Preparation method of red vat dye

Abstract

The invention discloses a preparation method of a red vat dye, and relates to the technical field of compound preparation. According to the preparation method of the red vat dye provided by the invention, a halogenated benzoylation reagent is adopted to replace a primary amino group on an ornamental blue parent nucleus, so that the color of the ornamental blue derivative dye can be adjusted to enable the ornamental blue derivative dye to finally present red; according to the invention, the washing liquor compounded by ethanol, ethyl acetate and petroleum ether in a volume ratio of (1-5): (1-2): 1 is used for washing the reaction product, and based on regulation and control on solubility, surface tension and the like, the purity and the yield of the red vat dye product can be synchronously improved, so that the purity of the product is up to 98.9% or above, and the yield is up to 73.01% or above.

Description

Technical Field

[0001] This invention relates to the field of compound preparation technology, and more specifically, to a method for preparing a red vat dye. Background Technology

[0002] Red is one of the three primary colors of light. Its longer wavelength and stronger penetrating power make it widely used. Currently, many researchers have discovered that modifying or transforming the structure of existing compounds can produce different colors. For example, CN114702837A discloses that introducing the same substituent at different positions in the core of an azo compound can transform the compound from orange to red. Among many compound cores, blue pigment, as a natural blue pigment obtained through microbial fermentation, is simple and environmentally friendly to acquire. Therefore, how to efficiently chemically modify it to produce a red color is of great significance to the dye industry. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for preparing a red vat dye. This method modifies the chemical structure of the blue core, enabling the blue dye to turn red.

[0004] The above-mentioned objective of this invention is achieved through the following technical solution: A method for preparing a red vat dye includes the following steps: The blue dye and the halobenzoylating agent were reacted in a solvent at a temperature of 180-210℃ and in the presence of a catalyst for 1-3 hours. The crude solid was separated from the solid and then washed with a cleaning agent and dried to obtain the red vat dye. The halogenated benzoylating agent includes at least one of 2,4-dihalobenzoyl halide, 2,4-dihalobenzoamide, and 2,4-dihalobenzoic acid ester. The molar ratio of the blue and the halogenated benzoylating agent is 1:(2-4). The cleaning agent comprises ethanol, ethyl acetate and petroleum ether in a volume ratio of (1-5):(1-2):1.

[0005] This invention provides a method for preparing a red vat dye. By replacing the primary amino group on the core of the blue alumina with a benzoyl halide reagent, the color of the blue alumina derivative dye can be adjusted to ultimately produce a red color. The red vat dye obtained by this invention is N,N'-di-m-dichlorobenzoyl blue alumina, wherein N,N'-di-m-dichlorobenzoyl blue alumina has the structure shown in the following formula: .

[0006] The inventors of this application have discovered that the reaction between the halogenated benzoylating agent and Vibrant Blue requires a temperature of 180-210°C and the presence of a catalyst in the system. If the temperature is too low or there is no catalyst in the system, the reactants cannot easily overcome the corresponding potential barriers to react; if the temperature is too high, side reactions are likely to occur. Furthermore, in order to ensure that the product is a disubstituted red dye (monosubstituted dyes cannot produce red) and to prevent excessive self-coupling and other side reactions in the system, this application also requires limiting the molar ratio of Vibrant Blue to the halogenated benzoylating agent to 1:(2-4).

[0007] Besides the specific requirements for reaction conditions, post-reaction cleaning and impurity removal are essential to improve the purity of the product and make it suitable for industrial applications. The inventors discovered that a washing solution prepared from ethanol, ethyl acetate, and petroleum ether in a volume ratio of (1-5):(1-2):1) has lower surface tension, allowing it to easily penetrate the gaps and surface of the product. This effectively removes and dissolves impurities (including unreacted reactants and undesirable byproducts, such as the product that benzoylatees the secondary amino group on the core of *Gynostemma pentaphyllum*; and halogenated benzoylating agents, such as 2,4-dichlorobenzoyl chloride, which react with *Gynostemma pentaphyllum* to produce hydrochloric acid, also considered impurities) from the product surface, thus improving product purity. Furthermore, the self-prepared washing solution of this invention has very low solubility in the product, reducing washing losses and even increasing the product yield. This is presumably because the difference in solubility between the washing agent and the residual solvent on the product surface allows the residual solvent to have an extraction effect, increasing the product concentration in the solvent and its crystallization and precipitation capabilities.

