Synthesis method of 2-chloro-4-nitro-6-bromo-anilineTechnical Field
The invention relates to the technical field of disperse dye intermediate chemical industry, in particular to a synthetic method of 2-chloro-4-nitro-6-bromo-aniline.
Background
2-Chloro-4-nitro-6-bromo-aniline, the name of which is 2-bromo-6-chloro-4-nitroaniline, is 2-bromo-6-chloro-4-nitroaniline. The 2-chloro-4-nitro-6-bromoaniline is an important disperse dye intermediate and is mainly used for synthesizing disperse dyes such as disperse orange, disperse yellow brown and the like. The conventional dye produced by using 2, 6-dichloro-4-nitroaniline contains higher compounds such as benzene chloride and toluene chloride, and the content of the benzene chloride and the toluene chloride on the fabric dyed by the dye exceeds the limit requirement of OEKO-TEX 100. However, the above problems can be well solved after 2-chloro-4-nitro-6-bromoaniline is substituted for 2, 6-dichloro-4-nitroaniline. And the properties of the dye are substantially consistent over the past. Therefore, the method for producing the 2-chloro-4-nitro-6-bromoaniline is sought, which has the advantages of simple process, high product yield, less sewage and stable product quality, and is a problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a synthesis method of 2-chloro-4-nitro-6-bromo-aniline, which aims to solve the problems in the prior art.
In order to solve the technical problems, the invention provides the following technical scheme:
The synthesis method of the 2-chloro-4-nitro-6-bromo-aniline comprises the following preparation steps:
(1) Uniformly mixing 2-chloroaniline and a magnetic supported heteropoly acid catalyst according to the mass ratio of 1 (0.01-0.02), uniformly dropwise adding a mixed acid solution at 30-35 ℃ for 300-400 r/min within 1.5-2 h, heating to 50-55 ℃ after the dropwise adding is finished, reacting for 3-3.5 h, separating the magnetic supported heteropoly acid catalyst by using an external magnetic field, adding diethyl ether for extraction, separating an organic phase, washing to be neutral by using a sodium bicarbonate solution with the concentration of 5mol/L, adding anhydrous magnesium sulfate for drying for 12h, and removing diethyl ether by rotary evaporation to obtain o-chloro-p-nitroaniline;
(2) Brominating, namely uniformly mixing o-chloro-p-nitroaniline and a brominating agent according to a molar ratio of 1 (1.05-1.1), adding an acidic solution and a magnetic supported heteropolyacid catalyst with the mass of 1% -1.5% of that of the o-chloro-p-nitroaniline, stirring for 20-30 min at room temperature, uniformly dropwise adding an oxidant for 1-2 h, reacting for 2-3 h at room temperature after dropwise adding, separating and recovering the magnetic supported heteropolyacid catalyst by using an external magnetic field, filtering, recovering a filtrate, washing the filtrate with pure water to be neutral, and vacuum drying for 10-12 h at 50-60 ℃ to obtain 2-chloro-4-nitro-6-bromo-aniline.
