阅读说明：本技术 6-溴-2,4-二硝基苯胺的制备方法 (Preparation method of 6-bromo-2, 4-dinitroaniline ) 是由 何卫华 宋光伟 周庆锋 谢小强 曹阳 王小东 于 2021-08-17 设计创作，主要内容包括：本发明提供一种6-溴-2,4-二硝基苯胺的制备方法,包括：提供一种反应原液,上述反应原液以酸溶液为介质,其中还包括催化剂和反应原料2,4-二硝基苯胺；提供一种溴化剂,上述溴化剂为二溴海因；提供一种溴化反应,上述溴化反应的产物即为6-溴-2,4-二硝基苯胺；上述溴化剂的添加方法为分批次添加,单次添加量不超过总添加量的1/20。本发明的方法以二溴海因做溴化剂,适配催化剂形成新的合成路线,设备要求低,产物易分离提纯,反应彻底且平稳,原料转化率和产物收率高,母液循环利用效率高,减少了废水排放量,降低了生产成本。(The invention provides a preparation method of 6-bromo-2, 4-dinitroaniline, which comprises the following steps: providing a reaction stock solution, wherein the reaction stock solution takes an acid solution as a medium, and also comprises a catalyst and a reaction raw material 2, 4-dinitroaniline; providing a brominating agent, wherein the brominating agent is dibromohydantoin; providing a bromination reaction, wherein the product of the bromination reaction is 6-bromo-2, 4-dinitroaniline; the adding method of the brominating agent is adding in batches, and the single adding amount does not exceed 1/20 of the total adding amount. The method of the invention uses dibromohydantoin as a brominating agent, matches with a catalyst to form a new synthesis route, has low equipment requirement, easy separation and purification of products, thorough and stable reaction, high conversion rate of raw materials and product yield, high recycling efficiency of mother liquor, reduced wastewater discharge and reduced production cost.)

1. A preparation method of 6-bromo-2, 4-dinitroaniline is characterized by comprising the following steps:

providing a reaction stock solution, wherein the reaction stock solution takes an acid solution as a medium, and also comprises a catalyst and a reaction raw material 2, 4-dinitroaniline;

providing a brominating agent, wherein the brominating agent is dibromohydantoin;

providing a bromination reaction, wherein the product of the bromination reaction is 6-bromo-2, 4-dinitroaniline;

the adding method of the brominating agent is batch adding, and the single adding amount does not exceed 1/20 of the total adding amount.

2. The method of claim 1, wherein: the acid solution is one or two of hydrochloric acid or hydrobromic acid solution, and the mass concentration of the acid solution is 2-35%.

3. The method of claim 1, wherein: the catalyst is at least one of tetrabutylammonium bromide, triethylbenzylammonium chloride, trioctyl ammonium chloride, hexadecyl trimethyl ammonium bromide and OP-10.

4. A method according to claim 1 or 3, characterized in that: the dosage of the catalyst is 0.1-10% of the mass of the 2, 4-dinitroaniline.

5. The method of claim 1, wherein: the ratio of the acid solution to the 2, 4-dinitroaniline in the reaction stock solution is (2.5-5) L:1 kg.

6. The method of claim 1, wherein: the preparation steps of the reaction stock solution are as follows: adding an acid solution into the reaction kettle, adding 2, 4-dinitroaniline, uniformly mixing, adding a catalyst, and stirring to obtain a reaction stock solution.

7. The method of claim 6, wherein: the stirring conditions are as follows: the temperature is 20-65 ℃ and the time is 0.5-2 h.

8. The method of claim 1, wherein: the mol ratio of the brominating agent dibromohydantoin to the 2, 4-dinitroaniline is (0.5-1.0): 1.

9. The method of claim 1, wherein: the batch addition operation is as follows: the single addition amount is 1/30-1/20 of the total addition amount, and the interval time is 1/30-1/20 of the total time of the addition; the total charging time of the dibromohydantoin is 1-6 h.

