Method for synthesizing hydroxy fatty acid branched-chain fatty acid ester by taking hydroxy fatty acid-containing natural oil as raw material

Abstract

The invention discloses a method for synthesizing hydroxy fatty acid branched-chain fatty acid ester by taking hydroxy fatty acid-containing natural grease as a raw material, which comprises the following steps: synthesizing tri-hydroxy fatty acid branched-chain fatty acid ester triglyceride by taking the natural hydroxy fatty acid-containing grease and fatty acid acyl chloride as core raw materials through esterification reaction; then completing purification by a molecular distillation technology; carrying out directional hydrolysis by taking water as a substrate and lipase as a catalyst to generate hydroxy fatty acid branched-chain fatty acid ester; and finally, through secondary molecular distillation deep purification, the high-purity hydroxy fatty acid branched chain fatty acid ester is successfully prepared. The technology has the advantages of being simple and convenient to operate, high in large-scale mass production capacity, wide in application scene and the like, and a new thought is provided for high-value utilization of the natural hydroxyl fatty acid-containing grease.

Description

Technical Field

[0001] This invention belongs to the field of oil processing technology, specifically relating to a method for synthesizing hydroxy fatty acid branched-chain fatty acid esters from natural oils containing hydroxy fatty acids. Background Technology

[0002] In 2014, American scientists discovered a new type of endogenous lipid in AG4OX mice (transgenic mice that overexpress Glut 4 in adipose tissue), namely branched-chain fatty acid hydroxy fatty acid esters (FAHFA). This type of lipid is a fatty acid ester composed of one molecule of fatty acid and one molecule of hydroxy fatty acid. The ester bond is composed of the hydroxyl group of the hydroxy fatty acid and the carboxyl group of the fatty acid.

[0003] Branched-chain fatty acid esters of hydroxy fatty acids generally exhibit the effects of improving insulin resistance and reducing inflammation in adipose tissue. Among them, 12-oleic hydroxystearate (12-OAHSA) can alleviate inflammation in adipose tissue and indirectly improve diabetes.

[0004] Currently, the synthesis of hydroxy fatty acid branched-chain fatty acid esters is still in the early experimental stage and cannot be mass-produced. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for synthesizing hydroxy fatty acid branched fatty acid esters from natural oils containing hydroxy fatty acids.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for synthesizing hydroxy fatty acid branched-chain fatty acid esters from natural oils containing hydroxy fatty acids, comprising, Using natural oils containing hydroxy fatty acids and fatty acid acyl chlorides as raw materials, tri-hydroxy fatty acid branched fatty acid ester triglyceride (TAG-FAHFA) is synthesized by esterification under the action of an acid-binding agent. High-purity TAG-FAHFA was obtained by molecular distillation; TAG-FAHFA was hydrolyzed by immobilized lipase to obtain hydroxy fatty acid branched-chain fatty acid esters (FAHFA). High-purity FAHFA was obtained by purifying branched-chain fatty acid esters of hydroxy fatty acids through multi-stage molecular distillation.

[0009] As a preferred embodiment of the method described in this invention, the natural oil containing hydroxy fatty acids is one or more of castor seed oil, Sal fat, Orychophragmus violaceus seed oil, Lesquerella oil, and their hydrogenated or fractionated products.

[0010] In a preferred embodiment of the method described in this invention, the fatty acid acyl chloride is one of the following: hexanoyl chloride, caprylic acid acyl chloride, capric acid acyl chloride, lauric acid acyl chloride, myristic acid acyl chloride, palmitic acid acyl chloride, palmitoleic acid acyl chloride, stearic acid acyl chloride, oleic acid acyl chloride, linoleic acid acyl chloride, linolenic acid acyl chloride, arachidic acid acyl chloride, arachidonic acid acyl chloride, behenic acid acyl chloride, lignochlorophenolic acid acyl chloride, EPA acyl chloride, DPA acyl chloride, DHA acyl chloride, and nervonic acid acyl chloride.

