Gallic acid antioxidant as well as preparation method and application thereof

Abstract

The invention provides a gallic acid antioxidant as well as a preparation method and application thereof. The gallic acid antioxidant comprises three gallic acid residues and a plurality of ring structures, the gallic acid residues contain a large number of phenolic hydroxyl groups, the oxidation free radical reaction can be terminated by providing hydrogen protons and lone pair electrons, the antioxidant has good oxidation resistance, meanwhile, the gallic acid antioxidant also contains a large number of rigid ring structures, and the oxidation resistance of the gallic acid antioxidant is improved. The gallic acid is a natural phenolic compound, so that the melting point of the antioxidant can be increased to enhance the high-temperature stability, and in addition, the gallic acid is a natural phenolic compound and has safety, so that the antioxidant disclosed by the invention can be applied to the fields with relatively high safety level requirements, such as food and medical treatment.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and relates to a gallic acid antioxidant, its preparation method, and its application. Background Technology

[0002] Poly(4-methyl-1-pentene) (PMP) is a semi-crystalline, isotactic polyolefin resin with a large helical side chain. Its unique molecular structure endows the material with many excellent properties, including a low density of 0.83 g / cm³. 3 High-end polyolefin resins, characterized by high melting points (235-240℃), high transparency, good oxygen permeability, and low dielectric constant and dielectric loss, have important applications in high-end medical and electronic communication materials. Currently, the types of antioxidants used in polyolefins include phenols, amines, phosphites, and thioethers. However, PMP materials are often used as important medical materials, and the added additives need to possess both good antioxidant and safety properties. Currently, the antioxidants commonly added to medical polyolefin materials are mainly natural and synthetic phenols. Compared to synthetic phenolic compounds, natural phenolic antioxidants have better safety.

[0003] Gallic acid, as a natural phenolic antioxidant, contains a large number of phenolic hydroxyl groups in its structure and has excellent antioxidant properties. It is often used as an antioxidant in chemical materials. [1] Dai Chunyan, Zhan Guofeng, Zhang Zhihui, et al. Synthesis of butyl gallate and its antioxidant effect on polypropylene [J]. Synthetic Materials Aging and Application, 2015(3):4. In this study, butyl gallate synthesized by esterification reaction using gallic acid and n-butanol can significantly improve the heat and oxygen resistance of polybutene. [1] Zhang Yudong, Liu Huan, Liu Xiaoming, et al. Effect of methyl gallate on antioxidant, rheological and thermal decomposition behavior of polypropylene [J]. Chemical Research, 2017, 28(1):7. In this study, methyl gallate was added to polypropylene materials. Under air atmosphere, methyl gallate can significantly improve the antioxidant properties of polypropylene. [1] Xin M, Ma Y, Xu K, et al. Gallate derivatives as antioxidant additives for polypropylene [J]. Journal of A study published in *Applied Polymer Science* in 2014 investigated the thermal oxidative degradation behavior of polypropylene (PP) by butyl gallate and found that low-alkyl-chain butyl gallate significantly improved the heat and oxygen resistance of PP. This indicates that adding gallic acid or its derivatives to materials can significantly improve their antioxidant properties. However, due to the high melting point of PMP materials, their processing temperature can reach 270–300℃, while the thermal decomposition temperature of gallic acid is between 250℃ and 260℃. Therefore, if gallic acid is used as an antioxidant, it will inevitably lead to thermal decomposition during processing, thus affecting the material's antioxidant properties.

[0004] Therefore, it is of great significance to develop a natural gallic acid antioxidant with good heat resistance and antioxidant properties. Summary of the Invention

[0005] To address the deficiencies in existing technologies, this invention provides a gallic acid antioxidant, its preparation method, and its application. The structure of the gallic acid antioxidant of this invention comprises three gallic acid residues and multiple cyclic structures. The gallic acid residues contain a large number of phenolic hydroxyl groups, which can terminate oxidative free radical reactions by providing hydrogen protons and lone pair electrons, thus giving the antioxidant good antioxidant properties. At the same time, the antioxidant also contains a large number of rigid cyclic structures, which can increase the melting point and enhance its high-temperature stability.

[0006] The first aspect of this invention provides a gallic acid antioxidant, the structural formula of which is as follows: Formula I:

[0007]

[0008] In Formula I, R1, R2, and R3 are each independently selected from one or more of -CH2-, -CH2-CH2-, and -CH(CH3)-.

