Method for purifying medium / long carbon chain triglyceride

Abstract

The invention provides a method for purifying medium / long carbon chain triglyceride, and relates to the technical field of chemical engineering. The method comprises the following steps: mixing ionic liquid with a polar diluent to obtain an extracting agent; the ionic liquid comprises an anionic surface active ionic liquid, a cationic surface active ionic liquid or a zwitterionic surface active ionic liquid; the method comprises the following steps: dissolving a medium / long carbon chain triglyceride raw material in a weak-polarity organic solvent to obtain a raw material solution; carrying out liquid-liquid extraction on the raw material liquid by using the extracting agent to obtain a raffinate phase, and distilling the raffinate phase to obtain a residue which is medium / long carbon chain triglyceride; the liquid-liquid extraction comprises cross-flow extraction, counter-flow extraction or fractional extraction. The purification method provided by the invention is simple in process, simple to operate, low in cost, large in treatment capacity, high in purification efficiency, high in purity of medium / long carbon chain triglyceride and high in yield.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a method for purifying medium / long carbon chain triglycerides. Background Art

[0002] Triglycerides refer to glycerides formed by esterification of the three hydroxyl groups of glycerol with fatty acids. According to the length of the alkyl chain, triglycerides can be divided into short-chain (C2-C5), medium-chain (C6-C12) and long-chain (C13-C24) triglycerides. Among them, medium-chain triglycerides can be completely absorbed into the small intestinal mucosa and enter the cells without bile salts, and directly enter the liver through the portal vein in the form of fatty acids, which can quickly provide energy for the body and will not form fat accumulation in the body, and have important health benefits. In clinical practice, it is mainly used for weight loss, promoting energy metabolism and promoting the recovery of people with brain degeneration. Moreover, triglycerides are also the main component of food fat, one of the main forms of energy acquisition and storage for animals and humans, and also an important raw material in the fields of chemical medicine. Structural triglycerides are the key raw materials for the production of a new generation of fat emulsions - structural fat emulsion injection (C6-24).

[0003] Triglycerides, including structured triglycerides, are prepared by chemical synthesis and enzymatic methods. In the preparation process, byproducts such as fatty acids, monoglycerides and diglycerides are inevitably produced, and separation and purification are required to obtain high-purity triglycerides. At present, the purification methods of triglycerides mainly include molecular distillation, chromatography, simulated moving bed, bio-enzyme catalytic hydrolysis and combined methods (such as silica gel adsorption / silica gel column adsorption-thin film / molecular distillation combined method, bio-enzyme catalysis), etc. Among them, molecular distillation has problems such as high distillation temperature and high equipment cost and parameter requirements. Chromatography is to separate triglycerides by using the difference in product polarity, but because chromatography is limited by the filling size of silica gel column and consumes a large amount of organic solvent, it is not suitable for industrial application of triglyceride purification. The purity of triglyceride monomers obtained by simulated moving bed separation and purification is close to 100%, but the simulated moving bed equipment is complex and the investment cost is high. The method of silica gel adsorption / silica gel column adsorption-thin film / molecular distillation combined obtains triglycerides with high purity, but the operation is cumbersome and the processing volume is small. The non-triglyceride components of the raw materials are hydrolyzed into non-triglyceride components by bio-enzyme catalysis, and then the water phase is removed to obtain triglycerides. The triglycerides obtained by this method are of high purity, but the cost is relatively high and the process is relatively complicated. Therefore, it is of great application value to study the purification method of medium / long carbon chain triglycerides with simple process, low cost and large scale. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for purifying medium / long carbon chain triglycerides. The purification method provided by the present invention has simple process, low cost, large processing capacity, high purification efficiency, and the obtained medium / long carbon chain triglyceride products have high purity and high yield.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for purifying medium / long carbon chain triglycerides, comprising the following steps:

[0007] Mixing an ionic liquid with a polar diluent to obtain an extractant; the ionic liquid includes an anionic surface-active ionic liquid, a cationic surface-active ionic liquid or an anionic and cationic surface-active ionic liquid;

[0008] Dissolving a medium / long carbon chain triglyceride raw material in a weak polar organic solvent to obtain a raw material liquid;

[0009] The extractant is used to perform liquid-liquid extraction on the raw liquid to obtain a raffinate phase, and the raffinate phase is distilled to obtain a residue of medium / long carbon chain triglycerides; the liquid-liquid extraction includes cross-current extraction, countercurrent extraction or fractional extraction.

