A process for the preparation of a mono-isopropanolamine

Abstract

The application provides a preparation method of monoisopropanolamine, and L-threonine is dissolved in ammonia water and introduced into a reactor to perform a thermal decarboxylation reaction at a reaction temperature to obtain product monoisopropanolamine. The application can avoid the use of toxic and harmful raw materials such as propylene oxide in the existing preparation process, and has the advantages of high reaction efficiency and high reaction yield compared with the existing threonine decarboxylation route for preparing monoisopropanolamine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of isopropanolamine production, more specifically to a preparation method of monoisopropanolamine. BACKGROUND

[0002] Monoisopropanolamine (MIPA) is also known as mono-isopropanolamine or 1-amino-2-propanol, and its molecular formula is as follows:

[0003]

[0004] Monoisopropanolamine has low-toxicity green environmental protection characteristics, and is currently widely used in the synthesis of surfactants, industrial and civilian cleaning agents, titanium dioxide, metal cutting, electronic cleaning, propylene diamine, paint and other industries.

[0005] In the prior art documents, the method of monoisopropanolamine is mostly to synthesize isopropanolamine mixture with ammonia or liquid ammonia and propylene oxide as raw materials, and then to separate mono-isopropanolamine, di-isopropanolamine and tri-isopropanolamine three products step by step, such as patents CN 1410416A, CN 109748805A and CN 101265196A. There are also patents using 1,2-propanediol, liquid ammonia and hydrogen as raw materials to produce monoisopropanolamine by hydrogenation reaction, such as CN112125814A. These routes for preparing monoisopropanolamine all use liquid ammonia, propylene oxide and other toxic compounds as raw materials. However, with the global recognition and implementation of carbon emission reduction, more and more chemical products tend to use bio-based materials, therefore, the preparation of bio-based monoisopropanolamine becomes an important development direction in the future.

[0006] Amino acids are currently very attractive bio-based materials. Due to the presence of both amino and carboxyl functional groups, amino acids can generate different products under different reaction conditions through catalytic conversion reactions. The decarboxylation of amino acids to synthesize amine compounds is a hot research direction of amino acid catalytic conversion. Threonine is also known as β-hydroxy-α-amino butyric acid, and its molecular formula is as follows:

[0007]

[0008] Threonine can be converted into monoisopropylamine by decarboxylation reaction, however, the reaction condition for preparing monoisopropylamine from threonine is very harsh, and the reaction yield is low, so there are few reports about the preparation of monoisopropylamine from threonine by decarboxylation. In order to reduce the harshness of the reaction and improve the conversion rate, a catalyst is generally added for threonine decarboxylation. Literature (ChemCatChem 10.1002 / cctc.201900800) reports that isophorone is used as a catalyst for threonine decarboxylation, and isopropyl alcohol is used as a solvent to generate 1-amino-2-propanol at 150 DEG C for 24 h, but the product yield is low, only 30%. Patent US20050222430A1 also uses a ketone catalyst to react at 150-160 DEG C, and the yield of 1-amino-2-propanol can reach 80.6%, but the reaction efficiency is low, and it needs to be continuously reacted for more than 72 h.

[0009] In summary, the existing threonine decarboxylation reaction for preparing monoisopropylamine has the defects of long reaction time and low reaction yield. SUMMARY

[0010] In view of the problems in the prior art, the present application provides a new method for preparing monoisopropylamine.

[0011] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0012] A method for preparing monoisopropylamine, L-threonine is dissolved in ammonia water and introduced into a reactor, and a thermal decarboxylation reaction is carried out at a reaction temperature to obtain the product monoisopropylamine.

[0013] The reaction mother liquor obtained after the reaction is treated by flash evaporation, dehydration and filtration to obtain monoisopropylamine.

[0014] In the present application, the L-threonine can be a solid preparation or an aqueous solution preparation, and is usually obtained by fermentation of sugars.

[0015] In the present application, the ammonia water is used as a solvent and does not participate in the reaction.

[0016] In the present application, the amount of ammonia water added is 1-4 times the mass of L-threonine.

[0017] In the present application, the concentration of ammonia water is 10-50 wt%, preferably 25-30 wt%.

[0018] In the present application, the reaction temperature is 100-220 DEG C, preferably 150-200 DEG C.

[0019] In the present application, the reaction pressure is 5-20 MPaA, preferably 11-15 MPaA.

[0020] In the present application, the thermal decarboxylation reaction time is 20-60 min, preferably 30-40 min.

[0021] In the present application, carbon dioxide and water are generated simultaneously in the reaction, and ammonia and carbon dioxide generated in the reaction are removed by flash evaporation. The ammonia can be recovered after condensation and reused.

[0022] In the present application, the dehydration refers to the removal of water in the reaction solvent and water generated in the reaction, and the obtained water can be recycled.

