NL2027535B1

NL2027535B1 - Synthesis method of monoacylglycerol

Info

Publication number: NL2027535B1
Application number: NL2027535A
Authority: NL
Inventors: Yang Guolong; Wang Gaoshang; Bi Yanlan; Chen Xiaowei; Ma Chuanguo; Sun Shangde
Original assignee: Univ Henan Technology
Priority date: 2021-02-10
Filing date: 2021-02-10
Publication date: 2022-09-12

Abstract

The present disclosure belongs to the field of glyceride synthesis, and provides a synthesis method of monoacylglycerol. The synthesis method of monoacylglycerol comprises the following steps: mixing triacylglycerol, glycerol and an amino acid based eutectic solvent and then carrying out the transesterification reaction to obtain monoacylglycerol, wherein the amino acid based eutectic solvent is prepared from amino acid and quaternary ammonium alkali. The present disclosure provides a synthesis method of monoacylglycerol, in which the amino acid based eutectic solvent is used as a catalyst, effectively solving the problem of device corrosion caused by using an inorganic alkali as the catalyst. Furthermore, the catalyst provided by the present disclosure is well compatible to a reaction substrate, so as to effectively improve reaction yield and product purity. The results from examples show that the monoacylglycerol using the synthesis method provided by the present disclosure has a yield of 37~64.84% and a purity of 97.61~99.92%.

Description

-1-

SYNTHESIS METHOD OF MONOACYLGLYCEROL

TECHNICAL FIELD The present disclosure relates to the field of glyceride synthesis, and particularly to a synthesis method of monoacylglycerol.

BACKGROUND Monoacylglycerol (MAG) is a kind of structural lipid formed by replacing two fatty acids with hydroxy groups in one type of triacylglycerol (TAG), which contains lipophilic long carbon chain alkyl and hydrophilic hydroxyl group in a molecular structure. It has a hydrophile-lipophile balance value of 3~4, showing a good emulsification characteristic, and is commonly applied to industries such as foods, medicines and chemicals as a nonionic surfactant.

At present, glycerolysis of oil is performed mainly by an enzyme method and a chemical method to prepare monoacylglycerol. Where, glycerolysis via the enzyme method mainly uses lipases most of which are immobilized lipases that have been commercialized. Production with the enzyme method has the advantages that reaction condition is mild, catalytic specificity is strong, the high-purity product is easily available, and the like. However, low reaction temperature renders the reaction system to have high viscosity, the reaction system is easily decomposed into a hydrophobic oil phase, a hydrophilic glycerol phase and an immobilized enzyme phase, which can reduce reaction efficiency. In addition, due to enzyme price and recycle problem, production cost is high, which limits the industrial production of preparation of immobilized through glycerolysis of oil via enzyme catalysis to a certain extent.

Compared with the enzyme method, preparation of monoacylglycerol through the chemical method is not limited by the reaction temperature, and production cost is low, large-scale production is easy to realize. However, when the existing chemical method is used

-2- to prepare the monoacylglycerol, inorganic alkali (KOH/NaOH) is commonly used as a catalyst, reaction is conducted at high temperature (220~260°C), in vacuum or under the protection of an inert gas, the yield of monoacylglycerol is 30%, and the catalyst in the above chemical method easily causes device corrosion.

SUMMARY The present disclosure provides a synthesis method of monoacylglycerol. The method provided by the present disclosure uses an amino acid based eutectic solvent as a catalyst, thereby effectively solving the problem of device corrosion caused by using the inorganic alkali as the catalyst. Furthermore, the yield and purity of monoacylglycerol prepared by the synthesis method provided by the present disclosure are high.

The present disclosure provides a synthesis method of monoacylglycerol, comprising the following steps: mixing triacylglycerol, glycerol and an amino acid based eutectic solvent and then carrying out the transesterification reaction to obtain monoacylglycerol, wherein the amino acid based eutectic solvent is prepared from amino acid and quaternary ammonium alkali.

Preferably, the temperature of the transesterification reaction is 80~120°C, and the time of the transesterification reaction is 5~240 min.

Preferably, a mass ratio of triacylglycerol to glycerol is 1:4.82~38.60.

