Preparation method of environment-friendly dye intermediate and environment-friendly dye intermediate prepared by using method

Abstract

The invention relates to a preparation method of an environment-friendly dye intermediate and the environment-friendly dye intermediate prepared by the method. The preparation method of the environment-friendly dye intermediate comprises the following steps: a dissolving step: 2-R-4-nitroaniline and halate are dissolved in an organic solvent to obtain an initial solution, the chemical structural formula of the 2-R-4-nitroaniline is shown in the formula (1), R represents-Cl,-Br or-CN: (1); a reaction step: hydrogen chloride gas is introduced into the initial solution for a reaction, and a reaction product is obtained; and a separation step: carrying out separation treatment on the reaction product to obtain mother liquor and a crude product. The preparation method of the environment-friendly dye intermediate is more reasonable in process, and the organic solvent is used in the preparation process, so that the environment-friendly index of the product reaches the standard, and no high-COC and / or PCP sewage is discharged.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of an environmentally friendly dye intermediate and an environmentally friendly dye intermediate prepared by using the method, and belongs to the field of fine chemical synthesis. BACKGROUND

[0002] Disperse dyes are the largest category of dyes at present, which are mainly used for dyeing hydrophobic synthetic fibers such as polyester. 2-R-4-nitro-6-chloroaniline (R represents -Cl, -Br or -CN) is an important intermediate for synthesizing various azo disperse dyes, and is also an intermediate for synthesizing heterocyclic compounds.

[0003] The existing production method of 2-R-4-nitro-6-chloroaniline is mainly aqueous phase method, which is to add 2-R-4-nitroaniline to the slurry after dilute hydrochloric acid is used as a primer, and then dropwise add sodium chlorate solution for chlorination to synthesize 2-R-4-nitro-6-chloroaniline.

[0004] When using the above synthesis method, there are two specific implementation schemes of one-time input of 2-R-4-nitroaniline slurry and batch input and gradual reaction. The one-time input scheme is simple to operate, and the yield is acceptable, but the liquid phase purity is relatively low, generally 92-95%. The yield and purity of the batch input scheme can be acceptable, but the consumption of sodium chlorate is higher than that of the one-time input scheme. Both of the above synthesis schemes have the problem of exceeding the standard of COC (polychlorobenzene) and PCP (polychlorophenol) in the product, which does not meet the current requirements of the dye industry.

[0005] In addition, when R represents -CN, chloronitroamine and cuprous cyanide synthesis can also be used. When chloronitroamine and cuprous cyanide synthesis generates the target product 2-cyano-4-nitro-6-chloroaniline, there will be by-product cuprous chloride, which not only has high production cost, but also affects the application performance of the subsequent synthesized dyes if the copper ions are not removed completely.

[0006] Chinese patent application CN111517963A discloses a preparation method of environmentally friendly 2,6-dichloro-4-nitroaniline. The method comprises the following steps: first, o-dichlorobenzene is added to a solution of nitric acid and sulfuric acid to obtain m-nitro-1,2-dichlorobenzene; second, the m-nitro-1,2-dichlorobenzene obtained in the first step is added to an ammonia solution to obtain 2-chloro-4-nitroaniline; third, hydrochloric acid and hydrogen peroxide solution are added dropwise to the 2-chloro-4-nitroaniline obtained in the second step. The step of the above-mentioned environmentally friendly synthesis scheme in this scheme is to chlorinate with hydrogen peroxide. Even in the case of excess hydrogen peroxide, it is not easy to produce polychlorobenzene substances. However, the amount of hydrogen peroxide used in the chlorination process is larger than that of sodium chlorate, the solid content of the reaction system is lower, and the production efficiency is lower. SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In view of the technical problems existing in the prior art, the present application first provides a preparation method of an environmentally friendly dye intermediate, the preparation method of the environmentally friendly dye intermediate of the present application has high purity and yield of the environmentally friendly dye intermediate prepared, and the environmental protection index is qualified.

