Method for recovering oxyfluorfen by-product

Abstract

The invention relates to the technical field of recovery and utilization of oxyfluorfen byproducts, in particular to a recovery method of oxyfluorfen byproducts, which comprises the following steps: extracting 2-chloro-4-trifluoromethylphenol in byproduct phenol waste liquid under the condition of oxyfluorfen microchannel continuous production through a supergravity bed reduced pressure distillation technology; adding an inert organic solvent and potassium carbonate into a condensation reaction kettle; dropwise adding 2-chloro-4-trifluoromethylphenol into the condensation reaction kettle to react with potassium carbonate to obtain phenol potassium salt; dropwise adding 2, 4-difluoronitrobenzene into the condensation reaction kettle to perform condensation reaction with phenol potassium salt to obtain an initial condensation solution; and dropwise adding the potassium alkoxide solution into the etherification kettle, and carrying out etherification reaction on the potassium alkoxide solution and the initial condensation liquid subjected to process water washing to obtain the target oxyfluorfen. According to the method disclosed by the invention, the low-cost and high-efficiency recovery of the byproduct phenol under the continuous flow micro-channel process condition can be realized, the discharge of the production waste process water is reduced, and the high-value utilization of the phenol-containing waste process water is realized.

Description

Technical Field

[0001] The invention relates to the technical field of oxyfluorfen byproduct recovery and utilization, in particular to a method for recovering oxyfluorfen byproduct. Background Art

[0002] Oxyfluorfen is a diphenyl ether herbicide with a wide range of uses, a broad weed control spectrum, a long lasting effect, a small amount per mu, and is easy to use. It can be used in combination with a variety of herbicides to expand the weed control spectrum and improve the efficacy. It can be used for both pre-emergence and post-emergence treatment and has low toxicity.

[0003] In the related art, oxyfluorfen is prepared by fully automatic continuous flow microchannel technology. 2-chloro-4-trifluoromethylphenol is a by-product in the production process of oxyfluorfen. The by-product 2-chloro-4-trifluoromethylphenol generated in this process cannot be recycled. Since a large amount of 2-chloro-4-trifluoromethylphenol contained in the waste process water is unstable, the trifluoromethyl group is easily hydrolyzed in the process, which may produce hydrogen fluoride and a strong irritating odor, which has a great impact on the environment. It is difficult for a large amount of waste process water to meet the discharge standards. Summary of the invention

[0004] In order to solve the above-mentioned problems of the prior art, the present invention provides a method for recovering oxyfluorfen byproducts, which can realize low-cost and high-efficiency recovery of byproduct phenol under continuous flow microchannel process conditions, which not only effectively reduces the discharge of production waste process water, but also realizes the high-value utilization of phenol-containing waste process water. An embodiment of the present invention provides a method for recovering oxyfluorfen byproducts, and the method for recovering oxyfluorfen byproducts comprises:

[0005] 2-Chloro-4-trifluoromethylphenol was extracted from the by-product phenol wastewater under the conditions of microchannel continuous production of oxyfluorfen by using high gravity bed vacuum distillation technology.

[0006] Adding an inert organic solvent into the condensation reaction kettle, and adding potassium carbonate into the condensation reaction kettle during the stirring of the inert organic solvent;

[0007] Adding the 2-chloro-4-trifluoromethylphenol dropwise into the condensation reaction kettle, while controlling the dropping temperature of the 2-chloro-4-trifluoromethylphenol to be below 38° C., so that the 2-chloro-4-trifluoromethylphenol reacts with the potassium carbonate to obtain potassium phenolate, wherein the potassium phenolate is potassium 2-chloro-4-trifluoromethylphenol;

[0008] The temperature of the condensation reaction kettle is controlled between 30 and 45° C., and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to make the 2,4-difluoronitrobenzene and the potassium phenolate undergo condensation reaction, and the temperature of the condensation reaction kettle is raised to 68 to 82° C., and the temperature is kept for 3 hours to obtain an initial condensation liquid, and the initial condensation liquid is washed with process water and then transported to the etherification kettle;

[0009] Add ethanol and potassium hydroxide into a potassium alcoholate preparation kettle to prepare a potassium alcoholate solution;

[0010] The potassium alcohol solution is added dropwise to the etherification kettle, so that the potassium alcohol solution and the initial condensation liquid after process water washing undergo etherification reaction to obtain the target oxyfluorfen.