[0010] Preferably, the anionic surfactant ionic liquid comprises short-chain cations and long carbon-chain anions;

[0011] The short-chain cation is a cation containing a short-chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation, a quaternary ammonium cation, an amino acid or a choline cation; the short-chain substituent includes an alkyl group, an olefin group or a hydroxyl-substituted alkyl group, and the carbon number of the short-chain substituent is ≤4;

[0012] The long carbon chain anion is an anion containing a long carbon chain substituent, and the anion includes a carboxylic acid anion, an amino acid anion, a phosphate anion, a sulfonic acid anion or a sulfate anion; the carbon number of the long carbon chain substituent is ≥6.

[0013] Preferably, the cationic surfactant ionic liquid comprises long carbon chain cations and anions;

[0014] The long carbon chain cation is a cation containing a long carbon chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation or a quaternary ammonium cation; the carbon number of the long carbon chain substituent is ≥6;

[0015] The anions include halogen ions, perchlorate ions, nitrate ions, hydrogen sulfate ions, dihydrogen phosphate ions, carboxylic acid anions containing short-chain substituents or amino acid anions containing short-chain substituents; the short-chain substituents in the carboxylic acid anions containing short-chain substituents and the amino acid anions containing short-chain substituents independently include alkyl groups, olefin groups or hydroxyl-substituted alkyl groups, and the carbon number of the short-chain substituent is ≤4.

[0016] Preferably, the anionic and cationic surfactant ionic liquid comprises a long carbon chain cation and a long carbon chain anion;

[0017] The long carbon chain cation is a cation containing a long carbon chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation or a quaternary ammonium cation; the carbon number of the long carbon chain substituent is ≥6;

[0018] The long carbon chain anion is an anion containing a long carbon chain substituent, and the anion includes a carboxylic acid anion, an amino acid anion, a phosphate anion, a sulfonic acid anion or a sulfate anion; and the carbon number of the long carbon chain substituent is independently ≥6.

[0019] Preferably, the long carbon chain substituent has 6 to 24 carbon atoms.

[0020] Preferably, the molar fraction of the ionic liquid in the extractant is 0.1 to 90%;

[0021] The polar diluent includes one or more of acetonitrile, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and methanol.

[0022] Preferably, the purity of the medium / long carbon chain triglyceride raw material is 20-90%;

[0023] The weakly polar organic solvent includes C6-C20 straight-chain saturated alkanes and / or branched-chain saturated alkanes;

[0024] The concentration of the raw material solution is 0.1-300 g / L.

[0025] Preferably, the process parameters of the cross-current extraction include: the number of extraction stages is 2 to 8, the flow ratio of the extractant to the raw material liquid is 1:(0.05 to 20), and the extraction temperature is 10 to 50°C.

[0026] Preferably, the process parameters of the countercurrent extraction include: the number of extraction stages is 2 to 8, the flow ratio of the extractant to the raw material liquid is 1:(0.03 to 20), and the extraction temperature is 10 to 50°C.

[0027] Preferably, a detergent is also added during the fractionation extraction process, and the detergent comprises a weak polar organic solvent;

[0028] The process parameters of the fractional extraction include: the number of extraction stages is 1 to 20, the number of washing stages is 1 to 10, the flow ratio of the extractant to the raw liquid is 1:(0.05 to 20), and the flow ratio of the extractant to the washing agent is 1:(0.05 to 20).