[0009] Further, the preparation method of the environmentally friendly dye intermediate of the present application is more reasonable in process, the organic solvent is used in the preparation process of the present application, the product environmental protection index is up to standard, and there is no high COC and / or PCP sewage discharge. Moreover, the mother liquor and part of the washing water generated by the method of the present application are basically realized, the sewage treatment cost is reduced, the production cost is lower, and it is more environmentally friendly, and it is suitable for mass production.

[0010] The solution for solving the problem

[0011] The present application provides a preparation method of an environmentally friendly dye intermediate, which comprises the following steps:

[0012] The dissolution step: 2-R-4-nitroaniline and halide are dissolved in an organic solvent to obtain an initial solution, wherein the chemical structural formula of 2-R-4-nitroaniline is shown as formula (1), and R represents -Cl, -Br or -CN:

[0013] (1) ;

[0014] The reaction step: hydrogen chloride gas is introduced into the initial solution to react to obtain a reaction product.

[0015] The separation step: the reaction product is separated and treated to obtain a mother liquor and a crude product.

[0016] According to the preparation method of the present application, the temperature of the dissolution step is 10-32℃; and / or,

[0017] The mass ratio of the organic solvent to the 2-R-4-nitroaniline is 3-6:1; and the molar ratio of the halide to the 2-R-4-nitroaniline is 0.33-0.5:1.

[0018] According to the preparation method of the present application, in the reaction step, the reaction temperature is below 32℃, and the reaction time is 1-2h; and / or,

[0019] The amount of hydrogen chloride introduced is 1.2-2 times the molar equivalent of 2-R-4-nitroaniline.

[0020] According to the preparation method of the present application, the reaction step further comprises a step of heat preservation and maturation.

[0021] The preparation method according to the present application, wherein the temperature of the heat preservation and ripening is 40-60 DEG C, and the time of the heat preservation and ripening is 1-2 hours.

[0022] The preparation method according to the present application, wherein the reaction end point of the reaction step is that the content of 2-R-4-nitroaniline is less than 0.01%.

[0023] The preparation method according to the present application, wherein the preparation method further comprises a step of recycling mother liquor, preferably, the temperature of the recycling mother liquor is less than 32 DEG C.

[0024] The preparation method according to the present application, wherein the preparation method further comprises a post-treatment step; the post-treatment step comprises a step of beating the crude product with water to obtain a beaten product.

[0025] The preparation method according to the present application, wherein in the beating process, the amount of water is 3-4 times of the mass of the crude product, and the time of the beating is 30-60 min.

[0026] The present application further provides an environmentally-friendly dye intermediate prepared by the preparation method.

[0027] Effects of the present application

[0028] The preparation method of the environmentally-friendly dye intermediate is more reasonable, and the organic solvent is used in the preparation process, so that the product meets the environmental protection index and has no high COC and / or PCP sewage discharge.

[0029] The preparation method of the environmentally-friendly dye intermediate has high purity, high yield and qualified environmental protection index. DETAILED DESCRIPTION

[0030] Various exemplary embodiments, features, and aspects of the present application are explained in detail in the following. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0031] In addition, in order to better illustrate the present application, numerous specific details are given in the following detailed description. Those skilled in the art should understand that the present application can be implemented without some specific details. In some other examples, methods, means, apparatuses and steps that are well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Unless otherwise required by context, singular terms shall include pluralities and vice versa. The nomenclature used herein is merely intended to be exemplary and is not intended to be limiting. The use of "may" and "can" indicates that a

[0033] In the present specification, the meaning indicated by "may" is included both the meaning of performing a certain process and the meaning of not performing a certain process.

[0034] In the present specification, the expressions "some embodiments", "other embodiments", "exemplary embodiments", etc. mean that specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiment include at least one of the embodiments described herein and can be present in other embodiments or can be absent in other embodiments. In addition, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0035] In the present specification, the numerical range indicated by "numerical value A ~ numerical value B" means a range including the end point values A, B.

[0036] <First aspect>

[0037] The first aspect of the present application provides a preparation method of an environmentally friendly dye intermediate, comprising the following steps:

[0038] The dissolving step is to dissolve 2-R-4-nitroaniline and halide in an organic solvent to obtain an initial solution, wherein the chemical structural formula of 2-R-4-nitroaniline is shown in formula (1), and R represents -Cl, -Br or -CN.

