2, 5-dibutyl adipic acid as well as preparation method and application thereof

Abstract

The invention is suitable for the technical field of electrolyte preparation, and provides 2, 5-dibutyl adipic acid as well as a preparation method and application thereof. The conductivity of the prepared 2, 5-dibutyl adipic acid can reach up to 1475S / cm only when the mass content of the 2, 5-dibutyl adipic acid in ethylene glycol is 4.3%, and the problem that the equivalent series internal resistance of a capacitor is increased due to the fact that the conductivity of a traditional electrolyte is low is solved. Compared with adipic acid, the polarity is enhanced, and the solubility in ethylene glycol is correspondingly improved. And due to the electron donating effect of the alpha-branched chain, when the 2, 5-dibutyl adipic acid is used as the electrolyte, the chemical self-repairing capability of the branched chain carboxylate and ethylene glycol system electrolyte can be enhanced, which is of great significance for improving the performance of the aluminum electrolytic capacitor. Due to the characteristics, a wide prospect is provided for manufacturing a capacitor product which is high in voltage resistance, low in effective resistance, high in ripple current bearing capacity, high in heat resistance and long in service life by using an ethylene glycol system containing branched-chain dicarboxylate.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolyte preparation, and in particular relates to 2,5-dibutyladipic acid and a preparation method and application thereof. Background Art

[0002] Branched carboxylic acid is the core electrolyte of aluminum electrolytic capacitor electrolyte and the key factor affecting the conductivity of aluminum electrolytic capacitor electrolyte, which in turn affects the performance of aluminum electrolytic capacitor. Aluminum electrolytic capacitor electrolyte is mainly composed of solvent, electrolyte and functional additives. The development of aluminum electrolytic capacitor electrolyte has gone through four stages. The first stage: boric acid + ethylene glycol system. The second stage: linear carboxylate + boric acid + ethylene glycol system. The third stage: linear carboxylate + ethylene glycol system. The leakage current of aluminum electrolytic capacitors has been significantly improved compared with the electrolyte of the second stage. Although the flash point of carboxylate increases due to the increase of molecular weight, its solubility decreases. The fourth stage: branched carboxylate + ethylene glycol system. Branched carboxylates replace or partially replace linear carboxylates. Branched carboxylates have large solubility, better thermal stability, and chemical self-repair ability. This system electrolyte has become the best aluminum capacitor working electrolyte, but the cost is generally high. The use of ethylene glycol systems containing branched dicarboxylates can produce capacitor products with high withstand voltage, low effective resistance, high tolerance to ripple current, high heat resistance and long life.

[0003] The reason why branched carboxylates have these excellent properties is closely related to the branches in their structure. The hydrogen on the α carbon of the carboxylic acid has a certain activity, which can be used to carry out alkylation reaction on the α hydrogen of the carboxylic acid and connect the alkyl group. Because the alkyl group has an electron-donating effect, the carboxylic acid with α alkyl branch has better solubility and thermal stability. Compared with α branched monocarboxylic acid, the dicarboxylic acid with two branches in the structure has better performance.

[0004] Therefore, in-depth research on branched dicarboxylic acids, exploration of new methods for synthesizing branched dicarboxylic acids, and the formation of independent research and development capabilities are of great significance for meeting market demand. To this end, the present invention provides 2,5-dibutyladipic acid and a preparation method and application thereof. Summary of the invention

[0005] The object of the present invention is to provide 2,5-dibutyladipic acid and a preparation method and application thereof, aiming to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions: A 2,5-dibutyladipic acid, the structural formula of which is as follows: .

[0007] A method for preparing 2,5-dibutyladipic acid as described above comprises the following steps: Step 1, synthesis of 2,5-dibutyl adipate: dissolving adipic acid and n-butyl bromide in THF, stirring the solution at a temperature of 0-30° C., adding an organic strong base equivalent to adipic acid, reacting for 6 hours, and after the reaction is completed, centrifuging at room temperature to obtain 2,5-dibutyl adipate; Step 2, preparation of 2,5-dibutyladipic acid: dissolve the 2,5-dibutyladipic acid obtained in step 1 in ethanol, add sodium hydroxide to carry out saponification reaction at a reflux temperature of 76°C for 8 hours, add nitric acid to acidify after the saponification reaction, acidify for 4 hours, centrifuge at room temperature to obtain a solid product, wash the solid product with ethanol, and obtain 3.77g of 2,5-dibutyladipic acid after drying.

