Preparation method and application of a syringic acid-based aromatic dibasic acid

Abstract

The application discloses a preparation method of a eugenol-based aromatic dibasic acid and application thereof. The preparation method comprises the following steps: heating and refluxing reaction of chloroacetic acid and eugenol in an alkaline solution, acidification to obtain a crude product after the reaction is completed, and obtaining the eugenol-based aromatic dibasic acid after post-treatment of the crude product. The eugenol-based aromatic dibasic acid synthesized by using the widely-sourced eugenol as a raw material is green and environment-friendly, can be used for synthesizing a bio-based polyamide, and has excellent mechanical properties and good dissolving and processing capacity, and the bio-based polyamide has high economy. The whole preparation process is simple in operation and easy to popularize.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic synthesis, and particularly relates to a preparation method of syringic acid-based aromatic dibasic acid and application thereof. BACKGROUND

[0002] Aromatic polyamide has excellent thermal, mechanical properties and dimensional stability, and is widely used in aerospace, military, rail transportation, automobile, electronic and electrical industries. The aromaticity of traditional aromatic polyamide is derived from petroleum-based raw materials, such as terephthalic acid, terephthaloyl chloride, p-phenylenediamine, m-phenylenediamine, etc. With the formal proposal of the "double carbon" target, energy consumption control is endowed with new connotations of the times. In the field of aromatic polyamide industry, the development direction of industrial structural upgrading and vigorous development of green low-carbon emerging industries is proposed. The development of new bio-based polyamide derived from biomass carbon of agricultural and forestry waste can accelerate carbon cycle and is an environmentally friendly new development approach.

[0003] Lignin is an environmentally friendly renewable resource, containing a large number of active functional groups, and has many excellent chemical properties. Lignin has a non-crystalline disordered structure, and phenylpropane is its basic structural unit, which is derived from three aromatic alcohol precursors, namely β-coniferyl alcohol, coniferyl alcohol and sinapyl alcohol, and is a very good natural chemical raw material. In addition, lignin has a huge output, as a byproduct of papermaking and cellulose products, the global annual output of lignin in the papermaking industry can reach 70 million tons, and it is cheap and easy to obtain. Lignin has been well developed in the fields of phenolic resin, polyurethane, etc., and has great development prospects in the fields of polyester, polyamide, etc. For example, Chinese invention patent CN115725173A discloses a high-performance degradable lignin-based nylon plastic and its preparation method and application. The invention patent uses nylon as the reaction matrix material and lignin as the modifier to synthesize high-performance degradable lignin-based nylon plastic in an organic acid solution by one-step method, which provides an important way for efficient and high-value utilization of lignin. Due to the existence of various active groups in the molecular structure of lignin, it is difficult to directly use it for the synthesis of high polymer, therefore, the research on lignin in the field of polyester and polyamide is mostly focused on small molecules derived from lignin, such as vanillin, vanillic acid, eugenol, guaiacol, ferulic acid, syringic acid, etc. The lignin derivatives must be prepared into small molecule compounds with bifunctional active groups before being used in the synthesis of polyamide.

[0004] Chinese invention patent CN104098765A discloses a kind of synthesis method of bio-based transparent semi-aromatic polyamide material, lignin material is purified and acetylated treatment;Again, acetylated lignin material, aromatic dicarboxylic acid, 6-12 carbon atom aliphatic diamine is reacted in organic solvent to prepare high-purity salt, then the salt prepared by reaction, deionized water and polymerization aid are placed in high-pressure reaction kettle, and pre-polymerization is carried out under the condition of being filled with high-purity inert gas;After pre-polymerization, temperature and pressure are increased to further prepare a new bio-based transparent semi-aromatic polyamide material by polymerization reaction.But this method synthesizes aromatic polyamide step by step and is not suitable for promotion.