10. The method of claim 1, wherein: the bromination reaction conditions were as follows: the temperature is 20-65 deg.C, and the time is 10-60 min.

Technical Field

The invention relates to the technical field of chemical synthesis, in particular to a preparation method of 6-bromo-2, 4-dinitroaniline.

Background

6-bromo-2, 4-dinitroaniline, also known as: 2-bromo-4, 6-dinitroaniline, molecular formula: c₆H₄BrN₃O₄Molecular weight: 262.02, yellow needle-like crystal appearance, melting point 153-154 ℃. Is easy to sublimate. Easily dissolved in hot water and hot acetone, and dissolved in hot acetic acid. Mainly used as an intermediate of disperse dyes, and is used for producing dyes and intermediates of certain acid dyes, such as disperse blue 270, 264, 259, 125, 130 and the like. The bromine dye produced by 6-bromine-2, 4-dinitroaniline belongs to high-grade dye, and its own colour is bright, and can raise colouring property and fastness of dye, and its market capacity is large. 6-bromo-2, 4-dinitroaniline is also a fine chemical intermediate with development potential.

At present, the industrial preparation method of 6-bromo-2, 4-dinitroaniline mainly uses 2, 4-dinitroaniline as raw material, bromizes the raw material with bromine in water, hydrochloric acid, chlorobenzene and other media, and then uses oxidant to oxidize hydrogen bromide generated in the bromination process, thereby continuously brominating the raw material to obtain the target product. The oxidant mainly comprises sodium chlorate, sodium hypochlorite, chlorine and hydrogen peroxide. However, the prior art has significant drawbacks that limit its application to production. For example: 1) the brominating agent bromine is an easy-to-prepare toxic chemical, and can be quickly evaporated at normal temperature, and the steam has suffocation stimulation flavor, is reddish brown and is not easy to operate; bromine has high corrosivity and toxicity, is directly contacted with equipment during reaction, has high requirements on the material of the equipment, and is complicated to react and operate. 2) Hydrogen bromide gas can be generated in the bromination process, and the hydrogen bromide has strong corrosivity and higher requirements on equipment. 3) The oxidants of sodium chlorate, hydrogen peroxide and the like used in the oxidation process are easily explosive or extremely toxic substances, and the chlorine is extremely toxic gas, so that the equipment requirement is high, the operation is complex, and high-acidity acidic water is generated; the method adopting sodium hypochlorite has the disadvantages of complicated production process, byproducts, salt-containing low-acidity acidic wastewater generated in the reaction process, long reaction time and low equipment utilization rate.

In order to solve the above problems, it is necessary to develop a new brominating agent, a new synthetic route and a new preparation method, so as to achieve the purposes of improving economic benefits and reducing production costs.

Disclosure of Invention

The invention provides a preparation method of 6-bromo-2, 4-dinitroaniline, which is used for solving the problems of strong toxicity and corrosivity of the existing brominating agent and byproducts, high equipment requirement, high wastewater discharge amount and the like.

Specifically, the invention provides a preparation method of 6-bromo-2, 4-dinitroaniline, which comprises the following steps:

providing a reaction stock solution, wherein the reaction stock solution takes an acid solution as a medium, and also comprises a catalyst and a reaction raw material 2, 4-dinitroaniline;

providing a brominating agent, wherein the brominating agent is dibromohydantoin;

providing a bromination reaction, wherein the product of the bromination reaction is 6-bromo-2, 4-dinitroaniline;

the adding method of the brominating agent is adding in batches, and the single adding amount does not exceed 1/20 of the total adding amount.

The acid solution is one or two of hydrochloric acid or hydrobromic acid solution, and the mass concentration is 2-35%. Preferably, the acid solution has a mass concentration of 2 to 10%.

The catalyst is at least one of tetrabutylammonium bromide, triethylbenzylammonium chloride, trioctylammonium chloride, hexadecyltrimethylammonium bromide and OP-10. Preferably, the catalyst is OP-10.

