L-carnitine-based ionic liquid aqueous two-phase system as well as preparation method and application thereof

Abstract

The invention discloses an L-carnitine-based ionic liquid aqueous two-phase system as well as a preparation method and application thereof, and belongs to the technical field of aqueous two-phase system separation. The prepared L-carnitine-based ionic liquid aqueous two-phase system is a novel ionic liquid aqueous two-phase system which is more efficient when active substances are extracted (extraction and separation can be achieved by stirring for 30 min and centrifuging for 5-8 min at the speed of 6000-8000 rpm), the extraction rate of vanillin, eugenol, p-hydroxybenzaldehyde, syringaldehyde and vanillic acid reaches 85.37% or above, and the L-carnitine-based ionic liquid aqueous two-phase system is a novel ionic liquid aqueous two-phase system. The method can be applied to the fields of organic compound extraction, medicine extraction, environmental protection and the like, and has a great development prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a levo-carnitine-based ionic liquid aqueous two-phase system, a preparation method and application thereof, and belongs to the technical field of aqueous two-phase system separation. BACKGROUND

[0002] An aqueous two-phase system (ATPS) is a special liquid-liquid phase separation system, which is composed of two incompatible aqueous phases under specific conditions. The two aqueous phases can be two polymers, a polymer and a salt, or even two salts.

[0003] An ionic liquid (IL) is a salt different from ordinary electrolytes, which is liquid at low temperature. The formation of an ionic liquid aqueous two-phase system is based on the interaction between an ionic liquid and other components in the aqueous phase, such as a salt or a polymer. Ionic liquids have unique physicochemical properties, such as non-volatility, low toxicity, non-flammability, high thermal stability and chemical stability, making them ideal materials for constructing aqueous two-phase systems.

[0004] Currently, the main application of ionic liquids is imidazole, pyridine, tropine, quinoline, and tetraalkyl phosphonium. Although ionic liquid aqueous two-phase systems have many advantages, there are still many problems: (1) high cost: the cost of ionic liquids is relatively high, which limits its large-scale application; (2) complex synthesis: the synthesis of some ionic liquids involves many steps and organic reagents, which will cause pollution; (3) long phase separation time: in some cases, the phase separation time is long, which affects the production efficiency.

[0005] Therefore, it is of great practical and economic value to develop a new type of ionic liquid aqueous two-phase system with good performance, environmental friendliness and low cost. SUMMARY

[0006] To solve the above problems, the present application provides a levo-carnitine-based ionic liquid aqueous two-phase system and a preparation method thereof. The levo-carnitine-based ionic liquid aqueous two-phase system is formed by mixing levo-carnitine-based ionic liquid, polymer and water. The present application fully utilizes the advantages of ionic liquid aqueous two-phase system and effectively applies it to the extraction of active substances.

[0007] The first object of the present application is to provide a method for preparing a levo-carnitine-based ionic liquid aqueous two-phase system, comprising the following steps:

[0008] (1) mixing levo-carnitine, organic acid and water, and reacting; drying after reaction to obtain levo-carnitine-based ionic liquid;

[0009] (2) mixing the levo-carnitine-based ionic liquid with a polyethylene glycol aqueous solution, and standing to obtain a levo-carnitine-based ionic liquid aqueous two-phase system;

[0010] The molar ratio of L-carnitine to the organic acid in step (1) is 1-4:1.

[0011] In one embodiment, the organic acid in step (1) comprises any one of L-lactic acid, malic acid, citric acid, and azelaic acid.

[0012] Optionally, the organic acid in step (1) is L-lactic acid, malic acid, or azelaic acid.

[0013] Optionally, when the organic acid is L-lactic acid or malic acid, the molar ratio of L-carnitine to L-lactic acid or malic acid is 0.8-1.2:1.

[0014] Optionally, when the organic acid is azelaic acid, the molar ratio of L-carnitine to azelaic acid is 1.8-2.2:1.

[0015] In one embodiment, the mixing temperature in step (1) is 25-55°C.

