Preparation method of yellow azoxy and azo stilbene dyes

Abstract

The present invention discloses a preparation method of yellow azoxy and azo stilbene dyes. Using 4-nitrotoluene-2-sulfonic acid as a raw material and water as a reaction solvent, in the presence of choline hydroxide, dye yellow 11 is obtained through a condensation reaction. The molecular structure of choline hydroxide contains a quaternary ammonium salt group and a hydroxyl group. The hydroxyl group provides additional hydrophilicity, which helps to improve the solubility and dispersibility of the dye in an aqueous medium and enhance the affinity between the dye and the fiber. Choline hydroxide can effectively provide the alkaline environment required for the reaction, promote the synthesis reaction of the dye, and better control the selectivity and yield of the reaction. Since the choline hydroxide molecule contains a hydroxyl group, it can form hydrogen bonds with the sulfonic acid groups in the dye molecule, enhance the stability between dye molecules, and improve the light fastness and acid and alkali resistance of the dye. Using choline hydroxide not only optimizes the reaction conditions, improves the purity and yield of the dye, but also significantly improves the performance of dye yellow 11.

Description

Technical Field

[0001] The present invention relates to a technology of azoxy and azo stilbene yellow dyes, in particular to a preparation method of azoxy and azo stilbene dyes. Background Art

[0002] In the paper manufacturing and printing industries, azoxy and azo stilbene dyes are widely used in the dyeing process of paper and packaging materials due to their bright colors and high dyeing performance. Among them, Direct Yellow 11 has become the most important and valuable one of such dyes due to its wide commercial applications. However, in the traditional production method of Direct Yellow 11, there are problems such as low yield, poor solubility and dispersibility of the dye in aqueous media, and limited affinity with fibers, which limit its wide application in the fields of high-quality printing and dyeing. Therefore, there is an urgent need to develop a new preparation method to improve the performance and production efficiency of Dye Yellow 11.

[0003] In the prior art, NaOH is often used as an alkaline substance to prepare azo stilbene azo dyes. However, this production process has some technical problems. For example, subsequent filtration or ultrafiltration steps are required, the process is relatively complex, and the obtained product needs to add organic amines to make it stable, which is not conducive to subsequent use.

[0004] Another common technical route is to use tetramethylammonium hydroxide as a strong organic base to prepare azo stilbene yellow dyes (CN 110373040 A). However, the quaternary ammonium salt structure of tetramethylammonium hydroxide is too hydrophobic, resulting in poor solubility and dispersibility of the dye in aqueous media, and thus affecting the affinity and dyeing effect of the dye. Summary of the Invention

[0005] The present invention aims to solve the problems existing in the production of direct dye yellow 11 in the prior art, especially the challenges such as poor dye solubility and dispersibility, limited affinity with fibers, and insufficient basic strength when using tetramethylammonium hydroxide as the basic reactant. In view of these problems, the present invention proposes a method for preparing direct dye yellow 11 using choline hydroxide as the basic reactant. The molecular structure of choline hydroxide contains a quaternary ammonium salt group and a hydroxyl group. The hydroxyl group provides additional hydrophilicity, which helps to improve the solubility and dispersibility of the dye in the aqueous medium, thereby enhancing the affinity between the dye and the fiber. At the same time, choline hydroxide, as a strong base, can effectively provide the basic environment required for the reaction, promote the progress of the dye synthesis reaction, and may have better control over the selectivity and yield of the reaction. In addition, since the choline hydroxide molecule contains a hydroxyl group, it can form hydrogen bonds with the sulfonic acid groups in the dye molecule, enhancing the stability between dye molecules, thereby improving the light fastness and acid and alkali resistance of the dye. In contrast, due to the lack of a hydroxyl group capable of forming hydrogen bonds, the interaction between tetramethylammonium hydroxide and the dye molecule is weaker, which affects the stability and durability of the dye. Therefore, using choline hydroxide as the basic reactant not only solves the problems existing in tetramethylammonium hydroxide, but also significantly improves the performance of dye yellow 11, providing a better technical solution for the production of direct dye yellow 11.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for preparing a yellow azooxy and azostilbene dye, using 4-nitrotoluene-2-sulfonic acid as a raw material, water as a reaction solvent, and in the presence of choline hydroxide, obtaining the yellow azooxy and azostilbene dye, namely dye yellow 11, through a condensation reaction.