[0029] The present invention mixes an ionic liquid with a polar diluent to obtain an extractant; the ionic liquid includes an anionic surfactant ionic liquid, a cationic surfactant ionic liquid or an anionic and cationic surfactant ionic liquid; a medium / long carbon chain triglyceride raw material is dissolved in a weak polar organic solvent to obtain a raw material liquid; the raw material liquid is subjected to liquid-liquid extraction using the extractant to obtain a raffinate phase, the raffinate phase is distilled, and the residue is a medium / long carbon chain triglyceride; the liquid-liquid extraction includes cross-current extraction, countercurrent extraction or fractional extraction. Ionic liquids generally refer to compounds composed of anions and cations that are liquid at room temperature or near room temperature. Compared with molecular solvents, the ionic liquids used in the present invention have a unique structure, which makes them have unique physical and chemical properties such as low volatility, low melting point, high cohesive energy, and non-flammability; in addition, as a designable solvent, the properties of the ionic liquid can be adjusted by changing the anionic and cationic structure; these characteristics enable ionic liquids to be used as environmentally friendly solvents to replace traditional volatile organic solvents in liquid-liquid extraction. The present invention utilizes ionic liquids to perform liquid-liquid extraction on medium / long carbon chain triglyceride raw materials, and has the advantages of large processing capacity and simple operation. Moreover, the present invention adopts ionic liquids with surface activity as extractants according to the structural characteristics of medium / long carbon chain triglycerides and their impurities, and realizes molecular recognition extraction and separation according to the difference in the strength of the interaction between the separation object and the impurities and the ionic liquids, such as hydrogen bonds, to obtain high-purity medium / long carbon chain triglycerides. The purification method provided by the present invention has simple process, low cost, large processing capacity, high purification efficiency, and the obtained medium / long carbon chain triglyceride products have high purity and high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The process flow diagrams for cross-current extraction, countercurrent extraction and fractional extraction are shown below;

[0031] Figure 2 The HPLC spectrum of the caprylic acid triglyceride product prepared in Example 1;

[0032] Figure 3 This is the HPLC spectrum of the n-undecanoic acid triglyceride product prepared in Example 2;

[0033] Figure 4 This is the HPLC spectrum of the 1,5-pentadecanoic acid triglyceride product prepared in Example 19. DETAILED DESCRIPTION

[0034] The present invention provides a method for purifying medium / long carbon chain triglycerides, comprising the following steps:

[0035] Mixing an ionic liquid with a polar diluent to obtain an extractant; the ionic liquid includes an anionic surface-active ionic liquid, a cationic surface-active ionic liquid or an anionic and cationic surface-active ionic liquid;

[0036] Dissolving a medium / long carbon chain triglyceride raw material in a weak polar organic solvent to obtain a raw material liquid;

[0037] The extractant is used to perform liquid-liquid extraction on the raw liquid to obtain a raffinate phase, and the raffinate phase is distilled to obtain a medium / long carbon chain triglyceride product as the residue; the liquid-liquid extraction includes cross-current extraction, countercurrent extraction or fractional extraction.

[0038] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0039] The invention mixes the ionic liquid with the polar diluent to obtain the extractant.

[0040] In the present invention, the ionic liquid includes anionic surface-active ionic liquid, cationic surface-active ionic liquid or anionic and cationic surface-active ionic liquid.

[0041] In the present invention, the anionic surfactant ionic liquid preferably includes a short-chain cation and a long carbon chain anion. In the present invention, the short-chain cation is preferably a cation containing a short-chain substituent, and the cation preferably includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation, a quaternary ammonium cation, an amino acid or a choline cation; the short-chain substituent preferably includes an alkyl, an olefin or a hydroxy-substituted alkyl, and the carbon number of the short-chain substituent is preferably ≤4, and in a specific embodiment, the carbon number can be 1, 2, 3 or 4. In the present invention, the long carbon chain anion is preferably an anion containing a long carbon chain substituent, and the anion preferably includes a carboxylic acid anion, an amino acid anion, a phosphate anion, a sulfonic acid anion or a sulfate anion; the carbon number of the long carbon chain substituent is preferably ≥6, more preferably 6 to 24, and further preferably 8 to 18. In specific embodiments, the carbon number can be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24.

[0042] In the present invention, the anionic surfactant ionic liquid preferably includes one or more of choline long-chain fatty acid salts, 1-ethyl-3-methylimidazole long-chain fatty acid salts, 1-hydroxyethyl-3-methylimidazole long-chain fatty acid salts, tetraethyl quaternary phosphonium long-chain fatty acid salts and tetraethyl quaternary ammonium long-chain fatty acid salts.

