CN117800844A - Method for recycling bromine-containing salt wastewater in synthesis process of benzyl bromide compound - Google Patents
Method for recycling bromine-containing salt wastewater in synthesis process of benzyl bromide compound Download PDFInfo
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- CN117800844A CN117800844A CN202311834165.4A CN202311834165A CN117800844A CN 117800844 A CN117800844 A CN 117800844A CN 202311834165 A CN202311834165 A CN 202311834165A CN 117800844 A CN117800844 A CN 117800844A
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- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 239000002351 wastewater Substances 0.000 title claims abstract description 74
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 title claims abstract description 56
- 229910052794 bromium Inorganic materials 0.000 title claims abstract description 56
- 150000003839 salts Chemical class 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 40
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 21
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 21
- -1 benzyl bromide compound Chemical class 0.000 title claims abstract description 18
- 238000004064 recycling Methods 0.000 title claims abstract description 18
- PLAZTCDQAHEYBI-UHFFFAOYSA-N 2-nitrotoluene Chemical compound CC1=CC=CC=C1[N+]([O-])=O PLAZTCDQAHEYBI-UHFFFAOYSA-N 0.000 claims abstract description 20
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical group OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 50
- 238000006243 chemical reaction Methods 0.000 claims description 40
- 239000000243 solution Substances 0.000 claims description 39
- 239000002253 acid Substances 0.000 claims description 37
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 claims description 34
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- HXBMIQJOSHZCFX-UHFFFAOYSA-N 1-(bromomethyl)-2-nitrobenzene Chemical group [O-][N+](=O)C1=CC=CC=C1CBr HXBMIQJOSHZCFX-UHFFFAOYSA-N 0.000 claims description 18
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 claims description 17
- 239000012074 organic phase Substances 0.000 claims description 17
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- 239000007800 oxidant agent Substances 0.000 claims description 10
- 230000001590 oxidative effect Effects 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 claims description 8
- 230000007613 environmental effect Effects 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 7
- 238000006418 Brown reaction Methods 0.000 claims description 6
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 6
- 238000007865 diluting Methods 0.000 claims description 6
- 239000003960 organic solvent Substances 0.000 claims description 6
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims description 5
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000012267 brine Substances 0.000 claims description 2
- 230000000977 initiatory effect Effects 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 2
- OZAIFHULBGXAKX-VAWYXSNFSA-N AIBN Substances N#CC(C)(C)\N=N\C(C)(C)C#N OZAIFHULBGXAKX-VAWYXSNFSA-N 0.000 claims 1
- 238000005893 bromination reaction Methods 0.000 abstract description 14
- 230000031709 bromination Effects 0.000 abstract description 8
- 238000009776 industrial production Methods 0.000 abstract description 2
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 description 24
- 229910000042 hydrogen bromide Inorganic materials 0.000 description 14
- 239000000203 mixture Substances 0.000 description 10
- BMYNFMYTOJXKLE-UHFFFAOYSA-N 3-azaniumyl-2-hydroxypropanoate Chemical compound NCC(O)C(O)=O BMYNFMYTOJXKLE-UHFFFAOYSA-N 0.000 description 9
- 239000006227 byproduct Substances 0.000 description 9
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 8
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 125000000950 dibromo group Chemical group Br* 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 6
- 239000005869 Pyraclostrobin Substances 0.000 description 6
- AGEZXYOZHKGVCM-UHFFFAOYSA-N benzyl bromide Chemical compound BrCC1=CC=CC=C1 AGEZXYOZHKGVCM-UHFFFAOYSA-N 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 6
- 229910052801 chlorine Inorganic materials 0.000 description 6
- 238000005562 fading Methods 0.000 description 6
- HZRSNVGNWUDEFX-UHFFFAOYSA-N pyraclostrobin Chemical compound COC(=O)N(OC)C1=CC=CC=C1COC1=NN(C=2C=CC(Cl)=CC=2)C=C1 HZRSNVGNWUDEFX-UHFFFAOYSA-N 0.000 description 6
- 238000000605 extraction Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 4
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- KCXMKQUNVWSEMD-UHFFFAOYSA-N benzyl chloride Chemical compound ClCC1=CC=CC=C1 KCXMKQUNVWSEMD-UHFFFAOYSA-N 0.000 description 2
- 229940073608 benzyl chloride Drugs 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000006266 etherification reaction Methods 0.000 description 2
- 230000000855 fungicidal effect Effects 0.000 description 2
- 239000000417 fungicide Substances 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 150000003254 radicals Chemical class 0.000 description 2