As an optimization, the preparation method of the magnetic supported heteropolyacid catalyst in the step (1) comprises the following preparation steps:
(A) Uniformly mixing 0.6mol/L of ferrous chloride aqueous solution and hexadecyl trimethyl ammonium chloride solution according to a volume ratio of 1:25, stirring for 3-4 hours at room temperature at 1200-1500 r/min, dripping 2.7mol/L ammonia water which is 0.75 times of the volume of the ferrous chloride aqueous solution at 3-4 drops per second, stirring for 2-3 hours at 400-600 r/min, adding tetraethyl orthosilicate which is 4.19 times of the volume of the ferrous chloride aqueous solution, adding 2.7mol/L ammonia water which is 3.25-3.75 times of the volume of the ferrous chloride aqueous solution, standing for 2-3 hours at 50-60 ℃, centrifuging for 15-20 minutes at 8000-10000 rpm, washing solid precipitate with propanol for 3-4 times, drying for 10-12 hours at 75-85 ℃, calcining for 2-3 hours at 350-400 ℃, and naturally cooling to room temperature to obtain the silicon dioxide coated magnetic nano particles;
(B) Uniformly mixing sodium dihydrogen phosphate dihydrate, sodium metavanadate dihydrate, sodium tungstate dihydrate, antimony chloride, copper acetate monohydrate and pure water in proportion, stirring for 20-30 min at room temperature to completely dissolve, adding sulfuric acid solution to adjust pH to 2.6, adding 20wt% sodium molybdate solution with the mass of 19.8 times that of sodium dihydrogen phosphate dihydrate, stirring for 30-40 min at room temperature, adding sulfuric acid solution to adjust pH to 2.6, carrying out reflux reaction for 2.5-3.5 h at 75-80 ℃, naturally cooling to room temperature, adding diethyl ether for extraction, taking out a lower liquid phase, drying diethyl ether for three times by using pure water, and carrying out vacuum drying for 4-5 h at 50-60 ℃ to obtain doped heteropolyacid;
(C) Uniformly mixing doped heteropolyacid and pure water according to a mass ratio of 1 (5-6), carrying out ultrasonic treatment for 10-20 min to completely dissolve, dropwise adding a 10wt% dimethyl octadecyl 3-trimethoxy silicon propyl ammonium chloride aqueous solution with the same mass as the pure water according to 3-5 drops per second, stirring for 12-14 h at a room temperature after the dropwise adding is completed, carrying out suction filtration, washing for 2-3 times by using the pure water, and carrying out vacuum drying for 8-10 h at a temperature of 50-60 ℃ to obtain the modified heteropolyacid;
(D) Uniformly mixing the silicon dioxide coated magnetic nano particles, the modified heteropolyacid and the ethanol according to the mass ratio of 1:0.4:10, carrying out ultrasonic treatment for 30-40 min at room temperature, standing for 1-1.5 h, separating by an external magnetic field, carrying out vacuum drying for 20-30 min at 30-40 ℃, sealing for 30-40 min in a water atmosphere at 40 ℃, standing for 12-14 h in a baking oven at 60-70 ℃, washing for 3-4 times by using the ethanol, and carrying out vacuum drying for 3-4 h at 40-50 ℃ to obtain the magnetic supported heteropolyacid catalyst.
As optimization, the mixed acid solution in the step (1) is prepared by using 65% of concentrated nitric acid and 98% of concentrated sulfuric acid according to the molar ratio of nitric acid to sulfuric acid to water of 1:0.625:1.95, and the addition amount is 1 (1.05-1.08) according to the molar ratio of 2-chloroaniline to nitric acid.
Preferably, the brominating agent in the step (2) is one of sodium bromide, potassium bromide and hydrobromic acid.
As optimization, the acid solution in the step (2) is one of hydrochloric acid and sulfuric acid, the concentration is 0.5-0.8 mol/L, and the addition amount is 4-5 times of the mass of the o-chloro-p-nitroaniline.
As optimization, the oxidant in the step (2) is one of hydrogen peroxide, hypochlorous acid, chloric acid, sodium hypochlorite, calcium hypochlorite, sodium chlorate, chlorine, sulfur trioxide and chlorine dioxide.
And (3) optimizing, wherein the mole ratio of the brominating agent to the oxidizing agent in the step (2) is 1 (1.05-1.1).
As an optimization, the reaction process of the nitrification and the bromination in the steps (1) and (2) is as follows:
。
Preferably, the cetyltrimethylammonium chloride solution in the step (B) is a 1-hexanol solution of cetyltrimethylammonium chloride with a molar concentration of 0.5 mol/L.
As optimization, the proportion of the step (B) is sodium dihydrogen phosphate dihydrate, sodium metavanadate dihydrate, sodium tungstate dihydrate, antimony chloride, copper acetate monohydrate and pure water according to the mass ratio of 1:3.04:11.63:0.37:0.32:80.
As optimization, the sulfuric acid solution in the step (B) is prepared by mixing 98% concentrated sulfuric acid and pure water according to a volume ratio of 1:1.