[0011] In a preferred embodiment of the method described in this invention, the acid-binding agent is one or more of triethylamine, pyridine, and N,N-diisopropylethylamine.

[0012] In a preferred embodiment of the method described in this invention, the esterification synthesis of tri-hydroxy fatty acid branched-chain fatty acid ester triglycerides, wherein, The substrate molar ratio is 1:4 to 1:10, the temperature is 20 to 50℃, the time is 2 to 24 h, the amount of acid-binding agent added is 10 to 20% of the total mass of the substrate, a solvent is added to aid dissolution, and a quenching agent is used to quench the reaction after it is completed. The solvent is one of dichloromethane or trichloromethane, and the amount added is 6 to 8 times the total mass of the substrate; The quenching agent is one of water, ethanol or methanol, and the amount added is 0.8 to 1.5 times the total mass of the substrate.

[0013] In a preferred embodiment of the method described in this invention, the parameters for the molecular distillation purification of TAG-FAHFA are as follows: Feed rate 0.5-1.5 mL / min, absolute pressure 2-8 Pa, evaporation surface temperature 120-180℃, scraper rotation speed 100-150 r / min, and the distillation residue is high-purity TAG-FAHFA.

[0014] As a preferred embodiment of the method described in this invention, the immobilized lipase is one or more of Palatase 20000L, Novozym 435, Lipozyme TL IM, Lipozyme RM IM, Novozym 40086, Lipase AY, Lipase DF-15, IM-NE100, NE-10, NE-20, R-001, RIM-03, AP6, and Amano PS.

[0015] As a preferred embodiment of the method described in this invention, the step of using immobilized lipase to enzymatically hydrolyze TAG-FAHFA to obtain hydroxy fatty acid branched-chain fatty acid esters includes, Using water and TAG-FAHFA as substrates, with a molar ratio of 1:600 ​​to 1:1500, the reaction time was 3 to 8 hours, the reaction temperature was 30 to 50°C, the enzyme accounted for 8% to 12% of the total substrate mass, and the emulsifier accounted for 0.2% of the total substrate mass. The emulsifier is one or more of deoxycholate, Tween 20, Triton 100, PEG-400, and polyricinoleate.

[0016] In a preferred embodiment of the method described in this invention, the parameters for purifying branched-chain fatty acid esters of hydroxy fatty acids via multi-stage molecular distillation are as follows: First-stage distillation: evaporation surface temperature 160-180℃, scraper rotation speed 100-150 r / min, feed rate 1-1.6 ml / min, condensation temperature 40-60℃, and collect the distillate; Secondary distillation: Evaporation surface temperature 200-260℃, scraper rotation speed 120-160r / min, feed rate 1-1.6ml / min, condensation temperature 30-40℃, and distillate collected.

[0017] Another objective of this invention is to overcome the shortcomings of the prior art and provide a hydroxy fatty acid branched fatty acid ester.

[0018] Beneficial effects of this invention: (1) This invention develops a method for preparing branched-chain fatty acid esters of hydroxy fatty acids. Compared with the direct esterification synthesis of hydroxy fatty acids and fatty acids, the glycerol backbone in the natural oil molecules containing hydroxy fatty acids is a natural protective group, which reduces the introduction of impurities during the synthesis process. Molecular distillation can significantly increase the yield, reduce the time cost, and ensure the purity of the product. At the same time, the method of directly using hydroxy fatty acids and fatty acid acyl chlorides to esterify will produce byproducts: straight-chain anhydrides formed by the esterification of fatty acid acyl chlorides and carboxyl groups of hydroxy fatty acids, and fatty acids formed by water quenching of fatty acid acyl chlorides. Among them, straight-chain anhydrides cannot be separated by molecular distillation and can only be separated by column chromatography. Fatty acids and FAHFA are more suitable for molecular distillation separation and not suitable for column chromatography separation, resulting in complicated separation steps and low efficiency. The method of this invention avoids the difficult-to-separate intermediate products, constructs TAG-FAHFA as an intermediate product, and uses molecular distillation for separation to improve separation efficiency, providing a basis for exploring the relationship between the structure and efficacy of branched-chain fatty acid esters of hydroxy fatty acids.