[0043] In the present invention, the cationic surfactant ionic liquid preferably includes a long carbon chain cation and an anion. In the present invention, the long carbon chain cation is preferably a cation containing a long carbon chain substituent, and the cation preferably includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation or a quaternary ammonium cation; the carbon number of the long carbon chain substituent is preferably ≥6, more preferably 6 to 24, and further preferably 8 to 18. In a specific embodiment, the carbon number can be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24. In the present invention, the anions preferably include halogen ions, perchlorate ions, nitrate ions, hydrogen sulfate ions, dihydrogen phosphate ions, carboxylic acid anions containing short-chain substituents or amino acid anions containing short-chain substituents; the short-chain substituents in the carboxylic acid anions containing short-chain substituents and the amino acid anions containing short-chain substituents independently preferably include alkyl, olefin or hydroxy-substituted alkyl, and the carbon number of the short-chain substituent is preferably ≤4, and in specific embodiments the carbon number can be 1, 2, 3 or 4.

[0044] In the present invention, the cationic surfactant ionic liquid preferably includes one or more of tetraethyl quaternary phosphonium dodecyl sulfonate, 1-vinyl-3-methylimidazolium dodecyl sulfonate, 1-dodecyl-3-methylimidazolium acetate, 1-dodecyl-3-methylimidazolium chloride, dodecyltrimethylammonium chloride and dodecylpyridinium chloride or 1-decyl-3-methylimidazolium hydrogen sulfate.

[0045] In the present invention, the anionic and cationic surfactant ionic liquid preferably includes long carbon chain cations and long carbon chain anions. The optional types of the long carbon chain cations are the same as the optional types of the long carbon chain cations in the cationic surfactant ionic liquid, and the long carbon chain anions are the same as the optional types of the long carbon chain anions in the anionic surfactant ionic liquid, which will not be repeated here one by one.

[0046] In the present invention, the anionic and cationic surfactant ionic liquid preferably includes one or more of tetraoctyl quaternary phosphonium long-chain fatty acid salt, 1-octyl-3-methylimidazole long-chain fatty acid salt, dodecyltrimethylammonium long-chain sulfonate, 1-octyl-3-methylimidazole long-chain sulfate and 1-octyl-3-methylimidazole long-chain amino acid salt.

[0047] In the present invention, the polar diluent preferably includes one or more of water, acetonitrile, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) and methanol.

[0048] In the present invention, the molar fraction of the ionic liquid in the extractant is preferably 0.1-90%, more preferably 0.5-50%, and in a specific embodiment of the present invention, it can be 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%. In the present invention, if the amount of ionic liquid added is too large, the viscosity of the extractant will be too large, which is not conducive to mass transfer.

[0049] The invention dissolves the medium / long carbon chain triglyceride raw material in a weak polar organic solvent to obtain a raw material liquid.

[0050] In the present invention, the purity of the medium / long carbon chain triglyceride raw material is preferably 20-90%, and in a specific embodiment of the present invention, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%. In the present invention, the impurities in the medium / long carbon chain triglyceride raw material preferably include one or more of medium / long carbon chain fatty acids, medium / long carbon chain monoglycerides and medium / long carbon chain diglycerides. In the present invention, the medium / long carbon chain triglycerides in the medium / long carbon chain triglyceride raw material preferably include medium carbon chain triglycerides or long carbon chain triglycerides; the carbon numbers of the medium / long carbon chains of the medium / long carbon chain triglycerides, medium / long carbon chain fatty acids, medium / long carbon chain monoglycerides and medium / long carbon chain diglycerides are independently preferably 8 to 24, and in specific embodiments of the present invention can be 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24.

[0051] In the present invention, the weakly polar organic solvent preferably includes straight-chain saturated alkanes and / or branched saturated alkanes of C6 to C20, and the C6 to C20 are more preferably C6 to C12. In a specific embodiment, the C6 to C20 can be C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19 or C20.

[0052] In the present invention, the concentration of the raw material solution is preferably 0.1-300 g / L, more preferably 20-200 g / L. In specific embodiments of the present invention, the concentration of the raw material solution can be 0.1 g / L, 0.5 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 1 35g / L, 140g / L, 145g / L, 150g / L, 155g / L, 160g / L, 165g / L, 170g / L, 175g / L, 180g / L, 185g / L, 190g / L, 195g / L, 200g / L, 205g / L, 210g / L, 215g / L, 220g / L, 225g / L, 230g / L, 235g / L, 240g / L, 245g / L, 250g / L, 255g / L, 260 g / L, 265g / L, 270g / L, 275g / L, 280g / L, 285g / L, 290g / L, 295g / L or 300g / L.