[0016] In one embodiment, the reaction in step (1) is stirred at 400-700 rpm for 2-6 h at room temperature.

[0017] Optionally, the drying is first rotary evaporation at 50-60°C for 1-3 h, and then vacuum drying for 12-24 h.

[0018] In one embodiment, the polyethylene glycol in step (2) comprises any one of PEG 20000, PEG 10000, PEG 6000, polyethylene glycol 12000, polypropylene glycol 400 (PPG 400), and polyethylene glycol block polypropylene glycol block polyethylene glycol (EO-PO-EO).

[0019] Optionally, the polyethylene glycol in step (2) is PEG 20000 or PEG 10000.

[0020] In one embodiment, the mass ratio of the L-carnitine-based ionic liquid to the polyethylene glycol in step (2) is 0.5-6:1.

[0021] Optionally, the mass ratio of the L-carnitine-based ionic liquid to the polyethylene glycol is 1-4:1.

[0022] A second object of the present application is to provide a L-carnitine-based ionic liquid aqueous two-phase system prepared by any of the above methods.

[0023] A third object of the present application is to provide a method for simultaneously improving the extraction rate of active ingredients and reducing the extraction time, using the L-carnitine-based ionic liquid aqueous two-phase system described above, comprising the steps of:

[0024] The active ingredient solution is mixed with the L-carnitine-based ionic liquid aqueous two-phase system, stirred, and then separated into two layers by standing, and the active ingredient is extracted in the upper layer.

[0025] In one embodiment, the active ingredient comprises any one of vanillin, eugenol, p-hydroxybenzaldehyde, syringaldehyde, or vanillic acid.

[0026] In one embodiment, the organic acid in step (1) comprises any one of L-lactic acid, malic acid, citric acid, or azelaic acid.

[0027] Alternatively, the organic acid in step (1) is L-lactic acid, malic acid, or azelaic acid.

[0028] Alternatively, when the organic acid is L-lactic acid or malic acid, the molar ratio of L-carnitine to L-lactic acid or malic acid is 0.8-1.2:1.

[0029] Alternatively, when the organic acid is azelaic acid, the molar ratio of L-carnitine to azelaic acid is 1.8-2.2:1.

[0030] In one embodiment, the stirring is performed at 25-45°C for 10-30 min, and the standing is performed for 2-4 h or centrifugation is performed (6000-8000 rpm, 5-8 min).

[0031] A fourth object of the present application is to provide the use of any of the above-mentioned methods or the above-mentioned L-carnitine-based ionic liquid aqueous two-phase system in the preparation of cosmetics.

[0032] In one embodiment, the L-carnitine-based ionic liquid aqueous two-phase system is used to extract active ingredients and is used in the preparation of cosmetics.

[0033] The present application has the following advantages:

[0034] The present application provides an L-carnitine-based ionic liquid aqueous two-phase system and a method for preparing the same. The aqueous two-phase system is formed by an L-carnitine-based ionic liquid, a polymer, and water. The present application fully utilizes the advantages of ionic liquid aqueous two-phase systems and is effectively applied to the extraction of active substances.

[0035] Specifically:

[0036] (1) The L-carnitine-based ionic liquid aqueous two-phase system described in the present application is a new type of ionic liquid aqueous two-phase system, which is more efficient in extracting active substances (stirring for 30 min, centrifugation at 6000-8000 rpm for 5-8 min can achieve extraction and separation), and the extraction rate of vanillin reaches 88.21% or more.

[0037] (2) The L-carnitine-based ionic liquid aqueous two-phase system can be applied to extract phenolic compounds, and has high extraction rates of different active substances such as eugenol, p-hydroxybenzaldehyde, syringaldehyde and vanillic acid, and the extraction rate is more than 85.37%, and can be applied to the fields of organic compound extraction, drug extraction, environmental protection and the like, and has great development prospect. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 An external number photograph of L-carnitine L-lactate ionic liquid (LAC) prepared;

[0039] Figure 2 An infrared spectrum of L-carnitine L-lactate ionic liquid (LAC) prepared;

[0040] Figure 3 An external number photograph of LAC / PEG 20000 / water system prepared;

[0041] Figure 4 A two-phase phase diagram of LAC-PEG 20000 at different temperatures;

[0042] Figure 5 A vanillin ultraviolet absorption standard curve. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present application are described below, and it should be understood that the embodiments are used to better explain the present application, and are not used to limit the present application.