[0008] Furthermore, the method for preparing the yellow azooxy and azostilbene dye includes the following steps:

[0009] (1) Preparation of an aqueous solution of choline hydroxide: Add an aqueous solution of trimethylamine to a reaction kettle, and then slowly add ethylene oxide. After the addition is completed, maintain the reaction temperature at 35 - 40 °C and the reaction time at 3 - 4 hours to obtain a choline hydroxide solution. The reaction route is as follows:

[0010]

[0011] (2) Condensation reaction: Dropwise add a solution of 4-nitrotoluene-2-sulfonic acid to the aqueous solution of choline hydroxide. After the addition is completed, react at 45 - 85 °C for 4 - 8 hours to obtain a mixed solution containing dye yellow 11;

[0012] (3) Adjust the pH of the mixed solution containing dye Yellow 11 obtained in step (2) to 7 - 9 with hydrochloric acid to obtain a yellow transparent solution containing direct yellow 11 dye.

[0013] Furthermore, in step (1), an aqueous solution of trimethylamine is added to the reaction kettle, the starting temperature is controlled at 5 - 15°C, and the feeding temperature when slowly adding ethylene oxide to the reaction kettle shall not exceed 30°C, and the feeding time is controlled within 2 - 3 hours.

[0014] Furthermore, in step (1), the mass concentration of the aqueous solution of trimethylamine is 25% - 45%, preferably 30%.

[0015] Furthermore, in step (1), the molar ratio of trimethylamine to ethylene oxide is 1:1.05 - 1:1.35, preferably 1:1.10.

[0016] Furthermore, in step (1), the mass concentration of the choline hydroxide solution is 30% - 50%.

[0017] Furthermore, in step (2), the addition temperature when dropping the 4 - nitrotoluene - 2 - sulfonic acid solution is 20 - 45°C, and the time during the addition process is controlled within 30 - 60 minutes.

[0018] In step (2), the mass concentration of the 4 - nitrotoluene - 2 - sulfonic acid solution is 30 - 55%, and the molar ratio of 4 - nitrotoluene - 2 - sulfonic acid to choline hydroxide is 1:1.5 - 1:2.5, preferably 1:1.8.

[0019] The structural formula of dye Yellow 11 is:

[0020]

[0021] wherein, X is a group

[0022] The present invention also provides a yellow azo - oxidized and azo - stilbene dye prepared by the above - mentioned preparation method. The azo - oxidized and azo - stilbene dye is a dye mixture solution mainly composed of Yellow 11, and the maximum absorption wavelength is 410 - 435 nm.

[0023] By adopting the above technical solutions, the present invention has the following beneficial effects:

[0024] The present invention prepares Direct Yellow 11 by using choline hydroxide as an alkaline reactant to react with 4-nitrotoluene-2-sulfonic acid. First, compared with tetramethylammonium hydroxide, the molecular structure of choline hydroxide contains a hydroxyl group, which provides additional hydrophilicity, enhances the solubility and dispersibility of the dye in the aqueous medium, and thus enhances the affinity between the dye and the fiber. Second, this condensation reaction needs to be carried out under strong alkaline conditions. Choline hydroxide has stronger alkalinity and is more likely to provide the required strong alkaline environment, which helps to improve the purity and yield of the dye. Therefore, the use of choline hydroxide not only optimizes the reaction conditions, improves the purity and yield of the dye, but also significantly improves the performance of Direct Yellow 11, demonstrating a breakthrough progress in technological innovation and performance improvement of the present invention. Specifically, it is manifested in the following aspects:

[0025] 1. Improve the dye performance: Due to the molecular structure characteristics of choline hydroxide, the affinity between the Direct Yellow 11 prepared in the present invention and the fiber is significantly improved, and at the same time, the light fastness, acid and alkali resistance of the dye are also improved.

[0026] 2. Improve the yield and purity: The strong alkalinity of choline hydroxide is beneficial to optimizing the reaction conditions, improving the synthesis yield and purity of Direct Yellow 11, thereby reducing the production cost and improving the product quality. Description of the Drawings

[0027] Figure 1 The test results of the colorimeter after dyeing blank paper with Yellow 11 dyes prepared using choline hydroxide (batch sample) and tetramethylammonium hydroxide (standard sample) as alkaline reactants respectively.

[0028] Figure 2 The test results of the colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using choline hydroxide alkaline reactant and after adding alkali (batch sample) respectively.