Further setting the dosage of the catalyst to be 0.1-10% of the mass of the 2, 4-dinitroaniline. The catalyst adopted in the invention can promote the reaction, has no defects of strong corrosivity, high equipment investment, environmental pollution, difficult recycling, difficult separation of products and a reaction system and the like, and is convenient to recycle.

Further, the ratio of the acid solution to the 2, 4-dinitroaniline in the reaction liquid is set to be (2.5-5) L:1 kg.

The preparation method is further configured as follows: adding an acid solution into the reaction kettle, adding 2, 4-dinitroaniline, uniformly mixing, adding a catalyst, and stirring to obtain a reaction stock solution.

Preferably, the stirring conditions are: the temperature is 20-65 ℃ and the time is 0.5-2 h.

The molar ratio of the brominating agent dibromohydantoin to the 2, 4-dinitroaniline is set to be (0.5-1.0): 1.

Further setting the total charging time of the dibromohydantoin to be 1-6 h. The brominating agent dibromo hydantoin is added into the reaction system in batches, so that the bromination reaction can be performed stably and thoroughly, side reactions can be reduced, the conversion rate of raw materials can be improved, the quality and yield of products can be ensured, and the loss and cost of the raw materials can be reduced.

Further, the operation of the batch addition is as follows: the single addition amount is 1/30-1/20 of the total addition amount, and the interval time is 1/30-1/20 of the total time of feeding.

Further configured, the bromination reaction conditions were as follows: the temperature is 20-65 deg.C, and the time is 10-60 min.

Further setting that the reaction liquid obtained by the bromination reaction is subjected to a purification process.

Specifically, the purification process comprises: cooling, filtering, washing with purified water and drying; the above washing was carried out to filter the resulting cake until the pH reached 6-7.

The preparation method provided by the invention adopts a new brominating agent and a synthetic route, and realizes the following beneficial effects:

1) the method takes dibromohydantoin as a brominating agent, forms a new synthetic route by adapting to a catalyst, avoids using highly corrosive hydrogen bromide or bromine as the brominating agent, reduces the requirements on equipment materials, is easy to separate products, is convenient for recycling the catalyst, has simple and convenient operation procedures, and is beneficial to industrial production and popularization;

2) according to the method, the brominating agent is added in batches, so that the bromination reaction is thorough, the system reaction is stable, side reactions and by-product generation are reduced, the brominating agent can be completely utilized, the conversion rate and the reaction rate of raw materials are improved, the yield of a target product is improved, the purification difficulty of the target product is reduced, an acid solution and a catalyst after the reaction can be recycled, green production is realized, and the production cost is reduced;

3) the product obtained by the method has high purity which can reach more than 96 percent, the yield reaches more than 90 percent, the production efficiency is high, the production operation is simple and easy, the mother liquor recycling efficiency is high, the wastewater discharge amount is reduced, the subsequent treatment cost is reduced, and the clean production is realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a nuclear magnetic hydrogen spectrum of a target product 6-bromo-2, 4-dinitroaniline of the present invention;

FIG. 2 is an HPLC chromatogram of the product 6-bromo-2, 4-dinitroaniline of example 1;

FIG. 3 is an HPLC chromatogram of the product 6-bromo-2, 4-dinitroaniline of example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art based on the embodiments of the present invention without any inventive step, also belong to the scope of protection of the present invention.

The chemical reaction equations involved in the present invention are as follows:

the specific synthetic route of the invention is as follows: adding 2, 4-dinitroaniline into an acid solution, adding dibromohydantoin in batches in the presence of a catalyst, and continuing the reaction after the addition is finished; and after the reaction is finished, filtering, washing the obtained filter cake with purified water until the pH value is 6-7, and drying to obtain the target product 6-bromo-2, 4-dinitroaniline.