[0053] After obtaining the extractant and the raw material liquid, the present invention uses the extractant to perform liquid-liquid extraction on the raw material liquid to obtain a raffinate phase, and the raffinate phase is distilled, and the residue is medium / long carbon chain triglycerides.

[0054] In the present invention, the extract includes cross-current extraction, counter-current extraction or fractional extraction. In the present invention, the process flow diagram of the cross-current extraction is shown in Figure 1 , each stage of cross-current extraction uses fresh extractant, and higher product purity can be obtained in a lower number of stages. In the present invention, the process flow diagram of the countercurrent extraction is shown in Figure 1 In the countercurrent extraction, the raw material and the detergent enter the extraction device from both ends respectively, and after each stage is fully mixed and separated, the light phase and the heavy phase enter the adjacent extraction stage respectively. The method is simple to operate. In the present invention, the process flow chart of the fractional extraction is shown in Figure 1 The fractionation extraction consists of an extraction section and a washing section. The raw liquid is injected between the extraction section and the washing section. This method can simultaneously obtain high purity and high recovery rate.

[0055] In the present invention, the process parameters of the cross-current extraction preferably include: the number of extraction stages is 2 to 8, and in a specific embodiment of the present invention, it can be 2, 3, 4, 5, 6, 7 or 8; the flow ratio (flow ratio) of the extractant to the raw material liquid is 1: (0.05 to 20), preferably 1: (0.1 to 10), and in a specific embodiment of the present invention, it can be 1: 0.05, 1: 0.1, 1: 0.5, 1: 1, 1: 1.5, 1: 2, 1: 2.5, 1: 3, 1: 3.5, 1: 4, 1: 4.5, 1: 5, 1: 5.5, 1: 6, 1: 6.5, 1: 7, 1: 7.5, 1: 8. 8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, 1:16.5, 1:17, 1:17.5, 1:18, 1:18.5, 1:19, 1:19.5 or 1:20; the extraction temperature is 10 to 50° C., preferably 20 to 35° C., and in a specific embodiment of the present invention, it can be 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., 40° C., 45° C. or 50° C. The medium / long carbon chain triglycerides obtained by cross-flow extraction of the present invention have high purity.

[0056] In the present invention, the process parameters of the countercurrent extraction preferably include: the number of extraction stages is 2 to 8, and in a specific embodiment of the present invention, it can be 2, 3, 4, 5, 6, 7 or 8; the flow ratio of the extractant to the raw material liquid is 1: (0.03 to 20), preferably 1: (0.1 to 10), and in a specific embodiment of the present invention, it can be 1: 0.03, 1: 0.04, 1: 0.05, 1: 0.1, 1: 0.5, 1: 1, 1: 1.5, 1: 2, 1: 2.5, 1: 3, 1: 3.5, 1: 4, 1: 4.5, 1: 5, 1: 5.5, 1: 6, 1: 6.5, 1: 7, 1: 7. 1:20; the extraction temperature is 10-50°C, preferably 20-35°C, and in specific embodiments of the present invention can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C.

[0057] In the present invention, a detergent is preferably added during the fractionation extraction process, and the detergent preferably includes a weak polar organic solvent. The optional types of the weak polar organic solvent are the same as the optional types of the weak polar organic solvent in the raw material liquid, and are not repeated here. In the present invention, the process parameters of the fractionation extraction preferably include: the number of extraction stages is 1 to 20, preferably 2 to 8, and in the specific embodiment of the present invention, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 5, 16, 17, 18, 19 or 20; the number of washing stages is 1 to 10, preferably 2 to 4, and in the specific embodiment of the present invention, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 ; The flow ratio of the extractant to the raw material liquid is 1:(0.05-20), preferably 1:(0.1-10), and in specific embodiments of the present invention can be 1:0.05, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, 1:16.5, 1:17, 1:17.5, 1:18, 1:18.5, 1:19, 1:19.5 or 1:20; the flow ratio of the extractant to the detergent is 1:(0.05-20), preferably 1:(0.1-10), and in specific embodiments of the present invention can be 1:0.05, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, 1:16.5, 1:17, 1:17.5, 1:18, 1:18.5, 1:19, 1:19.5 or 1:20. The medium / long carbon chain triglycerides obtained by fractional extraction of the present invention have high purity and high yield.

