Preparation method and application of a long-chain glycerol acetylpropionic acid carboxylic acid derivative

Abstract

This invention relates to the field of preservation materials technology, specifically to a method for preparing and applying a long-chain glycerol levulinic acid carboxylic acid derivative. The specific technical solution is as follows: a method for preparing a long-chain glycerol levulinic acid carboxylic acid derivative involves reacting the long-chain glycerol levulinic acid derivative with levulinic acid under heating in the presence of a catalyst. The reaction is carried out under vacuum, with a vacuum degree of 0.07–0.1 MPa, a reaction temperature of 80–150°C, and a reaction time of 1–5 hours. This invention solves the problem that existing glycerol monolaurate is difficult to use as a functional additive for PLA or PBAT.

Description

Technical Field

[0001] This invention relates to the field of preservation materials technology, specifically to a method for preparing and applying a long-chain glycerol acetylpropionic acid carboxylic acid derivative. Background Technology

[0002] Mushrooms are a popular food, prized not only for their delicious taste but also for their rich nutritional value. However, fresh mushrooms, especially rare and expensive varieties cultivated under limited techniques, often have a short shelf life and a very limited market. The common solution is to dry them at high temperatures to produce dried mushrooms, a process that inevitably damages their texture, flavor, and nutritional content.

[0003] Modified atmosphere packaging (MAP) is an emerging technology that adjusts the gas ratio inside and outside a membrane to keep the material inside in a low-biological-activity state. However, preserving fresh mushrooms has always been a challenging task. On the one hand, when using films made of low-permeability materials such as PE (polyethylene) for preservation, mushrooms often undergo anaerobic respiration. The water produced by their respiration cannot permeate, exacerbating autolysis, causing the mushrooms to soften and emit an unpleasant odor. Furthermore, PE preservation films often breed large amounts of mold in the later stages of mushroom preservation, rendering the mushrooms inedible. On the other hand, biodegradable materials have become a major new development direction in MAP in recent years. However, commonly used matrix materials, whether PLA or PBAT, have excessively high permeability. If appropriate films are used for MAP to provide a suitable internal environment for mushrooms, while the mushrooms can carry out normal physiological activities, mold will also thrive in a suitable environment, leading to sporadic mold growth in the later stages of preservation.

[0004] Therefore, to preserve mushrooms using environmentally friendly substrates such as PLA or PBAT, antibacterial components must be added to create an environment conducive to mold growth. Monolaurate is an ester containing glycerol groups and long-chain carboxylic acid groups—lauric acid. It is a highly safe antibacterial agent, and according to GB 2760-2014, the standard for the use of food additives, monolaurate can be directly added to various foods, including infant formula. Furthermore, due to its long-chain ester group, monolaurate derivatives have the potential to serve as plasticizers for biodegradable and environmentally friendly plastics such as PLA.

[0005] However, if glyceryl monolaurate is used as an additive in the processing of PLA or PBAT films, in solvent casting, glyceryl monolaurate is soluble in hot water and methanol but insoluble in dichloromethane, while PLA or PBAT is insoluble in hot water and methanol but soluble in dichloromethane, etc. Their solubility is completely different, making solvent casting unsuitable. Similarly, in melt extrusion, although they can be mixed and granulated at high temperatures, significant phase separation occurs, affecting various properties of the material. Furthermore, it can be predicted that over time, glyceryl monolaurate, as an additive, will continuously migrate and precipitate from the phase-separated material, further reducing its physicochemical properties and user experience. Therefore, this invention is proposed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a long-chain carboxylic acid glyceride derivative of levulinic acid, which solves the problem that existing monoglycerides of laurate are difficult to use as functional additives for PLA or PBAT.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention discloses a method for preparing a long-chain carboxylic acid glyceride derivative of levulinic acid. The long-chain carboxylic acid glyceride derivative is reacted with levulinic acid under heating in the presence of a catalyst. The reaction is carried out under vacuum with a vacuum degree of 0.07-0.1 MPa, a reaction temperature of 80-150°C, and a reaction time of 1-5 h.

