Method for continuously preparing N-hydroxysuccinimide fatty acid ester
The preparation of N-hydroxysuccinimide fatty acid esters by a microchannel continuous flow reactor solves the problems of long reaction time, low production capacity and serious pollution in batch reactor preparation, and realizes the continuous production of N-hydroxysuccinimide fatty acid esters with high efficiency, green synthesis and high yield.
Patent Information
- Application Number
- CN202511085019.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-11-14
AI Technical Summary
Existing batch reactor methods for preparing N-succinimide fatty acid esters suffer from problems such as long reaction time, low production capacity, high solvent consumption, and serious pollution from waste, making it difficult to achieve efficient and green synthesis.
A microchannel continuous flow reactor was used to carry out the mixing and esterification reaction of fatty acids with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, combined with a recrystallization step, to achieve continuous production of N-hydroxysuccinimide fatty acid esters.
It significantly shortens reaction time, increases yield to >95%, simplifies post-processing, reduces the generation of "three wastes", improves solvent recovery and utilization rate, and achieves efficient and green production.
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Figure CN120943771A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of compound synthesis technology, specifically to a method for the continuous preparation of N-hydroxysuccinimide fatty acid esters. Background Technology
[0002] N-hydroxysuccinimide fatty acid esters are activated esters formed by the condensation of fatty acids and N-hydroxysuccinimide (NHS). By converting the low-reactivity carboxyl group into a highly reactive succinimide group, they can react efficiently with nucleophiles under mild conditions, solving the problems of harsh and inefficient reactions of free fatty acids. Their main applications are concentrated in the modification of amino-containing systems: in the biological field, they are used for protein / peptide fatty acidation, liposome / nanoparticle targeted functionalization, and antibody-drug conjugate development; in the materials field, they are used for polymer hydrophobic modification and surface coating; and they can also serve as key synthetic intermediates. Compared to free fatty acids, they possess advantages such as ultra-high reactivity, precise selectivity, ease of operation, and easy separation of byproducts, making them an indispensable tool in bioconjugation chemistry, targeted delivery systems, and hydrophobic material modification.
[0003] Currently, batch reactors commonly use condensing agents such as DCC, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), or DIC for the preparation of N-succinimide fatty acid esters. Among these, DCC's byproduct dicyclohexylurea is difficult to remove, DIC is more suitable for solid-phase synthesis but its byproducts have poor water solubility, and although EDC is a preferred choice for biopharmaceuticals due to its water-soluble byproducts, aqueous phase compatibility, and high synergistic effect with NHS, it is limited by the low efficiency of batch reactors ("three transfers and one reaction"), resulting in long reaction times, low production capacity, high solvent consumption, and serious pollution from waste.
[0004] With the continuous development of microchemical technology in recent years, microchannel continuous flow technology has been widely used. It enhances mass and heat transfer through millisecond-level mixing and precise temperature control, significantly shortening reaction time and suppressing side reactions; its continuous nature directly improves production efficiency while simultaneously reducing safety risks; and the microchannel design greatly increases the reaction surface area, reducing solvent consumption and significantly reducing pollution. This technology provides an ideal solution for the efficient and green synthesis of N-hydroxysuccinimide fatty acid esters. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides a continuous preparation method for N-hydroxysuccinimide fatty acid esters. This invention enables continuous production of N-hydroxysuccinimide fatty acid esters, significantly shortens reaction time, substantially increases the yield of N-hydroxysuccinimide fatty acid esters, ensures thorough raw material reaction, and simplifies post-processing. It effectively reduces the generation of waste gas, wastewater, and solid waste, improves solvent recovery and utilization, and achieves efficient and green production.
[0006] The technical solution adopted in this invention is as follows:
[0007] A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, the method being carried out in a microchannel continuous flow reactor, includes the following steps:
[0008] (1) Dissolve fatty acids in a first organic solvent to form solution A, dissolve 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in a second organic solvent to form solution B, and dissolve N-hydroxysuccinimide in a third organic solvent to form solution C;
[0009] (2) Mix solution A and solution B at a first constant flow rate and enter the first microchannel continuous flow reactor for pre-activation reaction to obtain activated fatty acid intermediate;
[0010] (3) The activated fatty acid intermediate is mixed with solution C at a second constant flow rate and then introduced into the second microchannel continuous flow reactor for esterification reaction;
[0011] (4) After the reaction is complete, the effluent is concentrated to remove the organic solvent, then recrystallized, the crystals are collected by filtration and vacuum dried to obtain N-hydroxysuccinimide fatty acid ester.
[0012] In some embodiments, the first organic solvent, the second organic solvent, and the third organic solvent in step (1) are independently selected from any one of chloroform, acetonitrile, and dioxane.