[0044] Raw materials used in the embodiments are as follows:

[0045] L-carnitine is purchased from Adamas (Shanghai) Chemical Reagent Co., Ltd., and the CAS number is 541-15-1;

[0046] L-lactic acid is purchased from Adamas (Shanghai) Chemical Reagent Co., Ltd., and the CAS number is 79-33-4;

[0047] DL malic acid is purchased from Adamas (Shanghai) Chemical Reagent Co., Ltd., and the CAS number is 6915-15-7;

[0048] Citric acid is purchased from Shanghai McLean Biochemical Technology Co., Ltd., and the CAS number is 77-92-9;

[0049] Azelaic acid is purchased from Adamas (Shanghai) Chemical Reagent Co., Ltd., and the CAS number is 123-99-9;

[0050] Polyethylene glycol 20000 / 10000 / 6000 is purchased from China National Pharmaceutical Group Chemical Reagent Co., Ltd., and the CAS number is 25322-68-3;

[0051] Vanillin was purchased from Source Leaf Technologies, CAS No. 121-33-5;

[0052] Eugenol was purchased from Shanghai Macklin Biochemical Technology Co., Ltd., CAS No. 97-53-0;

[0053] p-Hydroxybenzaldehyde was purchased from Shanghai Macklin Biochemical Technology Co., Ltd., CAS No. 123-08-0;

[0054] Eugenal was purchased from Adamas Reagent (Shanghai) Co., Ltd., CAS No. 134-96-3;

[0055] Vanillic acid was purchased from Shanghai Macklin Biochemical Technology Co., Ltd., CAS No. 121-34-6.

[0056] Test method:

[0057] 1. Infrared detection method of ionic liquid:

[0058] The dried ionic liquid was dropped on the window sheet, and a Fourier infrared spectrometer was used for detection.

[0059] 2. UV detection method of phenolic substance content:

[0060] The solutions of the upper and lower phases of the aqueous two-phase system were diluted by a certain multiple, and the absorbance was measured using a UV spectrophotometer. The concentration was calculated according to the standard curve.

[0061] Example 1: Preparation of L-carnitine-based ionic liquid aqueous two-phase system

[0062] 1. Preparation of LAC ionic liquid, the steps are as follows:

[0063] (1) 1.612 g of L-carnitine and 1.001 g of 90% L-lactic acid solution were dissolved in 5 g of ultrapure water (molar ratio of L-carnitine to L-lactic acid was 1:1), and stirred at room temperature at 500 rpm for 4 h;

[0064] (2) The aqueous solution after reaction was evaporated at 60°C using a rotary evaporator for 2 h to remove most of the water; vacuum dried overnight to obtain LAC ionic liquid.

[0065] The prepared LAC ionic liquid was a colorless transparent liquid and had fluidity, and no obvious change occurred after storage at room temperature for 30 days, as shown in Figure 1 The results of using Fourier infrared spectrum to detect the structure of the ionic liquid are shown in Figure 2

[0066] 2. Preparation of aqueous two-phase system, the steps are as follows: ​

[0067] (1) 1.0 g PEG 20000 was dissolved in 1.5 g water to prepare a PEG 20000 aqueous solution with a mass fraction of 40%;

[0068] (2) 1.5 g LAC ionic liquid was dissolved in 1.0 g water to prepare a LAC aqueous solution with a mass fraction of 60%;

[0069] (3) The above two solutions were mixed well at 25°C, and after standing for 4 h, a phase equilibrium was reached to prepare a aqueous two-phase system (i.e., a L-carnitine-based ionic liquid aqueous two-phase system).