[0009] A second aspect of the present invention provides a method for preparing the gallic acid antioxidant described in the first aspect, comprising the following steps:

[0010] 1) React the hydroxyalkyl hexahydrotriazine of formula I-1 with p-4-aminobenzoyl chloride to obtain the intermediate of formula I-2;

[0011]

[0012] 2) React the intermediate shown in Formula I-2 with gallic acid to obtain the gallic acid antioxidant;

[0013]

[0014] In one optional embodiment, the hydroxyalkyl hexahydrotriazine comprises one or more of hydroxyethyl hexahydrotriazine, hydroxymethyl hexahydrotriazine, tris(N-hydroxypropyl)hexahydrotriazine, α-methyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol, and α,α-dimethyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol.

[0015] In an alternative embodiment, the reaction in step 1) further includes a first alkaline promoter and a first solvent.

[0016] In one alternative embodiment, the first alkaline promoter includes one or more of ethylenediamine, triethylamine, pyridine, N,N-diisopropylethylamine, and 4-dimethylaminopyridine.

[0017] In one alternative embodiment, the first solvent includes one or more of carbon tetrachloride, chloroform, dichloroethane, and methyl chloroform.

[0018] In an optional embodiment, step 2) further includes a second alkaline accelerator, a second solvent, and a condensing agent.

[0019] In one alternative embodiment, the second alkaline promoter comprises one or more of triethylamine, 4-dimethylaminopyridine, and N,N-diisopropylethylamine.

[0020] In one alternative embodiment, the second solvent includes one or more of dimethyl sulfoxide and dimethylformamide.

[0021] In one alternative embodiment, the condensing agent is selected from one or more of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, O-benzotriazole-tetramethylurea hexafluorophosphate, 1-hydroxybenzotriazole, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0022] In an optional embodiment, in step 1), the ratio of the amount of hydroxyalkyl hexahydrotriazine of formula I-1, the 4-aminobenzoyl chloride, the first basic accelerator, and the first solvent is 1 mmol: (3 mmol to 5 mmol): (0.3 g to 1 g): (10 mL to 20 mL).

[0023] In an optional embodiment, in step 2), the ratio of the intermediate shown in Formula I-2, the gallic acid, the condensing agent, the second basic promoter, and the second solvent is 1 mmol : (3 mmol to 5 mmol) : (0.05 to 0.3 g) : (0.3 g to 1 g) : (15 mL to 25 mL).

[0024] In one optional embodiment, the reaction temperature in step 1) is 25–70°C and the reaction time is 8–18 h.

[0025] In one optional embodiment, the reaction temperature in step 2) is 25–50°C, and the reaction time is 12–24 h.

[0026] A second aspect of the present invention provides a poly4-methyl-1-pentene material comprising the gallic acid antioxidant as described in claim 1.

[0027] In one optional embodiment, the gallic acid antioxidant content in the poly-4-methyl-1-pentene material is 0.1% to 1% by mass.

[0028] The implementation of this invention has at least the following advantages:

[0029] The antioxidant provided by this invention is synthesized from natural gallic acid, which is safe and can be used in fields with high safety requirements such as food and medicine. Furthermore, it contains a large number of phenolic hydroxyl groups, which can terminate the oxidation free radical reaction by providing hydrogen protons and lone pair electrons, thus exhibiting good antioxidant properties. It also contains a large number of rigid cyclic structures, which can increase the melting point and enhance the high-temperature stability of the antioxidant. Attached Figure Description

[0030] Figure 1 This is the mass spectrum of antioxidant AO1 in Example 1 of the present invention;

[0031] Figure 2This is the mass spectrum of antioxidant AO2 in Example 2 of the present invention;

[0032] Figure 3 This is the mass spectrum of antioxidant AO3 in Example 3 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] Poly(4-methyl-1-pentene) is a semi-crystalline, isotactic polyolefin resin with a large helical side chain. Its unique molecular structure endows the material with many excellent properties, including a low density of 0.83 g / cm³. 3 High-end polyolefin resins, characterized by high melting points (235-240℃), high transparency, good oxygen permeability, and low dielectric constant and dielectric loss, have important applications in high-end medical and electronic communication materials. Among them, PMP materials, as important medical materials, often utilize natural phenolic compounds as antioxidants due to safety considerations.

[0035] Gallic acid is a natural phenolic antioxidant containing a large number of phenolic hydroxyl groups, exhibiting excellent antioxidant properties and making it an ideal antioxidant for chemical materials, especially medical materials. However, PMP materials have a high melting point, with processing temperatures reaching 270–300°C, while the thermal decomposition temperature of gallic acid is between 250°C and 260°C. Using gallic acid as an antioxidant would inevitably lead to its thermal decomposition during processing, affecting the antioxidant performance of PMP materials and shortening their lifespan. The number of phenolic hydroxyl groups in an antioxidant directly affects its antioxidant performance. Therefore, increasing the number of gallic acid groups can increase the number of phenolic hydroxyl groups in the antioxidant, thereby improving its antioxidant performance. Furthermore, cyclic structures can restrict molecular rotation and bending, increasing molecular rigidity and improving thermal stability by reducing the degree of freedom of molecular motion at high temperatures. Therefore, introducing multiple rigid groups into the carrier molecule may improve the high-temperature stability of the antioxidant.