[0013] In some embodiments, the fatty acid in step (1) is a C8-C24 saturated or unsaturated fatty acid.
[0014] In some embodiments, the fatty acid in step (1) is stearic acid, oleic acid or palmitic acid.
[0015] In some embodiments, the molar ratio of the fatty acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and N-hydroxysuccinimide is 1:1 to 1.6:1 to 1.8.
[0016] In some embodiments, the first constant flow rate is 3-10 mL / min, the second constant flow rate is 3-10 mL / min, and the first constant flow rate is 50% of the second constant flow rate.
[0017] In some embodiments, the pre-activation reaction takes 2-9 minutes, and the esterification reaction takes 4-12 minutes.
[0018] In some embodiments, the inner diameter of the coils in the first microchannel continuous flow reactor and the second microchannel continuous flow reactor is 3-6 mm, and the length of the coils is 8-25 m.
[0019] In some embodiments, the reaction temperature in the first microchannel continuous flow reactor is 20-35°C.
[0020] In some embodiments, the reaction temperature in the second microchannel continuous flow reactor is 20-35°C.
[0021] Beneficial effects:
[0022] This invention utilizes the highly efficient "three-transfer" characteristics of a microchannel continuous reactor to significantly shorten the EDC / NHS reaction time of N-hydroxysuccinimide fatty acid esters. Under the same feed rate, the reaction time is reduced from 6-14 hours in batch processes to 8-15 minutes in continuous production, achieving efficient continuous production with high product yield (>95%), high purity, and thorough reaction of fatty acid raw materials, simplifying post-processing procedures. The entire process significantly reduces "three wastes" (waste gas, wastewater, and solid waste) and improves solvent recovery and utilization rates. Attached Figure Description
[0023] Figure 1 This is a process route diagram for Embodiment 1 of the present invention. Detailed Implementation
[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0025] Unless otherwise specifically stated, the numerical values set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values expressed as "within the range of ab" or "between the range of ab" do not include the endpoint values a and b; values expressed as "for ab," "is ab," or "ab" include the endpoint values a and b.
[0026] Furthermore, it should be noted that the use of terms such as "first" and "second" to define the reactor or reaction liquid is merely for the purpose of distinguishing the reactors or reaction liquids used in each reaction step. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.
[0027] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.
[0028] Yield = Actual product mass / Theoretical product mass.
[0029] Example 1
[0030] A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, the method being carried out in a microchannel continuous flow reactor, includes the following steps:
[0031] (1) Stearic acid (5.0 g, 17.6 mmol) and EDC (3.0 g, 19.33 mmol) were added to two 25 mL volumetric flasks respectively. The solvent was diluted to 25 mL with chloroform to form solutions A and B respectively. The flow rate of the syringe pump was set to 5.0 mL / min. Solutions A and B were injected. After the two were mixed to form the first reaction solution, they were pumped into the first group of microchannel continuous flow reactors (1 / 8 inch diameter, 6 m length) for the first reaction. The reaction temperature of the first reaction was 25 °C and the retention time was 5.0 min to obtain activated fatty acid intermediates.
[0032] (2) Solution C obtained by dissolving NHS (2.23 g, 19.33 mmol) in 50 mL of chloroform was pumped into the second group of microchannel continuous flow reactors (1 / 8 inch diameter, 20 m length) at a flow rate of 10 mL / min to carry out a second reaction with the activated fatty acid intermediate. The reaction temperature of the second reaction was 25 °C and the retention time was 9.0 min. The effluent was collected.
[0033] (3) The effluent was evaporated to dryness to obtain a white solid. 50 mL of isopropanol was added, and the product was recrystallized at 92 °C to obtain a white, flaky crude product. The recrystallization solvent ratio was 10 mL of isopropanol for every 1 g of fatty acid fed. The reflux temperature was 92 °C. After filtration, the product was recrystallized again with isopropanol to obtain white, flaky crystals, N-hydroxysuccinimide stearate (6.37 g, yield 95 wt%).
[0034] The product N-hydroxysuccinimide stearate was analyzed by 1H NMR spectroscopy. 1 H NMR (400MHz, CDCl3) δ: 2.76 (4H, s), 2.52 (2H, q), 1.66 (2H, q), 1.33 (2H, t), 1.19 (26H, m), 0.81 (3H, t).