[0070] After phase equilibrium, the aqueous two-phase system was divided into a PEG 20000-rich upper phase and a LAC-rich lower phase, as shown in Figure 3 .

[0071] 3. Phase diagram drawing of the aqueous two-phase system, steps as follows:

[0072] (1) 0.2 g PEG 20000 was dissolved in 0.2 g water to prepare a PEG 20000 aqueous solution with a mass fraction of 50%;

[0073] (2) 2.8 g LAC was dissolved in 1.2 g water to prepare a LAC aqueous solution with a mass fraction of 70%;

[0074] (3) The PEG aqueous solution was placed in a constant-temperature water bath at 25°C, 35°C, or 45°C, and the LAC aqueous solution was added dropwise while stirring until the solution became turbid, and the mass of the added LAC aqueous solution was recorded. Then, ultrapure water was added dropwise to the turbid system while stirring until the solution became clear, and the mass of the added ultrapure water was recorded. The process was repeated to prepare an aqueous two-phase phase diagram of LAC and PEG 20000 at different temperatures, and the results are shown in Figure 4 . The results show that as the temperature increases, the binodal line deviates more from the origin, indicating that the phase formation ability of the system is enhanced. The system has good temperature sensitivity.

[0075] Example 2: Application of the L-carnitine-based ionic liquid aqueous two-phase system in extracting substances

[0076] The aqueous two-phase system prepared in Example 1 was used to detect the extraction effect on vanillin.

[0077] 1. Draw the standard curve of vanillin UV absorption, steps as follows:

[0078] (1) Take 0.01 g of vanillin and dilute it to 100 mL in a volumetric flask to make a 0.1 g / L solution, and dilute it to 0.002 g / L, 0.003 g / L, 0.004 g / L, 0.005 g / L, 0.006 g / L, 0.007 g / L, and 0.008 g / L, respectively;

[0079] (2) Use a UV-visible absorption spectrometer to detect the absorbance of the above solutions at the characteristic absorption peak, and draw a standard curve as shown in Figure 5

[0080] 2. Detecting the extraction effect of the aqueous two-phase system on vanillin

[0081] Mix 1.0 g of PEG 20000, 1.5 g of LAC (i.e. the mass ratio of PEG 20000 to LAC is 4:6), and 2.5 g of 0.1 g / L vanillin aqueous solution, stir at 25°C for 30 min, and separate the layers by standing (2-4 h) or centrifugation (6000-8000 rpm, 5-8 min);

[0082] Dilute the upper and lower phase solutions, respectively, and use a UV-visible spectrophotometer to detect the absorbance at the characteristic peak, and calculate the extraction rate of vanillin in the upper phase to be 91.97%.

[0083] 3. Temperature sensitivity

[0084] Mix 1.0 g of PEG 20000, 1.5 g of LAC, and 2.5 g of 0.1 g / L vanillin aqueous solution, and stir at 30°C, 35°C, and 40°C for 30 min, respectively, and separate the layers by standing;

[0085] Dilute the upper and lower phase solutions, respectively, and use a UV-visible absorption spectrometer to detect the absorbance at the characteristic peak, and find that as the temperature increases, the extraction efficiency decreases, from 91.97% at 25°C to 87.22% at 40°C.

[0086] Example 3: Change the extraction material

[0087] On the basis of Example 2, change vanillin to eugenol, p-hydroxybenzaldehyde, syringaldehyde, and vanillic acid, and the remaining steps are consistent with Example 2, and the extraction effect is detected.

[0088] The results show that the extraction rates of the L-leucine-based ionic liquid aqueous two-phase system for eugenol, p-hydroxybenzaldehyde, syringaldehyde, and vanillic acid are 95.72%, 93.65%, 89.29%, and 85.37%, respectively.

[0089] Example 4: Use different ionic liquids

[0090] ​(1) Based on Example 1, change L-lactic acid to malic acid, citric acid, and the remaining steps are consistent with Example 1, to prepare the ionic liquid, and detect the extraction effect of different ionic liquid aqueous two-phase systems on vanillin.

