A 2,5-dibutyladipic acid, its preparation method and application

Abstract

This invention relates to the field of electrolyte preparation technology, providing 2,5-dibutyladipic acid, its preparation method, and its applications. The 2,5-dibutyladipic acid prepared by this invention achieves a conductivity as high as 1475 µS / cm in ethylene glycol with only 4.3% by mass, solving the problem of increased equivalent series resistance in capacitors caused by low conductivity in traditional electrolytes. Compared to adipic acid, its polarity is enhanced, and its solubility in ethylene glycol is correspondingly improved. Furthermore, due to the electron-donating effect of the α-branch, 2,5-dibutyladipic acid, when used as an electrolyte, can enhance the chemical self-healing ability of the branched carboxylate + ethylene glycol electrolyte system, which is of great significance for improving the performance of aluminum electrolytic capacitors. These characteristics provide broad prospects for manufacturing capacitors with high voltage resistance, low effective resistance, high ripple current tolerance, high heat resistance, and long lifespan using ethylene glycol systems containing branched dicarboxylate.

Description

Technical Field

[0001] This invention belongs to the field of electrolyte preparation technology, and particularly relates to a 2,5-dibutyladipic acid, its preparation method and application. Background Technology

[0002] Branched carboxylic acids are the core electrolyte in aluminum electrolytic capacitor electrolytes and a key factor affecting the conductivity of the electrolyte, thus influencing the performance of the aluminum electrolytic capacitor. The development of aluminum electrolytic capacitor electrolytes has gone through four stages: Stage 1: Boric acid + ethylene glycol system. Stage 2: Straight-chain carboxylate + boric acid + ethylene glycol system. Stage 3: Straight-chain carboxylate + ethylene glycol system. Aluminum electrolytic capacitors in this stage showed significant improvement in leakage current compared to the Stage 2 electrolytes. Although the flash point of the carboxylate increased due to its larger molecular weight, its solubility decreased. Stage 4: Branched-chain carboxylate + ethylene glycol system. Branched-chain carboxylates replace or partially replace straight-chain carboxylates. Branched-chain carboxylates have high solubility, superior thermal stability, and chemical self-healing capabilities. This system has become the best working electrolyte for aluminum capacitors, but its cost is generally higher. Using ethylene glycol systems containing branched dicarboxylic acids, capacitors with high voltage resistance, low effective resistance, high ripple current tolerance, high heat resistance, and long lifespan can be manufactured.

[0003] The superior properties of branched carboxylates are closely related to the branching in their structure. The hydrogen atom on the α-carbon of a carboxylic acid is reactive, allowing for alkylation reactions to attach an alkyl group. Because alkyl groups have an electron-donating effect, carboxylic acids with α-alkyl branches exhibit better solubility and thermal stability. Compared to α-branched monocarboxylic acids, dicarboxylic acids with two branches in their structure perform even better.

[0004] Therefore, in-depth research on branched dicarboxylic acids, exploration of new methods for synthesizing branched dicarboxylic acids, and the development of independent research and development capabilities are of great significance for meeting market demands. To this end, this invention proposes a 2,5-dibutyladipic acid, its preparation method, and its applications. Summary of the Invention

[0005] The purpose of this invention is to provide 2,5-dibutyladipic acid, its preparation method, and its application, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A 2,5-dibutyladipic acid, the structural formula of which is as follows:

[0008] .

[0009] A method for preparing 2,5-dibutyladipic acid as described above includes the following steps:

[0010] Step 1: Synthesis of dibutyl 2,5-dibutyladipate: Adipic acid and n-butane bromo were dissolved in THF, the solution was stirred at 0~30℃, an organic strong base equivalent to that of adipic acid was added, and the reaction was carried out for 6 hours. After the reaction was completed, the mixture was centrifuged at room temperature to obtain dibutyl 2,5-dibutyladipate.

[0011] Step 2: Preparation of 2,5-dibutyladipic acid: The 2,5-dibutyladipic acid dibutyl obtained in Step 1 was dissolved in ethanol. Sodium hydroxide was added at reflux temperature of 76°C to carry out a saponification reaction for 8 hours. After the saponification reaction was completed, nitric acid was added for acidification. After acidification for 4 hours, the product was centrifuged at room temperature to obtain a solid product. The solid product was washed with ethanol and dried to obtain 3.77 g of 2,5-dibutyladipic acid.