[0036] Based on this, the first aspect of the present invention provides a gallic acid antioxidant, the structural formula of which is as follows: Formula I:

[0037]

[0038] In Formula I, R1, R2, and R3 are each independently selected from one or more of -CH2-, -CH2-CH2-, and -CH(CH3)-.

[0039] As can be seen from Formula I, in the structure of the gallic acid antioxidant of the present invention, three gallic acid residues are linked to the carrier molecule in the form of amide bonds. The structure of the carrier compound is shown in Formula I-2 below. The carrier molecule in the present invention is a compound molecule that can link several gallic acid groups together. The carrier molecule contains three p-4-aminobenzoyl groups. The amino groups on its structure can form amide bonds with the carboxyl groups of gallic acid, which are the binding sites of gallic acid.

[0040]

[0041] Each gallic acid residue contains three free phenolic hydroxyl groups (-OH). These hydroxyl groups provide hydrogen atoms to react with free radicals, forming relatively stable phenoxy free radicals, thereby preventing the oxidation chain reaction and exerting an antioxidant effect. The carrier molecule contains multiple cyclic structures. These cyclic structures restrict molecular rotation and bending, increasing molecular rigidity and reducing the degree of freedom of molecular motion at high temperatures, thus improving thermal stability. Simultaneously, the antioxidant of this invention also contains multiple aromatic rings with extensive π-electron conjugation. This conjugation effect disperses energy, making the antioxidant molecule more stable under thermal conditions. Furthermore, the cyclic structure may also lead to greater steric hindrance, hindering the approach and reaction of other molecules or groups, thereby reducing molecular decomposition or rearrangement reactions at high temperatures. Therefore, the abundance of phenolic hydroxyl groups and cyclic structures in the antioxidant of this invention endow it with both good antioxidant properties and high-temperature stability.

[0042] A second aspect of the present invention provides a method for preparing the above-mentioned gallic acid antioxidant, comprising the following steps:

[0043] 1) React the hydroxyalkyl hexahydrotriazine of formula I-1 with p-4-aminobenzoyl chloride to obtain the intermediate of formula I-2;

[0044]

[0045] 2) React the intermediate shown in Formula I-2 with gallic acid to obtain gallic acid antioxidant;

[0046]

[0047] In step 1), one hydroxyalkyl hexahydrotriazine of formula I-1 undergoes an esterification reaction with three molecules of p-4-aminobenzoyl chloride to obtain intermediate formula I-2.

[0048] In one preferred embodiment, the hydroxyalkyl hexahydrotriazine shown in Formula I-1 includes one or more of hydroxyethyl hexahydrotriazine, hydroxymethyl hexahydrotriazine, tris(N-hydroxypropyl)hexahydrotriazine, α-methyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol, and α,α-dimethyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol. These compounds all have three branches, and each branch contains a hydroxyl group, which facilitates the subsequent binding of multiple gallic acid groups, thereby improving the antioxidant properties of the antioxidant.

[0049] When the hydroxyalkyl hexahydrotriazine shown in Formula I-1 undergoes an esterification reaction with p-4-aminobenzoyl chloride, three molecules of hydrochloric acid are simultaneously removed. To promote the forward reaction, a first basic promoter with basicity can be added to neutralize the hydrochloric acid generated during the reaction. This invention does not limit the type of the first basic promoter; it can be a basic compound conventionally used in the art, including both organic and inorganic basic compounds, such as one or more of ethylenediamine, triethylamine, pyridine, N,N-diisopropylethylamine, and 4-dimethylaminopyridine.

[0050] Furthermore, 4-aminobenzoyl chloride contains an acyl chloride group. Due to the high electronegativity of the chlorine atom, the carbonyl carbon atom in the acyl chloride carries a partial positive charge, making it susceptible to nucleophilic attacks. This makes the acyl chloride highly reactive in chemical reactions, readily hydrolyzing in the presence of moisture to form the corresponding carboxylic acid. Therefore, non-aqueous and non-hydrophilic solvents are preferred as reaction solvents, such as chloroalkanes, specifically including but not limited to one or more of carbon tetrachloride, chloroform, dichloroethane, or methyl chloroform. These solvents not only provide an ideal anhydrous environment but also ensure the high efficiency and selectivity of the esterification reaction through their inert properties.

[0051] Furthermore, in order to prevent the decomposition of 4-aminobenzoyl chloride and improve its conversion rate, it is considered to add the 4-aminobenzoyl chloride solution to the hydroxyalkyl hexahydrotriazine solution shown in Formula I-1 by slow dropwise addition, so as to control the reaction rate and suppress the occurrence of side reactions.