[0091] (2) Based on Example 1, change L-lactic acid to azelaic acid, and the molar ratio of azelaic acid to L-carnitine is 1:2, and the reaction solvent is anhydrous ethanol, and the remaining steps are consistent with Example 1, to prepare the ionic liquid, and detect the extraction effect of the ionic liquid aqueous two-phase system on vanillin.

[0092] The results show that the efficiency of the aqueous two-phase system formed by L-lactic acid and PEG 20000 for extracting vanillin is the highest, reaching 91.97%, followed by azelaic acid, with an extraction rate of 90.88%, then malic acid, with an extraction rate of 88.21%, and the worst is citric acid, with an extraction rate of 82.43%. The extraction rates of the four acids are the same as the relationship with temperature, and low temperature is more conducive to extraction.

[0093] Example 5: Use of different molecular weight polyethylene glycols

[0094] Based on Example 1, change PEG 20000 to PEG 6000 and PEG 10000, and the remaining steps are consistent with Example 1, to prepare the ionic liquid, and detect the extraction effect of different ionic liquid aqueous two-phase systems on vanillin.

[0095] It is found that the larger the molecular weight of PEG, the higher the extraction rate of the aqueous two-phase system formed with LAC for vanillin. The extraction rates of the ionic liquids prepared using PEG 6000 and PEG 10000 for vanillin are 78.21% and 85.77%, respectively. This is mainly because the larger the molecular weight of PEG, the greater the difference between the two phases in terms of hydrophilicity and hydrophobicity, and the more obvious the enrichment of the PEG-rich phase for vanillin.

[0096] Comparative Example 1: Use of conventional aqueous two-phase systems

[0097] A dextran (DEX) 500000 + polyethylene glycol 20000 system for extracting vanillin is prepared as follows:

[0098] Mix 0.3g of DEX 500000, 0.2g of PEG 20000, 2g of ultrapure water, and 2.5g of a 0.1g / L vanillin aqueous solution thoroughly, stir at 25°C for 30min, and then let stand for 12h to separate into two phases. Dilute the upper and lower phase solutions separately, and detect the absorbance at the characteristic peak using a UV-visible absorption spectrometer. Vanillin is mainly distributed in the upper phase (PEG-rich phase), and the extraction rate is calculated to be 68.05%.

[0099] The results show that compared with the system of the present application, the conventional aqueous two-phase system has a longer standing phase separation time and a lower extraction rate.

[0100] Comparative Example 2: using different ionic liquid

[0101] On the basis of Example 1, L-carnitine was changed to choline lactate and betaine lactate, and the remaining steps were consistent with Example 1 to prepare an ionic liquid, which was used to form an aqueous two-phase system with PEG 20000, vanillin was extracted according to the operation of Example 2, and the extraction effect of p-vanillin was detected.

[0102] The results show that the extraction rates of vanillin by the aqueous two-phase systems formed by L-carnitine and L-lactic acid ionic liquid and PEG are 78.84% and 83.07%, respectively. It can be seen that the extraction rates are lower than those of the ionic liquid aqueous two-phase system of the present application.

[0103] Example 6: changing the ratio of ionic liquid

[0104] On the basis of Example 1, the molar ratio of L-carnitine and L-lactic acid was changed to 2:1, 3:1, and 4:1, and the remaining steps were consistent with Example 1 to detect the extraction effect of vanillin.

[0105] The results show that as the proportion of L-carnitine increases, the ability of the prepared ionic liquid to form an aqueous two-phase system with PEG 20000 to extract vanillin decreases. Specifically, when the molar ratio of L-carnitine and L-lactic acid is 2:1, 3:1, and 4:1, the extraction rates are 90.11%, 88.36%, and 80.29%, respectively, which are lower than the efficiency of the ionic liquid prepared when the molar ratio of L-carnitine and L-lactic acid is 1:1.