[0019] (2) This invention provides a basis for the high-value utilization of natural oils containing hydroxy fatty acids. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 The images show the liquid chromatograms of the esterified synthetic product (triglycerides 12-oleic acid hydroxystearate, TAG-12-OAHSAs) and the molecularly distilled purified TAG-12-OAHSAs from Example 1.

[0021] Figure 2 The image shows the liquid chromatograms of the products after enzymatic hydrolysis, primary molecular distillation, and secondary molecular distillation in Example 1.

[0022] Figure 3 The image shows a secondary mass spectrum of 12-oleic hydroxystearate (12-OAHSA) in Example 1, where the instrument used was ultra-high performance liquid chromatography-quadrupole tandem time-of-flight mass spectrometry (UPLC-Q-TOF).

[0023] Figure 4 The image shows a secondary mass spectrum of 12-oleic hydroxy oleate (12-OAHSO) in Example 2, where the instrument used was UPLC-Q-TOF.

[0024] Figure 5 This is a secondary mass spectrum of 12-lauric hydroxystearic acid (12-LAHSA) in Example 3, where the instrument used was UPLC-Q-TOF. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available; all FAHFA mass spectrometry detections in this invention are performed in negative ion mode.

[0027] Example 1 This embodiment provides a method for preparing hydroxy fatty acid branched fatty acid esters, including the following steps: (1) Weigh 40g of hydrogenated castor oil, dissolve it in 1L of dichloromethane, add 12g of pyridine dropwise, stir for 5min, then add 80g of oleic acid chloride dropwise, and let it react at room temperature for 16h.

[0028] After the reaction was complete, 100 mL of anhydrous ethanol was added to quench the oleoyl chloride. The organic phase was washed with 750 mL of 0.5 M hydrochloric acid aqueous solution, 750 mL of saturated sodium bicarbonate aqueous solution, and 750 mL of saturated sodium chloride. Then, the dichloromethane phase was removed and rotary evaporated under vacuum to obtain the esterified product. The composition of the esterified product is shown in [reference needed]. Figure 1 .

[0029] (2) The esterification product was subjected to molecular distillation to obtain high-purity TAG-12-OAHSAs, the liquid chromatogram of which is shown in the figure. Figure 1 The specific parameters for molecular distillation were: feed rate 1.6 ml / min, evaporation surface temperature 160℃, condensation surface temperature 25℃, system absolute pressure 3 Pa, scraper rotation speed 150 r / min, and the distillate residue was TAG-12-OAHSAs.

[0030] (3) Take 20g of TAG-12-OAHSAs purified by molecular distillation and add it to 300g of 0.2% deoxycholate aqueous solution (w / w). After shaking evenly, add 25g of Lipozyme RM IM (enzyme activity: 275 IUN / g) and stir at 45℃ for 4 hours. After the reaction was completed, the immobilized lipase was removed by filtration, and the immobilized enzyme and filtrate were extracted with 100 ml of n-hexane (2-3 times). Finally, the n-hexane phases were combined, and anhydrous sodium sulfate was added to remove water. The enzymatic hydrolysis product was obtained by rotary evaporation under vacuum. The liquid chromatogram of the enzymatic hydrolysis product is shown in [Figure number missing]. Figure 2 .

[0031] (4) The enzymatic hydrolysis product was subjected to molecular distillation again under the following conditions: evaporation surface temperature 180℃, condensation surface temperature 25℃, scraper rotation speed 150r / min, feed rate 1.6mL / min, absolute pressure 1~3Pa. The distillate residue was collected as the enzymatic hydrolysis product from which fatty acids were removed. Figure 2 ).