According to the synthetic route, the preparation steps are as follows:

1) adding an acid solution with the mass concentration of 2-35% into a reaction kettle, then adding 2, 4-dinitroaniline, uniformly mixing, then adding a catalyst with the mass of 0.1-10% of that of the 2, 4-dinitroaniline, and stirring for 0.5-2h at the temperature of 20-65 ℃ to obtain a reaction stock solution; the proportion of the acid solution and the 2, 4-dinitroaniline is (2.5-5) L:1 kg; the catalyst is at least one of tetrabutylammonium bromide, triethylbenzylammonium chloride, trioctyl ammonium chloride, hexadecyl trimethyl ammonium bromide and OP-10; the acid solution is one or two of hydrochloric acid or hydrobromic acid;

2) under the condition of heat preservation, adding a brominating agent of dibromohydantoin to the reaction stock solution in batches, and continuing to carry out bromination reaction for 10-60min at the temperature of 20-65 ℃ under the heat preservation condition to obtain a reaction solution; the mol ratio of the dibromohydantoin to the 2, 4-dinitroaniline is (0.5-1.0) to 1; the operation of adding dibromohydantoin in batches is as follows: the single addition amount is 1/30-1/20 of the total addition amount, the interval time is 1/30-1/20 of the total charging time, and the total charging time of the dibromohydantoin is 1-6 h;

3) and cooling and filtering the reaction liquid, washing the obtained filter cake with purified water until the pH value reaches 6-7, and drying to obtain the target product 6-bromo-2, 4-dinitroaniline of which the appearance is yellow needle-shaped crystals.

Further, the reaction product is subjected to nuclear magnetic hydrogen spectrum analysis, and the nuclear magnetic hydrogen spectrum is shown in the attached figure 1. The analytical data are as follows: 1H-NMR (400MHz, DMSO), delta (ppm):3.338(s, 2H); 8.447-8.454(d, 1H); 8.775-8.782(d, 1H). The peak at 2.50-2.51ppm should be the solvent peak. The single peak at 3.338ppm should belong to the hydrogen on the amino group. The peaks at 8.44ppm and 8.78ppm should belong to two hydrogens on the benzene ring.

Example 1:

a preparation method of 6-bromo-2, 4-dinitroaniline comprises the following steps:

1) adding 17L of hydrochloric acid solution with the mass concentration of 2.5% into a reaction kettle, then adding 4kg of 2, 4-dinitroaniline, uniformly mixing, then adding 20g of OP-10, and stirring for 1h at the temperature of 50-55 ℃ to obtain reaction stock solution;

2) under the condition of heat preservation, adding 3.2kg of brominating agent dibromohydantoin to the reaction stock solution in batches, and continuing to carry out bromination reaction at the temperature of 50-55 ℃ for 30min after the adding is finished to obtain reaction solution; the operation of adding dibromohydantoin in batches is as follows: the single addition amount is 1/20 of the total addition amount, the interval time is 1/20 of the total feeding time, and the total feeding time of the dibromohydantoin is 3 h;

3) and cooling and filtering the reaction liquid, washing the obtained filter cake with purified water until the pH value reaches 6-7, and drying to obtain the target product 6-bromo-2, 4-dinitroaniline of which the appearance is yellow needle-shaped crystals.

In the embodiment, 5.2kg of target product is obtained, the yield is 91.4%, and the purity is more than or equal to 98.2% by HPLC.

FIG. 2 shows the HPLC chromatogram of the product 6-bromo-2, 4-dinitroaniline. Test methods refer to purity determinations in HG/T3753-2014. The spectral analysis is given in table 1 below.

