 MPa) to remove water. The bottom temperature of the tower can be 107-155°C, preferably 107-135°C, and more preferably 109-118°C. Generally, commercially available AMP-95 has a MAMP content of 0.8-3% and a water content of about 5%. Before the purification step of the present invention, it can be dehydrated by the above method to meet the water content requirements.

[0013] In some embodiments, in step (1), the impurities include but are not limited to: 2-methylamino-2-methyl-1-propanol (MAMP).

[0014] In some embodiments, in step (1), the temperature of the molten impure 2-amino-2-methyl-1-propanol (AMP) is 113-119°C.

[0015] In some embodiments, in step (1), the temperature of the molten 2-amino-2-methyl-1-propanol (AMP) containing impurities is cooled to 36°C.

[0016] In some embodiments, in step (1), the cooling rate is 0.8-1.2°C / h.

[0017] In some embodiments, in step (1), the incubation time at 27-30° C. is 0.5-1 h.

[0018] In some embodiments, in step (2), the remaining material is heated to 33-34°C at a rate of 0.8-1.2°C / h.

[0019] In some embodiments, in step (2), the incubation time at 33-34° C. is 3-5 h.

[0020] In some embodiments, both steps (1) and (2) can be performed in a melt crystallizer. In this case, the purification method further comprises step (3): heating the crystals after the sweating treatment in step (2) to 40-90°C, preferably 40-50°C, to melt all the remaining materials in the melt crystallizer, and transferring them to a product tank. At the same time, the uncondensed liquid separated in step (1) can be transferred to a mother liquid tank, and the sweat produced in step (2) can be transferred to a sweat tank for subsequent treatment.

[0021] In some embodiments, steps (1)-(2) or steps (1)-(3) may be repeated one or more times to achieve the required product purity.

[0022] In a second aspect, the present invention provides 2-amino-2-methyl-1-propanol obtained by the above purification method, wherein the purity of the 2-amino-2-methyl-1-propanol reaches 99.0-99.9%.

[0023] Beneficial Effects

[0024] The present invention separates MAMP from AMP, which is difficult to separate by general methods such as distillation, through the crystallization sweating process without introducing additional impurities, to achieve the effect of purifying AMP. According to the different MAMP contents of the raw materials and the changes in the operating conditions, an AMP product with an AMP content of 99.0-99.9% can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the gas chromatogram of commercially available AMP-95 in Example 1.

[0026] Figure 2 It is the gas chromatogram of AMP after purification in Example 1. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] AMP and MAMP were analyzed by gas chromatography (Agilent 7890A) before and after purification. The chromatographic conditions were as follows: chromatographic column was DB-624 (60m), vaporization chamber was 250°C; column box: start at 60°C, keep warm for 2 min, increase to 90°C at 10°C / min, then increase to 220°C at 20°C / min and keep warm for 10 min; detector temperature was 280°C.

[0030] The processes, conditions, reagents, experimental methods, etc. for implementing the present invention, except for those specifically mentioned below, are common knowledge and common common sense in the art and are not particularly limited by the present invention.

[0031] Example 1

[0032] (1) 2000 g of commercially available AMP-95 (MAMP content: 0.7%) was added to the bottom of the dehydration distillation tower. The water content in the bottom of the tower was controlled to be below 0.005% at a vacuum degree of -0.09 MPa and a bottom temperature of 113°C.

[0033] (2) The anhydrous AMP obtained from the bottom of the tower was introduced into a melt crystallizer and first cooled to 36°C. Then the temperature was cooled from 36°C to 30°C at a rate of 1°C / h and kept at this temperature for 0.5h for crystallization. The uncondensed liquid was transferred to the mother liquid tank through the bottom collector, and 231g of liquid was collected.

[0034] (3) After all the uncondensed liquid is discharged, the temperature of the crystallizer is raised to 34°C at a rate of 1°C / h and then kept at this temperature for 3 hours for sweating treatment. The sweat is transferred out of the crystallizer through the bottom collector to a sweat tank, and 265 g of sweat sample is obtained.

[0035] (4) After all the sweat was removed, the temperature of the melt crystallizer was raised to 45°C to melt all the solid phase materials, and then 1498 g of purified AMP product was collected from the discharge port, with an AMP content of 99.8%.

[0036] In the above process, the gas chromatograms of commercially available AMP-95 and AMP after the above purification process are shown in Figure 1 and Figure 2 .

[0037] Figure 1 In the above data, the first peak is methanol, the peak at 17.519 min is 4,4-dimethyl-1,3-oxazolidine, the peak at 17.893 min is AMP, and the peak at 19.093 min is MAMP. According to the peak area percentage, the AMP concentration is 99.21% and the MAMP concentration is 0.75%.

[0038] Figure 2 In the above analysis, the first peak is methanol, the peak at 17.52 min is 4,4-dimethyl-1,3-oxazolidine, the peak at 17.911 min is AMP, and the peak at 19.099 min is MAMP. According to the peak area percentage, the AMP concentration is 99.79% and the MAMP concentration is 0.20%.

[0039] Example 2

[0040] (1) 2000 g of commercially available AMP-95 (MAMP content: 1.0%) was added to the bottom of the dehydration distillation tower. The water content in the bottom of the tower was controlled to be below 0.004% at a vacuum degree of -0.085 MPa and a bottom temperature of 118°C.