[0032] (5) The distillate from (4) was subjected to two-stage molecular distillation under the following conditions: evaporation surface temperature 240℃, and other conditions as in (4). The distillate was high-purity 12-OAHSA. The liquid chromatogram of this substance is shown in [reference needed]. Figure 2 The secondary mass spectrum is shown below. Figure 3High-resolution mass spectrometry analysis showed that the ion with a mass-to-charge ratio (m / z) of 564.4600 could be clearly attributed to the quasi-molecular ion [MH]⁻ of 12-OAHSA, which is consistent with the molecular weight of 12-OAHSA (564.92). The characteristic fragment at m / z 281.2281 was an oleic acid (oleic acid molecular weight is 282.46) derivative ion. This fragment had a dual origin: it came from the oleic acid structural unit in the 12-OAHSA molecule that forms an ester with hydroxystearic acid, and it also came from the characteristic derivative fragment generated after the hydroxystearic acid group in the molecule underwent a dehydration reaction (hydroxystearic acid dehydrates to form oleic acid). The characteristic ion at m / z 299.2363 was a fragment ion formed after the hydroxystearic acid structural unit in the 12-OAHSA molecule was cleaved (12-hydroxystearic acid molecular weight is 300.48).

[0033] (6) The anti-inflammatory activity of the synthesized FAHFA was characterized using a RAW 264.7 cell inflammation model. RAW 264.7 cells were stimulated to transform into the M1 type using lipopolysaccharide (LPS, 100 ng / mL), and then different concentrations of the above-mentioned synthetic FAHFA were administered. The gene expression levels of Tnf-α, IL-6, IL-1β and IL-16 were characterized by real-time quantitative PCR (qPCR) (with the LPS group as the control).

[0034] Example 2 The difference between this embodiment and Example 1 is that the hydrogenated castor oil in (1) is replaced with castor oil, and the remaining steps are the same as in Example 1 to obtain 12-OAHOA.

[0035] The secondary mass spectrum of 12-OAHOA in Example 2 is shown below. Figure 4 The fragment with m / z 561.4479 belongs to the quasi-molecular ion [MH] of 12-OAHOA. - The fragment at m / z 281.2216 is an oleic acid-derived ion; this oleic acid comes from 12-OAHOA; the characteristic ion at m / z 279.2124 comes from the dehydration product of hydroxyoleic acid (hydroxyoleic acid dehydrates to form linoleic acid); the characteristic fragment at m / z 297.2175 comes from hydroxyoleic acid in OHAHOA (that is, ricinoleic acid, with a molecular weight of 298.46).

[0036] Example 3 The difference between this embodiment and Example 1 is that oleoyl chloride in (1) is replaced with lauroyl chloride, and the remaining steps are the same as in Example 1 to obtain 12-LAHSA.

[0037] The secondary mass spectrum of 12-LAHSA in Example 3 is shown below. Figure 5The characteristic ion with m / z 481.3906 is the quasi-molecular ion [MH] of 12-LAHSA. - Fragment m / z 199.1555 is a lauric acid fragment from LAHSA (lauric acid has a molecular weight of 200.32); fragment m / z 281.2281 is a product of the dehydration of hydroxystearic acid; fragment m / z 299.2363 is derived from hydroxystearic acid.

[0038] The anti-inflammatory activities of different FAHFAs synthesized in Examples 1, 2 and 3 were compared, as shown in Table 1.

[0039] It is evident that different configurations of 12-FAHFA exhibit varying anti-inflammatory activities. 12-OAHSA and 12-OAHOA showed significantly stronger downregulation effects on the expression of four inflammatory genes than 12-LAHSA. However, overall, all three FAHFAs possess anti-inflammatory activity. 12-OAHOA showed the most significant downregulation effect and could significantly reduce Tnf-α expression, suggesting that its mechanism of action may differ from the others.