[0029] Figure 3 The test results of the colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using tetramethylammonium hydroxide alkaline reactant and after adding alkali (batch sample) respectively.

[0030] Figure 4 The test results of the colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using choline hydroxide alkaline reactant and after adding acid (batch sample) respectively.

[0031] Figure 5 The test results of the colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using tetramethylammonium hydroxide alkaline reactant and after adding acid (batch sample) respectively.

[0032] Figure 6Test results of a colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using choline hydroxide as the alkaline reactant and after light exposure (batch sample).

[0033] Figure 7 Test results of a colorimeter after dyeing blank paper with Yellow 11 dye (standard sample) prepared using tetramethylammonium hydroxide as the alkaline reactant and after light exposure (batch sample).

[0034] Figure 8 1H NMR spectrum of the azooxy and azostilbene dye, i.e., the Yellow 11 dye sample, prepared in Example 1 Detailed implementation mode

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the content of the above invention.

[0036] Example 1

[0037] The preparation method of the yellow azooxy and azostilbene dye in this example is as follows:

[0038] (1) Preparation of choline hydroxide aqueous solution: Add an aqueous solution of trimethylamine with a mass concentration of 30% to the reaction kettle, and control the starting temperature at 15°C; slowly add ethylene oxide to the reaction kettle, and the molar ratio of trimethylamine to ethylene oxide is 1:1.10. The temperature inside the reaction kettle rises continuously, and the feeding temperature shall not exceed 30°C (when the temperature reaches 30°C, stop feeding and continue feeding after cooling), and the feeding time is controlled within 2 hours; after the feeding is completed, keep warm at 40°C and react for 3 hours to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to adjust to obtain an aqueous solution of choline hydroxide with a mass concentration of 45%. The reaction route is as follows:

[0039]

[0040] (2) Condensation reaction stage: Slowly add a 45% aqueous solution of 4-nitrotoluene-2-sulfonic acid to the 45% aqueous solution of choline hydroxide (the system temperature is controlled at 40°C), and the molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide is 1:1.8. Stir to form a blue-violet solution, and stir and react at 70°C for 5 hours. After the reaction is completed, a reddish-brown transparent solution is formed;

[0041] (3) Add hydrochloric acid with a mass fraction of 30% to the reddish-brown transparent solution to adjust the pH to 7, and obtain a yellow transparent solution with a maximum absorption wavelength of 420 nm.

[0042] The dye structural formula I is as follows:

[0043]

[0044] Wherein, X represents a group

[0045] Example 2

[0046] The preparation method of the yellow azoxy and azo stilbene dyes in this example is as follows:

[0047] (1) Preparation of choline hydroxide aqueous solution: Add an aqueous solution of trimethylamine with a mass concentration of 25% to the reaction kettle, and control the initial temperature at 5°C; slowly add ethylene oxide to the reaction kettle, and the molar ratio of trimethylamine to ethylene oxide is 1:1.05. The temperature inside the reaction kettle keeps rising, and the feeding temperature shall not exceed 30°C (when the temperature reaches 30°C, stop feeding, cool down and then continue feeding), and the feeding time is controlled within 3 hours; after the feeding is completed, keep it warm at 35°C and react for 4 hours to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to it to adjust to obtain an aqueous solution of choline hydroxide with a mass concentration of 30%;

[0048] (2) Condensation reaction stage: Slowly add a 30% aqueous solution of 4-nitrotoluene-2-sulfonic acid to the 30% aqueous solution of choline hydroxide (the system temperature is controlled at 20°C), and the molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide is 1:1.5. Stir to form a blue-violet solution, and stir and react at 45°C for 6 hours. After the reaction is completed, a reddish-brown transparent solution is formed;

[0049] (3) Add hydrochloric acid with a mass fraction of 30% to the reddish-brown transparent solution, adjust the pH to 9 to obtain a yellow transparent solution, and the maximum absorption wavelength is 410 nm.