[0039] (1) ;

[0040] The reaction step is to pass hydrogen chloride gas into the initial solution to react and obtain a reaction product.

[0041] The separation step is to separate and process the reaction product to obtain a mother liquor and a crude product.

[0042] dissolution step

[0043] 2-R-4-nitroaniline and halide are dissolved in an organic solvent to obtain an initial solution, wherein R represents -Cl, -Br or -CN.

[0044] Specifically, the dissolving step includes adding an organic solvent in a reaction kettle, then adding 2-R-4-nitroaniline to stir and dissolve, and finally adding halide to stir and dissolve.

[0045] The inventors of the present application found in experiments that the organic solvent has very good solubility for the product, and after the reaction is completed, the product is basically dissolved in the solvent, only a small amount of solid can be precipitated, so that the mother liquor can be recycled.

[0046] In order to better carry out the reaction, the temperature of the dissolving step is 10-32℃, for example: 12℃, 15℃, 18℃, 20℃, 22℃, 25℃, 28℃, 30℃, etc., which can generally be carried out at room temperature.

[0047] In some specific embodiments, the mass ratio of the organic solvent to 2-R-4-nitroaniline is 3-6:1, for example: 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1, 5.2:1, 5.5:1, 5.8:1, etc. When the mass ratio of the organic solvent to 2-R-4-nitroaniline is 3-6:1, the organic solvent can better dissolve various raw materials required for the reaction, and the product can be precipitated at the end of the reaction.

[0048] Further, the molar ratio of the halide salt to the raw material 2-R-4-nitroaniline is 0.33-0.5:1, for example: 0.35:1, 0.38:1, 0.4:1, 0.42:1, 0.45:1, 0.48:1, etc.; when the molar ratio of the halide salt to the raw material 2-R-4-nitroaniline is 0.33-0.5:1, the subsequent reaction can be carried out sufficiently, and the conversion rate of the raw material can be greater than 99%.

[0049] Specifically, in the present application, the halide salt can be sodium chlorate and / or potassium chlorate; the organic solvent can be one or a combination of two or more of dimethylformamide (DMF), diethylformamide, methanol, N-methylpyrrolidone, dimethylacetamide, etc. As preferred, when dimethylformamide is used as the solvent, it has the best solubility, and the conversion rate of 2-R-4-nitroaniline is the highest.

[0050] reaction step

[0051] The hydrogen chloride gas is introduced into the initial solution to carry out the reaction, and the reaction product is obtained.

[0052] Specifically, in the reaction step, the reaction temperature is 32℃ or lower, preferably 20-32℃, for example: 22℃, 24℃, 26℃, 28℃, 30℃, etc.; the reaction time is 1-2h, 1.2h, 1.4h, 1.6h, 1.8h, etc. The end point of the reaction step is that the content of 2-R-4-nitroaniline is 0.01% or lower. Specifically, HPLC high performance liquid chromatography can be used for detection.

[0053] The inventor of the present application found that, in the middle of the reaction, increasing the temperature of the reaction system can significantly accelerate the reaction speed, but in the middle control sample detection and finished product detection, the COC value is higher than that of the reaction product under the experimental conditions, and the over-standard multiple is more. Therefore, the reaction temperature is controlled to be below 32℃, so that the reaction can proceed better.

[0054] Further, in the reaction step of the present application, the molar equivalent of hydrogen chloride introduced is 1.2-2 times that of the raw material, for example: 1.4 times, 1.6 times, 1.8 times, etc.; considering the reaction conversion rate of the main raw material and the escape of hydrogen chloride during the reaction, the usage amount is appropriately increased, for example, 1.2-2 molar equivalents can make the reaction more fully completed, and the first batch of reaction can use 1.7-2 molar equivalents because there is no mother liquor to be used, and the subsequent mother liquor can be appropriately reduced after being used.