[0005] According to the source of raw materials, polyamide is generally divided into two categories, one is obtained by polycondensation of amino acid or ring-opening polymerization of lactam, also known as AB type polyamide;One is obtained by polycondensation of diacid and diamine, also known as AABB type polyamide.For AABB type polyamide, the preparation of diacid is extremely important, so if a method for preparing diacid from renewable lignin is provided, it will open up a new way for the synthesis of bio-based polyamide. SUMMARY

[0006] The application provides a preparation method of eugenol-based aromatic diacid, which uses widely-sourced eugenol as raw material, and obtains eugenol-based aromatic diacid through simple reaction, provides a new idea for the synthesis of aromatic polyamide, and has green and environmentally-friendly reaction process, high economic efficiency and easy popularization.

[0007] To achieve the above technical effects, the application adopts the following technical scheme:

[0008] The application provides a preparation method of eugenol-based aromatic diacid: under alkaline conditions, aromatic nucleophilic substitution reaction occurs between chloroacetic acid and the hydroxyl group on eugenol, an ether bond is generated, a carboxyl group is introduced, and eugenol-based aromatic diacid is obtained.

[0009] Further, the following steps are included:

[0010] S1. Heating and refluxing reaction of chloroacetic acid and eugenol in alkaline solution, and obtaining crude product after acidification after reaction;

[0011] S2. Washing, suction filtering and drying the crude product in S1 with organic solvent to obtain the eugenol-based aromatic diacid.

[0012] Further, the molar ratio of the chloroacetic acid to the eugenol is 1:1.2-2.

[0013] Further, the solute of the alkaline solution is sodium hydroxide.

[0014] Further, the reaction temperature is 50-100℃.

[0015] Further, the reaction is carried out while constantly adding sodium hydroxide to keep the pH of the alkaline solution at 10-11.

[0016] Further, after the reaction is completed, hydrochloric acid or sulfuric acid is added to acidify to pH 3-4.

[0017] Further, the organic solvent includes: acetone, petroleum ether.

[0018] Further, the acetone is first added to dissolve, and then the petroleum ether is added to precipitate.

[0019] Further, the volume of the petroleum ether added is 3-4 times the volume of the acetone added.

[0020] Further, the structure of the eugenol-based aromatic dibasic acid monomer is as follows:

[0021]

[0022] The eugenol-based aromatic dibasic acid prepared by the preparation method of the eugenol-based aromatic dibasic acid provided by the application has an application in the synthesis of polyamide.

[0023] The synthesis method of the bio-based polyamide provided by the application comprises:

[0024] The eugenol-based aromatic dibasic acid is prepared by the aforementioned method;

[0025] and the bio-based polyamide is synthesized by using the eugenol-based aromatic dibasic acid.

[0026] For example, the eugenol-based aromatic dibasic acid can be subjected to a polycondensation reaction with a diamine in a manner known in the art, so as to prepare the bio-based polyamide.

[0027] Compared with the prior art, the application has the following beneficial effects:

[0028] (1) The eugenol used in the application is widely available, and the application is green, environmentally friendly, economical, and simple in synthesis steps and easy to popularize.

[0029] (2) The aromatic dibasic acid prepared by the method of the application has a flexible methoxy group in addition to a benzene ring in structure. The polyamide synthesized by using the dibasic acid as a raw material has excellent mechanical properties of aromatic polyamide and good solubility and processing capacity, and the raw material is stable in source and simple in synthesis, and has high commercial value. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0031] Figure 1 is an infrared spectrum of the product obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0032] The present application will be more fully understood from the following detailed description taken in connection with the accompanying drawings. Detailed embodiments of the present application are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the present application, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but only as a representative basis for teaching one skilled in the art to employ the present application in virtually any appropriate detailed embodiment. It will be apparent to those skilled in the art that numerous modifications, both as to the equipment and methods described, can be made without departing from the scope of the present application.

[0033] The present application provides a preparation method of a syringic acid-based aromatic diacid: under alkaline conditions, aromatic nucleophilic substitution reaction occurs between chloroacetic acid and the hydroxyl group on syringic acid to generate an ether bond, introduce a carboxyl group, and obtain a syringic acid-based aromatic diacid.