[0009] Preferably, the product after the reaction is dissolved in a solvent, the pH is adjusted to neutral, washed and dried, and the solvent is removed and dried again to obtain the glycerol derivative of long-chain carboxylic acid levulinic acid.

[0010] Preferably, the solvent is one of dichloromethane, chloroform, ethyl acetate, dimethyl carbonate, methanol, and naphthol.

[0011] Preferably, the catalyst is p-toluenesulfonic acid, and the amount of the catalyst used is 1 to 5% of the molar mass fraction of levulinic acid.

[0012] Preferably, the molar ratio of the long-chain carboxylic acid glyceride derivative to levulinic acid is 1:(1-2).

[0013] Preferably, the long-chain carboxylic acid glyceride derivative is one of laurate monoglyceride, decanoate monoglyceride, and monolong-chain carboxylic acid polyglyceride.

[0014] Preferably, the preparation process of the single long-chain carboxylic acid polyglycerol ester is as follows: polyglycerol is reacted with lauric acid or decanoic acid by heating, and the molar ratio of polyglycerol to lauric acid or decanoic acid is 1:1.

[0015] Accordingly, the long-chain carboxylic acid glyceride derivative of levulinic acid was prepared according to the above preparation method.

[0016] Accordingly, a method for preparing a polylactic acid film comprising a long-chain glycerol levulinic acid derivative or the aforementioned long-chain glycerol levulinic acid derivative prepared by the above preparation method comprises mixing the long-chain glycerol levulinic acid derivative with PLA or PBAT, adding a chain extender for co-extrusion, or dissolving it in a solvent to obtain a polylactic acid film; wherein the solvent is one of dichloromethane, chloroform, dimethyl carbonate, and naphthol, and the amount of chain extender added is 0.2% to 0.5 wt%.

[0017] Correspondingly, the polylactic acid film prepared by the above method is used in the preservation of fungi.

[0018] The present invention has the following beneficial effects:

[0019] The introduction of the levulinic acid group in this invention provides a certain polarity to the long-chain carboxylic acid glyceride derivative, increasing its compatibility with PLA or PBAT. In addition, a hydroxyl group of the long-chain carboxylic acid glyceride derivative is retained, preserving its hydrophilicity and enabling the adjuvant to possess amphiphilicity, thus retaining the antibacterial function of the long-chain carboxylic acid glyceride derivative. Attached Figure Description

[0020] Figure 1 The preservation effect of the prepared A1 film is shown in the figure.

[0021] Figure 2 The preservation effect of the prepared C2 film is shown in the figure.

[0022] Figure 3 They are glyceryl monolaurate, levulinic acid, and product 1, respectively. 1 1H NMR spectrum. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0025] 1. This invention discloses a method for preparing a long-chain glycerol levulinic acid derivative. The long-chain glycerol levulinic acid derivative is reacted with levulinic acid under heating in the presence of a catalyst. When the number of hydroxyl groups on the long-chain glycerol levulinic acid is 2, levulinic acid undergoes monosubstitution; when the number of hydroxyl groups on the long-chain glycerol levulinic acid is greater than 2, levulinic acid undergoes monosubstitution or disubstitution. The reaction is carried out under vacuum (0.07–0.1 MPa), at a temperature of 80–150 °C, for a time of 1–5 h. The product is dissolved in a solvent, the pH is adjusted to neutral with K₂CO₃(aq), washed, dried, and the solvent is removed before drying to obtain the long-chain glycerol levulinic acid derivative. The solvent is one of dichloromethane, chloroform, ethyl acetate, dimethyl carbonate, methanol, or naphthol. The catalyst is p-toluenesulfonic acid, and the amount of catalyst used is 1–5% of the molar mass fraction of levulinic acid. The molar ratio of the long-chain glycerol levulinic acid derivative to levulinic acid is 1:(1–2). The long-chain carboxylic acid glyceride derivative is one of lauric acid monoglyceride, decanoic acid monoglyceride, and monolong-chain carboxylic acid polyglyceride.