[0008] Preferably, the mass ratio of the cleaning agent to the crude solid is (5-8):1.

[0009] If the volume of the cleaning agent is too low and the amount used is too small, a good cleaning effect cannot be achieved, and the yield and purity of the product will decrease to a certain extent. However, if the amount of cleaning agent is further increased from the 8:1 ratio, the effect on the reaction effect will not be improved, and the cost will increase.

[0010] Preferably, the molar ratio of the blue and the halogenated benzoylating agent is 1:(2-3).

[0011] More preferably, the halogenated benzoylating agent includes 2,4-dihalobenzoyl halide.

[0012] More preferably, the 2,4-dihalobenzoyl halide includes 2,4-dichlorobenzoyl chloride. Using an acyl halide as the acylation reagent results in a higher yield.

[0013] Preferably, the solvent includes at least one of dichloromethane, acetonitrile, pyrrolidone, tetrahydrofuran, benzoyl chloride, dimethyl sulfoxide, and dimethylformamide.

[0014] More preferably, the solvent comprises pyrrolidone and tetrahydrofuran in a volume ratio of (5-8):(0.5-5).

[0015] More preferably, the solvent comprises pyrrolidone and tetrahydrofuran in a volume ratio of (6-7):(3-4).

[0016] By using compound solvents, the viscosity of the reaction system can be adjusted, allowing the reactants to be better dispersed, which is beneficial to the reaction.

[0017] More preferably, the mass ratio of the blue pigment to the solvent is 1:(1-6).

[0018] More preferably, the mass ratio of the blue pigment to the solvent is 1:(3-4).

[0019] Preferably, the catalyst comprises a Lewis base catalyst.

[0020] More preferably, the Lewis base catalyst comprises 4-dimethylaminopyridine.

[0021] 4-Dimethylaminopyridine (DMAP), as a nucleophilic Lewis base catalyst, can donate electron pairs in the reaction system to form a nucleophilic intermediate that attacks the acyl carbon of dichlorobenzoyl chloride, generating DMAP-CO-C6H3Cl2. + Intermediate, while observing the blue amino group attacking DMAP-CO-C6H3Cl2 + It can efficiently generate the target product.

[0022] More preferably, the mass ratio of the catalyst to the blue violet is (0.5-3):100.

[0023] Preferably, the reaction is carried out under reflux conditions.

[0024] Preferably, the reaction temperature is 195-205℃ and the time is 2-3 h.

[0025] Preferably, the solid-liquid separation is performed by centrifugation.

[0026] Preferably, the drying temperature is 60-80°C.

[0027] Compared with the prior art, the present invention has the following beneficial effects: The compound preparation method provided by this invention, based on the structural modification of the safflower core, enables the compound to emit a red color, and the reaction substrate is environmentally friendly and safe safflower. Furthermore, based on the specific selection of the crude product cleaning agent in this invention, a product with a purity of over 98.9% and a yield of over 73.01% can be obtained, with efficient processing and low cost. Attached Figure Description

[0028] Figure 1 The image shows the HPLC chromatogram of the red vat dye obtained in Example 1.

[0029] Figure 2 The image shows the ultraviolet absorption spectrum of the red vat dye obtained in Example 1.

[0030] Figure 3 The image shows the 1H NMR spectrum of the red reducing dye obtained in Example 1.

[0031] Figure 4 The image shows the MS spectrum of the red vat dye obtained in Example 1.

[0032] Figure 5 The images show optical photographs of the red vat dye and its solution obtained in Example 1. Figure a) shows the solid powder of the compound, and Figure b) shows the solutions obtained by dissolving the dye at different concentrations in DMSO. The concentrations from left to right are 3 g / L, 5 g / L, 7 g / L, and 9 g / L. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0034] The high-performance liquid chromatography (HPLC) detection method for the product is described in the following examples.

[0035] Chromatographic conditions: Mobile phase: gradient elution of methanol and pure water, as shown in the gradient table below: Wavelength 600 nm, flow rate 1.0 mL / min, sample solution: DMSO, injection volume: 10 μL, column temperature 35℃, run time 20 min. Column: Galasil EF-C18M 4.6 mmid × 250 mm L (SN B06211801).