[0011] According to some embodiments of the present invention, the temperature of the condensation reaction kettle is controlled between 30 and 45° C., and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to allow the 2,4-difluoronitrobenzene to undergo a condensation reaction with the potassium phenolate, and the temperature of the condensation reaction kettle is raised to 68 to 82° C. and kept for 3 hours to obtain an initial condensation liquid, comprising:

[0012] The inert organic solvent is subjected to reduced pressure distillation, and the distillation temperature is controlled to 120° C. and the vacuum degree is -0.095 MPa, and the distillation is terminated;

[0013] Controlling the temperature of the condensation reaction kettle to drop to 100° C., adding toluene to the condensation reaction kettle to extract the initial condensation liquid obtained through the condensation reaction, and washing the extracted initial condensation liquid with water and then conveying it to the etherification kettle;

[0014] The residue in the condensation reaction kettle is extracted and dissolved by adding process water, and then potassium fluoride, a by-product of the condensation reaction, is recovered.

[0015] According to some embodiments of the present invention, the step of washing the initial condensation liquid with water and then transferring it to an etherification kettle comprises:

[0016] The initial condensation liquid is transported from the condensation reaction kettle to the condensation process water washing kettle, the first process water is added to the condensation process water washing kettle, the initial condensation liquid and the first process water are stirred, and allowed to stand for 30 minutes to separate the layers, and the target condensation liquid in the lower layer is transported to the etherification kettle.

[0017] According to some embodiments of the present invention, the step of adding ethanol and potassium hydroxide to a potassium alcoholate preparation kettle to prepare a potassium alcoholate solution comprises:

[0018] Ethanol and solid potassium hydroxide are added into the interior of the potassium alkoxide preparation kettle, and ice salt process water is introduced into the jacket of the potassium alkoxide preparation kettle to cool the potassium alkoxide preparation kettle to 10° C. The ethanol and solid potassium hydroxide are stirred until the potassium hydroxide is completely dissolved to obtain a potassium alkoxide solution.

[0019] According to some embodiments of the present invention, the step of adding the potassium alcoholate solution dropwise to the etherification kettle so that the potassium alcoholate solution undergoes an etherification reaction with the initial condensation liquid after process water washing comprises:

[0020] The potassium alcohol solution is added dropwise to the etherification kettle to allow the potassium alcohol solution to undergo an etherification reaction with the initial condensation liquid after process water washing, and the kettle temperature of the etherification kettle is controlled between 37 and 48° C. After keeping the temperature for 4 hours, the material in the etherification kettle is sampled and tested until the sampling test result meets the preset stop condition, thereby obtaining an etherification product, wherein the etherification product contains oxyfluorfen.

[0021] According to some embodiments of the present invention, after obtaining the etherification product, the method comprises:

[0022] Adding toluene and second process water to the etherification process water washing kettle, passing ice salt process water into the jacket of the etherification process water washing kettle to cool the potassium alcohol preparation kettle to 10° C., conveying the etherification product in the etherification kettle to the etherification process water washing kettle, stirring for 10 minutes, standing for 30 minutes to separate layers, and obtaining a first upper oil phase and a lower alkaline solution;

[0023] The lower alkaline solution is pumped into a neutralization kettle, toluene is added into the neutralization kettle so that the toluene extracts the lower alkaline solution, the kettle temperature of the neutralization kettle is controlled at 10° C., the mixture is stirred for 10 minutes, and allowed to stand for 30 minutes to separate layers, thereby obtaining a second upper oil phase and a first lower aqueous phase, and the first lower aqueous phase is transported to a transfer tank;