[0052] To improve the efficiency, stability, and economy of the esterification reaction, it is necessary to control the content of each component. Precise control of the amount of 4-aminobenzoyl chloride ensures its complete reaction with the hydroxyalkyl hexahydrotriazine shown in Formula I-1, thereby improving the conversion and yield. Optimizing the dosage range of the first basic promoter effectively accelerates the reaction rate and avoids side reactions or product degradation caused by excessive use. The first solvent provides sufficient reaction medium, and controlling its dosage ensures good solubility and uniform distribution of the reactants. Based on these considerations, in step 1), the dosage ratio of hydroxyalkyl hexahydrotriazine, 4-aminobenzoyl chloride, the first basic promoter, and the first solvent shown in Formula I-1 is controlled within the range of 1 mmol:(3 mmol–5 mmol):(0.3 g–1 g):(10 mL–20 mL), achieving high efficiency, stability, and economy in the reaction.

[0053] The reaction temperature and time directly affect the yield and purity of the intermediate. Excessive temperature leads to an excessively high reaction rate and a short reaction time, which is detrimental to the stability of the reactant with 4-aminobenzoyl chloride and also generates more byproducts. Conversely, excessively low temperature results in a slow reaction rate and a long reaction time, which may also lead to the formation of more byproducts. Based on these considerations, the reaction temperature in step 1) is controlled within the range of 25–70℃, and the reaction time is controlled within the range of 8–18 hours to balance the reaction rate and the yield of the intermediate.

[0054] In step 2), one molecule of intermediate undergoes an amidation reaction with three molecules of gallic acid groups, and the amino group in the intermediate structure reacts with the carboxyl group of gallic acid to remove one molecule of water, thus obtaining the antioxidant of the present invention.

[0055] Since an alkaline environment favors the deprotonation of amino groups, making them more susceptible to attacking the carbonyl carbon in the carboxyl group, thereby accelerating the reaction rate and improving the overall efficiency of the reaction, the addition of a second alkaline promoter to the reaction system is considered. This second alkaline promoter includes one or more of triethylamine, 4-dimethylaminopyridine, and N,N-diisopropylethylamine. These substances not only provide an alkaline environment but also act as catalysts, significantly improving the efficiency of the amidation reaction upon their addition.

[0056] The intermediate's molecular structure contains numerous amino and ester bonds, which can form hydrogen bonds, leading to strong intermolecular interactions and reducing the intermediate's solubility. Experiments have shown that the intermediate has weak solubility in common solvents, but exhibits good solubility in dimethyl sulfoxide and dimethylformamide. Therefore, these two organic compounds were chosen as the second solvent.

[0057] The carboxyl group in gallic acid has low reactivity with the amino group, resulting in low efficiency in directly reacting with the amino group to form an amide. Therefore, it is considered to add a condensing agent to the amidation reaction system to activate the carboxyl group, making it easier for it to react with the amino group. In one specific embodiment, the condensing agent includes one or more of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, O-benzotriazole-tetramethylurea hexafluorophosphate, 1-hydroxybenzotriazole, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0058] The amount of each component in the amidation reaction system significantly affects the reaction rate. In step 2), the ratio of the intermediate, gallic acid, condensing agent, second basic promoter, and second solvent shown in Formula I-2 is controlled within the range of 1 mmol : (3 mmol–5 mmol) : (0.05–0.3 g) : (0.3 g–1 g) : (15 mL–25 mL). This can reduce the synthesis cost of the antioxidant while ensuring a certain reaction rate. Adding excess gallic acid ensures complete reaction of the intermediate, thus achieving cost savings.

[0059] Furthermore, the reaction temperature and time of the amidation reaction directly affect the antioxidant yield. Appropriate reaction temperature and time are beneficial for improving the amidation reaction rate and product yield. At excessively high temperatures, although the reaction time will be shortened, the phenolic hydroxyl groups may be oxidized, thus reducing the antioxidant effect. Conversely, at excessively low temperatures, the reaction rate decreases, leading to an excessively long reaction time. A better reaction rate and antioxidant yield can be obtained when the amidation reaction temperature is between 25℃ and 50℃ and the reaction time is controlled between 12 and 24 hours.

[0060] In the above preparation methods, an intermediate is prepared by esterification, and then the intermediate is subjected to amidation reaction with gallic acid to obtain an antioxidant, which can achieve efficient preparation of antioxidants.

[0061] A third aspect of the present invention provides a poly4-methyl-1-pentene material comprising the gallic acid antioxidant described in the first aspect above.

[0062] In one specific embodiment, the antioxidant content in the poly-4-methyl-1-pentene material is 0.1% to 1% by mass. The antioxidant content directly affects the antioxidant performance of the material, but too much content will result in waste. Therefore, its content is controlled within the above range.