[0055] In some specific embodiments, the reaction step further comprises a step of incubation and curing; preferably, the temperature of incubation and curing is 40-60℃, for example: 42℃, 45℃, 48℃, 50℃, 52℃, 55℃, 58℃, etc.; the time of incubation and curing is 1-2 hours, 1.2h, 1.4h, 1.6h, 1.8h, etc.

[0056] Specifically, if the reaction is incubated and cured for 1-2 hours after the hydrogen chloride gas is introduced, and the reaction endpoint is detected by liquid phase detection, if the sample is not at the endpoint (the solid precipitate HPLC high performance liquid chromatography detects that the raw material is not reduced to below 0.01%) after 1-2 hours of hydrogen chloride gas introduction, the system can be warmed to 45-55℃ and incubated and cured for 1-2 hours until the detection is qualified. It has been verified by experiments that, in the late reaction period close to the endpoint, appropriately increasing the system temperature can accelerate the reaction process, and will not cause the COC and PCP detection to exceed the standard.

[0057] In some specific embodiments, the 2-R-4-nitroaniline includes one or a combination of two or more of 2-cyano-4-nitroaniline, 2-bromo-4-nitroaniline, and 2-chloro-4-nitroaniline.

[0058] separation step

[0059] The reaction product is subjected to separation treatment to obtain a mother liquor and a crude product. In the separation step, the reaction product is separated, and the mother liquor is collected for reuse. The present application does not make special limitations on the separation method, which can be a separation step commonly used in the art.

[0060] When the product and the mother liquor are separated, the residual mother liquor in the product is minimized, and the excess residual mother liquor increases the water consumption in the subsequent washing step.

[0061] Further, in some specific embodiments, the preparation method further comprises a step of recycling the mother liquor, preferably, the temperature of the mother liquor during recycling is below 32℃. During the recycling of the mother liquor, the temperature of the solution system will rise when the halide salt is pulped, therefore, the system needs to be cooled to keep the temperature below 32℃. During the recycling of the mother liquor, there is a small amount of unreacted raw material (mainly hydrogen chloride) in the mother liquor, when the next batch of 2-R-4-nitroaniline is put into the mother liquor and dissolved, and then the solid halide salt is put in for dissolution, the reaction can directly start during the dissolution process, at this time, if the heat of the reaction is not removed, the temperature of the system will exceed 32℃, and in the case of a large amount of raw material, the temperature is too high to cause the generation of COC or PCP.

[0062] work-up step

[0063] In some specific embodiments, the preparation method further comprises a post-treatment step; the post-treatment step comprises a step of pulping the crude product with water to obtain a pulped product.

[0064] The pulping of the crude product with water is mainly to separate the residual organic solvents, inorganic salts, etc. in the crude product. The organic solvents can be miscible with water, and sodium chloride has a large solubility in water. It has been verified by experiments that the impurities in the crude product can be fully separated by adding 3-4 times the mass of water, and the slurry has good flowability.

[0065] Specifically, the amount of water for pulping is 3-4 times the mass of the separated crude product, for example: 3.2 times, 3.4 times, 3.6 times, 3.8 times, etc.; the pulping time is 30-60 min, for example: 32 min, 35 min, 38 min, 40 min, 45 min, 48 min, etc.

[0066] Further, the pulped product can be washed. The washing water is 1-2 times the mass of the crude product, for example: 1.2 times, 1.4 times, 1.6 times, 1.8 times, etc.; since the organic solvents and sodium chloride basically enter the water phase during pulping, the amount of washing water is small, and the filter cake can be fully washed with 1-2 times the mass of the crude product.

[0067] <Second aspect>

[0068] The second aspect of the present application provides an environmentally friendly dye intermediate prepared by the preparation method of the first aspect of the present application. The preparation method of the environmentally friendly dye intermediate of the present application can prepare an environmentally friendly dye intermediate with high purity, high yield and qualified environmental indicators.

[0069] Examples

[0070] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. The specific conditions not noted in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not noted by the manufacturer, which are all conventional products that can be obtained by purchase.