[0024] The first lower aqueous phase in the transfer tank is pumped into the neutralization kettle, waste sulfuric acid is added to the neutralization kettle for acidification adjustment until the pH value is between 3 and 4, and the mixture is allowed to stand for 30 minutes to separate layers. The second lower aqueous phase after separation is transported to an etherification acidification centrifuge for centrifugation to obtain filter cake potassium fluoride and the first centrifugal mother liquor;

[0025] Alkali solution is added to the neutralization kettle, the pH value of the second upper aqueous phase in the neutralization kettle is adjusted between 9 and 10, and the second upper aqueous phase with pH adjustment is transported to the ethanol recovery kettle for ethanol recovery.

[0026] According to some embodiments of the present invention, the method further comprises:

[0027] The second upper oil phase is pumped back to the etherification process water washing kettle, and the third process water is added to the etherification process water washing kettle, and the first upper oil phase and the second upper oil phase are washed with process water. The phases are allowed to stand for 30 minutes to separate, and the third upper oil phase after separation is transported to the desolventizing kettle for desolventizing treatment.

[0028] According to some embodiments of the present invention, the step of transporting the third upper oil phase after stratification to a desolventizing kettle for desolventizing includes:

[0029] When the temperature of the desolventizing kettle is controlled to be between 95°C and 110°C, the third upper oil phase is desolventized. When the temperature of the desolventizing kettle rises to 115°C, the atmospheric distillation is changed to vacuum distillation until the pressure in the desolventizing kettle is 0.095 MPa. When the temperature of the desolventizing kettle rises to 145°C and there is no distillate, the distillation is stopped.

[0030] The nitrogen in the desolventizing kettle is exhausted, the kettle temperature of the desolventizing kettle is controlled to drop to 90° C., ethanol is added to the desolventizing kettle, and the interior of the desolventizing kettle is stirred until the kettle temperature of the desolventizing kettle drops to 60° C. to obtain a desolventized material;

[0031] The desolventized material is transported to a crystallization kettle, and the kettle temperature of the crystallization kettle is controlled to slowly drop to 10° C. to obtain a crystallized material;

[0032] The crystallized material is transported to a first centrifuge for centrifugal treatment to obtain a filter cake etherified product and a second centrifugal mother liquor.

[0033] According to some embodiments of the present invention, the step of transporting the third upper oil phase after stratification to a desolventizing kettle for desolventizing treatment comprises:

[0034] The filter cake etherified product is conveyed to a dryer, and the filter cake etherified product is dried under reduced pressure until the temperature of the dryer drops to 45-60° C. and the pressure in the dryer is 0.09 MPa, and then the drying is stopped to obtain the target oxyfluorfen;

[0035] The second centrifuged mother liquor is transported to the ethanol recovery kettle for ethanol recovery.

[0036] The beneficial effects of the present invention are embodied in that 2-chloro-4-trifluoromethylphenol is extracted from by-product phenol waste liquid under microchannel continuous production conditions of oxyfluorfen by means of supergravity bed vacuum distillation technology; an inert organic solvent is added to a condensation reaction kettle, and potassium carbonate is added to the condensation reaction kettle during the stirring of the inert organic solvent; 2-chloro-4-trifluoromethylphenol is dripped into the condensation reaction kettle, and the dripping temperature of 2-chloro-4-trifluoromethylphenol is controlled to be below 38° C., so that 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate to obtain potassium phenolate, and the potassium phenolate is 2-chloro-4-trifluoromethylphenol potassium salt;

[0037] The kettle temperature of the condensation reaction kettle is controlled between 30 and 45°C, and 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle after being kept warm for 1 hour, so that 2,4-difluoronitrobenzene and potassium phenolate undergo condensation reaction, and the kettle temperature of the condensation reaction kettle is raised to 68 to 82°C, and kept warm for 3 hours to obtain an initial condensation liquid, and the initial condensation liquid is washed with process water and then transported to the etherification kettle; ethanol and potassium hydroxide are added to the potassium alcoholate preparation kettle to prepare a potassium alcoholate solution; the potassium alcoholate solution is added dropwise to the etherification kettle, so that the potassium alcoholate solution and the initial condensation liquid after the process water washing undergo an etherification reaction to obtain the target oxyfluorfen. Through this method, the present application can achieve low-cost and efficient recovery of by-product phenol under continuous flow microchannel process conditions, which not only effectively reduces the discharge of production waste process water, but also achieves high-value utilization of phenol-containing waste process water. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a method for recovering oxyfluorfen byproducts provided by an embodiment of the first aspect of the present invention;