[0035] Example 2
[0036] A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, the method being carried out in a microchannel continuous flow reactor, includes the following steps:
[0037] (1) Take palmitic acid (5.0g, 19.5mmol) and EDC (3.33g, 21.45mmol) and add them to two 25mL volumetric flasks respectively. Use chloroform to dilute to 25mL respectively to form solution A and solution B. Set the flow rate of the syringe pump to 5.0mL / min and start injecting solution A and solution B. After mixing the two to form the first reaction solution, pump it into the first group of microchannel continuous flow reactors (1 / 8 inch diameter, 6m length) for the first reaction. The reaction temperature of the first reaction is 25℃ and the retention time is 5.0min to obtain activated fatty acid intermediate;
[0038] (2) Solution C obtained by dissolving NHS (2.47 g, 21.45 mmol) in 50 mL of chloroform was pumped into the second group of microchannel continuous flow reactors (1 / 8 inch diameter, 20 m length) at a flow rate of 10 mL / min to carry out a second reaction with the activated fatty acid intermediate. The reaction temperature of the second reaction was 25 °C and the retention time was 9.0 min. The effluent was collected.
[0039] (3) The solvent in the effluent was evaporated to obtain a white solid. 50 mL of isopropanol was added, and the product was recrystallized at 92 °C to obtain a white, flaky crude product. The recrystallization solvent ratio was 10 mL of isopropanol for every 1 g of fatty acid fed. The reflux temperature was 92 °C. After filtration, the product was recrystallized again with isopropanol to obtain white, flaky crystals, N-hydroxysuccinimide palmitate product (6.34 g, yield 92 wt%).
[0040] The product N-hydroxysuccinimide palmitate was analyzed by 1H NMR spectroscopy. 1 H NMR (400MHz, CDCl3) δ: 2.79 (4H, s), 2.55 (2H, q), 1.69 (2H, q), 1.36 (2H, t), 1.22 (22H, m), 0.84 (3H, t).
[0041] Example 3
[0042] A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, the method being carried out in a microchannel continuous flow reactor, includes the following steps:
[0043] (1) Oleic acid (5.0 g, 17.7 mmol) and EDC (3.02 g, 19.47 mmol) were added to two 25 mL volumetric flasks respectively. The solvent was diluted to 25 mL with chloroform to form solutions A and B respectively. The flow rate of the syringe pump was set to 5.0 mL / min, and solutions A and B were injected. After the two were mixed to form the first reaction solution, they were pumped into the first set of microchannel continuous flow reactors (1 / 8 inch diameter, 6 m length) for the first reaction. The reaction temperature of the first reaction was 25 °C and the retention time was 5.0 min to obtain activated fatty acid intermediates.
[0044] (2) Solution C obtained by dissolving NHS (2.24 g, 19.47 mmol) in 50 mL of chloroform was pumped into the second group of microchannel continuous flow reactors (1 / 8 inch diameter, 20 m length) at a flow rate of 10 mL / min to carry out a second reaction with the activated fatty acid intermediate. The reaction temperature of the second reaction was 25 °C and the retention time was 9.0 min. The effluent was collected.
[0045] (3) The effluent was evaporated to dryness to obtain a white solid. 50 mL of isopropanol was added, and the product was recrystallized at 92 °C to obtain a white, flaky crude product. The recrystallization solvent ratio was 10 mL of isopropanol for every 1 g of fatty acid fed. The reflux temperature was 92 °C. After filtration, the product was recrystallized again with isopropanol to obtain white, flaky crystals, N-hydroxysuccinimide oleate (6.25 g, yield 93 wt%).
[0046] The product N-hydroxysuccinimide oleate was analyzed by 1H NMR spectroscopy. 1 H-NMR(400MHz, CDCl3)δ:5.35(2H,m),2.83(4H,s),2.60(2H,t),2.01(4H,m),1.75(2H,q),1.41-1.27(20H,m),0.88(3H,t).
[0047] Example 4
[0048] A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, the method being carried out in a microchannel continuous flow reactor, includes the following steps:
[0049] (1) Lauric acid (5.0 g, 25.0 mmol) and EDC (3.88 g, 27.5 mmol) were added to two 25 mL volumetric flasks respectively. The solvent was diluted to 25 mL with chloroform to form solutions A and B respectively. The flow rate of the syringe pump was set to 5.0 mL / min. Solutions A and B were injected. After the two were mixed to form the first reaction solution, they were pumped into the first group of microchannel continuous flow reactors (1 / 8 inch diameter, 6 m length) for the first reaction. The reaction temperature of the first reaction was 25 °C and the retention time was 5.0 min to obtain activated fatty acid intermediates.
[0050] (2) Solution C obtained by dissolving NHS (3.16 g, 27.5 mmol) in 50 mL of chloroform was pumped into the second group of microchannel continuous flow reactors (1 / 8 inch diameter, 20 m length) at a flow rate of 10 mL / min to carry out a second reaction with the activated fatty acid intermediate. The reaction temperature of the second reaction was 25 °C and the retention time was 9.0 min. The effluent was collected.