- 230000036632 reaction speed Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- LQAQMOIBXDELJX-UHFFFAOYSA-N 2-methoxyprop-2-enoic acid Chemical compound COC(=C)C(O)=O LQAQMOIBXDELJX-UHFFFAOYSA-N 0.000 description 1
- 239000005730 Azoxystrobin Substances 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical group C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical group [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- FUMLKAFCVQJVEZ-UHFFFAOYSA-N [bromo(nitro)methyl]benzene Chemical compound [O-][N+](=O)C(Br)C1=CC=CC=C1 FUMLKAFCVQJVEZ-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- WFDXOXNFNRHQEC-GHRIWEEISA-N azoxystrobin Chemical compound CO\C=C(\C(=O)OC)C1=CC=CC=C1OC1=CC(OC=2C(=CC=CC=2)C#N)=NC=N1 WFDXOXNFNRHQEC-GHRIWEEISA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000006278 bromobenzyl group Chemical group 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011033 desalting Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 1
- 235000019799 monosodium phosphate Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011591 potassium Chemical group 0.000 description 1
- 229910052700 potassium Chemical group 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000008247 solid mixture Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A method for recycling and applying bromine-containing salt wastewater in the synthesis process of a benzyl bromide compound is characterized in that the bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound is used for a bromination section of o-nitrotoluene after being simply treated, and a higher yield is obtained, wherein the yield reaches more than 77%, the bromine in the wastewater is fully utilized, the closed circulation of bromine element is realized, the cost of the bromination section is greatly reduced, the treatment cost of the wastewater is also greatly reduced, and the industrial production is facilitated.
Description
Technical Field
The invention belongs to the technical field of preparation of bromobenzyl compounds, and particularly relates to a method for recycling and applying bromine-containing salt wastewater in a benzyl bromide compound synthesis process.
Background
Pyraclostrobin is currently the most active methoxy acrylic acid ester fungicide, which is the earliest developed and researched by basf company in germany and is introduced in European market in 2002; pyraclostrobin has the advantages of high efficiency, low toxicity, environmental friendliness and wide application range of crops, and the market share is second to azoxystrobin in all fungicide varieties.
The main flow of the production process of the o-nitrobenzyl bromide in the existing pyraclostrobin production process is as follows: the hydrobromic acid is oxidized by hydrogen peroxide to generate bromine, the bromine reacts with o-nitrotoluene under the catalysis of AIBN to generate benzyl bromide, and the hydrogen bromide generated by the oxidation of the hydrogen peroxide is oxidized until the bromine is consumed, so that the bromine utilization rate is improved.
Chinese patent CN 107098812a discloses a process for synthesizing o-nitrobenzyl bromide as intermediate of pyraclostrobin, in which chlorobenzene is used as solvent, and hydrogen peroxide oxidizes hydrogen bromide to produce bromine and o-nitrotoluene to produce bromination reaction under the catalysis of AIBN, so as to produce o-nitrobenzyl bromide.
Chinese patent CN 107778181A discloses a new synthesis process of o-nitrobenzyl bromide, and the o-nitrotoluene is prepared in organic solvent and HBr/H 2 O 2 As brominating reagent and azo-bis-isobutyronitrile (AIBN) as initiator, o-nitrobenzyl bromide is obtained by free radical bromination reaction.
However, such processes are expensive, with essentially the outsourced hydrogen bromide as the bromine source. There are few reports of sodium bromide as a bromine source, and the following two are mainly used.
Chinese patent CN1265639a discloses a preparation method of substituted benzyl bromide, adding mixed solution of o-nitrotoluene and chlorobenzene into aqueous solution of sodium bromide and sodium dihydrogen phosphate and AIBN sulfate, introducing chlorine gas to oxidize sodium bromide into bromine, and then generating bromination reaction. The method needs to introduce chlorine, is complex in operation and has a certain danger, and the yield is only about 50%.
Chinese patent CN 117101571A discloses a preparation method of pyraclostrobin, and provides a bromination method for preparing o-nitrotoluene by introducing chlorine into a mixed solution of sodium bromide, deionized water, o-nitrotoluene and dichloroethane, wherein the description of analyzing the benzyl bromide content in a reaction system in a bromination reaction kettle and ensuring that the sum of the peak areas of benzyl bromide and benzyl chloride is more than 50 percent can know that the reaction generates a mixture of benzyl bromide and benzyl chloride, the proportion is unknown, the sum of the peak areas is about 50 percent, the yield is about 50 percent from the experience, and the operation of introducing chlorine is inconvenient and has a certain danger.