[0026] Furthermore, the preparation process of the single long-chain carboxylic acid polyglycerol ester is as follows: polyglycerol is reacted with lauric acid or decanoic acid by heating, and the molar ratio of polyglycerol to lauric acid or decanoic acid is 1:1. The polyglycerol is diglycerol, triglycerol, decaglycerol, etc.

[0027] The preparation process of the long-chain carboxylic acid glyceride derivative of the present invention is described in detail below.

[0028] 1. The preparation process is shown in formula (Ⅰ).

[0029]

[0030] The molar ratio of lauric acid monoglyceride to levulinic acid in formula (Ⅰ) is 1:1, the amount of p-toluenesulfonic acid monohydrate used is 1-5% of the mass fraction of levulinic acid, the reaction temperature is 80-150℃, the reaction is carried out under vacuum with a vacuum degree of 0.07-0.1 MPa, and the reaction time is 1-5 h.

[0031] Post-reaction treatment: After cooling, the product is dissolved in dichloromethane (or chloroform, or ethyl acetate, or dimethyl carbonate, or methanol, or naphthol), the pH is adjusted to neutral with K2CO3(aq), washed three times with deionized water, dried with anhydrous MgSO4 or anhydrous NaSO4, filtered to remove the solvent by rotary evaporation, and dried under vacuum.

[0032] 2. The preparation process is shown in formula (II).

[0033]

[0034] In formula (II), diglycerol can be replaced with triglycerol or other polyglycerols, lauric acid can be replaced with decanoic acid, and the acetylpropionic acid group can be monosubstituted on any hydroxyl group.

[0035] In formula (II), the molar ratio of diglycerol to lauric acid is 1:1, the molar ratio of monodiglycerol laurate to levulinic acid is 1:(1-2), and the remaining reaction conditions are the same as those in formula (I).

[0036] The products prepared in the above manner all provide good compatibility, plasticity and anti-migration properties.

[0037] 2. This invention discloses a method for preparing polylactic acid film, the process of which is as follows:

[0038] Long-chain glycerol levulinic acid derivatives are co-extruded with PLA or PBAT and a chain extender (such as ADR-4468), with the chain extender added at an amount of 0.2–0.5 wt%. The chain extender is used to enhance melt strength. The blended product is blown into a film using a blown film machine to obtain a polylactic acid film. The amount of long-chain glycerol levulinic acid derivative added is 0.2–15%.

[0039] Alternatively, a long-chain glycerol levulinic acid derivative can be co-dissolved with PLA or PBAT in dichloromethane (or chloroform, or dimethyl carbonate, or naphthol), and the blended product can be used to obtain a polylactic acid film by solvent casting. The amount of the long-chain glycerol levulinic acid derivative added is 0.2% to 15%.

[0040] 3. The polylactic acid film prepared by this invention is used for the preservation of fungi.

[0041] Example 1

[0042] 13.72 g of glyceryl monolaurate, 5.81 g of levulinic acid, and p-toluenesulfonic acid monohydrate as catalyst were added to a reactor. The catalyst dosage was 3% of the molar mass fraction of levulinic acid. The reaction temperature was 100 °C, and a vacuum of 0.08 MPa was applied using a water pump for 1 hour. After cooling, the crude product was dissolved in dichloromethane, and the pH was adjusted to neutral with K₂CO₃(aq). The product was washed three times with deionized water, dried with anhydrous MgSO₄, filtered, and the solvent was removed by rotary evaporation. The product was then dried under vacuum to obtain product 1. (The ingredients are: glyceryl monolaurate, levulinic acid, and product 1.) 1 The H NMR spectrum is as follows Figure 3 As shown.