[0039] Figure 2 It is a schematic flow chart of another method for recovering oxyfluorfen byproducts provided by an embodiment of the second aspect of the present invention;

[0040] Figure 3 It is a schematic flow diagram of the vacuum distillation and extraction of the initial condensation liquid provided by the embodiment of the second aspect of the present invention;

[0041] Figure 4 It is a schematic diagram of a process for treating an etherification product to obtain target oxyfluorfen-butyl provided in an embodiment of the second aspect of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In conjunction with the accompanying drawings, a method for recovering oxyfluorfen byproducts provided by an embodiment of the present invention is described in detail through specific embodiments and application scenarios.

[0044] Embodiment 1:

[0045] Reference Figure 1 , Figure 1 A method for recovering oxyfluorfen byproducts provided by an embodiment of the first aspect of the present invention is shown, the method comprising the following steps:

[0046] Step S110, extracting 2-chloro-4-trifluoromethylphenol from the by-product phenol waste liquid under the oxyfluorfen microchannel continuous production conditions by using supergravity bed vacuum distillation technology.

[0047] It should be noted that, for the by-product phenol waste liquid under the conditions of the microchannel continuous preparation process of oxyfluorfen, this application adopts ultra-gravity bed vacuum distillation technology to extract 2-chloro-4-trifluoromethylphenol, and uses distillation to effectively recover the by-product phenol waste liquid. This process has no chemical reaction, and no other agents are added, so there is almost no secondary pollution.

[0048] In the present embodiment, the by-product phenol waste liquid produced in the continuous preparation of oxyfluorfen microchannel is efficiently extracted by using the supergravity bed vacuum distillation technology. This technology breaks through the traditional treatment method, realizes resource utilization, and reduces production costs. At the same time, it protects the environment and conforms to the concept of green chemistry. Compared with the traditional treatment method, the supergravity bed vacuum distillation technology has obvious advantages in processing efficiency, extraction purity and ease of operation. At the same time, the supergravity bed is more energy-saving and has a small footprint. In addition, by accurately controlling the reaction conditions, the etherification reaction is optimized and the quality and output of the product oxyfluorfen are improved.

[0049] Step S120, adding an inert organic solvent into the condensation reaction kettle, and adding potassium carbonate into the condensation reaction kettle during the process of stirring the inert organic solvent.

[0050] In the present embodiment, the inert organic solvent is DMF, which is the abbreviation of N,N-dimethylformamide, has the chemical formula C3H7NO, and is a colorless and transparent liquid; in other embodiments, the inert organic solvent is dimethyl sulfoxide, which is a sulfur-containing organic compound with the molecular formula C2H6OS. It is a colorless, odorless, transparent liquid at room temperature and is a hygroscopic and flammable liquid; in other embodiments, it may also be other inert organic solvents that can be used in the condensation reactor, and is not limited to the embodiments of the present application.

[0051] Step S130, adding 2-chloro-4-trifluoromethylphenol dropwise to the condensation reaction kettle, while controlling the dropping temperature of 2-chloro-4-trifluoromethylphenol to be below 38° C., so that 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate to obtain potassium phenolate.

[0052] In this step, the potassium phenolate is 2-chloro-4-trifluoromethylphenol potassium salt. After 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate, the condensation reactor contains potassium phenolate, process water, inert organic solvent, a small amount of 2-chloro-4-trifluoromethylphenol that has not reacted completely, and a small amount of potassium carbonate.