[0023] The present application has the following beneficial effects:

[0024] (1) L-threonine can be obtained by fermentation of sugars, which can significantly reduce the carbon footprint of the product monoisopropanolamine, and compared with the existing process of propylene oxide route, the safety of the product can be greatly improved, which is a green and sustainable bio-based production route;

[0025] (2) The product obtained by the existing propylene oxide route usually contains a large amount of diisopropanolamine and triisopropanolamine and other by-products, while the present route can completely avoid the generation of diisopropanolamine and triisopropanolamine, and obtain monoisopropanolamine with extremely high purity;

[0026] (3) The present application uses ammonia water as the solvent, which can efficiently absorb the carbon dioxide gas generated by the decarboxylation of threonine, thereby making the reaction proceed in the forward direction and improving the reaction conversion rate. On the other hand, ammonia water can also better avoid the deamination side reaction of threonine at high temperature, promote the reaction to proceed in the decarboxylation direction, and improve the reaction yield. DETAILED DESCRIPTION

[0027] The present application will be further described through specific examples, and the examples described in the present application are only used to illustrate the present application and do not limit the scope of the present application.

[0028] If the specific experimental steps or conditions are not specified in the examples, the operations or conditions can be carried out according to the corresponding conventional experimental steps in the technical field. If the reagents or instruments used are not specified by the manufacturer, they are conventional products that can be obtained by purchase.

[0029] Product analysis method: gas chromatography is used to analyze the mass fraction of alkylene oxide, mono-substituted product, di-substituted product and tri-substituted product in the reaction liquid collected from the reactor, and the conversion rate of alkylene oxide and the ratio between the substituted products are calculated.

[0030] Gas chromatography detection conditions: Agilent GC-7890A; column: DB-5MS (60 m x 0.25 mm x 0.25 um); vaporization chamber temperature: 270°C; programmed temperature conditions: initial temperature 40°C, hold for 3 min, increase to 300°C at 15°C / min, hold for 11 min; detector temperature: 300°C; carrier gas: high-purity nitrogen (purity 99.999%); column flow rate: 1-1.5 ml / min; analysis method: normalization.

[0031] Example 1

[0032] Put 238 g of L-threonine solid preparation into a 1 L reaction kettle, and add 600 g of 30 wt% ammonia water, start stirring, and use programmed temperature to increase to 170°C, supplement nitrogen to 12 MPaA, and maintain for 60 min. After the reaction is completed, flash distillation to remove ammonia at 0.7-1.0 MPa, and after the ammonia is removed, the mother liquor is dehydrated by intermittent rectification, the rectification conditions are: the theoretical plate number of the rectification column is 21 blocks, the reflux ratio is 1:1, the pressure is 30 mbar (absolute pressure), the tower low heating temperature is 80°C, and finally after filtration, the filtrate product monoiso-propanolamine 145 g is obtained, and the product yield is 97%.

[0033] Example 2

[0034] Put 238 g of L-threonine solid preparation into a 1 L reaction kettle, and add 600 g of 30 wt% ammonia water, start stirring, and use programmed temperature to increase to 170°C, supplement nitrogen to 12 MPaA, and maintain for 60 min. After the reaction is completed, flash distillation to remove ammonia at 0.7-1.0 MPa, and after the ammonia is removed, the mother liquor is dehydrated by intermittent rectification, the rectification conditions are: the theoretical plate number of the rectification column is 21 blocks, the reflux ratio is 1:1, the pressure is 30 mbar (absolute pressure), the tower low heating temperature is 80°C, and finally after filtration, the filtrate product monoiso-propanolamine 145 g is obtained, and the product yield is 97%.

[0035] Example 3

[0036] Put 238 g of L-threonine solid preparation into a 1 L reaction kettle, and add 600 g of 30 wt% ammonia water, start stirring, and use programmed temperature to increase to 170°C, supplement nitrogen to 12 MPaA, and maintain for 60 min. After the reaction is completed, flash distillation to remove ammonia at 0.7-1.0 MPa, and after the ammonia is removed, the mother liquor is dehydrated by intermittent rectification, the rectification conditions are: the theoretical plate number of the rectification column is 21 blocks, the reflux ratio is 1:1, the pressure is 30 mbar (absolute pressure), the tower low heating temperature is 80°C, and finally after filtration, the filtrate product monoiso-propanolamine 145 g is obtained, and the product yield is 97%.

[0037] Example 4

[0038] Into a 1L reactor, 238g of L-threonine solid was charged, and 400g of 50wt% ammonia water was introduced, and stirring was started. The temperature was raised to 170°C in stages, and the pressure was raised to 12MPaA with nitrogen, and maintained for 60 minutes. After the reaction was completed, ammonia was removed by flashing at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent distillation to remove water. The distillation conditions were as follows: the theoretical plate number of the distillation column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the lower column heating temperature was 80°C, and finally, filtration was performed to obtain a filtrate product, monoisopropanolamine 145g, and the product yield was 97%.