Compared with the prior art, the invention has the following beneficial effects:
When the 2-chloro-4-nitro-6-bromo-aniline is prepared, firstly preparing silicon dioxide coated magnetic nano particles, then preparing doped heteropolyacid and further modifying to prepare modified heteropolyacid, loading the modified heteropolyacid on the silicon dioxide coated magnetic nano particles to prepare a magnetic supported heteropolyacid catalyst, and using the 2-chloroaniline as a raw material to perform nitration and bromination under the catalysis of the magnetic supported heteropolyacid catalyst to obtain the product 2-chloro-4-nitro-6-bromo-aniline.
Firstly, preparing silicon dioxide coated magnetic nano particles by using an inverse microemulsion method, wherein paramagnetic ferroferric oxide particles are coated inside by a silicon dioxide layer, so that the corrosion and oxidization of air, strong acid and alkali on the ferroferric oxide particles can be effectively prevented, the surface of the silicon dioxide contains a large number of hydroxyl groups, other functional groups or active substances can be easily grafted and loaded, copper and antimony doped phosphotungstic molybdenum vanadium heteropolyacid is prepared, antimony doped occupies the position of counter ions, the thermal stability can be effectively improved, the service life of the catalyst is prolonged, copper doped also occupies the position of counter ions, the oxidation-reduction capability is improved, the catalytic capability can be effectively improved, then the doped heteropolyacid and dimethyl octadecyl 3-trimethoxy silicon propyl ammonium chloride are subjected to ion exchange reaction, so as to obtain modified heteropolyacid, the modified heteropolyacid has pseudo-liquid phase characteristic, meanwhile, the introduced long carbon chain has good adsorption effect on a reaction substrate, the effective reactant is adsorbed and the catalytic reaction is carried out, the product after the reaction is led out of active sites, the blocking of the internal active sites and the generation of carbon are avoided, the modified heteropolyacid is loaded on the silicon dioxide coated magnetic nano particles, the magnetic nano particles can be effectively improved, the magnetic catalyst can be separated from the strong acid, the magnetic catalyst can be easily recovered, the magnetic catalyst can be easily and the magnetic catalyst is recovered, the magnetic stability of the magnetic nano particles is difficult to recover the magnetic catalyst, and the magnetic catalyst can be easily recovered, and the magnetic stability can be easily recovered.
Secondly, 2-chloroaniline is used as a raw material, nitric acid and sulfuric acid mixed acid are firstly used for carrying out nitration reaction under the catalysis of a magnetic supported heteropoly acid catalyst to prepare o-chloro-p-nitroaniline, the consumption of nitric acid and sulfuric acid can be greatly reduced under the action of the magnetic supported heteropoly acid catalyst, nitric acid is not required to be added multiple times, only a small excess amount is required, the production of waste acid is greatly reduced, the selectivity of the reaction is effectively improved under the action of the magnetic supported heteropoly acid catalyst, the mixed acid and the magnetic supported heteropoly acid catalyst can be simply separated after the reaction is finished, the mixed acid can be simply treated and then put into the next application, the product has good purity due to high selectivity and high conversion rate caused by the catalyst, and the complicated purification procedure is not required.