[0041] (2) The anhydrous AMP obtained from the bottom of the tower was introduced into a melt crystallizer and first cooled to 36°C. Then the temperature was cooled from 36°C to 29°C at a rate of 0.8°C / h and kept at this temperature for 1 hour for crystallization. The uncondensed liquid was transferred to the mother liquid tank through the bottom collector, and 251 g of liquid was collected.

[0042] (3) After all the uncondensed liquid is discharged, the temperature of the crystallizer is raised to 33.5°C at a rate of 0.8°C / h and then kept at this temperature for 5 hours for sweating treatment. The sweat is transferred out of the crystallizer through the bottom collector to a sweat tank, and 285g of sweat sample is obtained.

[0043] (4) After all the sweat was removed, the temperature of the melt crystallizer was raised to 43°C to melt all the solid phase materials, and then 1439 g of purified product was collected from the discharge port, wherein the AMP content was 99.6%.

[0044] Example 3

[0045] (1) 2000 g of commercially available AMP-95 (MAMP content: 2.0%) was added to the bottom of the dehydration distillation tower. The water content in the bottom of the tower was controlled to be below 0.003% at a vacuum degree of -0.095 MPa and a bottom temperature of 109°C.

[0046] (2) The anhydrous AMP obtained from the bottom of the tower was introduced into a melt crystallizer and first cooled to 36°C. Then the temperature was cooled from 36°C to 29°C at a rate of 1.2°C / hour and kept at this temperature for 1 hour for crystallization. The uncondensed liquid was transferred to the mother liquid tank through the bottom collector, and 273g of liquid was collected.

[0047] (3) After all the uncondensed liquid was discharged, the temperature of the crystallizer was raised to 33.5°C at a rate of 1.2°C / h and then kept at this temperature for 5 hours for sweating treatment. The sweat was transferred out of the crystallizer through the bottom collector to a sweat tank, and 321 g of sweat sample was obtained.

[0048] (4) After all the sweat was removed, the temperature of the melt crystallizer was raised to 40°C to melt all the solid phase materials, and then 1391 g of purified product was collected from the discharge port, wherein the AMP content was 99.2%.

[0049] The above description is only an explanation of the preferred embodiments of the present invention and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present invention is not limited to the technical scheme formed by a specific combination of the above technical features, but also should cover other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) to form a technical scheme.

Claims

1. A method for purifying 2-amino-2-methyl-1-propanol, comprising the following steps: (1) cooling the molten 2-amino-2-methyl-1-propanol containing impurities to 35-37° C., then cooling it to 27-30° C. at a rate of 0.5-1.5° C. / h and keeping it at that temperature for 0.5-2 h to crystallize, and separating the uncondensed liquid; (2) After the uncondensed liquid is separated, the remaining material is heated to 33-34°C at a rate of 0.5-1.5°C / h and kept at this temperature for 6-12h to induce sweating, and the sweat is separated to obtain purified 2-amino-2-methyl-1-propanol.

2. The purification method according to claim 1, characterized in that In step (1), the water content of the 2-amino-2-methyl-1-propanol used for melting is less than 0.01%, preferably less than 0.005%.

3. The purification method according to claim 2, characterized in that In step (1), the water content of the 2-amino-2-methyl-1-propanol used for melting is higher than 0.01%, and it needs to be dehydrated; Preferably, water is removed by distilling 2-amino-2-methyl-1-propanol in a dehydration distillation tower under reduced pressure conditions (e.g., a vacuum degree of -0.100 to -0.070 MPa, preferably -0.095 to -0.085 MPa), and the bottom temperature is 107-155°C, preferably 107-135°C, and more preferably 109-118°C.

4. The purification method according to claim 1, characterized in that In step (1), the impurities include: 4,4-dimethyl-1,3-oxazolidine and 2-methylamino-2-methyl-1-propanol.

5. The purification method according to claim 1, characterized in that: In step (1), the temperature of the molten impure 2-amino-2-methyl-1-propanol is 113-119°C.

6. The purification method according to claim 1, characterized in that: In step (1): Cooling the molten impure 2-amino-2-methyl-1-propanol to 36°C; and / or The cooling rate is 0.8-1.2℃ / h; and / or The insulation time at 27-30℃ is 0.5-1h.

7. The purification method according to claim 1, characterized in that: In step (2): the remaining material is heated to 33-34° C. at a rate of 0.8-1.2° C. / h; The holding time at 33-34°C is 3-5h.

8. The purification method according to claim 1, characterized in that: Steps (1) and (2) are both carried out in a melt crystallizer. In this case, the purification method further comprises step (3): The crystals after the sweating treatment in step (2) are heated to 40-90°C, preferably 40-50°C, so that all the remaining materials in the melt crystallizer are melted and transferred to the product tank; at the same time, the uncondensed liquid separated in step (1) is transferred to the mother liquid tank, and the sweat produced in step (2) can be transferred to the sweat tank for subsequent treatment.

9. The purification method according to claim 1 or 8, characterized in that: Repeat steps (1)-(2) or steps (1)-(3) once or multiple times to achieve the required product purity.

10. 2-Amino-2-methyl-1-propanol obtained by the purification method according to any one of claims 1 to 9, wherein the purity thereof reaches 99.0-99.9%.

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