Heterocyclic tetraacids, methods for their preparation and use

Abstract

The application provides a heterocyclic quaternary acid and a preparation method and application thereof. The heterocyclic quaternary acid has a structure shown in formula I, wherein Y is selected from a substituted or unsubstituted heterocyclic group, R1 and R2 are independently selected from a linear or branched alkyl group with 1-6 carbon atoms or a substituted or unsubstituted aromatic ring. 10 The heterocyclic quaternary acid has the advantages of good biological compatibility and low toxicity due to the presence of an amide bond, and is suitable for synthesizing a low-toxicity plasticizer.

Description

Technical Field

[0001] This invention belongs to the field of organic chemistry technology, specifically relating to a heterocyclic tetracarboxylic acid, its preparation method, and its application. Background Technology

[0002] Plasticizers are substances added during the processing of high molecular polymers such as plastics and coatings to increase their plasticity and flexibility. They are essential additives in the plastics industry.

[0003] Currently, plasticizers mainly include phthalates and phospholipids, with phthalates accounting for 80% of all plasticizers. However, studies have shown that contact with phthalates can cause endocrine disorders and has potential carcinogenicity in humans. A series of standards have been introduced both domestically and internationally to restrict harmful phthalates. Therefore, developing new, low-toxicity, and environmentally friendly plasticizers is one of the urgent problems to be solved. Summary of the Invention

[0004] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions:

[0005] One objective of this invention is to provide a heterocyclic tetracarboxylic acid containing an amide bond, which has good biocompatibility, low toxicity, and can be used to synthesize environmentally friendly plasticizers.

[0006] The heterocyclic tetracarboxylic acid has the structure shown in Formula I.

[0007]

[0008] Wherein, Y is selected from substituted or unsubstituted heterocyclic groups, and R1 and R2 are independently selected from substituted or unsubstituted C1 to C2 groups. 10 Straight-chain or branched alkyl or substituted or unsubstituted aromatic rings.

[0009] In some embodiments, Y is selected from nitrogen heterocycles, oxygen heterocycles, or sulfur heterocycles.

[0010] In some embodiments, Y is selected from furan group, tetrahydrofuran group, pyrrole group, pyridine group, piperidine group, thiophene group, pyrimidine group, imidazole group or pyrazine group.

[0011] In some more preferred embodiments, Y is selected from 2,5-furan group, 2,5-tetrahydrofuran group, 2,5-thiophene group, or 2,5-pyrrole group. The 2,5-furan group and 2,5-tetrahydrofuran group are bio-based and have the characteristics of being green, environmentally friendly, low-toxicity, and pollution-free.

[0012] In some embodiments, R1 and R2 are independently selected from C1-C6 straight-chain or branched alkyl groups or benzene rings. Further, R1 and R2 are independently selected from ethyl, propyl, isopropyl, sec-butyl, or phenyl groups. These groups can be bio-based and possess the characteristics of being green, environmentally friendly, low-toxicity, and pollution-free.

[0013] A second objective of this invention is to provide a method for preparing a heterocyclic tetracarboxylic acid, the method comprising: subjecting a heterocyclic compound and compound A to an amidation reaction, wherein compound A contains two carboxyl groups and at least one amino group, the heterocyclic group of the heterocyclic compound has at least two substituted chains, each substituted chain having at least one active group, and one of the active groups undergoing the amidation reaction with the amino group in compound A to obtain a hybrid tetracarboxylic acid.

[0014] In some embodiments, compound A has the structure shown in Formula II:

[0015]

[0016] Wherein, R is selected from substituted or unsubstituted C1 to C1. 10 Branched or straight-chain alkyl or substituted or unsubstituted aromatic rings.

[0017] In some preferred embodiments, R is selected from C1 to C6 straight-chain or branched alkyl groups or benzene rings.

[0018] In some more preferred embodiments, compound A includes at least one selected from 2-aminoterephthalic acid, 5-aminoisophthalic acid, 3-aminophthalic acid, aminoglutaric acid, aminosuccinic acid, 2-amino-3-methylsuccinic acid, 2-amino-3-butylsuccinic acid, and 2-aminohexanoic acid. Compound A may be of type D, type L, or a mixture of types D and L.

[0019] In some embodiments, the heterocyclic compound has the structure shown in Formula III.

[0020] R4-Y-R3

[0021] III

[0022] Where Y is a substituted or unsubstituted heterocyclic group, and R3 and R4 are acyl chloride groups.

[0023] In some preferred embodiments, Y is selected from furan group, tetrahydrofuran group, pyrrole group, pyridine group, piperidine group, thiophene group, pyrimidine group, imidazole group or pyrazine group.