[0063] The present invention does not impose any particular limitation on the preparation method of the above-mentioned poly4-methyl-1-pentene material. It can be obtained by uniformly mixing the poly4-methyl-1-pentene polymer and the antioxidant shown in Formula I using conventional blending methods.

[0064] For example, in one specific embodiment, the antioxidant shown in Formula I can be added to the poly4-methyl-1-pentene polymer, and after extrusion granulation, the poly4-methyl-1-pentene material of the present invention can be obtained.

[0065] The present invention does not limit the granulation apparatus; it can be used to granulate materials by extrusion, such as a twin-screw extruder.

[0066] Furthermore, the extrusion granulation temperature is 270–300°C, which is the processing temperature of poly4-methyl-1-pentene. Controlling the extrusion temperature within this range is beneficial for material forming.

[0067] To determine the changes in the antioxidant properties of poly-4-methyl-1-pentene before and after the addition of antioxidants, it is also necessary to test the oxidation induction period and mechanical properties of the poly-4-methyl-1-pentene material after the addition of antioxidants.

[0068] In summary, this invention provides a gallic acid antioxidant. The antioxidant molecule contains a large number of phenolic hydroxyl groups, which can terminate the oxidation free radical reaction by providing hydrogen protons and lone pair electrons, thus exhibiting good antioxidant performance. At the same time, the structure also contains a large number of rigid cyclic structures, which can increase its melting point and enhance its high-temperature stability.

[0069] The gallic acid antioxidant provided by the present invention will be further described below with reference to specific embodiments.

[0070] Unless otherwise specified, the experimental methods used in the following embodiments can be conventional methods in the art.

[0071] In the following embodiments, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0072] Example 1

[0073] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0074] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0075] (1) Esterification reaction: Under a nitrogen atmosphere, 10 mmol of hydroxymethyl hexahydrotriazine, 6 g of N,N-diisopropylethylamine, and 120 ml of chloroform were added sequentially to a side-mouth flask. At 0 °C, 30 ml of chloroform solution containing 40 mmol of 4-aminobenzoyl chloride was slowly added dropwise using a constant pressure dropping funnel. After refluxing at 40 °C for 12 h, the reaction system was washed with water and separated. After separation, the organic phase was subjected to vacuum distillation to obtain intermediate 1. The yield of intermediate 1 was 98.3%.

[0076] (2) Amide reaction: Under a nitrogen atmosphere, 5 mmol of intermediate 1, 0.75 g of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, and 3 g of N,N-diisopropylethylamine were weighed and dissolved in 80 mL of dimethyl sulfoxide. Then, 20 mL of dimethyl sulfoxide solution containing 20 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 25 °C for 18 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain antioxidant AO1. The volume ratio of petroleum ether to ethyl acetate in the eluent used in the silica gel column chromatography was 6:1. The yield of antioxidant AO1 was calculated to be 92.6%.

[0077] Figure 1 This is the mass spectrum of the antioxidant AO1 prepared in this embodiment, based on... Figure 1 The mass spectrometry data of AO1 were obtained as follows: MS-EI (m / z): 990.0.

[0078] In addition, the proton NMR data for AO1 are as follows: 1 H NMR(CD3Cl,400MHz): δ(ppm)3.43(s,6H,-N-CH2-N-),5.32(s,6H,-N-CH2-O-),5.35(s ,9H,-OH),6.93(s,6H,N-CO-Ar-H),7.77-7.88(d,12H,O-CO-Ar-H),9.15(s,3H,-NH).

[0079] Example 2

[0080] 1. This embodiment provides a gallic acid antioxidant AO2, the structural formula of which is shown in Table 1;

[0081] 2. This embodiment provides a method for preparing gallic acid antioxidant AO2, which is basically the same as that in Example 1, except that:

[0082] In step (1), hydroxymethyl hexahydrotriazine was replaced with hydroxyethyl hexahydrotriazine to prepare intermediate 2, wherein the yield of intermediate 2 in step (1) was 91.9%.

[0083] In step (2), the AO2 yield was 90.4%;

[0084] Figure 2 This is the mass spectrum of the antioxidant AO2 prepared in this embodiment, based on... Figure 2 The mass spectrometry data of AO2 were obtained as follows: MS-EI (m / z): 1031.8.

[0085] In addition, the proton NMR data for AO2 are as follows: 1H NMR(CD3Cl,400MHz): δ(ppm)2.80(t,6H,-N-CH2-),3.43(s,6H,-N-CH2-N-),4.67(t,6H,-CH2-O- ),5.35(s,9H,-OH),6.93(s,6H,N-CO-Ar-H),7.77-7.88(d,12H,O-CO-Ar-H),9.15(s,3H,-NH).