[0058] Before the distillation, the present invention preferably further comprises water washing, and the obtained water washing residue is subjected to subsequent distillation, and the purity of the medium / long carbon chain triglyceride product obtained by distillation after water washing is higher. The present invention has no special limitation on the distillation, and it can remove the solvent, such as vacuum distillation.

[0059] Ionic liquids generally refer to compounds composed of anions and cations that are liquid at room temperature or near room temperature. Compared with molecular solvents, the ionic liquids used in the present invention have a unique structure, which makes them have unique physical and chemical properties such as low volatility, low melting point, high cohesive energy, and non-flammability; in addition, as a designable solvent, ionic liquids can adjust the properties of ionic liquids by changing the anion and cation structure; these characteristics make ionic liquids an environmentally friendly solvent that can replace traditional volatile organic solvents for liquid-liquid extraction. The present invention uses ionic liquids to perform liquid-liquid extraction on medium / long carbon chain triglyceride raw materials, which has the advantages of large processing capacity and simple operation. Moreover, the present invention uses ionic liquids with surface activity as extractants for the structural characteristics of medium / long carbon chain triglycerides and their impurities, and realizes molecular recognition extraction and separation according to the difference in the strength of the interaction between the separation object and the impurities and the ionic liquid, such as hydrogen bonds, to obtain high-purity medium / long carbon chain triglycerides. The purification method provided by the present invention has simple process, low cost, large processing capacity, high purification efficiency, and the obtained medium / long carbon chain triglyceride products have high purity and high yield.

[0060] In order to further illustrate the present invention, the purification method of medium / long carbon chain triglycerides provided by the present invention is described in detail below in conjunction with the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0061] In the following embodiments, caprylic acid triglyceride is normal caprylic acid triglyceride, undecanoic acid triglyceride is normal undecanoic acid triglyceride, pentadecanoic acid triglyceride is normal pentadecanoic acid triglyceride, and lignoceryl triglyceride is normal lignoceryl triglyceride.

[0062] Example 1

[0063] The caprylic acid triglyceride raw material (HPLC purity of 62.1%) was dissolved in n-hexane to obtain a raw material liquid with a concentration of 50 g / L; acetonitrile and choline laurate were mixed to obtain an extractant with a choline laurate concentration of 5 mol%; the raw material liquid was subjected to 4-stage cross-current extraction using the extractant, and in each stage of extraction, the flow ratio of the extraction phase to the raw material phase was 0.5:1, and the extraction temperature was 30°C. The residual phase was collected, washed with water, and then distilled under reduced pressure, and the residue was the caprylic acid triglyceride product. The HPLC purity of the caprylic acid triglyceride product was 97.3%, and the yield was 80.4%. The HPLC graph of the caprylic acid triglyceride product is as follows Figure 2 shown.

[0064] Example 2

[0065] The undecanoic acid triglyceride raw material (HPLC purity of 73.0%) was dissolved in n-hexane to obtain a raw material solution with a concentration of 100 g / L; choline laurate was mixed with DMSO to obtain an extractant with a choline laurate concentration of 10 mol%; at 30°C, the extractant was subjected to 4-stage cross-current extraction on the raw material solution, the flow ratio of the extractant to the raw material solution was 1:1, and the extraction temperature was 30°C; the resulting residual phase was washed with water and then distilled under reduced pressure to obtain the undecanoic acid triglyceride product. The HPLC purity of the undecanoic acid triglyceride product is 97.9%, and the yield is 74.0%. The HPLC graph of the undecanoic acid triglyceride product is as follows Figure 3 shown.

[0066] Example 3

[0067] The only difference from Example 2 is that a second-stage cross-current extraction is performed, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.3%, and the yield is 83.2%.

[0068] Example 4

[0069] The only difference from Example 2 is that the ionic liquid cation is different, the ionic liquid is 1-butyl-3-methylimidazolium laurate, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.1%, and the yield is 76.9%.

[0070] Example 5

[0071] The only difference from Example 2 is that the anion of the ionic liquid is different. The ionic liquid is choline caprylate, and the HPLC purity of the obtained undecanoic acid triglyceride product is 94.4%, and the yield is 80.1%.

[0072] Example 6

[0073] The only difference from Example 2 is that the multi-stage extraction method is a 4-stage countercurrent extraction, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.5%, and the yield is 86.2%.