[0043] Example 2

[0044] 12.32 g of decanoic acid monoglyceride, 5.81 g of levulinic acid, and p-toluenesulfonic acid monohydrate catalyst were added to a reactor. The catalyst dosage was 2% of the molar mass fraction of levulinic acid. The reaction temperature was 120 °C, and a vacuum of 0.07 MPa was applied using a water pump. The reaction time was 2 h. After cooling, the crude product was dissolved in chloroform, and the pH was adjusted to neutral with K₂CO₃(aq). The product was washed three times with deionized water, dried with anhydrous MgSO₄, filtered, and the solvent was removed by rotary evaporation. The product was then dried under vacuum to obtain product 2.

[0045] Example 3

[0046] 16.62 g of diglycerol and 20.03 g of lauric acid were added to the reactor, and p-toluenesulfonic acid monohydrate was used as a catalyst. The mixture was heated for 2 hours, and the product was used directly in the next step without post-treatment.

[0047] Take 17.42 g of the product from the previous step, 4.07 g of levulinic acid, and p-toluenesulfonic acid monohydrate as catalyst (catalyst amount: 1.5% of the molar mass fraction of levulinic acid). The reaction temperature is 120℃, and a vacuum of 0.09 MPa is applied using a water pump for 3 hours. After cooling, dissolve the crude product in naphthol, adjust the pH to neutral with K₂CO₃(aq), wash three times with deionized water, dry the product with anhydrous MgSO₄, remove the solvent by rotary evaporation after filtration, and dry under vacuum to obtain product 3.

[0048] Example 4

[0049] 24.01 g of triglycerides and 20.03 g of lauric acid were added to a reactor. P-Toluenesulfonic acid monohydrate was used as a catalyst, and the reaction was heated for 2 hours. After post-treatment purification, 21.13 g of the product was reacted with 11.61 g of levulinic acid. The amount of levulinic acid monohydrate catalyst was 2% of the molar mass fraction of levulinic acid. The reaction temperature was 120℃, and a vacuum of 0.07 MPa was applied using a water pump for 2 hours. After cooling, the crude product was dissolved in dichloromethane, and the pH was adjusted to neutral with K₂CO₃(aq). The product was washed three times with deionized water, dried with anhydrous MgSO₄, filtered, and the solvent was removed by rotary evaporation. The product was then dried under vacuum to obtain product 4.

[0050] Example 5

[0051] Thin film preparation:

[0052] 1. 9.5 parts of the product prepared in Example 1 were mixed with 90 parts of polylactic acid, and 0.5 parts of chain extender were added. The mixture was melt-blended and extruded using a twin-screw extruder. The resulting granules were then blown into film using a blown film extruder to obtain film A1. The mechanical properties of film A1 were tested using the method described in GB / T 1040.3-2006. The test results showed that the tensile strength was 40.65 MPa and the elongation at break was 43.77%.

[0053] 2. Ten parts of the product prepared in Example 1 and 90 parts of polylactic acid were dissolved in dichloromethane to prepare a 20% (w / v) solution. The solution was then molded on a film-forming machine to obtain film A2. The mechanical properties of film A2 were tested using the method described in GB / T1040.3-2006. The test results showed a tensile strength of 35.78 MPa and an elongation at break of 51.27%.

[0054] 3. Mix 0.7 parts of the product prepared in Example 3 with 99 parts of polylactic acid, add 0.3 parts of chain extender, and melt-blend extrude using a twin-screw extruder. Then, blown film is obtained by passing the resulting granules through a blown film extruder to obtain film B1. The mechanical properties of film B1 are tested using the method described in GB / T 1040.3-2006. The test results show that the tensile strength is 35.33 MPa and the elongation at break is 79.28%.

[0055] 4. One part of the product prepared in Example 1 and 99 parts of polylactic acid were dissolved in dichloromethane to prepare a 20% (w / v) solution. The solution was then molded on a film-forming machine to obtain film B2. The mechanical properties of film B2 were tested using the method described in GB / T 1040.3-2006. The test results showed a tensile strength of 36.21 MPa and an elongation at break of 89.92%.