[0086] Example 3

[0087] 1. This embodiment provides a gallic acid antioxidant AO3, the structural formula of which is shown in Table 1;

[0088] 2. This embodiment provides a method for preparing gallic acid antioxidant AO3, which is basically the same as that in Example 1, except that:

[0089] The intermediate 3 was prepared by replacing the hydroxymethyl hexahydrotriazine in step (1) with tris(N-hydroxypropyl)hexahydrotriazine. The yield of intermediate 3 in step (1) was 85.8%.

[0090] The yield of AO3 in step (2) was 86.7%;

[0091] Figure 3 This is the mass spectrum of the antioxidant AO3 prepared in this embodiment, based on... Figure 3 The mass spectrometry data of AO3 were obtained as follows: MS-EI (m / z): 1074.3.

[0092] In addition, the proton NMR data for AO3 are as follows: 1 H NMR(CD3Cl,400MHz): δ(ppm)1.37(d,9H,-CH3-),2.65-2.90(m,6H,-N-CH2-),4.37(m,3H,-CH-O- ),5.35(s,9H,-OH),6.93(s,6H,N-CO-Ar-H),7.77-7.88(d,12H,O-CO-Ar-H),9.15(s,3H,-NH).

[0093] Example 4

[0094] 1. This embodiment provides a gallic acid antioxidant AO4, the structural formula of which is shown in Table 1;

[0095] 2. This embodiment provides a method for preparing gallic acid antioxidant AO4, which is basically the same as that in Example 1, except that:

[0096] In step (1), hydroxymethylhexahydrotriazine was replaced with α-methyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol to prepare intermediate 4. The yield of intermediate 4 in step (1) was 86.6%.

[0097] The yield of AO4 in step (2) was 87.5%.

[0098] Example 5

[0099] 1. This embodiment provides a gallic acid antioxidant AO5, the structural formula of which is shown in Table 1;

[0100] 2. This embodiment provides a method for preparing gallic acid antioxidant AO5, which is basically the same as that in Example 1, except that:

[0101] The intermediate 4 was prepared by replacing the hydroxymethylhexahydrotriazine in step (1) with α,α-dimethyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol. The yield of antioxidant intermediate 4 in step (1) was 86.1%.

[0102] The yield of AO5 in step (2) was 87.0%.

[0103] Example 6

[0104] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0105] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0106] (1) Under a nitrogen atmosphere, 10 mmol of hydroxymethylhexahydrotriazine, 3 g of N,N-diisopropylethylamine, and 80 mL of chloroform were added sequentially to a side-necked flask. Then, 20 mL of a chloroform solution containing 35 mmol of 4-aminobenzoyl chloride was slowly added dropwise using a constant-pressure dropping funnel at 0 °C. The mixture was refluxed at 25 °C for 12 h. After the reaction, the reaction system was washed with water and separated. The organic phase was then subjected to vacuum distillation to obtain intermediate 1, with a yield of 89.4%.

[0107] (2) Under a nitrogen atmosphere, 5 mmol of intermediate, 0.5 g of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, and 1.5 g of N,N-diisopropylethylamine were weighed and dissolved in 60 mL of dimethyl sulfoxide. 15 mL of dimethyl sulfoxide solution containing 15 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 25 °C for 18 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography. The volume ratio of petroleum ether to ethyl acetate in the eluent was 6:1. The yield of antioxidant AO1 was calculated to be 84.7%.

[0108] Example 7

[0109] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0110] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0111] (1) Under a nitrogen atmosphere, 10 mmol of hydroxymethylhexahydrotriazine and 6 g of [unclear text] were added sequentially to a bottle with a side arm.

[0112] 4-Dimethylaminopyridine and 150 ml of carbon tetrachloride were slowly added dropwise at 0 °C using a constant pressure dropping funnel. 50 ml of carbon tetrachloride solution containing 50 mmol of 4-aminobenzoyl chloride was added dropwise. The mixture was refluxed at 70 °C for 8 h. After the reaction, the reaction system was washed with water and separated. The organic phase was then subjected to vacuum distillation to obtain intermediate 1. The yield of intermediate 1 was 96.6%.

[0113] (2) Under a nitrogen atmosphere, 5 mmol of intermediate, 0.25 g of O-benzotriazole-tetramethylurea hexafluorophosphate, and 1.5 g of 4-dimethylaminopyridine were weighed and dissolved in 100 mL of dimethyl sulfoxide. 25 mL of dimethyl sulfoxide solution containing 25 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 30 °C for 15 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography. The volume ratio of petroleum ether to ethyl acetate in the eluent was 6:1. The yield of antioxidant AO1 was calculated to be 81.0%.