[0040] Table 1

[0041] Comparative Example 1 The difference between this comparative example and Example 1 is that the reaction time in step (1) is changed to 6 hours, while the rest of the steps are the same as in Example 1, and 12-OAHSA is obtained.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that the molecular distillation evaporation surface temperature in step (2) is changed to 100°C, while the rest of the steps are the same as in Example 1, and 12-OAHSA is obtained.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that the reaction time in step (3) is changed to 16h, while the rest of the steps are the same as in Example 1, and 12-OAHSA is obtained.

[0044] Comparative Example 4 The difference between this comparative example and Example 1 is that the mass of the deoxycholate aqueous solution in step (3) is changed to 100g, the concentration remains unchanged, and the remaining steps are the same as in Example 1 to obtain 12-OAHSA.

[0045] Comparative Example 5 The difference between this comparative example and Example 1 is that the amount of enzyme in step (3) is changed to 35g, while the remaining steps are the same as in Example 1, and 12-OAHSA is obtained.

[0046] The lipid compositions at each stage of synthesis, separation, and purification of Examples 1, 2, and 3 were compared with those of Comparative Examples 1, 2, 3, 4, and 5 (the degree of esterification of TAG-FAHFA and the purity of TAG-FAHFA after molecular distillation purification were quantified by high performance liquid chromatography equipped with a differential detector; the content of FAHFA after enzymatic hydrolysis and secondary molecular distillation purification of TAG-FAHFA was detected by UPLC-Q-TOF and quantified by external standard method), as shown in Table 2.

[0047] Table 2

[0048] a: The degree of esterification of TAG-FAHFA is calculated as the percentage of the TAG-FAHFA peak area to the total area of ​​the remaining peaks after deducting the fatty acid ethyl ester peak.

[0049] The following conclusions can be drawn: the degree of esterification of TAG-FAHFA is related to the reaction time; the longer the reaction time, the higher the degree of esterification. The purity of TAG-FAHFA is crucial for the subsequent preparation of FAHFA. High-purity TAG-FAHFA can increase the proportion of FAHFA after enzymatic hydrolysis. Residual fatty acid ethyl esters and incompletely esterified hydrogenated castor oil introduce new impurities (if esterification is incomplete, hydroxy acids will remain on the glycerol group, introducing impurities after enzymatic hydrolysis; for example, hydroxy acids are produced after the enzymatic hydrolysis of 1,3-FAHFA-2-hydroxystearic acid triglyceride), reducing yield and affecting the purity of the final product. The enzymatic hydrolysis reaction of TAG-FAHFA is similar to that of ordinary triglycerides. Sn-1,3-specific lipase does not hydrolyze the ester bonds of FAHFA, but it does hydrolyze the ester bonds between FAHFA and glycerol. In the enzymatic hydrolysis reaction, the higher the water content, the longer the reaction time, and the higher the enzyme content, the higher the proportion of FAHFA in the product. Because fully hydrogenated castor oil still contains some non-hydroxy fatty acids (palmitic acid and stearic acid), lipases will also hydrolyze these non-hydroxy fatty acids. These fatty acids appear as a small shoulder peak after FAHFA in normal-phase chromatograms, making direct quantification impossible. Therefore, a C18 reversed-phase column combined with external standard method is required for quantification. The final results show that two-stage molecular distillation can separate FAHFA and fatty acids, achieving the goal of enriching FAHFA. This method can be used for large-scale production of high-purity FAHFA.

[0050] Comparative Example 6 The difference between this comparative example and Example 1 is that the molecular distillation purification method in steps (2) and (5) is changed to column chromatography separation, while the remaining steps are the same as in Example 1, and 12-OAHSA is obtained.

[0051] The specific method for separating TAG-FAHFA by column chromatography is as follows: the mass ratio of the analyte to silica gel is 1:20, and hexane / diethyl ether (90:10, V / V) is used as the eluent. When the eluent volume reaches approximately 4 times the column volume, the target component TAG-FAHFA is collected. After removing the solvent, enzymatic hydrolysis is performed.