[0051] (3) The effluent was evaporated to dry solvent to obtain a white solid. 50 mL of isopropanol was added, and the product was recrystallized at 92 °C to obtain a white flaky crude product. The recrystallization solvent ratio was 10 mL of isopropanol for every 1 g of fatty acid fed. The reflux temperature was 92 °C. After filtration, the product was recrystallized again with isopropanol to obtain white flaky crystals, N-hydroxysuccinimide laurate product (7.06 g, yield 95 wt%).
[0052] The product N-hydroxysuccinimide laurate was analyzed by 1H NMR spectroscopy. 1 H NMR (400MHz, CDCl3) δ: 2.73 (4H, s), 2.49 (2H, q), 1.62 (2H, q), 1.21 (16H, m), 0.81 (3H, t).
[0053] Comparative Example
[0054] A batch reactor method for preparing N-hydroxysuccinimide stearate includes the following steps:
[0055] (1) Take a 500mL round-bottom flask, weigh stearic acid (5.0g, 17.6mmol) and EDC (3.0g, 19.33mmol) into the round-bottom flask, protect with nitrogen, add 150mL chloroform into the flask, and after 0.5h the system becomes clear and transparent. Continue stirring at room temperature for 3h for pre-reaction.
[0056] (2) Weigh NHS (2.23 g, 19.33 mmol), dissolve it in 50 mL of chloroform, and add it dropwise to the reaction system at 0 °C. Stir for 0.5 h, remove the ice bath, and react overnight at room temperature. After the reaction of the starting material is complete, add 50 mL of saturated NH4Cl aqueous solution for extraction. After extraction three times, collect the organic phase, evaporate the solvent to obtain a white crude product, then add 50 mL of isopropanol, recrystallize at 92 °C to obtain a white flaky product, filter and recrystallize again with isopropanol to obtain white flaky crystals, N-hydroxysuccinimide stearate product (5.36 g, yield 80 wt%).
[0057] Compared to the examples, in the comparative example, with the same molar ratio of stearic acid, EDC, and NHS as the examples (stearic acid:EDC:NHS = 1:1.1:1.1), but using a different production process, the yield of N-hydroxysuccinimide stearate produced by the batch reactor was significantly lower than that of the microchannel continuous flow method of this invention. The yield of N-hydroxysuccinimide stearate produced by the method of this invention was greater than 90 wt%. Furthermore, compared to the examples, the reaction time of the comparative example was much longer than that of the microchannel continuous flow method of this invention; the reaction time of N-hydroxysuccinimide stearate produced by the method of this invention was only 14 min.
[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for the continuous preparation of N-hydroxysuccinimide fatty acid esters, characterized in that, This method is carried out in a microchannel continuous flow reactor and includes the following steps: (1) Dissolve fatty acids in a first organic solvent to form solution A, dissolve 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in a second organic solvent to form solution B, and dissolve N-hydroxysuccinimide in a third organic solvent to form solution C; (2) Mix solution A and solution B at a first constant flow rate and enter the first microchannel continuous flow reactor for pre-activation reaction to obtain activated fatty acid intermediate; (3) The activated fatty acid intermediate is mixed with solution C at a second constant flow rate and then introduced into the second microchannel continuous flow reactor for esterification reaction; (4) After the reaction is complete, the effluent is concentrated to remove the organic solvent, then recrystallized, the crystals are collected by filtration and vacuum dried to obtain N-hydroxysuccinimide fatty acid ester.
2. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 1, characterized in that, In step (1), the first organic solvent, the second organic solvent, and the third organic solvent are independently selected from any one of chloroform, acetonitrile, and dioxane.
3. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 2, characterized in that, In step (1), the fatty acids are C8-C24 saturated or unsaturated fatty acids.
4. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 3, characterized in that, The fatty acid in step (1) is stearic acid, lauric acid, oleic acid or palmitic acid.
5. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 1, characterized in that, The molar ratio of the fatty acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 1:1 to 1.6:1 to 1.
8.
6. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 1, characterized in that, The first constant flow rate is 3-10 mL / min, the second constant flow rate is 3-10 mL / min, and the first constant flow rate is 50% of the second constant flow rate.
7. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 6, characterized in that, The pre-activation reaction takes 2-9 minutes, and the esterification reaction takes 4-12 minutes.
8. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 7, characterized in that, The inner diameter of the coil in the first microchannel continuous flow reactor and the second microchannel continuous flow reactor is 3-6 mm, and the length of the coil is 8-25 m.
9. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 8, characterized in that, The reaction temperature in the first microchannel continuous flow reactor is 20-35℃.
10. The method for continuous preparation of N-hydroxysuccinimide fatty acid esters according to claim 9, characterized in that, The reaction temperature in the second microchannel continuous flow reactor is 20-35℃.