[0008] Furthermore, the specific process of step one is: dissolving 2g of adipic acid and 7.5g of n-butyl bromide in THF, stirring the solution at a temperature of 0-30°C at a speed of 500rpm / min, adding an organic strong base equivalent to adipic acid, reacting for 6h, and after the reaction is completed, centrifuging at room temperature to obtain dibutyl 2,5-dibutyl adipate.

[0009] Furthermore, the specific process of step 2 is as follows: dissolving the 2,5-dibutyl adipate obtained in step 1 in 100 ml of ethanol, adding 0.8 g of sodium hydroxide to carry out saponification reaction at a reflux temperature of 76° C. for 8 hours, and after the saponification reaction is completed, adding 0.9 ml of 65% nitric acid for acidification, acidifying for 4 hours, and centrifuging at room temperature to obtain a solid product, washing the solid product three times with ethanol, and obtaining 3.77 g of 2,5-dibutyl adipate after drying.

[0010] Furthermore, the organic strong base is t-BuOK, tert-butyl lithium, s-isobutyl lithium or lithium diisopropylamide.

[0011] An application of the 2,5-dibutyladipic acid as described above is to mix the 2,5-dibutyladipic acid with a solvent, and after fully dissolving the solvent, prepare an electrolyte for an aluminum electrolytic capacitor.

[0012] Furthermore, the solvent is ethylene glycol.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The 2,5-dibutyl adipic acid prepared by the present invention only needs 4.3% by mass in ethylene glycol, and its conductivity can be as high as 1475µS / cm. This significantly improved conductivity effectively solves the problem of increased equivalent series internal resistance of capacitors caused by low conductivity of traditional electrolytes. At the same time, compared with adipic acid, the polarity of 2,5-dibutyl adipic acid is enhanced, and its solubility in ethylene glycol is also improved accordingly. In addition, due to the electron-donating effect of the α-branch, when 2,5-dibutyl adipic acid is used as an electrolyte, the chemical self-healing ability of the branched carboxylate + ethylene glycol system electrolyte can be enhanced, which is of great significance for improving the performance of aluminum electrolytic capacitors. These characteristics provide broad prospects for the use of ethylene glycol systems containing branched dicarboxylates to manufacture capacitor products with high withstand voltage, low effective resistance, high tolerance to ripple current, high heat resistance, and long life. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a flow chart for the preparation of 2,5-dibutyladipic acid.

[0015] Figure 2 This is the infrared spectrum of adipic acid.

[0016] Figure 3 This is the infrared spectrum of 2,5-dibutyladipic acid.

[0017] Figure 4 This is the conductivity test result of 2,5-dibutyladipic acid + ethylene glycol solution.

[0018] Figure 5 This is the conductivity test result of adipic acid + ethylene glycol solution.

[0019] Figure 6 This is the appearance picture of 2,5-dibutyladipic acid.

[0020] Figure 7 This is the appearance of adipic acid.

[0021] Figure 8 This is a water solubility experiment, where the left picture is 2g adipic acid / 50ml deionized water, and the right picture is 2g 2,5-dibutyl adipic acid / 50ml deionized water. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] An embodiment of the present invention provides a 2,5-dibutyladipic acid, the structural formula of which is as follows: .

[0024] The preparation method of 2,5-dibutyladipic acid comprises the following steps (such as Figure 1 shown): Step 1, synthesis of 2,5-dibutyl adipate: 2 g of adipic acid and 7.5 g of n-butyl bromide are dissolved in THF (tetrahydrofuran), the solution is stirred at a temperature of 0-30°C at a speed of 500 rpm / min, an organic strong base equivalent to adipic acid (t-BuOK, tert-butyl lithium, s-isobutyl lithium or lithium diisopropylamide can be used) is added, and the reaction is carried out for 6 hours. After the reaction is completed, centrifugation is carried out at room temperature to obtain 2,5-dibutyl adipate; Step 2, preparation of 2,5-dibutyladipic acid: dissolve the 2,5-dibutyladipic acid obtained in step 1 in 100 ml of ethanol, add 0.8 g of sodium hydroxide at a reflux temperature of 76°C for saponification reaction, and continue for 8 hours. After the saponification reaction is completed, add 0.9 ml of 65% nitric acid for acidification. After acidification for 4 hours, centrifuge at room temperature to obtain a solid product, wash the solid product three times with ethanol, and obtain 3.77 g of 2,5-dibutyladipic acid after drying.