Name of component	Retention time min	Peak width sec	Area mu AU.s	Area%	Height mAU
						1	4.258	23.5	2803.470	0.01	0.181
2	7.788	34.6	638123.900	1.71	31.401
						3	13.942	47.8	36759020.00	98.29	1257.963
Total up to			37399950.00	100.00	1289.545

Example 2:

a preparation method of 6-bromo-2, 4-dinitroaniline comprises the following steps:

1) adding 3L of hydrobromic acid solution with the mass concentration of 5% into a reaction kettle, then adding 1kg of 2, 4-dinitroaniline, uniformly mixing, then adding 50g of tetrabutylammonium bromide, and stirring at the temperature of 60-65 ℃ for 0.5h to obtain reaction stock solution;

2) under the condition of heat preservation, adding 865g of brominating agent dibromo hydantoin to the reaction stock solution in batches, and continuing to carry out bromination reaction for 60min at the temperature of 60-65 ℃ under the heat preservation condition to obtain a reaction solution; the operation of adding dibromohydantoin in batches is as follows: the single addition amount is 1/30 of the total addition amount, the interval time is 1/30 of the total feeding time, and the total feeding time of the dibromohydantoin is 1 h;

3) and cooling and filtering the reaction liquid, washing the obtained filter cake with purified water until the pH value reaches 6-7, and drying to obtain the target product 6-bromo-2, 4-dinitroaniline of which the appearance is yellow needle-shaped crystals.

In the embodiment, 1.29kg of target product is obtained, the yield is 90.6%, and the purity is more than or equal to 96.5% by HPLC.

FIG. 3 is an HPLC chromatogram of the product 6-bromo-2, 4-dinitroaniline. The test method was referenced to the purity assay in HG/T3753-2014. The spectral analysis is given in table 2 below.

Name of component	Retention time min	Peak width sec	Area mu AU.s	Area%	Height mAU
						1	5.442	103.4	48764.600	0.14	0.860
2	6.521	29.7	17435.010	0.05	0.914
						3	7.204	26.4	303446.100	0.88	17.611
4	7.826	34.0	9612.893	0.03	0.498
						5	10.977	47.4	734815.900	2.13	21.595
6	12.163	36.2	33463360.00	96.78	1432.740
						Total up to			34577440.00	100.00	1474.217

Example 3:

a preparation method of 6-bromo-2, 4-dinitroaniline comprises the following steps:

1) adding 5L of mixed acid solution with the mass concentration of 5% into a reaction kettle, then adding 1.5kg of 2, 4-dinitroaniline, uniformly mixing, then adding 50g of OP-10, and stirring at 55-60 ℃ for 1.5h to obtain reaction stock solution; the mixed acid solution is obtained by mixing a hydrochloric acid solution with the mass concentration of 5% and a hydrobromic acid solution, and the volume ratio of the hydrochloric acid solution to the hydrobromic acid solution is 1: 1.5;

2) under the condition of heat preservation, adding 1.4kg of brominating agent dibromo hydantoin into the reaction stock solution in batches, and continuing to carry out bromination reaction at 55-60 ℃ for 45min under the heat preservation condition to obtain reaction solution; the operation of adding dibromohydantoin in batches is as follows: the single addition amount is 1/25 of the total addition amount, the interval time is 1/25 of the total feeding time, and the total feeding time of the dibromohydantoin is 2.5 h;

3) and cooling and filtering the reaction liquid, washing the obtained filter cake with purified water until the pH value reaches 6-7, and drying to obtain the target product 6-bromo-2, 4-dinitroaniline of which the appearance is yellow needle-shaped crystals.

In the embodiment, 1.97kg of target product is obtained, the yield is 92.3%, and the purity is more than or equal to 97.6% by HPLC.

Example 4:

in this example, according to the method of example 1, 4kg of 2, 4-dinitroaniline in 2.5% hydrochloric acid solution and 3.2kg of dibromohydantoin serving as a brominating agent are taken, and the influence of the presence or absence of a catalyst on the reaction is examined under the condition that other conditions are kept unchanged, and the experimental results are shown in table 3 below.

TABLE 3 Effect of catalyst on bromination

The following conclusions can be drawn from the above experimental data: the existence of the catalyst has a remarkable promoting effect on the bromination reaction, so that the production efficiency is improved, and the yield per unit time is improved.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; while the invention has been described in detail and with reference to the foregoing embodiments, those skilled in the art will appreciate that; the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.