[0036] Example 1 A method for preparing a red vat dye includes the following steps: In a solvent containing the catalyst 4-dimethylaminopyridine, a red vat dye was obtained by reflux reaction of 1:2.5 of chlorin and 2,4-dichlorobenzoyl chloride at a molar ratio of 1:2.5 for 2.5 h. The crude solid was collected by centrifugation, then washed with a cleaning agent and dried at 80 °C. The solvent comprises pyrrolidone and tetrahydrofuran in a volume ratio of 7:3, and the mass ratio of blue to solvent is 1:3; The mass ratio of the catalyst to the blue violet is 1:100; The cleaning agent comprises ethanol, ethyl acetate and petroleum ether in a volume ratio of 3:1:1, and the mass ratio of the cleaning agent to the crude solid is 5:1.

[0037] The red vat dye obtained in this embodiment was tested, and the results are as follows: Figure 1-4 As shown, the main product is N,N'-di-m-dichlorobenzoyl blue, which eluted at 18.26 min in HPLC and had an absorption wavelength of 497 nm. The NMR elution peaks of N,N'-di-m-dichlorobenzoyl blue are as follows: 1H NMR (400 MHz, DMSO-d6) δ9.79 (s, 1H), 9.34 (s, 1H), 7.64 (s, 1H), 7.58 (s, 1H), 7.55 (d, 1H), 7.44 (d, 1H).

[0038] Mass spectrometry: [M / Z 591].

[0039] Example 2 A method for preparing a red vat dye, wherein the only difference from Example 1 is: Replace 2,4-dichlorobenzoyl chloride with an equimolar amount of 2,4-dichlorobenzamide, and use a solvent comprising pyrrolidone and tetrahydrofuran in a volume ratio of 8:0.5.

[0040] Example 3 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent consists of ethanol, ethyl acetate and petroleum ether in a volume ratio of 5:2:1, and the volume ratio of the cleaning agent to the crude solid is 5:1.

[0041] Example 4 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent consists of ethanol, ethyl acetate and petroleum ether in a volume ratio of 1:2:1, and the volume ratio of the cleaning agent to the crude solid is 8:1.

[0042] Example 5 A method for preparing a red vat dye, wherein the only difference from Example 1 is: In the solvent, tetrahydrofuran is replaced with an equal volume of pyrrolidone.

[0043] Example 6 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The mass ratio of blue to solvent was 1:6, the reflux reaction temperature was 210℃, the reaction time was 1 h, and the molar ratio of blue to 2,4-dichlorobenzoyl chloride was 1:4.

[0044] Example 7 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The mass ratio of blue to solvent was 1:1, the reflux reaction temperature was 180℃, the reaction time was 3 h, and the molar ratio of blue to 2,4-dichlorobenzoyl chloride was 1:2.

[0045] Example 8 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The catalyst is an equal mass of aluminum fluoride.

[0046] Example 9 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The solvent is a mixture of pyrrolidone and tetrahydrofuran in a volume ratio of 5:5.

[0047] Example 10 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The solvent is pyrrolidone and tetrahydrofuran in a volume ratio of 10:0.5.

[0048] Example 11 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The solvent is pyrrolidone and tetrahydrofuran in a volume ratio of 7:10.

[0049] Example 12 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The solvent is used to replace pyrrolidone with an equal volume of tetrahydrofuran.

[0050] Comparative Example 1 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The reaction temperature is 170℃.

[0051] Comparative Example 2 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The reaction temperature is 220℃.

[0052] Comparative Example 3 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol.

[0053] Comparative Example 4 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethyl acetate.

[0054] Comparative Example 5 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is petroleum ether.

[0055] Comparative Example 6 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol, ethyl acetate and diethyl ether in a volume ratio of 3:1:1.

[0056] Comparative Example 7 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is methanol.

[0057] Comparative Example 8 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol, propyl acetate and petroleum ether in a volume ratio of 3:1:1.

[0058] Comparative Example 9 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol and ethyl acetate in a volume ratio of 3:1.

