Preparation method of xylylamine blue I

Abstract

The invention discloses a preparation method of xylylamine blue I. The preparation method comprises the following steps: (1) sequentially adding 3-hydroxy-2-naphthoic acid and a first solvent into a reaction flask at room temperature, stirring and dissolving until the solution is clear, slowly adding N, N '-carbonyldiimidazole, stirring and reacting at room temperature for 0.15-2 hours after the material is added, adding 2, 4-dimethylaniline, stirring and reacting for 1-1.5 hours, separating out a large amount of solids, and filtering to obtain a filtrate; continuously stirring and reacting for 12-24 hours to obtain an intermediate 3; and (2) adding the intermediate 3 into a 80% methanol aqueous solution of sodium hydroxide, cooling to 0-2 DEG C, controlling the temperature to be below 5 DEG C, slowly dropwise adding a pre-prepared diazonium salt solution, controlling the pH value to be 8-9, finishing, slowly heating to room temperature, stirring for 12-24 hours, pouring the reaction solution into saturated salt water, adjusting the pH value to be 5-6, stirring, and separating out xylylamine blue I. Compared with the prior art, the method has the advantages of convenient raw material source and high product purity, and is suitable for industrial mass production.

Description

Technical Field

[0001] The invention relates to the technical field of dyes and indicators, and in particular to a method for preparing xylidine blue I. Background Art

[0002] Xylidine Blue I is also known as Xylidine Blue I Sodium Salt, Xylene Azo Violet I, Xylene Blue I Sodium Salt, Xylene Azo Violet I [Spectrophotometric Reagent for Magnesium] and Magonsulfonate, etc. Its chemical name is Xylene Azo Violet I Sodium Salt, its molecular formula is C25H20N3NaO6S, and its molecular weight is 513.4976. Xylidine Blue I is an organic synthetic dye. It is a blue crystal that is soluble in water and ethanol and is hygroscopic. Xylidine Blue I is commonly used as a biological dye in the fields of biochemistry and medicine, especially in the labeling and color development experiments of cell nucleic acids. It can also be used in the preparation of pigments, inks and dyes.

[0003]

[0004] In the prior art, there are few reports on the preparation method of xylene blue I, and the purity of the synthesized product is not high. Therefore, it is of great significance to find a preparation method of xylene blue I with easy-to-obtain raw materials, simple operation and high purity. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention develops a method for preparing xylidine blue I, which is easy to operate, saves costs, has high product purity, and can meet the needs of large-scale industrial production.

[0006] One of the technical problems to be solved by the present invention is to provide a method for preparing xylidine blue I, comprising the following steps: (1) Add 3-hydroxy-2-naphthoic acid and the first solvent to a reaction flask at room temperature in sequence, stir and slowly add N,N'-carbonyldiimidazole until the solution becomes clear, after the addition is complete, stir and react at room temperature for 0.15-2h, add 2,4-dimethylaniline, stir and react for 1-1.5h until a large amount of solid begins to precipitate, continue stirring and react for 12-24h to obtain N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthoamide; (2) Add 2-aminophenol-4-sulfonic acid, water, and the second solvent to a four-necked flask in sequence, control the temperature below 5°C, and add a sodium nitrite aqueous solution dropwise. After the addition is completed, keep the temperature below 5°C for 1-2 hours to obtain a diazonium salt solution for standby use. Add N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide to an 80% methanol or ethanol aqueous solution of sodium hydroxide or potassium hydroxide, cool to 0-2°C, control the temperature below 5°C, and slowly add the pre-prepared diazonium salt solution dropwise for coupling reaction. At the same time, continue to add a 80% methanol or ethanol aqueous solution of sodium hydroxide or potassium hydroxide dropwise to control the pH to 8-9. After completion, slowly warm the temperature to room temperature and stir for 12-24 hours. Pour the reaction solution into saturated brine, adjust the pH to 5-6 with concentrated hydrochloric acid, and stir to precipitate a reddish-brown solid xylidine blue I. .