[0034] Further, the preparation method comprises the following steps:

[0035] S1. Heating and refluxing chloroacetic acid and syringic acid in an alkaline solution to obtain a crude product after acidification;

[0036] S2. Washing, suction filtering and drying the crude product obtained in S1 with an organic solvent to obtain a syringic acid-based aromatic diacid monomer.

[0037] Example 1

[0038] (1) Preparation of raw materials

[0039] 29.73 g of syringic acid, two portions of 12 g of sodium hydroxide, and 28.35 g of chloroacetic acid were weighed with an electronic balance, respectively.

[0040] (2) Preparation of crude product by reaction

[0041] a. Pour 29.73 g of syringic acid weighed into a clean 500 mL three-necked flask, add 100 mL of deionized water, then slowly add 12 g of sodium hydroxide, mix and shake to obtain a uniform solution.

[0042] b. Add 100mL of deionized water to a clean 200mL beaker, add 28.35g of weighed chloroacetic acid to the deionized water, slowly add 12g of sodium hydroxide, and transfer the solution to a three-necked flask after the solid in the beaker has completely dissolved. Test the pH of the mixture to be 8 before the reaction.

[0043] c. The mixture was refluxed in a water bath at 100°C for 7 hours. During the reaction, the pH of the mixed solution in the three-necked flask was tested every 45 minutes, and sodium hydroxide was added to maintain the pH of the mixed solution in the range of 10-11.

[0044] d. After the reaction is complete, first add 100 mL of deionized water to dilute, then add 1 mol / L dilute hydrochloric acid dropwise to adjust the pH of the mixed solution to 3. Stir at room temperature for 15 min, filter to obtain a white powder, place it in an oven and dry at 70℃ for 12 hours to obtain a white crude product.

[0045] (3) Purification of crude product

[0046] The white crude product obtained in step (2) was ground into a fine powder in a mortar and poured into a 1000 mL beaker. 200 mL of acetone was added to dissolve the powder for 30 min, and then 600 mL of petroleum ether was slowly added to allow the product in the solution to precipitate. The powder was then filtered and dried to obtain 25.46 g of white powder, with a yield of 66.25%. This white powder is the target product, eugenol-based aromatic dicarboxylic acid.

[0047] The white powder obtained in step (3) was placed in an infrared spectrometer to obtain its infrared spectrum. (See attached image.) Figure 1 In the infrared spectrum, a broad peak appears in the wavenumber range of 2500–3300, which is a characteristic peak of carboxylic acids. Two stretching vibration peaks of C=O carbonyl groups appear at 1682 and 1733, indicating that there are two types of carboxyl groups in the synthesized syringic acid derivative: one directly attached to the benzene ring and the other attached to the methylene group. The positions of the characteristic peaks are different due to the different chemical environments of the two carboxyl groups.

[0048] Furthermore, the eugenol-based aromatic diacid obtained in this embodiment was reacted with a diamine to prepare eugenol-based polyamide. The reaction was carried out by solution polymerization with N-methylpyrrolidone as the solvent system. The molar ratio of the diacid to the diamine in the system was 1:1. The concentration of the acid and amine added was 0.4 mol / L. 4% anhydrous lithium chloride was added as a co-solvent in the reaction system, and 25% pyridine and 0.8 mol / L triphenyl phosphite were added as condensation aids.

[0049] Specifically, the synthesis process of the syringic acid-based polyamide includes: under the condition of nitrogen protection, 2.56 g of syringic acid-based aromatic dibasic acid is added into a three-neck flask containing 20 mL of N-methylpyrrolidone, a 4 wt% anhydrous lithium chloride solution is added, the reaction device is heated to 80°C, and stirring is performed for half an hour to obtain a clear solution. Then, 1.08 g of p-phenylenediamine, 5 mL of pyridine, and 5.6 mL of triphenyl phosphite are added, and the temperature is increased to 130°C for reaction for 4 hours. After the reaction is completed, the reaction solution is poured into deionized water to precipitate the polymer solid, the polymer is washed with deionized water for 2-3 times, and the polymer is dried in a 70°C oven. Finally, 3.17 g of biomass syringic acid-based polyamide is obtained, which can be well dissolved in solvents such as DMSO, DMF, DMAc, and NMP. After testing by using the same mechanical test method, it can be seen that the tensile strength of the syringic acid-based polyamide prepared in this embodiment can reach 80 MPa, close to the tensile strength 90 MPa of aramid 1414, and the elongation at break is 20%, far exceeding the elongation at break 5% of aramid 1414.