Preferably, a mass ratio of amino acid based eutectic solvent to triacylglycerol is 0.01~0.2:1.

Preferably, amino acid in the amino acid based eutectic solvent comprises one or more of arginine, lysine, histidine, tryptophan and glutamic acid.

Preferably, the quaternary ammonium alkali in the amino acid based eutectic solvent comprises one or more of choline hydroxide, tetramethyl

-3- ammonium hydroxide hydrate and tetrabutyl ammonium hydroxide hydrate.

Preferably, the amino acid based eutectic solvent comprises [tetramethyl ammonium hydroxide:pentahydrate] [arginine], [tetrabutyl ammonium hydroxide:trinydrate] [arginine] and [choline hydroxide] [arginine].

Preferably, the preparation method of the amino acid based eutectic solvent comprises the following steps: (1) reacting quaternary ammonium alkali aqueous solution with amino acid aqueous solution in water and then removing water to obtain a product mixture; and (2) mixing the product mixture with an organic solvent, precipitating out an impurity component followed by de-solvation of the solution to obtain the amino acid based eutectic solvent.

Preferably, in the step (1), a mole ratio of quaternary ammonium alkali in quaternary ammonium alkali aqueous solution to amino acid in amino acid aqueous solution is 1:1~1.5.

Preferably, in the step (2), the organic solvent comprises one or more of acetonitrile, methanol, anhydrous ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, acetone, tetrahydrofuran, ethyl acetate, ether, dichloromethane, chloroform and n-hexane.

The present disclosure provides a synthesis method of monoacylglycerol, comprising the following steps: mixing triacylglycerol, glycerol and the amino acid based eutectic solvent and then carrying out the transesterification reaction to obtain monoacylglycerol, wherein the amino acid based eutectic solvent is prepared from amino acid and quaternary ammonium alkali. The present disclosure provides a synthesis method of monoacylglycerol, in which the amino acid based eutectic solvent is used as the catalyst, effectively solving the problem of device corrosion caused by using an inorganic alkali as the catalyst.

-4- Furthermore, the catalyst used by the present disclosure is well compatible to a reaction substrate, so as to effectively improve reaction yield and product purity. The results from examples show that the monoacylglycerol provided by the present disclosure has a yield of 37~64.84% and a purity of 97.61~99.92%.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a GC chromatogram of a product prepared in example 1 according to the present disclosure.

DETAILED DESCRIPTION The present disclosure provides a synthesis method of monoacylglycerol, comprising the following steps: mixing triacylglycerol, glycerol and an amino acid based eutectic solvent and then carrying out the transesterification reaction to obtain monoacylglycerol, wherein the amino acid based eutectic solvent is composed of amino acid and quaternary ammonium alkali.

According to the present disclosure, triacylglycerol, glycerol and the amino acid based eutectic solvent are mixed and then the transesterification reaction is carried out to obtain monoacylglycerol.

In the present disclosure, triacylglycerol preferably comprises plant oil, the plant oil further preferably comprises one or more of soybean oil, sunflower seed oil, palm oil, olive oil, corn oil, peanut oil and coconut oil. The present disclosure has no specific requirement on sources of triacylglycerol and glycerol, which are available commercially. In the present disclosure, the mass ratio of triacylglycerol to glycerol is preferably 1:4.82-38.60, further preferably 1:9.64~28.92, more preferably 1:19.28.

In the present disclosure, triacylglycerol and glycerol are preferably mixed, and then mixed with the amino acid based eutectic solvent. In the present disclosure, the temperature of the transesterification reaction is

-5. preferably 80~120°C, further preferably 90~110°C, the time of the transesterification reaction is 5~240 min, further preferably 10~200 min, more preferably 20~100 min, most preferably 30~60 min. During the reaction of the present disclosure, triacylglycerol and glycerol are subjected to the transesterification reaction to prepare monoacylglycerol. The transesterification reaction is shown in formula |, wherein triacylglycerol is represented by “TAG”, glycerol is represented by “G”, diacylglycerol is represented by “DAG”, and monoacylglycerol is represented by “MAG”: HR - 0 o Tr TH jj Catalyst R OCR OCR CHaCHCH; + CH,OHCHOHCH,0H ———» —— + LE CHORLOH je ee 0