[0012] Furthermore, the specific process of step one is as follows: 2g of adipic acid and 7.5g of bromobutane are dissolved in THF, the solution is stirred at 500rpm / min at a temperature of 0~30℃, an organic strong base equivalent to that of adipic acid is added, the reaction is carried out for 6h, and after the reaction is completed, the mixture is centrifuged at room temperature to obtain dibutyl 2,5-dibutyladipate.

[0013] Further, the specific process of step two is as follows: the 2,5-dibutyladipic acid dibutyl obtained in step one is dissolved in 100 ml of ethanol, and 0.8 g of sodium hydroxide is added at a reflux temperature of 76 °C to carry out a saponification reaction for 8 h. After the saponification reaction is completed, 0.9 ml of 65% nitric acid is added for acidification. After acidification for 4 h, centrifugation is carried out at room temperature to obtain a solid product. The solid product is washed three times with ethanol and dried to obtain 3.77 g of 2,5-dibutyladipic acid.

[0014] Furthermore, the organic strong base is t-BuOK, tert-butyllithium, s-isobutyllithium, or diisopropylaminolithium.

[0015] An application of 2,5-dibutyladipic acid as described above involves mixing 2,5-dibutyladipic acid with a solvent and dissolving it completely to prepare an electrolyte for aluminum electrolytic capacitors.

[0016] Furthermore, the solvent is ethylene glycol.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The 2,5-dibutyladipic acid prepared in this invention achieves a conductivity as high as 1475 µS / cm with only 4.3% mass content in ethylene glycol. This significantly improved conductivity effectively solves the problem of increased equivalent series resistance in capacitors caused by the low conductivity of traditional electrolytes. Simultaneously, compared to adipic acid, 2,5-dibutyladipic acid exhibits enhanced polarity, resulting in increased solubility in ethylene glycol. Furthermore, due to the electron-donating effect of the α-branch, 2,5-dibutyladipic acid, when used as an electrolyte, can enhance the chemical self-healing ability of the branched carboxylate + ethylene glycol electrolyte system, which is of great significance for improving the performance of aluminum electrolytic capacitors. These characteristics provide broad prospects for manufacturing capacitors with high voltage withstand capability, low effective resistance, high ripple current tolerance, high heat resistance, and long lifespan using ethylene glycol systems containing branched dicarboxylate. Attached Figure Description

[0019] Figure 1 The flowchart shows the preparation process of 2,5-dibutyladipic acid.

[0020] Figure 2 The infrared spectrum of adipic acid.

[0021] Figure 3 The infrared spectrum of 2,5-dibutyladipic acid.

[0022] Figure 4 The conductivity test results are for a solution of 2,5-dibutyladipic acid and ethylene glycol.

[0023] Figure 5 The results are the conductivity test results for an adipic acid + ethylene glycol solution.

[0024] Figure 6 The image shows the appearance of 2,5-dibutyladipic acid.

[0025] Figure 7 This is an image of the appearance of adipic acid.

[0026] Figure 8 The experiment is for water solubility. The left figure shows 2g adipic acid / 50ml deionized water, and the right figure shows 2g 2,5-dibutyladipic acid / 50ml deionized water. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] An embodiment of the present invention provides a 2,5-dibutyladipic acid, the structural formula of which is as follows:

[0029] .

[0030] The preparation method of the 2,5-dibutyladipic acid includes the following steps (such as...) Figure 1 (as shown)

[0031] Step 1: Synthesis of dibutyl 2,5-dibutyladipate: Dissolve 2g of adipic acid and 7.5g of bromobutane in THF (tetrahydrofuran). Stir the solution at 500rpm / min at 0~30℃. Add an organic strong base equivalent to that of adipic acid (t-BuOK, tert-butyllithium, s-isobutyllithium, or diisopropylaminolithium can be selected). React for 6h. After the reaction is completed, centrifuge at room temperature to obtain dibutyl 2,5-dibutyladipate.