Bromine in benzyl bromide in the pyraclostrobin etherification section exists in wastewater in the form of bromine salt (sodium salt or potassium salt), and if the wastewater is subjected to harmless emission, the treatment cost is high. If bromine salt is extracted, complex extraction, adsorption, decolorization, incineration, filtration, crystallization and other modes are usually carried out to obtain byproduct bromine salt, so that the cost is high, the price of the byproduct bromine salt is difficult to reach the price of high-quality bromine salt in the market, and the loss is large. If the bromine element in the part of bromine salt wastewater can be used for the synthesis section of nitrobenzyl bromide, the closed circulation of the bromine element is realized, and the cost of the bromination section can be greatly reduced.
Disclosure of Invention
The invention aims to provide a method for recycling bromine-containing salt wastewater in the synthesis process of a benzyl bromide compound, which is a novel synthesis process for using the bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound in a bromination section of o-nitrotoluene after simple treatment, and has higher yield, the yield reaches more than 77%, the cost of raw materials is obviously reduced, and the bromine in the wastewater is fully utilized.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a method for recycling bromine-containing salt wastewater in the synthesis process of a benzyl bromide compound comprises the following steps:
1) Pretreatment of
Stirring and mixing the bromine-containing salt wastewater and an extractant uniformly, standing for layering, separating to obtain purified bromine-containing salt wastewater, and diluting brine until the concentration of bromine salt is 20-30wt% for later use;
2) Reaction
Adding an organic solvent, AIBN, o-nitrotoluene and water into a reactor, uniformly mixing, heating to 75-80 ℃, then firstly dropwise adding a mixed acid solution prepared from bromine-containing salt wastewater and acid and an oxidant solution into the reactor, generating elemental bromine, stopping dropwise adding, initiating a reddish brown reaction after 5-10 minutes, starting to dropwise add the oxidant and the mixed acid solution, dropwise adding the mixed acid solution for 38-42 minutes, finishing dropwise adding the oxidant for 50-55 minutes, and carrying out heat preservation reaction at 75-80 ℃ for 1-1.5 hours after all dropwise adding is finished;
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, wherein the lower organic phase is o-nitrobenzyl bromide-containing solution, and the upper salt-containing wastewater is subjected to further environmental protection treatment.
Preferably, the extractant is one or more of dichloroethane, chloroform, dichloromethane and n-butanol.
Preferably, the organic solvent is selected from one or more of dichloroethane, chlorobenzene and chloroform.
Preferably, the mole ratio of the oxidant to the bromine salt in the bromine salt-containing wastewater is 1:1.2-2.
Preferably, the oxidant is a hydrogen peroxide solution with a concentration of 20-30%.
Preferably, the mole ratio of bromine salt to acid in the mixed acid solution is 1:1.2-1.5.
Preferably, the acid is hydrochloric acid and/or sulfuric acid.
Preferably, the mole ratio of the o-nitrotoluene to the bromine salt in the bromine salt-containing wastewater is 1:1.2-2.
The invention extracts organic matters in the bromine-containing salt wastewater by using an extractant in the synthesis process of the benzyl bromide compound, stands for layering, separates and obtains purified bromine-containing salt wastewater, controls the concentration of bromine salt in the wastewater to be 20-30wt% for standby, and after the concentration is higher than the concentration, the solid mixture of sodium bromide and sodium chloride can be separated out from the water phase, so that the dripping is influenced, and the wastewater with too low concentration is excessively large.
Obtaining purified bromine-containing salt wastewater, then mixing the purified bromine-containing salt wastewater with acid liquor to replace hydrobromic acid in a bromination section, and using o-nitrotoluene in an organic solvent as MBr/HCl/H 2 O 2 As brominating reagent (M is sodium and potassium) and Azodiisobutyronitrile (AIBN) as initiator, o-nitrobenzyl bromide is obtained through free radical bromination reaction, and the reaction formula is as follows:
after the reaction is finished, the temperature is reduced to room temperature, the solution is separated, the lower organic phase is o-nitrobenzyl bromide solution, the solution can be directly used for the subsequent etherification working section without purification, and the upper salt-containing wastewater is subjected to further environmental protection treatment.