[0050] Example 2

[0051] (1) Preparation of raw materials

[0052] 29.73 g of syringic acid, 12 g of sodium hydroxide, 9 g of sodium hydroxide, and 21.26 g of chloroacetic acid are weighed by using an electronic balance.

[0053] (2) Preparation of crude product by reaction

[0054] a. The 29.73 g of syringic acid weighed is poured into a washed 500 mL three-neck flask, 100 mL of deionized water is added, 12 g of sodium hydroxide is slowly added, and the mixture is shaken to obtain a uniform solution.

[0055] b. In a washed 200 mL beaker, 100 mL of deionized water is added, and 21.26 g of chloroacetic acid weighed is added to the deionized water. 9 g of sodium hydroxide is slowly added, and after the solid in the beaker is completely dissolved, the solution is transferred to the three-neck flask.

[0056] c. Water bath heating is performed at 70°C for reflux reaction for 10 hours. During the reaction process, the pH value of the mixed solution in the three-neck flask is constantly tested, and sodium hydroxide is added to keep the pH value of the mixed solution in the range of 10-11.

[0057] d. After the reaction is completed, 100 mL of deionized water is first added for dilution, and then 1 mol / L dilute hydrochloric acid is added dropwise. The pH value of the mixed solution is adjusted to 4, and stirring is performed at room temperature for 15 min. White powder is obtained by filtration, which is placed in an oven and dried at 70°C for 12 hours to obtain white crude product.

[0058] (3) Purification of crude product

[0059] The white crude product obtained in step (2) was ground in a mortar and then poured into a 1000 mL beaker, 200 mL of acetone was added to dissolve for 30 min, and then 800 mL of petroleum ether was slowly added to make the product in the solution settle down. After suction filtration and drying, white powder 27.21 g was obtained, with a yield of 70.8%.

[0060] Example 3

[0061] (1) Preparation of raw materials

[0062] 29.73 g of syringic acid, 12 g of sodium hydroxide, 7.2 g of sodium hydroxide, and 17.01 g of chloroacetic acid were weighed with an electronic balance.

[0063] (2) Preparation of crude product by reaction

[0064] a. The 29.73 g of syringic acid weighed was poured into a clean 500 mL three-necked flask, 100 mL of deionized water was added, 12 g of sodium hydroxide was slowly added, and the mixture was shaken to obtain a uniform solution.

[0065] b. In a clean 200 mL beaker, 100 mL of deionized water was added, and 17.01 g of chloroacetic acid weighed was added to the deionized water, 7.2 g of sodium hydroxide was slowly added, and the solution was transferred to the three-necked flask after the solid in the beaker was completely dissolved.

[0066] c. Water bath heating was carried out at 50°C for 12 hours, and the pH value of the mixed solution in the three-necked flask was tested constantly during the reaction, and sodium hydroxide was added to keep the pH value of the mixed solution in the range of 10-11.

[0067] d. After the reaction was completed, 100 mL of deionized water was added for dilution, and then 1 mol / L dilute hydrochloric acid was added dropwise, the pH value of the mixed solution was adjusted to 3-4, and the mixture was stirred at room temperature for 15 min. After suction filtration, white powder was obtained, which was placed in an oven and dried at 70°C for 12 hours to obtain white crude product.