Finally, the o-chloro-p-nitroaniline, a product of the nitration reaction, a brominating agent and an oxidant are subjected to bromination reaction under the action of a magnetic supported heteropoly acid catalyst to prepare a target product 2-chloro-4-nitro-6-bromo-aniline, a large amount of brominating agent and oxidant are not required to be added under the action of the magnetic supported heteropoly acid catalyst, the atom utilization rate is effectively improved, the magnetic supported heteropoly acid catalyst can be separated in a mode of an externally applied magnetic field after the reaction is finished, the generated wastewater only contains an acidic medium and a small amount of brominating agent and can be directly recycled for the next reaction, the method greatly reduces the generation and treatment of the wastewater, and each step of reaction has high conversion rate and high selectivity under the action of the magnetic supported heteropoly acid catalyst, and the prepared 2-chloro-4-nitro-6-bromo-aniline also has high purity.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The magnetically supported heteropolyacid catalyst used in the following examples was prepared according to the following preparation steps:
(A) Uniformly mixing 0.6mol/L of ferrous chloride aqueous solution and 0.5mol/L of hexadecyl trimethyl ammonium chloride 1-hexanol solution according to a volume ratio of 1:25, stirring for 3 hours at room temperature at 1500r/min, dropwise adding 2.7mol/L ammonia water which is 0.75 times of the volume of the ferrous chloride aqueous solution at 4 drops per second, stirring for 3 hours at 500r/min, adding tetraethyl orthosilicate which is 4.19 times of the volume of the ferrous chloride aqueous solution, adding 2.7mol/L ammonia water which is 3.5 times of the volume of the ferrous chloride aqueous solution, standing for 2.5 hours at 50 ℃, centrifuging at 10000rpm for 15 minutes, washing solid precipitate with propanol for 4 times, drying for 10 hours at 80 ℃, calcining for 2 hours at 350 ℃, and naturally cooling to room temperature to obtain silicon dioxide coated magnetic nano particles;
(B) Uniformly mixing sodium dihydrogen phosphate dihydrate, sodium metavanadate dihydrate, sodium tungstate dihydrate, antimony chloride, copper acetate monohydrate and pure water according to the mass ratio of 1:3.04:11.63:0.37:0.32:80, stirring for 25min at room temperature until the sodium dihydrogen phosphate dihydrate, stirring for 25min until the sodium dihydrogen phosphate dihydrate is completely dissolved, adding a sulfuric acid solution to adjust the pH value to 2.6, adding a 20wt% sodium molybdate solution with the mass of 19.8 times of that of sodium dihydrogen phosphate dihydrate, stirring for 35min at room temperature, adding a sulfuric acid solution to adjust the pH value to 2.6, carrying out reflux reaction for 3h at 80 ℃ and 250r/min, naturally cooling to room temperature, adding diethyl ether for extraction, taking a lower liquid phase, drying the diethyl ether, recrystallizing for three times with pure water, and carrying out vacuum drying for 5h at 55 ℃ to obtain doped heteropolyacid;
(C) Uniformly mixing doped heteropolyacid and pure water according to a mass ratio of 1:6, carrying out ultrasonic treatment for 15min until the mixed heteropolyacid and the pure water are completely dissolved, dropwise adding 10wt% dimethyl octadecyl 3-trimethoxy silicon propyl ammonium chloride aqueous solution with the same mass as the pure water according to 4 drops per second, stirring for 12h at the room temperature of 250r/min after the dropwise adding is completed, carrying out suction filtration, washing 3 times by using the pure water, and carrying out vacuum drying for 10h at the temperature of 55 ℃ to obtain the modified heteropolyacid;
(D) Uniformly mixing the silicon dioxide coated magnetic nano particles, the modified heteropolyacid and the ethanol according to the mass ratio of 1:0.4:10, carrying out ultrasonic treatment at room temperature for 35min, standing for 1.5, separating by an external magnetic field, carrying out vacuum drying at 35 ℃ for 25min, sealing for 35min in a water atmosphere at 40 ℃, standing for 12h in a drying oven at 65 ℃, washing for 4 times by using the ethanol, and carrying out vacuum drying at 45 ℃ for 3h to obtain the magnetic supported heteropolyacid catalyst.
Example 1:
the synthesis method of 2-chloro-4-nitro-6-bromo-aniline comprises the following preparation steps:
(1) Uniformly mixing 2-chloroaniline and a magnetic supported heteropoly acid catalyst according to the mass ratio of 1:0.01, uniformly dropwise adding a mixed acid solution according to the molar ratio of 2-chloroaniline to nitric acid of 1:1.05 within 1.5h at the temperature of 30 ℃ and 300r/min, heating to 50 ℃ after the dropwise adding is finished, 400r/min, reacting for 3.5h, separating the magnetic supported heteropoly acid catalyst by using an external magnetic field, adding diethyl ether for extraction, separating an organic phase, washing to be neutral by using a sodium bicarbonate solution of 5mol/L, adding anhydrous magnesium sulfate for drying for 12h, and removing diethyl ether by rotary evaporation to obtain o-chloro-p-nitroaniline;
(2) Bromination, namely uniformly mixing o-chloro-p-nitroaniline and potassium bromide according to a molar ratio of 1:1.05, adding 0.8mol/L hydrochloric acid which is 4 times the mass of the o-chloro-p-nitroaniline and a magnetic supported heteropolyacid catalyst which is 1% of the mass of the o-chloro-p-nitroaniline, stirring for 30min at room temperature, uniformly dropwise adding 30% hydrogen peroxide for 1h according to a molar ratio of 1:1.05 of the potassium bromide and the hydrogen peroxide, reacting for 3h at room temperature after dropwise adding, separating and recovering the magnetic supported heteropolyacid catalyst by an external magnetic field, filtering, recovering a filtrate, washing the filtrate for the next batch, washing the solid to be neutral by pure water, and drying in vacuum for 12h at 50 ℃ to obtain 2-chloro-4-nitro-6-bromo-aniline.