[0039] Example 5

[0040] Into a 1L reactor, 238g of L-threonine solid was charged, and 600g of 30wt% ammonia water was introduced, and stirring was started. The temperature was raised to 110°C in stages, and the pressure was raised to 15MPaA with nitrogen, and maintained for 60 minutes. After the reaction was completed, ammonia was removed by flashing at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent distillation to remove water. The distillation conditions were as follows: the theoretical plate number of the distillation column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the lower column heating temperature was 80°C, and finally, filtration was performed to obtain a filtrate product, monoisopropanolamine 136g, and the product yield was 91%.

[0041] Example 6

[0042] Into a 1L reactor, 238g of L-threonine solid was charged, and 240g of 30wt% ammonia water was introduced, and stirring was started. The temperature was raised to 220°C in stages, and the pressure was raised to 18MPaA with nitrogen, and maintained for 30 minutes. After the reaction was completed, ammonia was removed by flashing at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent distillation to remove water. The distillation conditions were as follows: the theoretical plate number of the distillation column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the lower column heating temperature was 80°C, and finally, filtration was performed to obtain a filtrate product, monoisopropanolamine 139g, and the product yield was 93%.

[0043] Example 7

[0044] Into a 1L reactor, 238g of L-threonine solid was charged, and 600g of 30wt% ammonia water was introduced, and stirring was started. The temperature was raised to 170°C in stages, and the pressure was raised to 12MPaA with nitrogen, and maintained for 90 minutes. After the reaction was completed, ammonia was removed by flashing at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent distillation to remove water. The distillation conditions were as follows: the theoretical plate number of the distillation column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the lower column heating temperature was 80°C, and finally, filtration was performed to obtain a filtrate product, monoisopropanolamine 144g, and the product yield was 96%.

[0045] Example 8

[0046] Into a 1L reactor, 238g of L-threonine solid was charged, and 950g of 30wt% ammonia water was introduced, stirring was started, and the temperature was raised to 170°C by programming, the nitrogen pressure was supplemented to 7MPaA, and maintained for 60min. After the reaction was completed, ammonia was flashed off at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent rectification for dehydration, the rectification conditions were as follows: the theoretical plate number of the rectification column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the tower low heating temperature was 80°C, and finally, filtration was performed to obtain the filtrate product, monoisopropylolamine 132g, and the product yield was 88%.

[0047] Example 9

[0048] Into a 1L reactor, 238g of L-threonine solid was charged, and 600g of 30wt% ammonia water was introduced, stirring was started, and the temperature was raised to 170°C by programming, the nitrogen pressure was supplemented to 15MPaA, and maintained for 60min. After the reaction was completed, ammonia was flashed off at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent rectification for dehydration, the rectification conditions were as follows: the theoretical plate number of the rectification column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the tower low heating temperature was 80°C, and finally, filtration was performed to obtain the filtrate product, monoisopropylolamine 143g, and the product yield was 95%.

[0049] Comparative Example 1

[0050] Into a 1L reactor, 238g of L-threonine solid was charged, and 600g of 30wt% ammonia water was introduced, stirring was started, and the temperature was raised to 170°C by programming, the nitrogen pressure was supplemented to 15MPaA, and maintained for 60min. After the reaction was completed, ammonia was flashed off at 0.7-1.0MPa, and the mother liquor after ammonia removal was subjected to intermittent rectification for dehydration, the rectification conditions were as follows: the theoretical plate number of the rectification column was 21, the reflux ratio was 1:1, the pressure was 30mbar (absolute pressure), the tower low heating temperature was 80°C, and finally, filtration was performed to obtain the filtrate product, monoisopropylolamine 143g, and the product yield was 95%.

Claims

1. A process for the preparation of monoisopropanolamine, characterized in that, L-threonine is dissolved in ammonia water and introduced into a reactor to carry out a thermal decarboxylation reaction at a reaction temperature, so as to obtain a product monoisopropanolamine.

2. The production method according to claim 1, characterized by, The ammonia water is added in an amount of 1-4 times the mass of L-threonine.

3. The preparation method according to claim 1, characterized in that, The ammonia water has a concentration of 10-50 wt%.

4. The production method according to claim 3, characterized by, The ammonia water has a concentration of 25-30 wt%.

5. The preparation method according to claim 1, characterized in that, The reaction temperature is 100-220 DEG C.

6. The production method according to claim 5, wherein The reaction temperature is 150-200 DEG C.

7. The preparation method according to claim 1, characterized in that, The reaction pressure is 5-20 MPaA.

8. The preparation method according to claim 7, characterized in that, The reaction pressure is 11-15 MPaA.

9. The method of claim 1, wherein, The thermal decarboxylation reaction time is 20-60 min.

10. The method of claim 9, wherein, The thermal decarboxylation reaction time is 30-40 min.

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