[0106] Example 7: changing the composition ratio of two phases

[0107] On the basis of Example 2, the mass ratio of LAC and PEG 20000 was changed to 8:2, 7.5:2.5, 7:3, and 6.5:3.5, and the remaining steps were consistent with Example 2 to detect the extraction effect of vanillin.

[0108] The results show that as the mass fraction of PEG 20000 increases, the ability of the aqueous two-phase system to extract vanillin increases, and the mass ratio of LAC and PEG 20000 is 8:2, 7.5:2.5, 7:3, and 6.5:3.5, the extraction rates are 71.62%, 72.83%, 81.85%, and 90.61%, respectively, which are lower than the results of Example 2.

[0109] Comparative Example 3: using other polymers

[0110] On the basis of Example 1, polyethylene glycol 20000 was changed to dextran 500000, and the rest of the steps were consistent with Example 1. It was found that LAC could not form a double water phase with dextran 500000. Therefore, it cannot be used for subsequent extraction.

[0111] Although the present application has been disclosed in its preferred embodiments as described above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be defined by the claims.

Claims

1. A method for preparing a L-carnitine-based ionic liquid aqueous two-phase system, characterized in that: Including steps: (1) mixing L-carnitine, an organic acid, and water, reacting the mixture; and drying the mixture after the reaction to obtain a L-carnitine-based ionic liquid; (2) mixing the L-carnitine-based ionic liquid with a polyethylene glycol aqueous solution and allowing the mixture to stand to obtain a L-carnitine-based ionic liquid aqueous two-phase system; Wherein, the molar ratio of L-carnitine to the organic acid in step (1) is 1 to 4:1, and the organic acid includes any one of L-lactic acid, malic acid, citric acid, and azelaic acid.

2. The method according to claim 1, characterized in that In step (1), the organic acid is L-lactic acid, malic acid or azelaic acid; Optionally, when the organic acid is L-lactic acid or malic acid, the molar ratio of L-carnitine to L-lactic acid or malic acid is 0.8 to 1.2:1; Optionally, when the organic acid is azelaic acid, the molar ratio of L-carnitine to azelaic acid is 1.8-2.2:

1.

3. The method according to claim 1, characterized in that The reaction in step (1) is stirred at 400-700 rpm at room temperature for 2-6 hours; Optionally, the drying is first performed by rotary evaporation at 50-60° C. for 1-3 hours, and then vacuum drying for 12-24 hours.

4. The method according to claim 1, wherein In step (2), the polyethylene glycol includes any one of PEG 20000, PEG 10000, PEG 6000, polyethylene glycol 12000, polypropylene glycol 400 (PPG 400), and polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol (EO-PO-EO); Optionally, the polyethylene glycol in step (2) is PEG 10000 or PEG 20000.

5. The method according to claim 1, wherein The mass ratio of L-carnitine-based ionic liquid to polyethylene glycol in step (2) is 0.5 to 6:1 Optionally, the mass ratio of L-carnitine-based ionic liquid to polyethylene glycol is 1 to 4:

1.

6. A L-carnitine-based ionic liquid aqueous two-phase system prepared by the method according to any one of claims 1 to 5.

7. A method for simultaneously improving the extraction rate of active ingredients and reducing the extraction time, characterized in that: The extraction using the L-carnitine-based ionic liquid aqueous two-phase system according to claim 6 comprises the steps of: The L-carnitine-based ionic liquid two-phase aqueous system is mixed with the active ingredient solution, stirred, layered, and the active ingredient is extracted from the upper phase.

8. The method according to claim 7, characterized in that The active ingredient includes any one of vanillin, eugenol, p-hydroxybenzaldehyde, syringaldehyde and vanillic acid.

9. The method according to claim 7, characterized in that Stir at 25-45°C for 10-30 minutes, let stand for 2-4 hours or centrifuge at 6000-8000 rpm for 5-8 minutes.

10. Use of the method according to any one of claims 1 to 5, the method according to any one of claims 7 to 9, or the L-carnitine-based ionic liquid aqueous two-phase system according to claim 6 in the preparation of cosmetics.

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