Compared with the prior art, the invention has the following beneficial effects:
the invention uses bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound to directly replace hydrobromic acid to be applied to a bromination section after being simply treated and being mixed with acid liquor, thereby greatly reducing the raw material cost of a bromination reagent, reducing the wastewater concentration and waste salt purification cost, and obtaining the yield which is more than 77 percent and basically consistent with the yield when the commercial high-purity bromine salt is used. In the prior art (Chinese patent CN1265639A and Chinese patent CN 117101571A) the technology using sodium bromide as the raw material has the yield of only about 50%, and the chlorine is a highly toxic gas, so that the operation difficulty of controlling the bromination reaction speed by controlling the flow of the chlorine is high, and a certain amount of bromine is also contained in the chlorine tail gas, so that the utilization rate of bromine is reduced.
Detailed Description
To facilitate understanding of the present invention, examples are set forth below. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
1) Pretreatment of
Adjusting the pH of 500g of high-salt wastewater containing sodium bromide to 8-9 by hydrobromic acid, mixing 150g of chloroform with the high-salt wastewater for three times for extraction, calibrating the content of bromide ions in water after separating, and diluting the bromide ions in the purified wastewater to 30% for later use by using water; combining chloroform layers for desolventizing, and recycling chloroform;
2) Reaction
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the temperature is raised to 75 ℃ after the mixture is uniformly mixed, then a mixed acid solution prepared from bromine-containing salt wastewater and acid and a hydrogen peroxide solution are firstly dripped into a reactor, elemental bromine is generated, the solution is brownish red, the dripping is stopped, the reddish brown reaction is eliminated after 5 minutes, and the double dripping of hydrogen peroxide and the mixed acid solution is started; the mixed acid solution is dripped for 38 minutes, the hydrogen peroxide is dripped for 50 minutes, and the mixed acid solution is reacted for 1.3 hours at the temperature of 78 ℃ after the dripping is completed; the mixed acid solution consists of 103g of 30% purified wastewater and 43g of 30% hydrochloric acid, and the mole ratio of hydrogen peroxide to bromine salt in the bromine salt-containing wastewater is 1:1.2;
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, using the lower organic phase for the next reaction, and performing further environmental protection treatment on the upper salt-containing wastewater.
The content of o-nitrobenzyl bromide in the organic phase was 27.10%, the yield was 81.0% based on hydrogen bromide, and the content of by-product dibromo product was 2.05%.
Example 2
1) Pretreatment of
Regulating the pH of 500g of high-salt wastewater containing potassium bromide to 8-9 by hydrobromic acid, mixing 150g of chloroform with the high-salt wastewater for extraction for three times, calibrating the content of bromide ions in water after separating, and diluting the bromide ions in the purified wastewater to 20% by using water for later use; combining chloroform layers for desolventizing, and recycling chloroform;
2) Reaction
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the temperature is raised to 80 ℃ after the mixture is uniformly mixed, then a mixed acid solution prepared from bromine-containing salt wastewater and acid and a hydrogen peroxide solution are firstly dripped into a reactor, elemental bromine is generated, the solution is brownish red, the dripping is stopped, the reddish brown reaction is eliminated after 10 minutes, and the double dripping of hydrogen peroxide and the mixed acid solution is started; the mixed acid solution is dripped for 42 minutes, the hydrogen peroxide is dripped for 55 minutes, and the mixture is reacted for 1.2 hours at 75 ℃ after the dripping is completed; the mixed acid solution consists of 155g of 20% purified wastewater and 43g of 30% hydrochloric acid, wherein the mole ratio of hydrogen peroxide to bromine salt in the bromine salt-containing wastewater is 1:1.5;
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, using the lower organic phase for the next reaction, and performing further environmental protection treatment on the upper salt-containing wastewater.
The content of o-nitrobenzyl bromide in the organic phase was 26.50%, the yield was 80.2% based on hydrogen bromide, and the content of by-product dibromo product was 2.01%.