[0024] In some preferred embodiments, the heterocyclic compound includes at least one selected from 2,5-thiophene dicarboxylate chloride, 2,5-pyrrole dicarboxylate chloride, 2,5-furan dicarboxylate chloride, 2,5-tetrahydrofuran dicarboxylate chloride, and 4,6-pyrimidine dicarboxylate chloride.

[0025] In some embodiments, the preparation method specifically includes: dispersing the heterocyclic compound and compound A in a solvent to form a mixed reaction solution for carrying out the amidation reaction. Further, dispersing the heterocyclic compound of formula III and compound A of formula II in a solvent to form a mixed reaction solution for carrying out the amidation reaction.

[0026] The solvent includes, but is not limited to, one or more combinations of non-aqueous solvents such as water or organic solvents. For example, the organic solvent may be selected from monoalcohols (ethanol), ketones (acetone), halogenated hydrocarbons (dichloromethane), nitrogen compounds, and sulfur compounds (DMF, DMSO), etc. Preferably, the solvent includes at least one of water, dichloroethane, chloroform, acetone, ethanol, dichloromethane, N,N-dimethylformamide, and dimethyl sulfoxide.

[0027] In some embodiments, the amidation reaction can be carried out in the presence of an auxiliary agent, etc. Exemplarily, the auxiliary agent may include a catalyst, etc. The catalyst includes, but is not limited to, triethylamine, pyridine, sodium carbonate, sodium hydroxide, etc.

[0028] In some embodiments, the molar ratio of the heterocyclic compound to compound A in the amidation reaction is 1:2 to 1:10. Preferably, the molar ratio of the heterocyclic compound to compound A is 1:2 to 1:4.

[0029] In some embodiments, the reaction temperature of the amidation reaction is 0–30°C.

[0030] In some embodiments, the reaction time for the amidation reaction is 60 to 600 min.

[0031] In some embodiments, the pH of the amidation reaction is 7 to 8.5.

[0032] In this invention, the entire synthesis reaction of the heterocyclic tetracarboxylic acid can be carried out in a single reaction vessel, i.e., synthesized by a one-pot reaction.

[0033] In this invention, after the amidation reaction is completed, the target product, namely the heterocyclic tetracarboxylic acid, can be separated by post-treatment of the reaction mixture. The post-treatment includes acidification, filtration, and washing with water to obtain the heterocyclic tetracarboxylic acid.

[0034] The third objective of this invention is to provide heterocyclic tetracarboxylic acids prepared by the above-mentioned preparation method.

[0035] A fourth objective of the present invention is to provide derivatives of any of the heterocyclic tetracarboxylic acids described above, wherein the derivatives include at least one of salts, esters, amides, and acyl halides.

[0036] The fifth objective of this invention is to provide the application of the above-mentioned heterocyclic tetracarboxylic acids in the preparation of environmentally friendly plasticizers.

[0037] The sixth objective of this invention is to provide a method for preparing a plasticizer, comprising mixing a heterocyclic tetracarboxylic acid as described above with a C2-C8 fatty alcohol, and then esterifying it at 120°C-180°C to obtain the plasticizer. Specifically, the plasticizer is obtained by esterification at 120°C-180°C followed by distillation to remove excess fatty alcohol.

[0038] A seventh object of the present invention is to provide a plasticizer obtained according to the above preparation method. Preferably, the plasticizer has a precipitation rate of less than 0.1%.

[0039] Compared with the prior art, the present invention has at least the following technical effects:

[0040] 1) A novel heterocyclic tetracarboxylic acid has been developed. The heterocyclic tetracarboxylic acid is of bio-based origin and has the advantages of being environmentally friendly and non-toxic. It can be used to prepare environmentally friendly plasticizers.

[0041] 2) The plasticizer synthesized using the heterocyclic tetracarboxylic acid in this invention has good biocompatibility due to the presence of amide bonds in its molecule. Furthermore, the substances produced after degradation are of bio-based origin and are non-toxic. It is a new type of green, environmentally friendly, and non-toxic plasticizer.

[0042] 3) The plasticizer synthesized using the heterocyclic tetracarboxylic acid provided by this invention has a large molecular weight, high viscosity, low volatility, good compatibility with other materials, and high thermal stability, thus it has great application prospects. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is the 1H NMR spectrum of the heterocyclic tetracarboxylic acid prepared in Example 3 of this invention. Detailed Implementation

[0045] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0046] Example 1:

[0047] Dissolve 10g of 2,5-thiophene dicarboxylic acid in 50g of dichloroethane and stir to obtain a 2,5-thiophene dicarboxylic acid solution; weigh 23g of 3-aminophthalic acid and dissolve it in 50g of water, and adjust the pH to 8.0 with sodium carbonate to obtain an aqueous solution of 3-aminophthalic acid.