[0074] Example 7

[0075] The raw material of undecanoic acid triglyceride (HPLC purity of 73.0%) is dissolved in n-hexane to obtain a raw material liquid with a concentration of 100 g / L; choline laurate is mixed with DMSO to obtain an extractant with a choline laurate concentration of 10 mol%; the extractant fractionates and extracts the raw material liquid at 30°C, the detergent is the same as the raw material solvent, the flow ratio of the raw material liquid, the extractant and the detergent is 0.8:1:0.2, the extraction section and the washing section are 3 and 1 respectively, and the extraction temperature is 30°C; the obtained raffinate phase is washed with water and then distilled under reduced pressure to obtain undecanoic acid triglyceride. The HPLC purity of the undecanoic acid triglyceride product is 95.1%, and the yield is 90.4%.

[0076] Example 8

[0077] The only difference from Example 7 is that the number of multi-stage extraction stages is different, the number of extraction stages is 5, and the number of washing stages is 3. The HPLC purity of the obtained undecanoic acid triglyceride product is 95.4%, and the yield is 98.3%.

[0078] Example 9

[0079] The only difference from Example 7 is that the concentration of choline laurate in the extractant is 5 mol %, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.4%, and the yield is 96.5%.

[0080] Example 10

[0081] The only difference from Example 7 is that the concentration of choline laurate in the extractant is 50 mol %, and the HPLC purity of the obtained undecanoic acid triglyceride product is 99.4%, and the yield is 98.5%.

[0082] Embodiment 11

[0083] The only difference from Example 7 is that the polar diluent in the extractant is NMP, and the HPLC purity of the obtained undecanoic acid triglyceride product is 98.6%, and the yield is 96.8%.

[0084] Example 12

[0085] The only difference from Example 7 is that the extraction temperature is 45° C., the HPLC purity of the obtained undecanoic acid triglyceride product is 94.3%, and the yield is 96.4%.

[0086] Embodiment 13

[0087] The only difference from Example 7 is that the concentration of the raw material solution is 20 g / L, the HPLC purity of the obtained undecanoic acid triglyceride product is 95.3%, and the yield is 94.6%.

[0088] Embodiment 14

[0089] The only difference from Example 7 is that the solvent in the raw material liquid is n-decane, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.5%, and the yield is 94.8%.

[0090] Embodiment 15

[0091] The only difference from Example 8 is that the HPLC purity of the undecanoic acid triglyceride raw material is 41.6%, the HPLC purity of the undecanoic acid triglyceride product obtained is 91.4%, and the yield is 97.6%.

[0092] Example 16

[0093] The only difference from Example 7 is that the ionic liquid is tetraethyl quaternary phosphonium dodecyl sulfonate, and the HPLC purity of the obtained undecanoic acid triglyceride product is 93.7%, and the yield is 98.1%.

[0094] Embodiment 17

[0095] The only difference from Example 7 is that the ionic liquid is 1-octyl-3-methylimidazole N-palmitoyl alanine salt, and the HPLC purity of the obtained undecanoic acid triglyceride product is 95.2%, and the yield is 99.0%.

[0096] Embodiment 18

[0097] The only difference from Example 7 is that the ionic liquid is 1-dodecyl-3-methylimidazolium chloride, and the HPLC purity of the obtained undecanoic acid triglyceride product is 96.7%, and the yield is 98.3%.

[0098] Embodiment 19

[0099] The only difference from Example 7 is that the raw material is 15-hydroxy-1-pentadienylglycerol raw material (HPLC purity is 74.9%), and the HPLC purity of the obtained 15-hydroxy-1-pentadienylglycerol product is 95.7%, and the yield is 94.1%. The HPLC chart of the 15-hydroxy-1-pentadienylglycerol product is as follows: Figure 4 shown.

[0100] Embodiment 20

[0101] The only difference from Example 7 is that the raw material is caprylic acid triglyceride raw material (HPLC purity is 69.2%), and the HPLC purity of the obtained caprylic acid triglyceride product is 95.9%, and the yield is 98.2%.

[0102] Embodiment 21

[0103] The only difference from Example 12 is that the raw material is tetracosyl triglyceride raw material (HPLC purity is 69.2%), and the HPLC purity of the obtained tetracosyl triglyceride product is 98.2%, and the yield is 97.3%.