[0007] In a preferred embodiment of the present invention, in the above step (1), the first solvent is one or more of tetrahydrofuran, dioxane, dichloromethane, chloroform, and ethyl acetate.

[0008] In a preferred embodiment of the present invention, in the above step (1), the molar ratio of 3-hydroxy-2-naphthoic acid to 2,4-dimethylaniline is 1: 1-1.5.

[0009] In a preferred embodiment of the present invention, in the above step (2), the above second solvent is one or more of hydrochloric acid, sulfuric acid, nitric acid, glacial acetic acid, and tetrafluoroboric acid.

[0010] In a preferred embodiment of the present invention, in the above step (2), the molar ratio of 2-aminophenol-4-sulfonic acid to sodium nitrite is 1:1-1.2.

[0011] In a preferred embodiment of the present invention, in the above step (2), the molar ratio of 2-aminophenol-4-sulfonic acid to N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide is 1:1-1.2.

[0012] In a preferred embodiment of the present invention, the above also includes purifying xylidine blue I by thermal reflux of methanol. Beneficial Effects

[0013] Compared with the existing preparation method of xylidine blue I, the method has convenient raw material sources, simple production process, high purity of the prepared compound product, low cost, is suitable for large-scale industrial production, and has good application prospects. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0015] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources. Example 1

[0016] Preparation of N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide Add 3-hydroxy-2-naphthoic acid (60.2g, 320mmol, 1eq) and 800ml of tetrahydrofuran to a 1000ml four-necked flask, stir at room temperature to dissolve, slowly add N,N'-carbonyldiimidazole (48.34g, 352mmol, 1.1eq), no obvious temperature rise during the addition process, gas is released, and after the addition, stir and react at room temperature for 1h, and the result is still an orange clear liquid. Then add 2,4-dimethylaniline (42.65g, 352mmol, 1.1eq), continue stirring and reacting for 12h, concentrate the reaction solution, add 400ml of water, stir and slurry for 15min, filter, and the obtained crude product is slurried with 400ml of water and 400ml of 3% hydrochloric acid aqueous solution, filtered, and the obtained filter cake is recrystallized with 95% ethanol and vacuum dried to obtain 60g of the product.

[0017] 1 H NMR (400 MHz, DMSO- d6 ): δ=11.84 (br, 1H), 10.47 (s, 1H), 8.68 (s, 1H), 7.95 (d, J = 8.2 Hz, 1H), 7.78 (dd, J 1 = 8.1 Hz, J 2=3.5Hz, 2H), 7.57-7.48 (m, 1H), 7.43-7.33 (m, 1H), 7.37 (s, 1H), 7.11 (d, J = 2.0 Hz, 1H), 7.06 (dd, J 1 = 8.1 Hz, J 2 = 2.1 Hz, 1H), 2.29 (d, J = 2.7 Hz, 6H). Example 2

[0018] Preparation of Xylidine Blue I Add 2-aminophenol-4-sulfonic acid (34.6 g, 182 mmol, 1 eq), 450 ml of water, and 45.5 ml (3 eq) of 37% concentrated hydrochloric acid to a 500 ml four-necked flask, cool to 0°C in an ice + salt water bath, and add 55 ml of a solution of sodium nitrite (13.2 g, 191 mmol, 1.05 eq) dropwise at a temperature below 5°C. After the addition is complete, keep the mixture at this temperature for 1 hour to obtain a diazonium salt solution for later use. N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide (52.96g, 182mmol, 1eq) was added with 400ml of 80% methanol aqueous solution of sodium hydroxide (7.28g, 182mmol, 1eq). The solution became turbid under stirring. The solution was cooled to 2℃ with ice-salt bath and the prepared diazonium salt solution was added dropwise with the temperature controlled below 5℃. Meanwhile, 80% methanol aqueous solution of sodium hydroxide was added dropwise with the pH controlled at 8-9. After the addition was completed, the solution was stirred at room temperature for 15h.