Example 3
1) Pretreatment of
Adjusting the pH of 500g of high-salt wastewater containing sodium bromide to 8-9 by hydrobromic acid, mixing 150g of chloroform with the high-salt wastewater for three times for extraction, calibrating the content of bromide ions in water after separating, and diluting the bromide ions in the purified wastewater to 30% for later use by using water; combining chloroform layers for desolventizing, and recycling chloroform;
2) Reaction
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the temperature is raised to 78 ℃ after the mixture is uniformly mixed, then a mixed acid solution prepared from bromine-containing salt wastewater and acid and a hydrogen peroxide solution are firstly dripped into a reactor, elemental bromine is generated, the solution is brownish red, the dripping is stopped, the reddish brown reaction is eliminated after 8 minutes, and the double dripping of hydrogen peroxide and the mixed acid solution is started; the mixed acid solution is dripped for 40 minutes, the hydrogen peroxide is dripped for 50 minutes, and the mixture is reacted for one hour at 75 ℃ after all dripping is finished; the mixed acid solution consists of 103g of 30% purified wastewater and 60g of 50% sulfuric acid, and the mole ratio of hydrogen peroxide to bromine salt in the bromine salt-containing wastewater is 1:2.0;
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, using the lower organic phase for the next reaction, and performing further environmental protection treatment on the upper salt-containing wastewater.
The content of o-nitrobenzyl bromide in the organic phase was 26.30%, the yield was 79.3% based on hydrogen bromide, and the content of by-product dibromo product was 1.95%.
Example 4
1) Pretreatment of
Regulating the pH of 500g of high-salt wastewater containing potassium bromide to 8-9 by hydrobromic acid, mixing 150g of chloroform with the high-salt wastewater for extraction for three times, calibrating the content of bromide ions in water after separating, and diluting the bromide ions in the purified wastewater to 30% for later use by using water; combining chloroform layers for desolventizing, and recycling chloroform;
4) Reaction
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the temperature is raised to 78 ℃ after the mixture is uniformly mixed, then a mixed acid solution prepared from bromine-containing salt wastewater and acid and a hydrogen peroxide solution are firstly dripped into a reactor, elemental bromine is generated, the solution is brownish red, the dripping is stopped, the reddish brown reaction is eliminated after 7 minutes, and the double dripping of hydrogen peroxide and the mixed acid solution is started; the mixed acid solution is dripped for 40 minutes, the hydrogen peroxide is dripped for 53 minutes, and the mixture is reacted for 1.5 hours at 75 ℃ after the dripping is completed; the mixed acid solution consists of 103g of 20% purified wastewater and 60g of 50% sulfuric acid, and the mole ratio of hydrogen peroxide to bromine salt in the bromine salt-containing wastewater is 1:1.7;
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, using the lower organic phase for the next reaction, and performing further environmental protection treatment on the upper salt-containing wastewater.
The content of o-nitrobenzyl bromide in the organic phase was 25.30%, the yield was 77.60% as hydrogen bromide and the content of by-product dibromo product was 1.85%.
Comparative example 1
31.5g of commercially available NaBr (98%), 70. 70g H 2 Preparing solution by O, adding 43g of 30% hydrochloric acid, uniformly stirring, adding into a constant pressure dropping funnel 1, and adding 45g of 31% hydrogen peroxide into a constant pressure dropping funnel 2;
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the mixture is uniformly mixed, the temperature is raised to 75 ℃, substances in a dropping funnel 1 and a dropping funnel 2 are simultaneously added into the reaction bottle in a double-drop manner, the slow dropping is started, the dropping speed is accelerated after obvious fading, the color of bromine steam in the bottle is observed, the dropping is stopped when the color is darker, the dropping is performed after the fading, the hydrogen bromide is completely dropped for about 40 minutes, the hydrogen peroxide is completely dropped for about 50 minutes, and the mixture is kept at 75 ℃ for 1 hour after the dropping is completed;
after the reaction is finished, the temperature is reduced to room temperature, liquid separation is carried out, the water phase is desalted, and the organic phase is used for the next reaction. The content of o-nitrobenzyl bromide in the organic phase was 27.5%, the yield was 82.2% based on hydrogen bromide, and the content of by-product dibromo product was 2.10%.
In comparative example 1, commercial high-purity sodium bromide is used as a reaction raw material, and the yield of the finally obtained o-nitrobenzyl bromide is similar to that of bromine-containing salt wastewater after simple treatment.
Comparative example 2
31.5g of commercially available NaBr (98%), 70. 70g H 2 Preparing solution by O, adding 60g of 50% sulfuric acid, uniformly stirring, adding into a constant pressure dropping funnel 1, and adding 45g of 31% hydrogen peroxide into a constant pressure dropping funnel 2;
100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water are added into a 500mL reaction bottle, the temperature is raised to 80 ℃, substances in a dropping funnel 1 and a dropping funnel 2 are dropwise added into the reaction bottle at a low speed, the dropping speed is accelerated after obvious fading, the dropwise adding is stopped when the color of bromine steam in the bottle is observed to be darker, the dropwise adding is performed after fading, the hydrogen bromide is dropwise added for about 40 minutes, the hydrogen peroxide is dropwise added for about 50 minutes, and the reaction is carried out at 80 ℃ for 1 hour after the dropwise adding is completed;
after the reaction is finished, the temperature is reduced to room temperature, liquid separation is carried out, the water phase is desalted, and the organic phase is used for the next reaction. The content of o-nitrobenzyl bromide in the organic phase was 26.8%, the yield was 80.3% based on hydrogen bromide, and the content of by-product dibromo product was 1.98%.