[0104] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for purifying medium / long chain triglycerides, comprising the following steps: Mixing an ionic liquid with a polar diluent to obtain an extractant; the ionic liquid includes an anionic surface-active ionic liquid, a cationic surface-active ionic liquid or an anionic and cationic surface-active ionic liquid; Dissolving a medium / long carbon chain triglyceride raw material in a weak polar organic solvent to obtain a raw material liquid; The extractant is used to perform liquid-liquid extraction on the raw liquid to obtain a raffinate phase, and the raffinate phase is distilled to obtain a residue of medium / long carbon chain triglycerides; the liquid-liquid extraction includes cross-current extraction, countercurrent extraction or fractional extraction.

2. The purification method according to claim 1, characterized in that The anionic surfactant ionic liquid comprises short-chain cations and long carbon-chain anions; The short-chain cation is a cation containing a short-chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation, a quaternary ammonium cation, an amino acid or a choline cation; the short-chain substituent includes an alkyl group, an olefin group or a hydroxyl-substituted alkyl group, and the carbon number of the short-chain substituent is ≤4; The long carbon chain anion is an anion containing a long carbon chain substituent, and the anion includes a carboxylic acid anion, an amino acid anion, a phosphate anion, a sulfonic acid anion or a sulfate anion; the carbon number of the long carbon chain substituent is ≥6.

3. The purification method according to claim 1, characterized in that The cationic surfactant ionic liquid comprises a long carbon chain cation and an anion; The long carbon chain cation is a cation containing a long carbon chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation or a quaternary ammonium cation; the carbon number of the long carbon chain substituent is ≥6; The anions include halogen ions, perchlorate ions, nitrate ions, hydrogen sulfate ions, dihydrogen phosphate ions, carboxylic acid anions containing short-chain substituents or amino acid anions containing short-chain substituents; the short-chain substituents in the carboxylic acid anions containing short-chain substituents and the amino acid anions containing short-chain substituents independently include alkyl groups, olefin groups or hydroxyl-substituted alkyl groups, and the carbon number of the short-chain substituent is ≤4.

4. The purification method according to claim 1, characterized in that The anionic and cationic surfactant ionic liquid comprises a long carbon chain cation and a long carbon chain anion; The long carbon chain cation is a cation containing a long carbon chain substituent, and the cation includes an imidazolium cation, a piperidinium cation, a pyridinium cation, a quaternary phosphonium cation or a quaternary ammonium cation; the carbon number of the long carbon chain substituent is ≥6; The long carbon chain anion is an anion containing a long carbon chain substituent, and the anion includes a carboxylic acid anion, an amino acid anion, a phosphate anion, a sulfonic acid anion or a sulfate anion; and the carbon number of the long carbon chain substituent is independently ≥6.

5. The purification method according to any one of claims 1 to 4, characterized in that: The carbon number of the long carbon chain substituent is 6-24.

6. The purification method according to any one of claims 1 to 4, characterized in that: The molar fraction of the ionic liquid in the extractant is 0.1 to 90%; The polar diluent includes one or more of acetonitrile, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and methanol.

7. The purification method according to claim 1, characterized in that The purity of the medium / long carbon chain triglyceride raw material is 20-90%; The weakly polar organic solvent includes C6-C20 straight-chain saturated alkanes and / or branched-chain saturated alkanes; The concentration of the raw material solution is 0.1-300 g / L.

8. The purification method according to claim 1, characterized in that The process parameters of the cross-current extraction include: the number of extraction stages is 2 to 8, the flow ratio of the extractant to the raw material liquid is 1:(0.05 to 20), and the extraction temperature is 10 to 50°C.

9. The purification method according to claim 1, characterized in that The process parameters of the countercurrent extraction include: the number of extraction stages is 2 to 8, the flow ratio of the extractant to the raw material liquid is 1:(0.03 to 20), and the extraction temperature is 10 to 50°C.

10. The purification method according to claim 1, characterized in that: A detergent is also added during the fractionation extraction process, and the detergent includes a weak polar organic solvent; The process parameters of the fractional extraction include: the number of extraction stages is 1 to 20, the number of washing stages is 1 to 10, the flow ratio of the extractant to the raw liquid is 1:(0.05 to 20), and the flow ratio of the extractant to the washing agent is 1:(0.05 to 20).

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