TAG G DAG MAG Formula | In the present disclosure, triacylglycerol TAG undergoes the glycerolysis reaction to form the primary product diacylglycerol DAG, and diacylglycerol DAG further glycerolysis toform monoacylglycerol MAG. The present disclosure preferably carries out the molecular distillation technology on the transesterification reaction products to purify monoglyceride. The present disclosure has no specific requirements on examples of molecular distillation as long as methods for purifying monoacylglycerol from monoacylglycerol, diacylglycerol and triacylglycerol are used, which are well known by those skilled in the art. In the examples of the present disclosure, the molecular distillation preferably comprises the primary distillation, secondary distillation and tertiary distillation which are carried out in turn; the temperature of the primary distillation is 150~172°C, the vacuum degree is preferably

51.2-54.5 Pa, and the light component obtained by the primary distillation is a monoacylglycerol crude product; the monoacylglycerol

-6- crude product is subjected to secondary distillation , the temperature of secondary distillation is 115~125°C, the vacuum degree is 25.6~27.8 Pa, and the light component obtained by secondary distillation is a monoacylglycerol purified product; the monoacylglycerol purified product is subjected to tertiary distillation, the temperature of tertiary distillation is 140-162°C, the vacuum degree is 19.0~21.2 Pa, and monoacylglycerol is obtained after tertiary distillation. In the present disclosure, the transesterification reaction is carried out under the condition that the amino acid based eutectic solvent is used as the catalyst; the amino acid based eutectic solvent is prepared from amino acid and quaternary ammonium alkali; the amino acid preferably comprises one or more of arginine, lysine, histidine, tryptophan and glutamic acid; the quaternary ammonium alkali preferably comprises one or more of choline hydroxide, tetramethyl ammonium hydroxide hydrate and tetrabutyl ammonium hydroxide hydrate; the amino acid based eutectic solvent preferably comprises [tetramethyl ammonium hydroxide -pentahydrate] [arginine] (abbreviated as [TMA] [Arg]), [tetrabutyl ammonium hydroxide:trinydrate] [arginine] (abbreviated as [TBA] [Arg]) and [choline hydroxide] [arginine] (abbreviated as [Choh] [Arg]). In the present disclosure, the mole ratio of quaternary ammonium alkali to amino acid in the amino acid based eutectic solvent is preferably 1:0.8 ~ 1.2, and further preferably 1:1. In the present disclosure, the mass ratio of amino acid based eutectic solvent and triacylglycerol is preferably 0.01 ~ 0.2:1, further preferably 0.05 ~ 0.15:1, more preferably

0.1~0.15:1. In the present disclosure, the preparation method of the amino acid eutectic solvent preferably comprises the following steps: (1) reacting quaternary ammonium alkali aqueous solution with amino acid aqueous solution in water and then removing the water to obtain the product mixture; (2) mixing the product mixture with an organic solvent, precipitating

-7- out the impurity component followed by de-solvation of the filtrate to obtain the amino acid based eutectic solvent.

In the present disclosure, after quaternary ammonium alkali aqueous solution reacts with amino acid aqueous solution in water, water is removed so as to obtain the product mixture.

In the present disclosure, the quaternary ammonium alkali aqueous solution is dropwise preferably added to the amino acid aqueous solution.

The present disclosure preferably adopts the above mixing manner, which is conducive to sufficient reaction of the quaternary ammonium alkali aqueous solution and the amino acid aqueous solution to obtain higher amino acid based eutectic solvent yield and catalytic effect.

In the present disclosure, the reaction between the quaternary ammonium alkali aqueous solution and the amino acid aqueous solution is preferably carried out at room temperature with preferred reaction time being 12-48 h.

In the reaction process of the present disclosure, the acid-alkali neutralization reaction occurs between the amino acid and the quaternary ammonium alkali to generate the amino acid based eutectic solvent.

The present disclosure adopts spin evaporation to remove water, the temperature of spin evaporation is preferably 70-90°C, further preferably 80°C; the spin evaporation is carried out preferably in vacuum.