[0032] Step 2: Preparation of 2,5-dibutyladipic acid: The 2,5-dibutyladipic acid dibutyl obtained in Step 1 was dissolved in 100 ml of ethanol. At a reflux temperature of 76 °C, 0.8 g of sodium hydroxide was added to carry out a saponification reaction for 8 h. After the saponification reaction was completed, 0.9 ml of 65% nitric acid was added for acidification. After acidification for 4 h, the product was centrifuged at room temperature to obtain a solid product. The solid product was washed three times with ethanol and dried to obtain 3.77 g of 2,5-dibutyladipic acid.

[0033] Figure 2 The infrared spectrum of adipic acid is shown. As can be seen from the image, the OH bonds in the carboxylic acid are located between 2500 and 3000 cm⁻¹. -1 The display shows a very wide band, 2900~3000cm. -1 It is the absorption peak of saturated CH in the adipic acid molecule, 1700 cm⁻¹ -1 It is the absorption peak of C=O, 1400 cm⁻¹ -1 and 920cm -1 It is the absorption peak of the OH bending vibration. Figure 3 The infrared spectrum of 2,5-dibutyladipic acid is shown. As can be seen from the figure, the concentration of 2,5-dibutyladipic acid in the 3000–3500 cm⁻¹ range is... -1 The absorption peak is the OH absorption peak of 2,5-dibutyladipic acid, at 2900 cm⁻¹. -1 up to 3000cm -1 The shoulder peaks between the two peaks are enhanced and parallel peaks appear, which are the CH absorption peaks of the molecular backbone and the butyl group on the α carbon. The C=O absorption peak is at 1550~1560 cm⁻¹. -1 Between. By Figure 2 and Figure 3 The comparison shows that, due to the influence of the branched butyl group, 2,5-dibutyl adipic acid has a lower concentration at 2900~3000 cm⁻¹. -1 The change in peak shape and the increase in absorption intensity between the two peaks indicate an increase in CH2 in the molecular structure. Figure 3In the middle, the C=O absorption peak of 2,5-dibutyladipic acid is at 1550~1560 cm⁻¹. -1 Between, below 1700cm -1 The reason may be that the electron-donating effect of the butyl group on the α-carbon causes the absorption peak of C=O to shift to a lower wavelength.

[0034] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0035] In Example 1, the conductivity of the 2,5-dibutyladipic acid + ethylene glycol solution system was significantly improved;

[0036] Using ethylene glycol as a solvent, 2,5-dibutyladipic acid and adipic acid prepared according to the above method were dissolved in ethylene glycol to form two ethylene glycol solution systems. The specific operation is as follows:

[0037] Take 10 ml of ethylene glycol, add 0.5 g of 2,5-dibutyladipic acid and dissolve it completely to prepare a 4.3% (w / w) 2,5-dibutyladipic acid + ethylene glycol solution.

[0038] Take another 10 ml of ethylene glycol, add 0.5 g of adipic acid and dissolve it completely to prepare a 4.3% (w / w) adipic acid + ethylene glycol solution.

[0039] Subsequently, the conductivity of the two solutions was measured using an ECscan30 conductivity meter at a test temperature of 40±5℃. Figure 4 The conductivity of a 2,5-dibutyladipic acid + ethylene glycol solution was demonstrated, with a value as high as 1475 µS / cm. In comparison, Figure 5 The conductivity of the adipic acid + ethylene glycol solution shown is only 8.17 µS / cm. This test result clearly demonstrates that, with a mass content of only 4.3%, the conductivity of the 2,5-dibutyladipic acid + ethylene glycol solution is 179.5 times higher than that of the adipic acid + ethylene glycol solution. This significant increase in conductivity will help reduce the equivalent series resistance of the capacitor, thereby improving the overall performance of the capacitor. Therefore, the 2,5-dibutyladipic acid + ethylene glycol solution system, due to its excellent conductivity, has a very broad application prospect in the manufacture of high-performance aluminum electrolytic capacitors.

[0040] Example 2: Appearance and water solubility;

[0041] (1) Appearance; By comparing the appearance of the synthesized 2,5-dibutyladipic acid with that of adipic acid, it can be observed that the 2,5-dibutyladipic acid with two butyl groups appears as a powder (e.g. Figure 6 As shown), adipic acid appears as distinct granules (as shown). Figure 7 (As shown).