[0114] Example 8

[0115] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0116] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0117] (1) Under a nitrogen atmosphere, 10 mmol of hydroxymethylhexahydrotriazine, 10 g of pyridine, and 100 ml of carbon tetrachloride were added sequentially to a side-mouth flask. At 0 °C, 40 ml of carbon tetrachloride solution containing 45 mmol of 4-aminobenzoyl chloride was slowly added dropwise using a constant pressure dropping funnel. The mixture was refluxed at 60 °C for 18 h. After the reaction, the mixture was washed with water and separated. The organic phase was then subjected to vacuum distillation to obtain intermediate 1. The yield of intermediate 1 was 97.4%.

[0118] (2) Under a nitrogen atmosphere, 5 mmol of intermediate, 1.5 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and 2.5 g of 4-dimethylaminopyridine were weighed and dissolved in 90 mL of dimethylformamide. 30 mL of dimethylformamide solution containing 25 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 40 °C for 18 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography. The volume ratio of petroleum ether to ethyl acetate in the eluent was 6:1. The yield of antioxidant AO1 was calculated to be 84.9%.

[0119] Example 9

[0120] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0121] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0122] (1) Under a nitrogen atmosphere, 10 mmol of hydroxymethylhexahydrotriazine, 10 g of ethylenediamine, and 100 ml of dichloroethane were added sequentially to a side-mouth flask. At 0 °C, 50 ml of a dichloroethane solution containing 50 mmol of 4-aminobenzoyl chloride was slowly added dropwise using a constant pressure dropping funnel. The mixture was refluxed at 70 °C for 12 h. After the reaction, the mixture was washed with water and separated. The organic phase was then subjected to vacuum distillation to obtain intermediate 1. The yield of intermediate 1 was 92.2%.

[0123] (2) Under a nitrogen atmosphere, 5 mmol of intermediate, 1.0 g of 1-hydroxybenzotriazole, and 2.5 g of 4-dimethylaminopyridine were weighed and dissolved in 90 mL of dimethylformamide. 30 mL of dimethylformamide solution containing 25 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 40 °C for 24 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography. The volume ratio of petroleum ether to ethyl acetate in the eluent was 6:1. The yield of antioxidant AO1 was calculated to be 85.7%.

[0124] Example 10

[0125] 1. This embodiment provides a gallic acid antioxidant AO1, the structural formula of which is shown in Table 1;

[0126] 2. This embodiment provides a method for preparing gallic acid antioxidant AO1, including the following steps:

[0127] (1) Under a nitrogen atmosphere, 10 mmol of hydroxymethylhexahydrotriazine, 10 g of triethylamine and 100 ml of methyl chloroform were added sequentially to a side-mouth flask. At 0 °C, 50 ml of carbon tetrachloride solution containing 50 mmol of 4-aminobenzoyl chloride was slowly added dropwise using a constant pressure dropping funnel. The mixture was refluxed at 70 °C for 18 h. After the reaction, the mixture was washed with water and separated. The organic phase was then subjected to vacuum distillation to obtain intermediate 1. The yield of intermediate 1 was 95.1%.

[0128] (2) Under a nitrogen atmosphere, 5 mmol of intermediate, 1.5 g of dicyclohexylcarbodiimide, and 2.5 g of 4-dimethylaminopyridine were weighed and dissolved in 90 mL of dimethylformamide. 30 mL of dimethylformamide solution containing 25 mmol of gallic acid was slowly added dropwise at room temperature. The reaction was carried out at 50 °C for 24 h. The solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography. The volume ratio of petroleum ether to ethyl acetate in the eluent was 6:1. The yield of antioxidant AO1 was calculated to be 81.9%.

[0129] Table 1

[0130]

[0131]

[0132]

[0133] To compare the preparation processes of different antioxidants AO1-AO5, relevant information on the key compounds in Examples 1-5 is shown in Table 2 below:

[0134] Table 2

[0135]

[0136] As shown in Table 2, among AO1-AO5, antioxidant intermediates 1 and AO1 have the highest yields, while antioxidant intermediates 3 and AO3 have the lowest yields.

[0137] To compare the effects of different reaction systems on antioxidant AO1, relevant information on key compounds in Examples 6-10 is shown in Table 3 below:

[0138] Table 3

[0139]

[0140]

[0141] Test case

[0142] In the granulation section of poly-4-methyl-1-pentene, 0.1%-1.0% of the above-mentioned antioxidant AO1-AO5 is added to its powder, and it is extruded, drawn into fibers and granulated by a twin-screw extruder at 270-300℃. Then, the oxidation induction period and mechanical properties of poly-4-methyl-1-pentene are tested. The test method for oxidation induction period is performed in accordance with GB 19466.3-2004, and the test method for mechanical properties is performed in accordance with GB / T1040-2018.