[0071] Example 1

[0072] Into a 500 mL flask with stirring, thermometer, 371 g (99%) DMF (10.202 mol) was added, the stirring was started, 83.03 g (98.3%) 2-cyano-4-nitroaniline (0.5 mol) was added, 19.17 g (99%) sodium chlorate (0.179 mol) was added, and the stirring was continued until the solution was clear. Then 34.87 g (99.9%) hydrogen chloride (0.955 mol) was bubbled in at 28-32°C, and the reaction was kept for 1 hour after the end of the bubbling. After the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%) was determined by HPLC, the solution was filtered. The mother liquor was 485.08 g, which was used for subsequent use. The crude product filter cake was 19.56 g, which was washed with about 70 g of water for about 40 min, and then washed with 20 g of water and dried to obtain 2-cyano-4-nitro-6-chloroaniline 10.2 g with a purity of 99.6%.

[0073] Example 2

[0074] Into a 500 mL flask with stirring, thermometer, 371 g (99%) DMF (10.202 mol) was added, the stirring was started, 83.03 g (98.3%) 2-cyano-4-nitroaniline (0.5 mol) was added, 19.17 g (99%) sodium chlorate (0.179 mol) was added, and the stirring was continued until the solution was clear. Then 34.87 g (99.9%) hydrogen chloride (0.955 mol) was bubbled in at 28-32°C, and the reaction was kept for 1 hour after the end of the bubbling. After the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%) was determined by HPLC, the solution was filtered. The mother liquor was 485.08 g, which was used for subsequent use. The crude product filter cake was 19.56 g, which was washed with about 70 g of water for about 40 min, and then washed with 20 g of water and dried to obtain 2-cyano-4-nitro-6-chloroaniline 10.2 g with a purity of 99.6%.

[0075] Example 3

[0076] In a 500 mL flask with stirring, thermometer, 440.51 g of the mother liquor of Example 3 was added, and stirring was started. 83.03 g (98.3%) of 2-cyano-4-nitroaniline (0.5 mol) was added below 32°C, and 19.17 g (99%) of sodium chlorate (0.179 mol) was added. After stirring until dissolution, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C, and after the addition was completed, the temperature was maintained for 2 hours. HPLC was used to determine that the end point was not qualified (the content of the raw material 2-cyano-4-nitroaniline was 0.04%). The temperature was increased to about 50°C, and the mixture was maintained for 1 hour. After HPLC was used to determine that the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%), the mixture was filtered. The mother liquor was 423.55 g, and was used for subsequent use. The crude product filter cake was 143.33 g. After the filter cake was washed with 500 g of water for about 40 min, and then washed with 180 g of water, 2-cyano-4-nitro-6-chloroaniline was obtained in a yield of 115.5 g and a purity of 99.4%.

[0077] Example 4

[0078] In a 500 mL flask with stirring, thermometer, 440.51 g of the mother liquor of Example 3 was added, and stirring was started. 83.03 g (98.3%) of 2-cyano-4-nitroaniline (0.5 mol) was added below 32°C, and 19.17 g (99%) of sodium chlorate (0.179 mol) was added. After stirring until dissolution, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C, and after the addition was completed, the temperature was maintained for 2 hours. HPLC was used to determine that the end point was not qualified (the content of the raw material 2-cyano-4-nitroaniline was 0.04%). The temperature was increased to about 50°C, and the mixture was maintained for 1 hour. After HPLC was used to determine that the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%), the mixture was filtered. The mother liquor was 423.55 g, and was used for subsequent use. The crude product filter cake was 143.33 g. After the filter cake was washed with 500 g of water for about 40 min, and then washed with 180 g of water, 2-cyano-4-nitro-6-chloroaniline was obtained in a yield of 115.5 g and a purity of 99.4%.