[0059] Comparative Example 10 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol and petroleum ether in a volume ratio of 3:1.

[0060] Comparative Example 11 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is a mixture of ethyl acetate and petroleum ether in a volume ratio of 3:1.

[0061] Comparative Example 12 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol, ethyl acetate and petroleum ether in a volume ratio of 7:2:1.

[0062] Comparative Example 13 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is a mixture of ethanol, ethyl acetate and petroleum ether in a volume ratio of 0.5:2:1.

[0063] Comparative Example 14 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol, ethyl acetate and petroleum ether in a volume ratio of 3:0.5:1.

[0064] Comparative Example 15 A method for preparing a red vat dye, wherein the only difference from Example 1 is: The cleaning agent is ethanol, ethyl acetate and petroleum ether in a volume ratio of 3:5:1.

[0065] Performance testing Purity and yield testing: The purity and yield of N,N'-di-m-dichlorobenzoyl blue obtained in the examples and comparative examples were tested by high performance liquid chromatography.

[0066] The test results are shown in Table 1 below: Table 1. As can be seen from the data in Table 1 above, the compound preparation method provided by this invention, based on the structural modification of the safflower core, enables the compound to emit a red color, and the reaction substrate is environmentally friendly and safe safflower. Furthermore, based on the screening of cleaning agents, the product purity of this invention is as high as 97.9% or more, and the yield is as high as 61.23% or more, demonstrating high efficiency and low cost.

[0067] According to Examples 1, 5, 9-12, the present invention preferably uses a mixture of pyrrolidone and tetrahydrofuran in a volume ratio of (5-8):(0.5-5) to form a solvent for providing the reaction system, which can adjust the viscosity of the reaction system, so as to achieve better dispersion of the reactants and facilitate the reaction (Examples 1, 9).

[0068] According to Comparative Examples 1-2, an unsuitable reaction temperature will prevent the formation of the desired product.

[0069] According to Comparative Example 3-15, the absence of any one or two components in the cleaning agent, or the replacement of a specific component with another similar cleaning agent, will not be able to fully remove impurities, thus affecting the purity.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a red vat dye, characterized in that, Includes the following steps: The blue dye and the halobenzoylating agent were reacted in a solvent at a temperature of 180-210℃ and in the presence of a catalyst for 1-3 h. The crude solid was separated from the solid and then washed with a cleaning agent and dried to obtain the red vat dye. The halogenated benzoylating agent includes at least one of 2,4-dihalobenzoyl halide, 2,4-dihalobenzoamide, and 2,4-dihalobenzoic acid ester. The molar ratio of the blue and the halogenated benzoylating agent is 1:(2-4). The cleaning agent comprises ethanol, ethyl acetate and petroleum ether in a volume ratio of (1-5):(1-2):

1.

2. The method for preparing red vat dye as described in claim 1, characterized in that, The mass ratio of the cleaning agent to the crude solid is (5-8):

1.

3. The method for preparing red vat dye as described in claim 1, characterized in that, The halogenated benzoylating agent includes 2,4-dihalobenzoyl halide.

4. The method for preparing the red vat dye as described in claim 1, characterized in that, The solvent includes at least one of dichloromethane, acetonitrile, pyrrolidone, tetrahydrofuran, benzoyl chloride, dimethyl sulfoxide, and dimethylformamide.

5. The method for preparing the red vat dye as described in claim 4, characterized in that, The solvent comprises pyrrolidone and tetrahydrofuran in a volume ratio of (5-8):(0.5-5).

6. The method for preparing the red vat dye as described in claim 4 or 5, characterized in that, The mass ratio of the blue pigment to the solvent is 1:(1-6).

7. The method for preparing red vat dye as described in claim 1, characterized in that, The catalyst includes a Lewis base catalyst.

8. The method for preparing the red vat dye as described in claim 7, characterized in that, The Lewis base catalyst includes 4-dimethylaminopyridine.

9. The method for preparing the red vat dye as described in claim 7, characterized in that, The mass ratio of the catalyst to the blue violet is (0.5-3):

100.

10. The method for preparing the red vat dye as described in claim 1, characterized in that, The reaction was carried out under reflux conditions; And / or, the reaction is carried out at a temperature of 195-205°C for 2-3 hours.

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