[0025] Figure 2 The infrared spectrum of adipic acid is shown. It can be seen from the figure that the OH bond in the carboxylic acid is between 2500 and 3000 cm -1 Shows a very wide band, 2900~3000cm -1 It is the saturated CH absorption peak in adipic acid molecule, 1700cm -1 It is the absorption peak of C=O, 1400cm -1 and 920cm -1 It is the OH bending vibration absorption peak. Figure 3 The infrared spectrum of 2,5-dibutyladipic acid is shown. It can be seen from the figure that the infrared spectrum of 2,5-dibutyladipic acid is 3000~3500cm -1 The absorption peak is the OH absorption peak of 2,5-dibutyladipic acid, 2900 cm -1 Up to 3000cm -1 The shoulder peaks between them are enhanced and parallel peaks appear, which are the CH absorption peaks of the main chain of the molecule and the butyl group on the α carbon. The C=O absorption peak is at 1550~1560cm -1 Between. Figure 2 and Figure 3 By comparison, due to the influence of the branched butyl group, 2,5-dibutyladipic acid has a peak concentration of 2900-3000 cm -1 The absorption peak shape changes and the absorption intensity increases, indicating that CH 2 Increase. Figure 3 The absorption peak of C=O of 2,5-dibutyladipic acid is at 1550~1560cm-1 Between, below 1700cm -1 The reason may be that the electron donation effect of the butyl group on the α carbon causes the absorption peak of C=O to move to a lower wavelength.

[0026] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0027] Example 1: The conductivity of the 2,5-dibutyladipic acid + ethylene glycol solution system is significantly improved; Using ethylene glycol as a solvent, 2,5-dibutyladipic acid and adipic acid prepared according to the above preparation method are dissolved in ethylene glycol respectively to form two ethylene glycol solution systems. The specific operation is as follows: Take 10 ml of ethylene glycol, add 0.5 g of 2,5-dibutyladipic acid and fully dissolve it to prepare a 2,5-dibutyladipic acid + ethylene glycol solution with a mass content of 4.3%.

[0028] Take another 10 ml of ethylene glycol, add 0.5 g of adipic acid and fully dissolve it to prepare a 4.3% adipic acid + ethylene glycol solution.

[0029] Subsequently, the conductivity of the above two solutions was measured using an ECscan30 conductivity meter at a test temperature of 40±5°C. Figure 4 The conductivity of 2,5-dibutyladipic acid + ethylene glycol solution is shown to be as high as 1475µS / cm. Figure 5 The conductivity of the adipic acid + ethylene glycol solution shown is only 8.17µS / cm. This test result clearly shows that the conductivity of the 2,5-dibutyl adipic acid + ethylene glycol solution is 179.5 times higher than that of the adipic acid + ethylene glycol solution when the mass content is only 4.3%. The significant increase in conductivity will help reduce the equivalent series internal resistance of the capacitor, thereby improving the overall performance of the capacitor. Therefore, the 2,5-dibutyl adipic acid + ethylene glycol solution system has a very broad application prospect in the manufacture of high-performance aluminum electrolytic capacitors due to its excellent conductivity performance.

[0030] Example 2, appearance and water solubility; (1) Appearance: Comparing the appearance of the synthesized 2,5-dibutyladipic acid with adipic acid, it can be observed that the 2,5-dibutyladipic acid with two butyl groups is in powder form (e.g. Figure 6 ), while adipic acid appears as obvious granules (as shown in Figure 7 as shown).