In the present disclosure, the product mixture preferably comprises a reaction product of quaternary ammonium alkali and amino acid and a mixture of excess amino acids.

In the present disclosure, the product mixture is mixed with an organic solvent, the impurity component is precipitated out, and the filtrate is de-solved to obtain the amino acid based eutectic solvent.

In the present disclosure, the organic solvent preferably comprises one or more of acetonitrile, methanol, absolute ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, acetone, tetrahydrofuran, ethyl acetate, ether, dichloromethane, chloroform and n-hexane, and is further preferably a mixed solvent of acetonitrile and methanol in a volume ratio

-8- of 7:3; the volume ratio of the organic solvent to the amino acid based eutectic solvent is preferably 1:1~5, further preferably 1:2~4. By adding the organic solvent, the excessive amino acids which is not involved in the reaction in the mixed solution are precipitated out in the form of impurity component. In the present disclosure, the precipitated impurity component is separated by vacuum suction filtration, and the filtrate is collected. In the present disclosure, the filtrate is de-solvated by preferably using spin evaporation to obtain light yellow liquid; the temperature of the spin evaporation is preferably 50~70°C, further preferably 60°C. When the solvent cannot be evaporated using spin evaporation, spin evaporation is stopped.

After the end of spin evaporation, the yellowish liquid obtained by spin evaporation is dried to obtain the amino acid based eutectic solvent. In the present disclosure, the temperature of the drying treatment is preferably 80~100°C, further preferably 90°C, and the time is preferably

0.5~2 h; the drying treatment is preferably carried out in vacuum.

The technical solution of the present disclosure will be described clearly and completely in combination with the examples of the present disclosure.

Example 1 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath 25 pot with a temperature of 80°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 1 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160 °C, the vacuum degree was 53.2 Pa, and the light component was

-9- monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 13.52 g of monoacylglycerol product was obtained. The yield of monoacylglycerol (MAG) in the product was 54.08%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 98.31%. In all examples of the present disclosure, the calculation method of the yield is the weight g of monoacylglycerol product/weight g of reactant triacylglycerol) x 100%. The spectrogram result of GC analysis in example 1 is shown in Fig.

1. In Fig. 1, MAG represents monoacylglycerol, TAG represents triacylglycerol, and DAG represents diacylglycerol. Example 2 25 g of (0.028mol) soybean oil (average molecular weight of 888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1.0.8) accounting for 10% of soybean oil weight was added for reaction. After reaction for 0.5 h, the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was the monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150 °C, the vacuum degree was 20.0 Pa), and 16.21 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in

-10 - the product was 64.84%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 99.15%.

Example 3 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 120°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1.2) accounting for 10% of soybean oil weight was added for reaction. After reaction for 0.5 h, the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was the monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 1594 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 63.76%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 99.28%.

Example 4 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 2.590 g of (0.028 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 10% of soybean oil weight {a mole ratio of TMA and Arg was 1:1) was added for

-11 - reaction. After reaction for 0.5 h, the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was the monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was

20.0 Pa), and 15.47 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 61.88%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 97.91%.

Example 5 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 8% of soybean oil weight was added for reaction. After reaction for 1 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was the monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 16.07 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 64.28%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity

-12- was 98.9%. Example 6 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 110°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 0.5h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 1589 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 63.56%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 99.52%. Example 7 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL 25 round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 8% of oil weight was added for reaction. After reaction for 0.5 h, the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation

-13- were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was the monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 14.82 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 59.28%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 97.90%.

Example 8 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 1 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 1568 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 62.72%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 97.61%. Example 9

-14 - 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of TMA to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 0.5 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 1598 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 63.92%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 99.92%.

Example 10 g of (0.028 mol} soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath 25 pot with a temperature of 80°C at a rotation speed of 300 rpm, then [TBA] [Arg] (a mole ratio of TBA to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 1 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was

-15- monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 9.25 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 37%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 98.31%.