Example 2:
the synthesis method of 2-chloro-4-nitro-6-bromo-aniline comprises the following preparation steps:
(1) Uniformly mixing 2-chloroaniline and a magnetic supported heteropoly acid catalyst according to the mass ratio of 1:0.015, uniformly dropwise adding a mixed acid solution into the mixture within 2h according to the mol ratio of 2-chloroaniline to nitric acid of 1:1.06 at 35 ℃ and at the mass ratio of 1:0.015, heating to 55 ℃ after the dropwise adding, reacting for 3h, separating the magnetic supported heteropoly acid catalyst by using an external magnetic field, adding diethyl ether for extraction, separating an organic phase, washing to neutrality by using 5mol/L sodium bicarbonate solution, adding anhydrous magnesium sulfate for drying for 12h, and removing diethyl ether by rotary evaporation to obtain o-chloro-p-nitroaniline;
(2) Bromination, namely uniformly mixing o-chloro-p-nitroaniline and potassium bromide according to a molar ratio of 1:1.08, adding 0.6mol/L hydrochloric acid which is 4.5 times of the mass of the o-chloro-p-nitroaniline and a magnetic supported heteropolyacid catalyst which is 1.25% of the mass of the o-chloro-p-nitroaniline, stirring for 25min at room temperature, uniformly dropwise adding 30% hydrogen peroxide according to a molar ratio of 1:1.08 of the potassium bromide and the hydrogen peroxide for 1.5h, reacting for 2.5h at room temperature after the dropwise adding is finished, separating and recovering the magnetic supported heteropolyacid catalyst by using an external magnetic field, filtering, recovering a filtrate sleeve for the next batch, washing the solid to be neutral by pure water, and vacuum drying for 11h at 55 ℃ to obtain the 2-chloro-4-nitro-6-bromo-aniline.
Example 3:
the synthesis method of 2-chloro-4-nitro-6-bromo-aniline comprises the following preparation steps:
(1) Uniformly mixing 2-chloroaniline and a magnetic supported heteropoly acid catalyst according to the mass ratio of 1:0.02, uniformly dropwise adding a mixed acid solution into the mixture within 2h according to the mol ratio of 2-chloroaniline to nitric acid of 1:1.08 at 35 ℃ and 400r/min, heating to 55 ℃ after the dropwise adding, 500r/min, reacting for 3h, separating the magnetic supported heteropoly acid catalyst by using an external magnetic field, adding diethyl ether for extraction, separating an organic phase, washing to neutrality by using 5mol/L sodium bicarbonate solution, adding anhydrous magnesium sulfate for drying for 12h, and removing diethyl ether by rotary evaporation to obtain o-chloro-p-nitroaniline;
(2) Bromination, namely uniformly mixing o-chloro-p-nitroaniline and potassium bromide according to a molar ratio of 1:1.1, adding 0.5mol/L hydrochloric acid which is 5 times the mass of the o-chloro-p-nitroaniline and a magnetic supported heteropolyacid catalyst which is 1.5% of the mass of the o-chloro-p-nitroaniline, stirring for 20min at room temperature, uniformly dropwise adding 30% hydrogen peroxide according to a molar ratio of 1:1.1 for 2h according to the molar ratio of the potassium bromide to the hydrogen peroxide, reacting for 2h at room temperature at 400r/min after dropwise adding, separating and recovering the magnetic supported heteropolyacid catalyst by using an external magnetic field, filtering, recovering the filtrate, using the filtrate to be used for the next batch, washing the solid to be neutral by using pure water, and vacuum drying for 10h at 60 ℃ to prepare the 2-chloro-4-nitro-6-bromo-aniline.