[0031] (2) Water solubility test: The solubility of carboxylic acids in water decreases as the number of carbon atoms increases. Due to their structural characteristics, dicarboxylic acids are often slightly soluble in water. In order 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-dibutyl adipic acid can be completely dissolved in 50ml of deionized water. This phenomenon not only proves to a certain extent that the polarity of 2,5-dibutyl adipic acid is enhanced compared to adipic acid, but also further indicates that its solubility in ethylene glycol is increased. In addition, due to the electron-donating effect of the α-branch, when 2,5-dibutyl adipic acid is used as an electrolyte, it can enhance the chemical self-healing ability of the branched carboxylate + ethylene glycol system electrolyte, which is of great significance for improving the performance of aluminum electrolytic capacitors.

[0032] Conclusion: The 2,5-dibutyladipic acid prepared by the present invention only needs 4.3% mass content in ethylene glycol, and its conductivity can be as high as 1475µS / cm. This significantly improved conductivity effectively solves the problem of increased equivalent series internal resistance of capacitors caused by low conductivity of traditional electrolytes. At the same time, compared with adipic acid, the polarity of 2,5-dibutyladipic acid is enhanced, and its solubility in ethylene glycol is also improved accordingly. In addition, due to the electron-donating effect of the α-branch, when 2,5-dibutyladipic acid is used as an electrolyte, it can enhance the chemical self-healing ability of the branched carboxylate + ethylene glycol system electrolyte, which is of great significance for improving the performance of aluminum electrolytic capacitors. These characteristics provide broad prospects for the use of ethylene glycol systems containing branched dicarboxylates to manufacture capacitor products with high withstand voltage, low effective resistance, high tolerance to ripple current, high heat resistance, and long life.

[0033] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A 2,5-dibutyladipic acid, characterized in that: Its structural formula is as follows: 。 2. A method for preparing 2,5-dibutyladipic acid as claimed in claim 1, characterized in that: The following steps are involved: Step 1, synthesis of 2,5-dibutyl adipate: dissolving adipic acid and n-butyl bromide in THF, stirring the solution at a temperature of 0-30° C., adding an organic strong base equivalent to adipic acid, reacting for 6 hours, and after the reaction is completed, centrifuging at room temperature to obtain 2,5-dibutyl adipate; Step 2, preparation of 2,5-dibutyladipic acid: dissolve the 2,5-dibutyladipic acid obtained in step 1 in ethanol, add sodium hydroxide to carry out saponification reaction at a reflux temperature of 76°C for 8 hours, add nitric acid to acidify after the saponification reaction, acidify for 4 hours, centrifuge at room temperature to obtain a solid product, wash the solid product with ethanol, and obtain 3.77g of 2,5-dibutyladipic acid after drying.

3. The method for preparing 2,5-dibutyladipic acid according to claim 2, characterized in that: The specific process of step 1 is as follows: 2 g of adipic acid and 7.5 g of n-butyl bromide are dissolved in THF, the solution is stirred at a temperature of 0-30° C. at a speed of 500 rpm / min, an organic strong base equivalent to adipic acid is added, and the reaction is carried out for 6 hours. After the reaction is completed, centrifugation is carried out at room temperature to obtain dibutyl 2,5-dibutyl adipate.

4. The method for preparing 2,5-dibutyladipic acid according to claim 2, characterized in that: The specific process of step 2 is: dissolving the 2,5-dibutyl adipate obtained in step 1 in 100 ml of ethanol, adding 0.8 g of sodium hydroxide at a reflux temperature of 76° C. to carry out saponification reaction for 8 hours, and after the saponification reaction is completed, adding 0.9 ml of 65% nitric acid for acidification, acidifying for 4 hours, and centrifuging at room temperature to obtain a solid product, washing the solid product three times with ethanol, and drying to obtain 3.77 g of 2,5-dibutyl adipate.

5. The method for preparing 2,5-dibutyladipic acid according to claim 2, characterized in that: The organic strong base is t-BuOK, tert-butyl lithium, s-isobutyl lithium or lithium diisopropylamide.

6. A use of 2,5-dibutyladipic acid as claimed in claim 1, characterized in that: The 2,5-dibutyladipic acid is mixed with a solvent and fully dissolved to prepare an electrolyte for an aluminum electrolytic capacitor.

7. The use of 2,5-dibutyladipic acid according to claim 6, characterized in that: The solvent is ethylene glycol.

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