[0019] The reaction solution was poured into 4.5L saturated saline, the pH value was adjusted to 6 with concentrated hydrochloric acid, and stirred. The product precipitated a reddish brown solid, which was filtered and dried to obtain 96g of crude product. The product was extracted with 6*600ml of methanol under hot reflux, and suction filtered while hot. The filtrate was concentrated to 300ml, cooled to 0℃, and crystals were precipitated. The product of xylidine blue I was filtered to obtain 42g, HPLC: 99.07% (220nm). Absorbance: 0.556 (14mg / L, borate buffer + ethanol (50vol%), 600.0 to 610.0 nm calculated based on dry matter).

[0020] 1 H NMR (400 MH, DMSO- d6 ): δ=11.52 (s, 1H), 11.20 (s, 1H), 8.92 (s, 1H), 8.44 (d, J = 8.2Hz, 1H), 8.21 (s, 1H), 8.15 (d, J = 8.2 Hz, 1H), 8.03 (d, J = 7.8 Hz, 1H), 7.80 (t, J = 7.9 Hz, 1H), 7.54 (t, J = 7.8 Hz, 1H), 7.46 (d, J = 8.4 Hz, 1H), 7.11 (s, 1H), 7.09-7.02 (m, 1H), 6.99 (d, J = 8.4 Hz, 1H), 2.41 (s, 3H), 2.28 (s, 3H).

[0021] The above examples are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing xylidine blue I, characterized in that: The steps include: (1) Add 3-hydroxy-2-naphthoic acid and the first solvent to a reaction flask at room temperature in sequence, stir and slowly add N,N'-carbonyldiimidazole until the solution becomes clear, after the addition is complete, stir and react at room temperature for 0.15-2h, add 2,4-dimethylaniline, stir and react for 1-1.5h until a large amount of solid begins to precipitate, continue stirring and react for 12-24h to obtain N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthoamide; (2) Add 2-aminophenol-4-sulfonic acid, water, and the second solvent to a four-necked flask in sequence, control the temperature below 5°C, and add a sodium nitrite aqueous solution dropwise. After the addition is completed, keep the temperature below 5°C for 1-2 hours to obtain a diazonium salt solution for standby use. Add N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide to an 80% methanol or ethanol aqueous solution of sodium hydroxide or potassium hydroxide, cool to 0-2°C, control the temperature below 5°C, and slowly add the pre-prepared diazonium salt solution dropwise for coupling reaction. At the same time, continue to add a 80% methanol or ethanol aqueous solution of sodium hydroxide or potassium hydroxide dropwise to control the pH to 8-9. After completion, slowly warm the temperature to room temperature and stir for 12-24 hours. Pour the reaction solution into saturated brine, adjust the pH to 5-6 with concentrated hydrochloric acid, and stir to precipitate a reddish-brown solid xylidine blue I. 。 2. The preparation method of xylidine blue I according to claim 1, wherein In step (1), the first solvent is one or more of tetrahydrofuran, dioxane, dichloromethane, chloroform, and ethyl acetate.

3. The preparation method of xylidine blue I according to claim 1, wherein In step (1), the molar ratio of 3-hydroxy-2-naphthoic acid to 2,4-dimethylaniline is 1: 1-1.

5.

4. The preparation method of xylidine blue I according to claim 1, wherein In step (2), the second solvent is one or more of hydrochloric acid, sulfuric acid, nitric acid, glacial acetic acid, and tetrafluoroboric acid.

5. The method for preparing methylxylenol blue free acid according to claim 1, characterized in that: In step (2), the molar ratio of 2-aminophenol-4-sulfonic acid to sodium nitrite is 1:1-1.

2.

6. The method for preparing methylxylenol blue free acid according to claim 1, characterized in that: In step (2), the molar ratio of 2-aminophenol-4-sulfonic acid to N-(2,4-dimethylphenyl)-3-hydroxy-2-naphthamide is 1:1-1.

2.

7. The method for preparing methylxylenol blue free acid according to claim 1, characterized in that: The method also includes purifying xylidine blue I by hot reflux of methanol.

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