[0143] The test results for antioxidant A01-AO5 are shown in Table 4 below:

[0144] Table 4

[0145]

[0146]

[0147] As shown in Table 4 above, compared with test examples 1-5, AO1 has the longest oxidation induction period and the longest tensile strength, while AO3 has the shortest oxidation induction period and the longest tensile strength. This indicates that AO1 has a good anti-oxidation effect and can also maintain good tensile properties of PMP material after its addition.

[0148] To better compare the antioxidant effect of the gallic acid antioxidant of the present invention, in the granulation section of poly-4-methyl-1-pentene, 0.5% gallic acid, alkyl gallic acid ester, or no antioxidant was added to the powder. The powder was then extruded, drawn into fibers, and granulated using a twin-screw extruder at 280°C. The oxidation induction period and mechanical properties of poly-4-methyl-1-pentene were then tested. The test results for the groups using AO1, gallic acid, alkyl gallic acid ester, and no antioxidant are shown in Table 5 below.

[0149] Table 5

[0150]

[0151] As shown in Table 5 above, compared with the test examples using gallic acid as an antioxidant, gallic acid ester as an antioxidant, and no antioxidant added, Test Example 1, using AO1 as an antioxidant, has a higher oxidation induction period and tensile strength. This indicates that the antioxidant of the present invention has better antioxidant properties and can also maintain good tensile properties of PMP material after being added.

[0152] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gallic acid antioxidant, characterized in that, The structural formula of the gallic acid antioxidant is as follows: Formula I: In Formula I, R1, R2, and R3 are each independently selected from one or more of -CH2-, -CH2-CH2-, and -CH(CH3)-.

2. A method for preparing the gallic acid antioxidant according to claim 1, characterized in that, Includes the following steps: 1) React the hydroxyalkyl hexahydrotriazine of formula I-1 with p-4-aminobenzoyl chloride to obtain the intermediate of formula I-2; 2) React the intermediate shown in Formula I-2 with gallic acid to obtain the gallic acid antioxidant; 3. The preparation method according to claim 2, characterized in that, The hydroxyalkyl hexahydrotriazine includes one or more of hydroxyethyl hexahydrotriazine, hydroxymethyl hexahydrotriazine, tris(N-hydroxypropyl)hexahydrotriazine, α-methyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol, and α,α-dimethyl-1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol.

4. The preparation method according to claim 2 or 3, characterized in that, The reaction in step 1) also includes a first alkaline promoter and a first solvent.

5. The preparation method according to claim 4, characterized in that, The first alkaline promoter includes one or more of ethylenediamine, triethylamine, pyridine, N,N-diisopropylethylamine, and 4-dimethylaminopyridine.

6. The preparation method according to claim 4 or 5, characterized in that, The first solvent includes one or more of carbon tetrachloride, chloroform, dichloroethane, and methyl chloroform.

7. The preparation method according to claim 2 or 3, characterized in that, The reaction in step 2) also includes a second alkaline accelerator, a second solvent, and a condensing agent.

8. The preparation method according to claim 7, characterized in that, The second alkaline promoter includes one or more of triethylamine, 4-dimethylaminopyridine, and N,N-diisopropylethylamine.

9. The preparation method according to claim 7 or 8, characterized in that, The second solvent includes one or more of dimethyl sulfoxide and dimethylformamide.

10. The preparation method according to any one of claims 7-9, characterized in that, The condensing agent is selected from one or more of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, O-benzotriazole-tetramethylurea hexafluorophosphate, 1-hydroxybenzotriazole, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

11. The preparation method according to claim 4, characterized in that, In step 1), the ratio of the amount of hydroxyalkyl hexahydrotriazine shown in Formula I-1, the 4-aminobenzoyl chloride, the first basic accelerator, and the first solvent is 1 mmol: (3 mmol to 5 mmol): (0.3 g to 1 g): (10 mL to 20 mL).

12. The preparation method according to claim 7, characterized in that, In step 2), the ratio of the intermediate shown in Formula I-2, the gallic acid, the condensing agent, the second basic promoter, and the second solvent is 1 mmol: (3 mmol to 5 mmol): (0.05 to 0.3 g): (0.3 g to 1 g): (15 mL to 25 mL).

13. The preparation method according to any one of claims 2-12, characterized in that, In step 1), the reaction temperature is 25–70℃ and the reaction time is 8–18h.

14. The preparation method according to any one of claims 2-13, characterized in that, In step 2), the reaction temperature is 25–50°C and the reaction time is 12–24 h.

15. A poly(4-methyl-1-pentene) material, characterized in that, Includes the gallic acid antioxidant as described in claim 1.

16. The poly-4-methyl-1-pentene material according to claim 15, characterized in that, The gallic acid antioxidant content in the poly-4-methyl-1-pentene material is 0.1% to 1% by mass.

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