Comparative example 1:
The synthesis method of 2-chloro-4-nitro-6-bromo-aniline of comparative example 1 is different from that of example 2 in that the preparation method of the magnetic supported heteropolyacid catalyst used in step (B) is modified in that sodium dihydrogen phosphate dihydrate, sodium metavanadate dihydrate, sodium tungstate dihydrate and pure water are uniformly mixed according to the mass ratio of 1:3.04:12.69:80, stirred at room temperature for 25 r/min until the sodium dihydrogen phosphate dihydrate, sodium molybdate solution with the weight of 19.8 times of that of the sodium molybdate solution with the weight of 20wt% is added, stirred at room temperature for 35 r/min, then added with sulfuric acid solution to adjust the pH to 2.6, reflux reaction is carried out for 3h at 80 ℃ and 250r/min, diethyl ether is naturally cooled to room temperature, extraction is carried out, the lower layer liquid phase is taken out, the diethyl ether is dried, recrystallized by pure water is used for three times, and vacuum drying is carried out for 5h at 55 ℃ to obtain the doped heteropolyacid. The rest of the procedure is the same as in example 2.
Comparative example 2:
The synthesis method of 2-chloro-4-nitro-6-bromo-aniline of comparative example 2 is different from that of example 2 in that the preparation method of the magnetic supported heteropolyacid catalyst used is not carried out in step (C), and the modification in step (D) is that silica coated magnetic nanoparticles, doped heteropolyacid and ethanol are uniformly mixed according to the mass ratio of 1:0.4:10, ultrasonic is carried out for 35min at room temperature, standing is carried out for 1.5, separation by an external magnetic field is carried out, vacuum drying is carried out for 25min at 35 ℃, sealing is carried out for 35min in a water atmosphere at 40 ℃, standing is carried out for 12h in a 65 ℃ oven, washing is carried out for 4 times by ethanol, and vacuum drying is carried out for 3h at 45 ℃ to obtain the magnetic supported heteropolyacid catalyst. The rest of the procedure is the same as in example 2.
Test example 1:
purity test the fractional product purity and yield of each example are recorded in table 1 and the total yield is calculated.
The results are shown in Table 1.
TABLE 1
From the comparison of the experimental data of examples 1-3 and comparative examples 1-2 in Table 1, it can be found that the 2-chloro-4-nitro-6-bromo-aniline prepared by the invention has good purity and yield.
By comparing the data in the table, the doping modification of the magnetic supported heteropolyacid catalyst by copper and antimony effectively improves the catalytic activity and the reaction selectivity, while the introduction of the dimethyl octadecyl 3-trimethoxy silicon propyl ammonium chloride improves the catalytic activity on one hand and improves the loading stability and the loading capacity of the doped heteropolyacid on the silicon dioxide coated magnetic nano particles on the other hand.
Test example 2:
Catalyst life test was repeatedly performed according to the conditions of each example and comparative example, the magnetically supported heteropolyacid catalyst used in each reaction step of each example and comparative example was recovered and then washed with pure water and ethanol alternately 3 times, and after washing, the same reaction step of the next production was put into, and when the total yield was lower than 80% of the total yield of the first time, the number of times of recycling of the magnetically supported heteropolyacid catalyst was recorded and recorded in table 2.
The results are shown in Table 2.
TABLE 2
From comparison of experimental data of examples 1-3 and comparative examples 1-2 in Table 2, it can be found that the magnetically supported heteropolyacid catalyst prepared by the present invention has a good cycle life.
By comparing the data in the table, the doping modification of copper and antimony to the magnetic supported heteropolyacid catalyst effectively improves the stability of the magnetic supported heteropolyacid catalyst, prolongs the service life of the magnetic supported heteropolyacid catalyst, and under the condition that dimethyl octadecyl 3-trimethoxy silicon propyl ammonium chloride is not introduced, the stability of the doped heteropolyacid supported on the catalyst is insufficient, and the catalyst is lost after one use.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.