[0048] A solution of 2,5-thiophene dicarboxylic acid chloride was slowly added dropwise to an aqueous solution of 3-aminophthalic acid. During the reaction, the pH was controlled between 7.5 and 8.0, and the temperature was controlled at 10±5℃. After the addition was completed, the mixture was stirred for 4 hours to stop the reaction and obtain a heterocyclic tetracarboxylic acid.

[0049] Take the upper aqueous solution, neutralize it with hydrochloric acid to pH 1-2, filter and wash with water to obtain the product, with a yield of 76%.

[0050] product 1 The 1H NMR data are δ 13.27 (s, 2H), 12.73 (s, 2H), 10.25 (s, 2H), 8.45 (s, 2H), 8.13 (m, 4H), and 7.91 (t, 2H).

[0051] The structural formula of the heterocyclic tetracarboxylic acid obtained in this embodiment is as follows:

[0052]

[0053] Example 2:

[0054] Dissolve 15g of 2,5-pyrroledicarboxylic acid in 70g of chloroform and stir to obtain a 2,5-pyrroledicarboxylic acid solution; weigh 31g of aminosuccinic acid and dissolve it in 200g of water, and adjust the pH to 8.5 with sodium carbonate to obtain an aqueous solution of aminosuccinic acid.

[0055] The 2,5-pyrrole dicarboxylic acid solution was slowly added dropwise to the aminosuccinic acid aqueous solution. During the reaction, the pH was controlled between 8.0 and 8.5, and the temperature was controlled at 20±5℃. After the addition was completed, the mixture was stirred for 6 hours to end the reaction.

[0056] The reaction solution was neutralized to pH 1-2, filtered, washed with water, and dried to obtain a heterocyclic tetracarboxylic acid with a yield of 73%.

[0057] The heterocyclic tetracarboxylic acid obtained in this embodiment 1 The 1H NMR data are δ 12.85 (s, 1H), 12.57 (s, 4H), 9.36 (s, 2H), 7.72 (s, 2H), 4.76 (t, 2H), and 2.90 (m, 4H).

[0058] The heterocyclic tetracarboxylic acid structure of this embodiment is as follows:

[0059]

[0060] Example 3:

[0061] Dissolve 15g of 2,5-furandicarboxylic acid chloride in 60g of acetone to prepare a 2,5-furandicarboxylic acid chloride solution; dissolve 40g of aminoglutaric acid in 100g of N,N-dimethylformamide (DMF) and add 20g of piperidine to prepare an aminoglutaric acid solution.

[0062] A solution of 2,5-furandicarboxylic acid was slowly added dropwise to a solution of aminoglutaric acid, with the temperature controlled at 30±5℃. After the addition was completed, the reaction was continued for 5 hours to obtain a heterocyclic tetracarboxylic acid.

[0063] After the reaction was completed, the pH was adjusted to about 1.5 by neutralization with hydrochloric acid, and the mixture was filtered and washed with water to obtain a heterocyclic tetracarboxylic acid with a yield of 57%.

[0064] product 1 The 1H NMR data are δ 12.66 (s, 2H), 12.01 (s, 2H), 8.18 (s, 2H), 7.64 (s, 2H), 4.55 (t, 2H), 2.30 (t, 4H), and 2.03 (m, 4H).

[0065] The structural formula of the heterocyclic tetracarboxylic acid obtained in this embodiment is as follows:

[0066]

[0067] Example 4:

[0068] Dissolve 30g of 2-amino-3-methylsuccinic acid in water, and adjust the pH to between 8.0 and 8.5 using sodium hydroxide to obtain an aqueous solution of 2-amino-3-methylsuccinic acid and butyric acid.

[0069] 10 g of solid 2,5-tetrahydrofurandicarboxylic acid was slowly added to an aqueous solution of 2-amino-3-methylsuccinic acid. The temperature was controlled at 5±5℃ and the pH was controlled between 8.0 and 8.5. After the addition was complete, the reaction was continued for 10 h. The reaction solution was neutralized to pH 1 to 2, filtered, washed with water, and dried to obtain a heterocyclic tetracarboxylic acid with a yield of 53%.

[0070] The heterocyclic tetracarboxylic acid obtained in this embodiment 1 The 1H NMR data are δ 13.89 (s, 2H), 12.13 (s, 2H), 8.32 (s, 2H), 4.69 (d, 2H), 3.41 (m, 2H), 2.21 (m, 4H), and 1.12 (d, 6H).

[0071] The heterocyclic tetracarboxylic acid structure of this embodiment is as follows:

[0072]

[0073] Example 5:

[0074] Dissolve 30g of 2-amino-3-methylglutaric acid in water, and adjust the pH to between 8.0 and 8.5 using sodium hydroxide to obtain an aqueous solution of 2-amino-3-methylglutaric acid;

[0075] 10 g of 4,6-pyrimidine dicarboxylic acid solid was slowly added to an aqueous solution of 2-amino-3-methylglutaric acid. The temperature was controlled at 5±5℃ and the pH was controlled between 8.0 and 8.5. After the addition was complete, the reaction was continued for 10 h. The reaction solution was neutralized to pH 1 to 2, filtered, washed with water, and dried to obtain a heterocyclic tetracarboxylic acid with a yield of 53%.