[0068] (3) Purification of crude product

[0069] The white crude product obtained in step (2) was ground in a mortar and then poured into a 1000 mL beaker, 200 mL of acetone was added to dissolve for 30 min, and then 800 mL of petroleum ether was slowly added to make the product in the solution settle down. After suction filtration and drying, white powder 27.21 g was obtained, with a yield of 70.8%.

[0070] Example 4

[0071] (1) Preparation of raw materials

[0072] Take 29.73 g of syringic acid, one portion of 12 g of sodium hydroxide, one portion of 9 g of sodium hydroxide, and 21.26 g of chloroacetic acid with an electronic balance, respectively.

[0073] (2) Reaction to prepare crude product

[0074] a. Pour the 29.73 g of syringic acid weighed into a clean 500 mL three-necked flask, add 100 mL of deionized water, then slowly add 12 g of sodium hydroxide, mix and shake to obtain a uniform solution.

[0075] b. Add 100 mL of deionized water to a clean 200 mL beaker, add 21.26 g of chloroacetic acid weighed into the deionized water, slowly add 9 g of sodium hydroxide, and when the solid in the beaker is completely dissolved, transfer the solution to the three-necked flask.

[0076] c. Water bath heating at 95°C for 6 hours, constantly test the pH value of the mixed solution in the three-necked flask during the reaction, and supplement sodium hydroxide to keep the pH of the mixed solution in the range of 10-11.

[0077] d. After the reaction is completed, first dilute with 100 mL of deionized water, then add 1 mol / L of dilute hydrochloric acid drop by drop, adjust the pH of the mixed solution to 3, stir at room temperature for 15 min, and filter to obtain a white powder, which is placed in an oven and dried at 70°C for 12 hours to obtain a white crude product.

[0078] (3) Purification of crude product

[0079] After the white crude product obtained in step (2) is finely ground in a mortar, it is poured into a 1000 mL beaker, 200 mL of acetone is added to dissolve for 30 min, then 600 mL of petroleum ether is slowly added to make the product in the solution settle down, and the white powder 26.33 g is obtained by filtering and drying, with a yield of 68.5%.

[0080] Example 5

[0081] (1) Raw material preparation

[0082] Take 29.73 g of syringic acid, one portion of 12 g of sodium hydroxide, one portion of 7.2 g of sodium hydroxide, and 17.01 g of chloroacetic acid with an electronic balance, respectively.

[0083] (2) Reaction to prepare crude product

[0084] a. Pour the 29.73 g of syringic acid weighed into a clean 500 mL three-necked flask, add 100 mL of deionized water, then slowly add 12 g of sodium hydroxide, mix and shake to obtain a uniform solution.

[0085] b. In a clean 200 mL beaker, add 100 mL of deionized water, add 17.01 g of weighed ehtylchloroacetic acid into the deionized water, slowly add 7.2 g of sodium hydroxide, and wait until the solid is completely dissolved in the beaker, then transfer the solution to a three-necked flask.

[0086] c. Water bath heating at 95°C for 6 hours, constantly test the pH value of the mixed solution in the three-necked flask during the reaction, and supplement sodium hydroxide to keep the pH value of the mixed solution in the range of 10-11.

[0087] d. After the reaction is completed, first dilute with 100 mL of deionized water, then add 1 mol / L dilute hydrochloric acid dropwise, adjust the pH value of the mixed solution to 4, stir at room temperature for 15 min, and filter to obtain a white powder, which is placed in an oven and dried at 70°C for 12 hours to obtain a white crude product.

[0088] (3) Purification of crude product

[0089] The white crude product obtained in step (2) is finely ground in a mortar and then poured into a 1000 mL beaker, 200 mL of acetone is added to dissolve for 30 min, then 600 mL of petroleum ether is slowly added to make the product in the solution settle down, and then filtered and dried to obtain a white powder 28 g, with a yield of 72.85%.

[0090] Example 6

[0091] (1) Raw material preparation

[0092] Weigh 29.73 g of eugenol, 12 g of sodium hydroxide, 7.2 g of sodium hydroxide, and 17.01 g of ethylchloroacetic acid with an electronic balance.