[0056] 5. Mix 0.35 parts of the product prepared in Example 2 and 0.05 parts of the product prepared in Example 4 with 99.4 parts of polylactic acid, add 0.2 parts of chain extender, and melt-blend extrude the mixture using a twin-screw extruder. Then, blown film is produced using a blown film extruder to obtain film C1. The mechanical properties of film C1 are tested using the method described in GB / T 1040.3-2006. The test results show that the tensile strength is 26.81 MPa and the elongation at break is 90.36%.

[0057] 6. 0.35 parts of the product prepared in Example 2 and 0.05 parts of the product prepared in Example 4 were dissolved in chloroform with 99.6 parts of polylactic acid to prepare a 20% (w / v) solution. The solution was then molded on a film-forming machine to obtain film C2. The mechanical properties of film C2 were tested using the method described in GB / T 1040.3-2006. The test results showed that the tensile strength was 29.44 MPa and the elongation at break was 96.07%.

[0058] Example 6

[0059] The preservation effect of film on mushrooms:

[0060] 1. Cut A1 film into bag shapes, wrap an appropriate amount of spotted mushrooms inside, and conduct a preservation experiment at room temperature. Seal the film using a heat sealer. Use commercially available polyethylene (PE) preservation film as a control group. Results are as follows. Figure 1 As shown, the PE group showed obvious mold growth at the roots starting from the eighth day, while the A1 film group remained fresh until the 12th day.

[0061] 2. C2 film was cut into bag shapes, and an appropriate amount of bamboo fungus was wrapped inside. A preservation experiment was conducted at room temperature, and the film was sealed using a heat sealer. Commercially available polyethylene (PE) preservation film was used as a control group. Results are as follows: Figure 2 As shown, the PE group had completely decomposed by the seventh day, while the C2 membrane group still maintained its tissue morphology.

[0062] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a long-chain carboxylic acid glyceride derivative of levulinic acid, characterized by: The long-chain carboxylic acid glyceride derivative and the levulinic acid are heated to react under the action of a catalyst, when the number of hydroxyl groups on the long-chain carboxylic acid glyceride derivative is 2, the levulinic acid is monosubstituted, when the number of hydroxyl groups on the long-chain carboxylic acid glyceride derivative is > 2, the levulinic acid is monosubstituted or disubstituted, the reaction is carried out under vacuum, the vacuum degree of the reaction is 0.07-0.1 MPa, the reaction temperature is 80-150 ℃, and the reaction time is 1-5 h; The catalyst is p-toluenesulfonic acid, and the amount of the catalyst is 1-5% of the molar mass fraction of the levulinic acid; the molar ratio of the long-chain carboxylic acid glyceride derivative to the levulinic acid is 1: (1-2) ; The long-chain carboxylic acid glyceride derivative is one of lauric acid monoglyceride, capric acid monoglyceride and single long-chain carboxylic acid polyglycerol ester; the single long-chain carboxylic acid polyglycerol ester is prepared by heating polyglycerol and lauric acid or capric acid, and the molar ratio of the polyglycerol to the lauric acid or capric acid is 1:1, and the polyglycerol is dimeric glycerol or trimeric glycerol.

2. The method of claim 1, wherein: The product after the reaction is dissolved in a solvent, the pH is adjusted to neutral, and then washed and dried, and then dried after removing the solvent to obtain the long-chain carboxylic acid glyceride derivative of levulinic acid.

3. The method of claim 2, wherein: The solvent is one of dichloromethane, chloroform, ethyl acetate, dimethyl carbonate, methanol and dinaphthyl.

4. A method for producing a polylactic acid film comprising the acetylenic acid long-chain carboxylic acid glyceride derivative produced by the production method according to any one of claims 1 to 3, characterized by: The long-chain carboxylic acid glyceride derivative of levulinic acid is mixed with PLA, a chain extender is added, and then extruded, or is dissolved in a solvent to prepare a polylactic acid film; the solvent is one of dichloromethane, chloroform, dimethyl carbonate and dinaphthyl, and the amount of the chain extender added is 0.2%-0.5wt%.

5. The polylactic acid film according to claim 4 is used for preserving fungi.

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