[0052] After enzymatic hydrolysis, 12-OAHSA was separated again by column chromatography, following the same procedure as when separating TAG-FAHFA. The target component was obtained after solvent removal. It is worth noting that column chromatography is difficult to separate fatty acids and FAHFA. Therefore, the purity of 12-OAHSA obtained by column chromatography is only about 70%, and column chromatography is more time-consuming and has lower yields compared to molecular distillation.

[0053] Comparative Example 7 The difference between this comparative example and Example 1 is that the lipase in step (3) was replaced with CALA (enzyme activity 500 IUN / g), while the other steps remained unchanged. It was found that CALA could not hydrolyze FAHFA from glycerol and therefore could not prepare FAHFA.

[0054] Comparative Example 8 The difference between this comparative example and Example 1 is that the esterification method in step (1) is changed to p-toluenesulfonic acid catalysis (accounting for 10% of the total mass of the substrate), and the fatty acid acyl chloride is replaced with the corresponding fatty acid. The specific operation is as follows: 40g of hydrogenated castor oil and 80g of fatty acid are dissolved in 1L of dichloromethane, 100g of molecular sieve and 12g of p-toluenesulfonic acid are added, and the reaction is carried out at 90°C for 6 hours.

[0055] The results showed that p-toluenesulfonic acid catalyzes the dehydration of hydroxy fatty acids to form unsaturated fatty acids, leading to a reduction in raw materials, a slow reaction process, and a low yield. The product prepared by p-toluenesulfonic acid catalysis contained only 53.21% TAG-FAHFA, and 11.56% non-hydroxy fatty acid triglycerides were formed. This necessitates increasing the evaporation surface temperature for TAG-FAHFA molecular distillation separation. In step (2), the evaporation surface temperature was increased to 240℃, yielding 80.92% TAG-FAHFA. Although FAHFA could still be obtained, the yield decreased due to the dehydration of some hydroxy fatty acid triglycerides into triglycerides.

[0056] The advantages of the synthesis method of this invention compared to the direct esterification synthesis using hydroxy fatty acids and fatty acids are as follows: the glycerol backbone in natural oil molecules containing hydroxy fatty acids is a natural protecting group, reducing the introduction of impurities during the synthesis process; molecular distillation can significantly increase yield, reduce time costs, and ensure product purity. Direct esterification of hydroxy fatty acids and fatty acid acyl chlorides produces the following byproducts: straight-chain anhydrides formed by the esterification of fatty acid acyl chlorides and the carboxyl groups of hydroxy fatty acids, and fatty acids formed by water quenching of fatty acid acyl chlorides. Straight-chain anhydrides cannot be separated by molecular distillation and can only be separated by column chromatography. Fatty acids and FAHFA are more suitable for molecular distillation than column chromatography, leading to complex separation steps and low efficiency. The method of this invention avoids these difficult-to-separate intermediates, constructs TAG-FAHFA as an intermediate, and uses molecular distillation for separation, thus improving separation efficiency.

[0057] Compared to synthesis schemes that use hydroxyl-containing terminal olefins (or other terminal groups that can be converted into carboxyl groups) as raw materials to carry out multi-step chemical reactions and finally convert the terminal groups into carboxyl groups, the present invention simplifies the operation steps, increases the yield, and ensures the purity. High-purity FAHFA can be obtained in large quantities with only 2 synthesis steps and 2 separation steps.

[0058] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for synthesizing branched-chain fatty acid esters of hydroxy fatty acids from natural oils containing hydroxy fatty acids, characterized in that: include, Using natural oils containing hydroxy fatty acids and fatty acid acyl chlorides as raw materials, tri-hydroxy fatty acid branched fatty acid ester triglyceride (TAG-FAHFA) is synthesized by esterification under the action of an acid-binding agent. High-purity TAG-FAHFA was obtained by molecular distillation; TAG-FAHFA was hydrolyzed by immobilized lipase to obtain hydroxy fatty acid branched-chain fatty acid esters (FAHFA). High-purity FAHFA was obtained by purifying branched-chain fatty acid esters of hydroxy fatty acids through multi-stage molecular distillation.