[0076] The heterocyclic tetracarboxylic acid obtained in this embodiment 1 The 1H NMR data are δ 12.38 (s, 2H), 11.78 (s, 2H), 9.89 (s, 1H), 9.46 (s, 1H), 9.38 (s, 2H), 4.25 (d, 2H), 2.86 (m, 2H), 2.18 (m, 4H), and 0.98 (d, 6H).

[0077] The heterocyclic tetracarboxylic acid structure of this embodiment is as follows:

[0078]

[0079] Example 6:

[0080] The heterocyclic tetracarboxylic acid prepared in Example 3 and 2-ethylhexanol were added to a reactor, sulfuric acid was added as a catalyst, and after nitrogen protection, the mixture was heated to 180°C and refluxed for 3 hours. Then, the temperature was raised to 190°C, and unreacted 2-ethylhexanol was removed by distillation to obtain an environmentally friendly plasticizer.

[0081] The above-prepared 58 parts of environmentally friendly plasticizer, 100 parts of PVC, and 1 part of calcium-zinc stabilizer were mixed to prepare a modified PVC sample, and its tensile strength was measured to be 210 kg / cm². 2The plasticizer was found to have a 0.1% leaching rate in the sample, as measured by the ASTM D3291 leaching test.

[0082] Comparative Example 1:

[0083] The plasticizer obtained in Example 6 was replaced with tetraoctyl pyromellitic acid, and a PVC sample was prepared using the same method as in Example 6. Its tensile strength was measured to be 200 kg / cm². 2 The precipitation rate of the plasticizer in the sample was measured to be 0.2% using the ASTM D3291 precipitation test. This demonstrates that the tetracarboxylic acid described in this invention can be used to prepare plasticizers, and its performance is comparable to existing plasticizers. However, due to its bio-based origin, it has the advantage of lower toxicity, and the presence of amide bonds increases intermolecular forces, thereby reducing the precipitation rate of the plasticizer and further reducing toxicity.

[0084] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0085] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0086] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A heterocyclic tetracarboxylic acid, characterized in that: The heterocyclic tetracarboxylic acid has the structure shown in Formula I. ； Wherein, Y is selected from 2,5-furan groups, and R1 and R2 are independently selected from ethyl, propyl, isopropyl, sec-butyl, or phenyl.

2. The method for preparing the heterocyclic tetracarboxylic acid according to claim 1, characterized in that, include: Amidation reaction of heterocyclic compound and compound A yields heterocyclic tetracarboxylic acid; Wherein, the heterocyclic compound is 2,5-furandicarboxylic acid chloride; and compound A is at least one of 2-aminoterephthalic acid, 5-aminoisophthalic acid, 3-aminophthalic acid, aminoglutaric acid, aminosuccinic acid, and 2-amino-3-methylsuccinic acid.

3. The method for preparing heterocyclic tetracarboxylic acids according to claim 2, characterized in that, Specifically, it includes: The heterocyclic compound and compound A are dispersed in a solvent to form a mixed reaction solution for carrying out the amidation reaction; the solvent is selected from at least one of water, dichloroethane, chloroform, acetone, ethanol, dichloromethane, N,N-dimethylformamide and dimethyl sulfoxide.

4. The method for preparing heterocyclic tetracarboxylic acids according to claim 2, characterized in that: In the amidation reaction, the molar ratio of the heterocyclic compound to compound A is 1:2 to 1:

10.

5. The method for preparing heterocyclic tetracarboxylic acids according to claim 4, characterized in that: In the amidation reaction, the molar ratio of the heterocyclic compound to compound A is 1:2 to 1:

4.

6. The method for preparing heterocyclic tetracarboxylic acids according to claim 2, characterized in that: The reaction temperature for the amidation reaction is 0~30℃.

7. The method for preparing heterocyclic tetracarboxylic acids according to claim 2, characterized in that: The reaction time for the amidation reaction is 60-600 min.

8. The method for preparing heterocyclic tetracarboxylic acids according to claim 2, characterized in that: The pH of the amidation reaction is 7 to 8.

5.

9. The application of the heterocyclic tetracarboxylic acid according to claim 1 in the preparation of plasticizers.

10. A method for preparing a plasticizer, characterized in that, The heterocyclic tetracarboxylic acid of claim 1 is mixed with a C2-C8 fatty alcohol and then esterified at 120°C-180°C to obtain a plasticizer.

11. The preparation method according to claim 10, characterized in that: The plasticizer has a release rate of less than 0.1%.

Images