[0079] Example 5

[0080] In a 500 mL flask with stirring, thermometer, 423.55 g of the mother liquor of Example 4 was added, the stirring was started, 83.03 g (98.3%) of 2-cyano-4-nitroaniline (0.5 mol) was added below 32°C, 19.17 g (99%) of sodium chlorate (0.179 mol) was added, stirring until dissolved, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C, after the addition was completed, it was kept for 2 hours, HPLC was used to measure the end point, the content of the raw material 2-cyano-4-nitroaniline was 0.08%, the temperature was increased to about 50°C, and it was kept for 1 hour to mature, after the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%) was measured by HPLC, it was filtered, 415.00 g of the mother liquor was obtained, and the mother liquor was used for subsequent use; the crude product filter cake 135.09 g was added to 480 g of water and stirred for about 40 min, then washed with 180 g of water and dried to obtain 2-cyano-4-nitro-6-chloroaniline 108.3 g, purity 99.2%.

[0081] Example 6

[0082] In a 500 mL flask with stirring, thermometer, 423.55 g of the mother liquor of Example 4 was added, the stirring was started, 83.03 g (98.3%) of 2-cyano-4-nitroaniline (0.5 mol) was added below 32°C, 19.17 g (99%) of sodium chlorate (0.179 mol) was added, stirring until dissolved, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C, after the addition was completed, it was kept for 2 hours, HPLC was used to measure the end point, the content of the raw material 2-cyano-4-nitroaniline was 0.08%, the temperature was increased to about 50°C, and it was kept for 1 hour to mature, after the end point was qualified (the content of the raw material 2-cyano-4-nitroaniline was less than 0.01%) was measured by HPLC, it was filtered, 415.00 g of the mother liquor was obtained, and the mother liquor was used for subsequent use; the crude product filter cake 135.09 g was added to 480 g of water and stirred for about 40 min, then washed with 180 g of water and dried to obtain 2-cyano-4-nitro-6-chloroaniline 108.3 g, purity 99.2%.

[0083] Example 7

[0084] In a 500 mL flask with stirring, thermometer, add 371 g (99%) DMF (10.202 mol), open the stirring, below the temperature of 32 ℃, add 88.07 g (98.5%) 2-chloro-4-nitroaniline (0.5 mol), add 19.17 g (99%) sodium chlorate (0.179 mol), stir until dissolved, temperature 28-32 ℃, 34.87 g (99.9%) hydrogen chloride (0.955 mol) is passed in, after the end of the pass, 1 hour, using HPLC high performance liquid chromatography (HPLC) end point qualified (raw material 2-chloro-4-nitroaniline content less than 0.01%) after suction filtration, the mother liquor 483.1 g, the mother liquor for subsequent use; crude product filter cake 29.8 g, add 100 g water, pulp about 40 min, then use 40 g water washing and drying, get 2,6-dichloro-4-nitroaniline 15.5 g, purity 99.5%.

[0085] Example 8

[0086] In a 500 mL flask with stirring, thermometer, add 483.1 g of the mother liquor of Example 7, open the stirring, below the temperature of 32 ℃, add 88.07 g (98.5%) 2-chloro-4-nitroaniline (0.5 mol), add 19.17 g (99%) sodium chlorate (0.179 mol), stir until dissolved, temperature 28-32 ℃, 26.68 g (99.9%) hydrogen chloride (0.731 mol) is passed in, after the end of the pass, 1 hour, using HPLC high performance liquid chromatography (HPLC) end point unqualified (raw material 2-chloro-4-nitroaniline content of 0.03%), heating to about 50 ℃, 1 hour, using HPLC high performance liquid chromatography (HPLC) end point qualified (raw material 2-chloro-4-nitroaniline content less than 0.01%) after suction filtration, the mother liquor 469.38 g, the mother liquor for subsequent use; crude product filter cake 142.44 g, add 500 g water, pulp about 40 min, then use 180 g water washing and drying, get 2,6-dichloro-4-nitroaniline 114.7 g, purity 99.3%.