2. The method as described in claim 1, characterized in that: The natural oil containing hydroxy fatty acids is one or more of castor seed oil, sal fat, Orychophragmus violaceus seed oil, Lesquerella oil, and their hydrogenated or fractionated products.

3. The method as described in claim 1 or 2, characterized in that: The fatty acid acyl chloride is one of the following: hexanoic acid acyl chloride, caprylic acid acyl chloride, capric acid acyl chloride, lauryl acid acyl chloride, myristic acid acyl chloride, palmitic acid acyl chloride, palmitoleic acid acyl chloride, stearic acid acyl chloride, oleic acid acyl chloride, linoleic acid acyl chloride, linolenic acid acyl chloride, arachidic acid acyl chloride, behenic acid acyl chloride, lignocellulosic acid acyl chloride, EPA acyl chloride, DPA acyl chloride, DHA acyl chloride, and nervonic acid acyl chloride.

4. The method as described in claim 1, characterized in that: The acid-binding agent is one or more of triethylamine, pyridine, and N,N-diisopropylethylamine.

5. The method as described in any one of claims 1, 2, or 4, characterized in that: The esterification process synthesizes tri-hydroxy fatty acid branched-chain fatty acid triglycerides, wherein... The substrate molar ratio is 1:4 to 1:10, the temperature is 20 to 50℃, the time is 2 to 24 h, the amount of acid-binding agent added is 10 to 20% of the total mass of the substrate, a solvent is added to aid dissolution, and a quenching agent is used to quench the reaction after it is completed. The solvent is one of dichloromethane or trichloromethane, and the amount added is 6 to 8 times the total mass of the substrate; The quenching agent is one of water, ethanol or methanol, and the amount added is 0.8 to 1.5 times the total mass of the substrate.

6. The method as described in claim 5, characterized in that: The parameters for the molecular distillation purification of TAG-FAHFA are as follows: Feed rate 0.5-1.5 mL / min, absolute pressure 2-8 Pa, evaporation surface temperature 120-180℃, scraper rotation speed 100-150 r / min, and the distillation residue is high-purity TAG-FAHFA.

7. The method as described in claim 1, characterized in that: The immobilized lipase is one or more of Palatase 20000L, Novozym 435, Lipozyme TL IM, Lipozyme RM IM, Novozym 40086, Lipase AY, Lipase DF-15, IM-NE100, NE-10, NE-20, R-001, RIM-03, AP6, and Amano PS.

8. The method as described in claim 1 or 7, characterized in that: The method involves using immobilized lipase to enzymatically hydrolyze TAG-FAHFA to obtain hydroxy fatty acid branched fatty acid esters. include, Using water and TAG-FAHFA as substrates, with a molar ratio of 1:600 ​​to 1:1500, the reaction time was 3 to 8 hours, the reaction temperature was 30 to 50°C, the enzyme accounted for 8% to 12% of the total substrate mass, and the emulsifier accounted for 0.2% of the total substrate mass. The emulsifier is one or more of deoxycholate, Tween 20, Triton 100, PEG-400, and polyricinoleate.

9. The method as described in claim 8, characterized in that: The parameters for purifying branched-chain fatty acid esters of hydroxy fatty acids via multi-stage molecular distillation are as follows: First-stage distillation: evaporation surface temperature 160-180℃, scraper rotation speed 100-150 r / min, feed rate 1-1.6 ml / min, condensation temperature 40-60℃, and collect the distillate; Secondary distillation: Evaporation surface temperature 200-260℃, scraper rotation speed 120-160r / min, feed rate 1-1.6ml / min, condensation temperature 30-40℃, and distillate collected.

10. The hydroxy fatty acid branched fatty acid ester prepared by the method of any one of claims 1 to 9.

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