[0050] Example 3

[0051] The preparation method of the yellow azoxy and azo stilbene dyes in this example is as follows:

[0052] (1) Preparation of choline hydroxide aqueous solution: Add an aqueous solution of trimethylamine with a mass concentration of 35% to the reaction kettle, and control the initial temperature at 10°C; slowly add ethylene oxide to the reaction kettle, and the molar ratio of trimethylamine to ethylene oxide is 1:1.35. The temperature inside the reaction kettle keeps rising, and the feeding temperature shall not exceed 30°C (when the temperature reaches 30°C, stop feeding, cool down and then continue feeding), and the feeding time is controlled within 2.5 hours; after the feeding is completed, keep it warm at 35°C and react for 4 hours to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to it to adjust to obtain an aqueous solution of choline hydroxide with a mass concentration of 50%;

[0053] (2) Condensation reaction stage: A 4-nitrotoluene-2-sulfonic acid solution with a mass concentration of 35% was slowly added to an aqueous choline hydroxide solution with a mass concentration of 50% (the system temperature was controlled at 30 °C). The molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide was 1:2.5. Stir to form a blue-violet solution, and stir and react at 85 °C for 4 h. After the reaction, a reddish-brown transparent solution was formed;

[0054] (3) Hydrochloric acid with a mass fraction of 30% was added to the reddish-brown transparent solution to adjust the pH to 7-9, obtaining a yellow transparent solution with a maximum absorption wavelength of 435 nm.

[0055] Example 4

[0056] The preparation method of the yellow azoxy and azo stilbene dyes in this example is as follows:

[0057] (1) Preparation of aqueous choline hydroxide solution: Add an aqueous trimethylamine solution with a mass concentration of 40% to the reaction kettle, and control the starting temperature at 12 °C; slowly add ethylene oxide to the reaction kettle. The molar ratio of trimethylamine to ethylene oxide is 1:1.2. The internal temperature of the reaction kettle rises continuously, and the feeding temperature shall not exceed 30 °C (when the temperature reaches 30 °C, stop feeding, cool and then continue feeding). The feeding time is controlled within 3 hours; after the feeding is completed, keep warm at 40 °C and react for 3 h to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to adjust to obtain an aqueous choline hydroxide solution with a mass concentration of 35%;

[0058] (2) Condensation reaction stage: A 4-nitrotoluene-2-sulfonic acid solution with a mass concentration of 40% was slowly added to an aqueous choline hydroxide solution with a mass concentration of 35% (the system temperature was controlled at 45 °C). The molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide was 1:2.2. Stir to form a blue-violet solution, and stir and react at 75 °C for 4 h. After the reaction, a reddish-brown transparent solution was formed;

[0059] (3) Hydrochloric acid with a mass fraction of 30% was added to the reddish-brown transparent solution to adjust the pH to 8, obtaining a yellow transparent solution with a maximum absorption wavelength of 425 nm.

[0060] Example 5

[0061] The preparation method of the yellow azoxy and azo stilbene dyes in this example is as follows:

[0062] (1) Preparation of choline hydroxide aqueous solution: Add aqueous trimethylamine solution with a mass concentration of 45% into the reaction kettle, and control the starting temperature at 15 °C; slowly add ethylene oxide into the reaction kettle, and the molar ratio of trimethylamine to ethylene oxide is 1:1.3. The temperature inside the reaction kettle keeps rising, and the feeding temperature shall not exceed 30 °C (when the temperature reaches 30 °C, stop feeding, cool down and then continue feeding), and the feeding time is controlled within 3 hours; after the feeding is completed, keep it warm at 37 °C and react for 4 h to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to it to adjust to an aqueous solution of choline hydroxide with a mass concentration of 40%;

[0063] (2) Condensation reaction stage: Slowly add a 4-nitrotoluene-2-sulfonic acid solution with a mass concentration of 45% into the aqueous choline hydroxide solution with a mass concentration of 40% (the system temperature is controlled at 35 °C), and the molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide is 1:2.0. Stir to form a blue-violet solution, and stir and react at 65 °C for 6 h. After the reaction is completed, a reddish-brown transparent solution is formed;

[0064] (3) Add hydrochloric acid with a mass fraction of 30% to the reddish-brown transparent solution to adjust the pH to 7, and obtain a yellow transparent solution with a maximum absorption wavelength of 415 nm.