[0087] Example 9

[0088] In a 500 mL flask with stirring, thermometer, 423.84 g of the mother liquor of Example 9 was added, and stirring was started. 88.07 g (98.5%) of 2-chloro-4-nitroaniline (0.5 mol) was added below 32°C, and 19.17 g (99%) of sodium chlorate (0.179 mol) was added. After stirring until dissolution, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C. After 1 hour of incubation, HPLC was used to determine that the end point was not qualified (the content of the raw material 2-chloro-4-nitroaniline was 0.17%). The temperature was increased to about 50°C, and incubation was performed for 1 hour. After HPLC was used to determine that the end point was qualified (the content of the raw material 2-chloro-4-nitroaniline was less than 0.01%), suction filtration was performed, and 406.05 g of the mother liquor was obtained. The mother liquor was used for subsequent use. The crude product filter cake 147.67 g was added to 500 g of water and stirred for about 40 min. Then, 180 g of water was used for washing and drying, and 2,6-dichloro-4-nitroaniline 119.4 g was obtained, with a purity of 99.2%.

[0089] Example 10

[0090] In a 500 mL flask with stirring, thermometer, 423.84 g of the mother liquor of Example 9 was added, and stirring was started. 88.07 g (98.5%) of 2-chloro-4-nitroaniline (0.5 mol) was added below 32°C, and 19.17 g (99%) of sodium chlorate (0.179 mol) was added. After stirring until dissolution, 26.68 g (99.9%) of hydrogen chloride (0.731 mol) was added at 28-32°C. After 1 hour of incubation, HPLC was used to determine that the end point was not qualified (the content of the raw material 2-chloro-4-nitroaniline was 0.17%). The temperature was increased to about 50°C, and incubation was performed for 1 hour. After HPLC was used to determine that the end point was qualified (the content of the raw material 2-chloro-4-nitroaniline was less than 0.01%), suction filtration was performed, and 406.05 g of the mother liquor was obtained. The mother liquor was used for subsequent use. The crude product filter cake 147.67 g was added to 500 g of water and stirred for about 40 min. Then, 180 g of water was used for washing and drying, and 2,6-dichloro-4-nitroaniline 119.4 g was obtained, with a purity of 99.2%.

[0091] Comparative Example 1

[0092] Into a 500 mL flask with stirring, thermometer, add 371 g (99%) DMF (10.202 mol), open the stirring, add 83.03 g (98.3%) 2-cyano-4-nitroaniline (0.5 mol), add 19.17 g (99%) sodium chlorate (0.179 mol), stir until dissolved, temperature 28-32 ℃, pass 34.87 g (99.9%) hydrogen chloride (0.955 mol), after passing, keep for 1 hour, use HPLC high performance liquid chromatography to detect the end point (the content of raw material 2-cyano-4-nitroaniline is less than 0.01%), slowly dilute in water 2000 g (temperature less than 32 ℃), stir for half an hour, then filter and wash, dry to obtain 2-cyano-4-nitro-6-chloroaniline 94.2 g, purity 99.5%.

[0093] Comparative Example 2

[0094] Into a 500 mL flask with stirring, thermometer, add 371 g (99%) DMF (10.202 mol), open the stirring, add 83.03 g (98.3%) 2-cyano-4-nitroaniline (0.5 mol), add 19.17 g (99%) sodium chlorate (0.179 mol), stir until dissolved, temperature 48-52 ℃, pass 34.87 g (99.9%) hydrogen chloride (0.955 mol), after passing, keep for 1 hour, use HPLC high performance liquid chromatography to detect the end point (the content of raw material 2-cyano-4-nitroaniline is less than 0.01%), slowly dilute in water 2000 g, stir for half an hour, then filter and wash, dry to obtain 2-cyano-4-nitro-6-chloroaniline 93.5 g, purity 99.3%.

[0095] Comparative Example 3

[0096] Into a 1000 mL flask with stirring, thermometer, add 400 g (30%) hydrochloric acid (3.288 mol), open the stirring, add 83.03 g (98.3%) 2-cyano-4-nitroaniline (0.5 mol), drop 64.5 g (30%) sodium chlorate solution (0.18 mol), temperature 48-52 ℃, after dropping, keep for 3 hours, use HPLC high performance liquid chromatography to detect the end point (the content of raw material 2-cyano-4-nitroaniline is less than 4%), filter and wash, dry to obtain 2-cyano-4-nitro-6-chloroaniline 89.34 g, purity 94.33%.

[0097] performance test

[0098] 1. Purity detection method: use HPLC high performance liquid chromatograph to test according to GB / T 26792-2019, the results are shown in Table 1.