[0093] (2) Reaction to prepare crude product

[0094] a. Pour 29.73 g of weighed eugenol into a clean 500 mL three-necked flask, add 100 mL of deionized water, slowly add 12 g of sodium hydroxide, mix well, and obtain a uniform solution.

[0095] b. In a clean 200 mL beaker, add 100 mL of deionized water, add 17.01 g of weighed ehtylchloroacetic acid into the deionized water, slowly add 7.2 g of sodium hydroxide, and wait until the solid is completely dissolved in the beaker, then transfer the solution to a three-necked flask.

[0096] c. Water bath heating at 80°C for 8 hours, constantly test the pH value of the mixed solution in the three-necked flask during the reaction, and supplement sodium hydroxide to keep the pH value of the mixed solution in the range of 10-11.

[0097] d. After the reaction, 100 mL of deionized water was added to dilute the solution, and then 1 mol / L dilute hydrochloric acid was added dropwise to adjust the pH of the mixed solution to 3. The solution was stirred at room temperature for 15 min, and then filtered to obtain a white powder. The powder was dried in an oven at 70°C for 12 h to obtain a white crude product.

[0098] (3) Purification of the crude product

[0099] The white crude product obtained in step (2) was ground in a mortar and then poured into a 1000 mL beaker. 200 mL of acetone was added to dissolve the product for 30 min, and then 600 mL of petroleum ether was slowly added to precipitate the product. The product was filtered and dried to obtain 27.6 g of a white powder, with a yield of 71.81%.

[0100] The above examples are merely illustrative of the principles of the application and their efficacy, and are not intended to limit the application. Any modification or change made by those skilled in the art without departing from the spirit and scope of the application should be covered by the claims of the application.

Claims

1. A method of synthesis of a bio-based polyamide, characterized in that The application relates to a method for synthesizing bio-based polyamide, comprising the following steps: S1. reacting chloroacetic acid with syringic acid in an alkaline solution with a pH value of 10-11 and heating and refluxing at 50-100 DEG C, and then acidifying the obtained product to obtain a crude product; the molar ratio of syringic acid to chloroacetic acid is 1:1.2-2; S2. dissolving the crude product in an organic solvent, settling and then drying to obtain a syringic acid-based aromatic dibasic acid with the following structural formula: S3. synthesizing bio-based polyamide by using the syringic acid-based aromatic dibasic acid; The syringic acid-based aromatic dibasic acid is reacted with a dibasic amine to prepare a syringic acid-based polyamide by adopting a solution polymerization mode, N-methyl pyrrolidone is used as a solvent system, the molar ratio of the syringic acid-based aromatic dibasic acid to the dibasic amine is 1:1, the concentration of the syringic acid-based aromatic dibasic acid and the dibasic amine is 0.4 mol / L respectively, 4% mass fraction of anhydrous lithium chloride is used as a cosolvent, and 25% pyridine with a volume fraction of N-methyl pyrrolidone and 0.8 mol / L of triphenyl phosphite are used as condensation aids; The reaction condition is that the reaction is carried out at 130 DEG C for 4 hours.

2. The method of synthesis of claim 1, wherein: The solute of the alkaline solution comprises sodium hydroxide.

3. The method of synthesis of claim 1, wherein, S1 comprises: During the reaction, alkaline substances are continuously or intermittently added to the reaction system so that the pH value of the reaction system is kept at 10-11.

4. The method of synthesis of claim 1, wherein, S1 further comprises: after the reaction, the obtained reaction mixture is acidified to a pH value of 3-4 by using acidic substances.

5. The method of synthesis of claim 1, wherein, The organic solvent in S2 comprises acetone and petroleum ether, and the post-treatment specifically comprises the following steps: firstly, the crude product is dissolved in acetone, petroleum ether is added into the obtained solution to carry out the settling treatment, the volume of the petroleum ether is 3-4 times that of the acetone, then the solid in the obtained solid-liquid mixed system is separated, and the drying treatment is carried out on the solid.

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