[0042] (2) Water solubility test; the solubility of carboxylic acids in water decreases with increasing carbon number. Dicarboxylic acids, due to their structural characteristics, are often slightly soluble in water. To verify the physical properties of 2,5-dibutyladipic acid, 2g of adipic acid and 2g of 2,5-dibutyladipic acid were dissolved in 50ml of deionized water, respectively. Figure 8 The results show that 2g of adipic acid cannot be completely dissolved in 50ml of deionized water, while the same mass of 2,5-dibutyladipic acid can be completely dissolved in 50ml of deionized water. This phenomenon not only proves to some extent that the polarity of 2,5-dibutyladipic acid is enhanced compared to adipic acid, but also further indicates its increased solubility in ethylene glycol. Furthermore, due to the electron-donating effect of the α-branch, 2,5-dibutyladipic acid, when used as an electrolyte, can enhance the chemical self-repairing ability of the branched carboxylate + ethylene glycol electrolyte system, which is of great significance for improving the performance of aluminum electrolytic capacitors.

[0043] Conclusion: The 2,5-dibutyladipic acid prepared in this invention achieves a conductivity as high as 1475 µS / cm with only 4.3% mass content in ethylene glycol. This significantly improved conductivity effectively solves the problem of increased equivalent series resistance in capacitors caused by the low conductivity of traditional electrolytes. Furthermore, compared to adipic acid, 2,5-dibutyladipic acid exhibits enhanced polarity, resulting in increased solubility in ethylene glycol. In addition, due to the electron-donating effect of the α-branch, 2,5-dibutyladipic acid, when used as an electrolyte, can enhance the chemical self-healing ability of the branched carboxylate + ethylene glycol electrolyte system, which is of great significance for improving the performance of aluminum electrolytic capacitors. These characteristics provide broad prospects for manufacturing capacitors with high voltage resistance, low effective resistance, high ripple current tolerance, high heat resistance, and long lifespan using ethylene glycol systems containing branched dicarboxylate.

[0044] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for preparing 2,5-dibutyladipic acid, characterized in that, Includes the following steps: Step 1: Synthesis of dibutyl 2,5-dibutyladipate: Adipic acid and n-butane bromo were dissolved in THF, the solution was stirred at 0~30℃, an organic strong base equivalent to that of adipic acid was added, and the reaction was carried out for 6 hours. After the reaction was completed, the mixture was centrifuged at room temperature to obtain dibutyl 2,5-dibutyladipate. The organic strong base is t-BuOK, tert-butyllithium, s-isobutyllithium or diisopropylaminolithium; Step 2: Preparation of 2,5-dibutyladipic acid: The 2,5-dibutyladipic acid dibutyl obtained in Step 1 was dissolved in ethanol. Sodium hydroxide was added at reflux temperature of 76°C to carry out a saponification reaction for 8 hours. After the saponification reaction was completed, nitric acid was added for acidification. After acidification for 4 hours, the product was centrifuged at room temperature to obtain a solid product. The solid product was washed with ethanol and dried to obtain 2,5-dibutyladipic acid. The structural formula of the 2,5-dibutyladipic acid is as follows: 。 2. The method for preparing 2,5-dibutyladipic acid according to claim 1, characterized in that, The specific process of step one is as follows: 2g of adipic acid and 7.5g of bromobutane are dissolved in THF, the solution is stirred at 500rpm / min at a temperature of 0~30℃, an organic strong base equivalent to that of adipic acid is added, the reaction is carried out for 6h, and after the reaction is completed, the mixture is centrifuged at room temperature to obtain dibutyl 2,5-dibutyladipate.

3. The method for preparing 2,5-dibutyladipic acid according to claim 1, characterized in that, The specific process of step two is as follows: the 2,5-dibutyladipic acid dibutyl obtained in step one is dissolved in 100 ml of ethanol, and 0.8 g of sodium hydroxide is added at a reflux temperature of 76 °C to carry out a saponification reaction for 8 h. After the saponification reaction is completed, 0.9 ml of 65% nitric acid is added for acidification. After acidification for 4 h, the product is centrifuged at room temperature to obtain a solid product. The solid product is washed three times with ethanol and dried to obtain 3.77 g of 2,5-dibutyladipic acid.

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