[0099] 2. Environmental indicator detection method: gas chromatography-mass spectrometry was used, and then detection was performed according to GB / T 20384-2006 and GB / T 24116-2021, and the results are shown in Table 1.

[0100] Table 1

[0101]

[0102] As can be seen from Table 1, the product 2-cyano-4-nitro-6-chloroaniline or 2-chloro-4-nitro-6-chloroaniline of the present application examples 1-10 has more excellent environmental performance than that of comparative examples 2 and 3. The product 2-cyano-4-nitro-6-chloroaniline or 2-chloro-4-nitro-6-chloroaniline of the present application examples 1 and 7 has a lower yield because the product 2-cyano-4-nitro-6-chloroaniline or 2-chloro-4-nitro-6-chloroaniline can be dissolved in DMF. Therefore, most of the product 2-cyano-4-nitro-6-chloroaniline or 2-chloro-4-nitro-6-chloroaniline exists in the mother liquor. The product 2-cyano-4-nitro-6-chloroaniline or 2-chloro-4-nitro-6-chloroaniline in the mother liquor has reached a state of substantial saturation, and therefore, more product cannot be dissolved in the mother liquor. Therefore, in subsequent use, the yield of the product 2-cyano-4-nitro-6-chloroaniline is much higher than that of the first preparation.

[0103] Although comparative example 1 can also obtain excellent environmental indicators, the direct dilution scheme thereof uses more water than the examples, which can increase production costs and is not conducive to workshop production. The product 2-cyano-4-nitro-6-chloroaniline obtained by the method of comparative examples 2-3 has poor environmental indicators.

[0104] Example 1 is a new feed, and examples 2-6 are batch mother liquor, and because the solubility of DMF is good, the direct yield of the first batch is low, and the average yield of each batch of examples 1-6 is 95.5 g, and the average yield is 96.56%.

[0105] It should be noted that although the technical solutions of the present application are introduced by specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0106] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles, practical applications, or technical improvements in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing an environmentally friendly dye intermediate, characterized in that, Includes the following steps: Dissolution step: Dissolve 2-R-4-nitroaniline and its halide in an organic solvent to obtain an initial solution, wherein the chemical structural formula of 2-R-4-nitroaniline is shown in formula (1), and R represents -Cl, -Br or -CN: （1）； Reaction steps: Hydrogen chloride gas is passed into the initial solution to carry out the reaction, and the reaction products are obtained; Separation step: The reaction products are separated to obtain mother liquor and crude product.

2. The preparation method according to claim 1, characterized in that, The temperature of the dissolution step is 10~32℃; and / or, The mass ratio of the organic solvent to the 2-R-4-nitroaniline is 3~6:1; the molar ratio of the halide salt to the 2-R-4-nitroaniline is 0.33~0.5:

1.

3. The preparation method according to claim 1 or 2, characterized in that, In the aforementioned reaction step, the reaction temperature is below 32°C, and the reaction time is 1-2 hours; and / or, The amount of hydrogen chloride introduced is 1.2 to 2 molar equivalents of 2-R-4-nitroaniline.

4. The preparation method according to any one of claims 1-3, characterized in that, The reaction steps also include a heat preservation and ripening step.

5. The preparation method according to claim 4, characterized in that, The temperature for heat preservation and curing is 40~60℃, and the time for heat preservation and curing is 1~2 hours.

6. The preparation method according to any one of claims 1-5, characterized in that, The reaction endpoint of the reaction step is when the content of 2-R-4-nitroaniline is less than 0.01%.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation method further includes the step of using the mother liquor, preferably, the temperature of the mother liquor during the use is below 32°C.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method further includes a post-processing step; the post-processing step includes pulping the crude product with water to obtain a pulped product.

9. The method according to claim 8, characterized in that, During the pulping process, the amount of water used is 3 to 4 times the mass of the crude product, and the pulping time is 30 to 60 minutes.

10. An environmentally friendly dye intermediate, which is prepared by the preparation method according to any one of claims 1-9.

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