[0065] Example 6

[0066] The preparation method of the yellow azoxy and azo stilbene dyes in this example is as follows:

[0067] (1) Preparation of choline hydroxide aqueous solution: Add aqueous trimethylamine solution with a mass concentration of 30% into the reaction kettle, and control the starting temperature at 15 °C; slowly add ethylene oxide into the reaction kettle, and the molar ratio of trimethylamine to ethylene oxide is 1:1.25. The temperature inside the reaction kettle keeps rising, and the feeding temperature shall not exceed 30 °C (when the temperature reaches 30 °C, stop feeding, cool down and then continue feeding), and the feeding time is controlled within 2.5 hours; after the feeding is completed, keep it warm at 36 °C and react for 4 h to obtain an aqueous solution of choline hydroxide, and then add an appropriate amount of water to it to adjust to an aqueous solution of choline hydroxide with a mass concentration of 45%;

[0068] (2) Condensation reaction stage: Slowly add a 4-nitrotoluene-2-sulfonic acid solution with a mass concentration of 55% into the aqueous choline hydroxide solution with a mass concentration of 45% (the system temperature is controlled at 25 °C), and the molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide is 1:1.8. Stir to form a blue-violet solution, and stir and react at 80 °C for 4 h. After the reaction is completed, a reddish-brown transparent solution is formed;

[0069] (3) Add hydrochloric acid with a mass fraction of 30% to the reddish-brown transparent solution, adjust the pH to 9 to obtain a yellow transparent solution, and the maximum absorption wavelength is 430 nm.

[0070] Comparative Example 1

[0071] In Comparative Example 1, tetramethylammonium hydroxide was directly used as the basic reactant to prepare Dye Yellow 11. For the specific method, refer to CN 110373040 A.

[0072] The performances of the Dye Yellow 11 obtained in Example 1 and Comparative Example 1 were compared as follows:

[0073] I. Comparison of affinity with fibers:

[0074] As Figure 1 shown in the figure, it is the test results of a colorimeter after dyeing a blank paper with Yellow 11 dyes prepared using tetramethylammonium hydroxide (standard sample, i.e., Comparative Example 1) and choline hydroxide (batch sample, i.e., Example 1) as basic reactants respectively.

[0075] It can be seen from the results that the dyeing strength of the batch sample on the paper is 108.75, which is greater than that of the standard sample (100). This shows that using choline hydroxide as the basic reactant, the direct Dye Yellow 11 prepared by reacting with 4-nitrotoluene-2-sulfonic acid has a stronger affinity for fibers. This is because the molecular structure of choline hydroxide contains a quaternary ammonium salt group and a hydroxyl group, and the hydroxyl group provides additional hydrophilicity, which helps to improve the solubility and dispersibility of the dye in the aqueous medium, thus enhancing the affinity between the dye and the fibers.

[0076] II. Comparison of alkali resistance:

[0077] As Figure 2 shown in the figure, it is the test results of a colorimeter after dyeing a blank paper with the Yellow 11 dye prepared using choline hydroxide as the basic reactant (standard sample, i.e., Example 1) after adding alkali (batch sample).

[0078] As Figure 3 shown in the figure, it is the test results of a colorimeter after dyeing a blank paper with the Yellow 11 dye prepared using tetramethylammonium hydroxide as the basic reactant (standard sample, i.e., Comparative Example 1) after adding alkali (batch sample).

[0079] It can be seen from the results that for the Yellow 11 dye prepared using choline hydroxide, in an alkaline environment, the dyeing strength of the batch sample on the paper is 99.69, and the dyeing strength is maintained well. However, for the Yellow 11 dye prepared using tetramethylammonium hydroxide as the basic reactant, in an alkaline environment, the dyeing strength of the batch sample on the paper is 97.41, and the dyeing strength decreases. By comparison, the Dye Yellow 11 prepared using choline hydroxide as the basic reactant has stronger alkali resistance.

[0080] III. Acid Resistance Comparison:

[0081] As Figure 4 shown, this figure is the test result of the colorimeter after dyeing blank paper with Yellow 11 dye prepared with choline hydroxide alkaline reactant (the standard sample is Example 1) and adding acid (batch sample).

[0082] As Figure 5 shown, this figure is the test result of the colorimeter after dyeing blank paper with Yellow 11 dye prepared with tetramethylammonium hydroxide alkaline reactant (the standard sample is Comparative Example 1) and adding acid (batch sample).

[0083] It can be seen from the results that for the Yellow 11 dye prepared with choline hydroxide, in an acidic environment, the dyeing strength of the batch sample on the paper is 98.98; for the Yellow 11 dye prepared with tetramethylammonium hydroxide as the alkaline reactant, in an acidic environment, the dyeing strength of the batch sample on the paper is 83.25. The contrast is obvious, and the Yellow 11 dye prepared with choline hydroxide as the alkaline reactant has better acid resistance.