Example 11 25 g of (0.028 mol) soybean oil (average molecular weight of

888.78) and 5.080 g of (0.056 mol) glycerol were added into a 150 mL round bottomed flask, a stirrer was put, a magnetic stirrer was opened, the above substances were stirred and preheated for 5 min in an oil bath pot with a temperature of 100°C at a rotation speed of 300 rpm, then [TMA] [Arg] (a mole ratio of CHOH to Arg was 1:1) accounting for 10% of soybean oil weight was added for reaction. After reaction for 4 h, and the product was taken out and treated via molecular distillation to obtain monoacylglycerol. The experimental parameters of molecular distillation were as follows: the temperature of first distillation was 160°C, the vacuum degree was 53.2 Pa, and the light component was monoacylglycerol crude product; the monoacylglycerol crude product was further purified (the temperature of second distillation was 120°C, the vacuum degree was 26.60 Pa; the temperature of tertiary distillation was 150°C, the vacuum degree was 20.0 Pa), and 11.65 g of monoacylglycerol product was obtained. The yield of monoacylglycerol in the product was 46.6%. The monoacylglycerol obtained by centrifugation and purification was subjected to GC analysis. The purity was 99.15%.

In conclusion, the monoacylglycerol prepared by the method provided by the present disclosure has a yield of 37-64.84%, a purity of

97.61-99.92% and a reaction time of 0.5-1 h. In the preparation method provided by the present disclosure, the yield of monoacylglycerol prepared with [TMA] [Arg] as the catalyst is the highest, which is

-16 -

54.08~64.84%. It can be seen that in the present disclosure, the amino acid based eutectic solvent is used as the catalyst, and the catalyst is well biocompatible with the reaction substrate, so that the reaction is rapid, the product yield and purity are high, and the emulsification and saponification phenomena are not found in the production process, and the product is clear. the above descriptions are only preferred examples of the present disclosure. It should be noted that a person of ordinary skill in the art can also make several improvements and refinements without departing from the principle of the present disclosure, and these improvements and refinements shall also be deemed as the protection scope of the present disclosure.

Claims

-17 - Conclusions

1. A synthesis method of monoacylglycerol, consisting of the following steps: mixing triacylglycerol, glycerol and an amino acid-based eutectic solvent, and then carrying out the esterification reaction to obtain monoacylglycerol, preparing the amino acid-based eutectic solvent from amino acid and a quaternary ammonium alkali.

The synthesis method according to claim 1, wherein the temperature of the esterification reaction is 80~120°C and the duration of the esterification reaction is 5~60 min.

The synthesis method according to claim 1 or 2, wherein a mass ratio of triacylglycerol to glycerol is 1:4.82 ~ 38.60.

The synthesis method according to claim 1 or 2, wherein a mass ratio of amino acid-based eutectic solvent to triacylglycerol is 0.01 ~ 0.2:1.

The synthesis method according to claim 1, wherein amino acid in the amino acid-based eutectic solvent contains one or more of arginine, histidine, tryptophan and glumatic acid.

The synthesis method of claim 1, wherein the quaternary ammonium alkali in the amino acid-based eutectic solvent contains one or more of choline hydroxide, tetramethyl ammonium hydroxide hydrate and tetrabutyl ammonium hydroxide hydrate.

-18-

The synthesis method according to claim 1, 5 or 6 wherein the amino acid-based eutectic solvent contains [tetramethylammonium hydroxide:pentahydrate][arginine], [tetrabutylammonium hydroxide:trinydrate][arginine] and [choline hydroxide][arginine].

The synthesis method according to claim 1, 5 or 6, wherein the preparation method of the amino acid-based eutectic solvent comprises the following steps: (1) reacting aqueous quaternary ammonium alkali solution with an aqueous amino acid aqueous solution and then removing of the water to obtain a product mixture; and (2) mixing the product mixture with an organic solvent to precipitate an impure component followed by dissolving the solution to obtain the amino acid-based eutectic solvent.

The synthesis method according to claim 8, wherein in step (1), a molar ratio of quaternary ammonium alkali in aqueous quaternary ammonium alkali solution to amino acid in aqueous amino acid solution is 1:1 ~ 1.5.

The synthesis method according to claim 8, wherein in step (2), the organic solvent is one or more of acetonitrile, methanol, anhydrous ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, acetone, tetrahydrofuran, ethyl acetate, ether , dichloromethane, chloroform and n-hexane.