In comparative example 1, commercial high-purity sodium bromide is used as a reaction raw material, and the yield of the finally obtained o-nitrobenzyl bromide is similar to that of bromine-containing salt wastewater after simple treatment.
Comparative example 3
60.75g of 40% hydrobromic acid is added into a constant pressure dropping funnel 1, 45g of 31% hydrogen peroxide is added into a constant pressure dropping funnel 2;
taking 100g of 1, 2-dichloroethane, 8g of AIBN,62.5g of o-nitrotoluene and 15g of water, adding into a 500mL reaction bottle, heating to 75-80 ℃, adding substances in a dropping funnel 1 and a dropping funnel 2 into the reaction bottle in a double-dropping manner, slowly dropping at the beginning, accelerating the dropping speed after obvious fading, observing the color of bromine steam in the bottle, stopping dropping when the color is darker, adding dropwise after fading, adding hydrogen bromide for about 50 minutes, adding hydrogen peroxide for about 60 minutes, and keeping the temperature for reacting for 1 hour at 75-80 ℃ after the adding is finished;
cooling to room temperature, separating liquid, desalting the water phase, and using the organic phase for the next reaction. The content of o-nitrobenzyl bromide in the organic phase was 28.4%, the yield was 84.8% based on hydrogen bromide, and the content of by-product dibromo product was 2.51%.
As can be seen from the results of comparative example 3, although the yield obtained by the method of the present invention is slightly lower than that of comparative example 3, the present invention uses wastewater as the raw material, which significantly reduces the raw material cost, and the reaction speed is faster than that of hydrobromic acid/hydrogen peroxide process, and is more suitable for industrial production.
Claims (8)
1. A method for recycling bromine-containing salt wastewater in the synthesis process of a benzyl bromide compound is characterized by comprising the following steps:
1) Pretreatment of
Stirring and mixing the bromine-containing salt wastewater and an extractant uniformly, standing for layering, separating to obtain purified bromine-containing salt wastewater, and diluting brine until the concentration of bromine salt is 20-30wt% for later use;
2) Reaction
Adding an organic solvent, AIBN, o-nitrotoluene and water into a reactor, uniformly mixing, heating to 75-80 ℃, then firstly dropwise adding a mixed acid solution prepared from bromine-containing salt wastewater and acid and an oxidant solution into the reactor, generating elemental bromine, stopping dropwise adding, initiating a reddish brown reaction after 5-10 minutes, starting to dropwise add the oxidant and the mixed acid solution, dropwise adding the mixed acid solution for 38-42 minutes, finishing dropwise adding the oxidant for 50-55 minutes, and carrying out heat preservation reaction at 75-80 ℃ for 1-1.5 hours after all dropwise adding is finished.
3) Post-treatment
After the reaction is finished, cooling to room temperature, separating liquid, wherein the lower organic phase is o-nitrobenzyl bromide-containing solution, and the upper salt-containing wastewater is subjected to further environmental protection treatment.
2. The method for recycling bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the extractant is one or more of dichloroethane, chloroform, dichloromethane and n-butanol.
3. The method for recycling bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the organic solvent is one or more selected from dichloroethane, chlorobenzene and chloroform.
4. The method for recycling and reusing bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the mole ratio of the oxidant to bromine in the bromine-containing salt wastewater is 1:1.2-2.
5. The method for recycling bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1 or 4, wherein the oxidant is hydrogen peroxide solution with the concentration of 20-30%.
6. The method for recycling bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the mole ratio of bromine salt to acid in the mixed acid solution is 1:2-1.5.
7. The method for recycling bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the acid is hydrochloric acid and/or sulfuric acid.
8. The method for recycling and reusing bromine-containing salt wastewater in the synthesis process of the benzyl bromide compound according to claim 1, wherein the molar ratio of the o-nitrotoluene to the bromine in the bromine-containing salt wastewater is 1:1.2-2.
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