[0084] IV. Light Stability Comparison:

[0085] As Figure 6 shown, this figure is the test result of the colorimeter after dyeing blank paper with Yellow 11 dye prepared with choline hydroxide alkaline reactant (the standard sample is Example 1) after light exposure (batch sample).

[0086] As Figure 7 shown, this figure is the test result of the colorimeter after dyeing blank paper with Yellow 11 dye prepared with tetramethylammonium hydroxide alkaline reactant (the standard sample is Comparative Example 1) after light exposure (batch sample).

[0087] It can be seen from the results that for the Yellow 11 dye prepared with choline hydroxide, in an acidic environment, the dyeing strength of the batch sample on the paper is 97.54; for the Yellow 11 dye prepared with tetramethylammonium hydroxide as the alkaline reactant, in an acidic environment, the dyeing strength of the batch sample on the paper is 80.05. It can be clearly compared that the Yellow 11 dye prepared with choline hydroxide as the alkaline reactant has stronger light stability.

[0088] Since the choline hydroxide molecule contains a hydroxyl group, it can form hydrogen bonds with the sulfonic acid groups in the dye molecule, enhancing the stability between dye molecules, thereby improving the lightfastness and acid and alkali resistance of the dye. In contrast, due to the lack of a hydroxyl group capable of forming hydrogen bonds, the interaction between tetramethylammonium hydroxide and the dye molecule is weaker, thus affecting the stability and durability of the dye. Therefore, using choline hydroxide as the basic reactant not only solves the problems existing in tetramethylammonium hydroxide, but also significantly improves the performance of dye yellow 11, providing a better technical solution for the production of direct dye yellow 11.

[0089] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing yellow azoxy and azo stilbene dyes, characterized in that: Using 4-nitrotoluene-2-sulfonic acid as the raw material, water as the reaction solvent, and in the presence of choline hydroxide, a condensation reaction is carried out to obtain yellow azoxy and azo stilbene dyes, namely dye yellow 11.

2. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 1, characterized in that It includes the following steps: (1) Preparation of choline hydroxide aqueous solution: Add aqueous trimethylamine solution to the reaction kettle, and then slowly add ethylene oxide. After the feeding is completed, keep the reaction temperature at 35 - 40 °C and the reaction time at 3 - 4 hours to obtain a choline hydroxide solution. The reaction route is as follows: (2) Condensation reaction: Dropwise add 4-nitrotoluene-2-sulfonic acid solution into the choline hydroxide aqueous solution. After the addition is completed, react at 45 - 85 °C for 4 - 8 h to obtain a mixed solution containing dye yellow 11; (3) Adjust the pH of the mixed solution containing dye yellow 11 obtained in step (2) to 7 - 9 with hydrochloric acid to obtain a yellow transparent solution containing direct yellow 11 dye.

3. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (1), add aqueous trimethylamine solution to the reaction kettle, control the starting temperature at 5 - 15 °C, and the feeding temperature when slowly adding ethylene oxide to the reaction kettle shall not exceed 30 °C, and the feeding time is controlled at 2 - 3 hours.

4. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (1), the mass concentration of the aqueous trimethylamine solution is 25% - 45%.

5. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (1), the molar ratio of trimethylamine to ethylene oxide is 1:1.05 - 1:1.

35.

6. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (1), the mass concentration of the choline hydroxide solution is 30% - 50%.

7. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (2), the addition temperature when dropping 4-nitrotoluene-2-sulfonic acid solution is 20 - 45 °C, and the time for the addition process is controlled within 30 - 60 minutes.

8. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: In step (2), the mass concentration of the 4-nitrotoluene-2-sulfonic acid solution is 30 - 55%, and the molar ratio of 4-nitrotoluene-2-sulfonic acid to choline hydroxide is 1:1.5 - 1:2.

5.

9. The preparation method of the yellow azoxy and azo stilbene dyes according to claim 2, characterized in that: The structural formula of dye yellow 11 is: wherein X is a group 10. The yellow azoxy and azo stilbene dyes prepared by the preparation method according to any one of claims 1-9, characterized in that: The yellow azoxy and azo stilbene dyes are dye mixture solutions mainly composed of yellow 11, and the maximum absorption wavelength is 410 - 435 nm.

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