[0053] Exemplarily, 320 kg of 2-chloro-4-trifluoromethylphenol, 112.5 kg of potassium carbonate and 450 kg of inert organic solvent are introduced into the condensation reactor. After the 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate, the main salt product obtained includes: 374.24 kg of potassium phenolate, 14.37 kg of process water, 6.4 kg of 2-chloro-4-trifluoromethylphenol, 2.38 kg of potassium carbonate, 450 kg of inert organic solvent and 35.11 kg of carbon dioxide. The 35.11 kg of carbon dioxide is transported to the high-efficiency organic waste gas treatment equipment for waste gas treatment.

[0054] Step S140, control the temperature of the condensation reaction kettle between 30 and 45°C, keep it warm for 1 hour, then add 2,4-difluoronitrobenzene to the condensation reaction kettle to make 2,4-difluoronitrobenzene and potassium phenolate undergo condensation reaction, raise the temperature of the condensation reaction kettle to 68 to 82°C, keep it warm for 3 hours, obtain the initial condensation liquid, wash the initial condensation liquid with process water and then transfer it to the etherification kettle.

[0055] In some embodiments, the temperature of the condensation reaction kettle is controlled to be 30°C, and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to cause condensation reaction between 2,4-difluoronitrobenzene and potassium phenolate. The temperature of the condensation reaction kettle is raised to 68°C and kept warm for 3 hours to obtain an initial condensation liquid, which is then washed with process water and transported to the etherification kettle. In some embodiments, the temperature of the condensation reaction kettle is controlled to be 45°C, and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to cause 2,4-difluoronitrobenzene to react with potassium phenolate. The condensation reaction is carried out with potassium phenolate, the kettle temperature of the condensation reaction kettle is raised to 82°C, and the temperature is kept for 3 hours to obtain an initial condensation liquid, which is then washed with process water and transported to the etherification kettle; in other embodiments, the kettle temperature of the condensation reaction kettle is controlled to be 35°C, and after being kept for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to allow 2,4-difluoronitrobenzene to undergo a condensation reaction with potassium phenolate, the kettle temperature of the condensation reaction kettle is raised to 75°C, and the temperature is kept for 3 hours to obtain an initial condensation liquid, which is then washed with process water and transported to the etherification kettle.

[0056] Exemplarily, 125 kg of 2,4-difluoronitrobenzene is added to the condensation reactor. After the condensation reaction of 2,4-difluoronitrobenzene and potassium phenolate, the condensation reactor contains 398.49 kg of nitrate, 90.29 kg of potassium fluoride, 9.21 kg of potassium phenolate, 6.4 kg of 2-chloro-4-trifluoromethylphenol, 2.38 kg of potassium carbonate, 450 kg of inert organic solvent, 14.37 kg of process water, and 1.25 kg of 2,4-difluoronitrobenzene, that is, the conversion rate of the condensation reaction is 97%.

[0057] Step S150, adding ethanol and potassium hydroxide into a potassium alcoholate preparation kettle to prepare a potassium alcoholate solution.

[0058] Exemplarily, 70.01 kg of ethanol is added to a potassium alcohol preparation kettle, followed by 271.95 kg of solid potassium hydroxide, and the ethanol and potassium hydroxide are stirred. Since the reaction between ethanol and potassium hydroxide is an exothermic reaction, ice salt process water is introduced into the jacket of the potassium alcohol preparation kettle to reduce the kettle temperature of the potassium alcohol preparation kettle to 10° C. The kettle is stirred until the ethanol and potassium hydroxide react completely to obtain a potassium alcohol solution.

[0059] Step S160, adding the potassium alcoholate solution dropwise into the etherification kettle, so that the potassium alcoholate solution and the initial condensation liquid after the process water washing undergo an etherification reaction, to obtain the target oxyfluorfen.

[0060] In this embodiment, the materials transported to the etherification kettle include potassium alcoholate solution, 391.38 kg of nitrate, 2587.25 kg of toluene, 0.8 kg of 2-chloro-4-trifluoromethylphenol, and 3.21 kg of inert organic solvent. After the potassium alcoholate solution undergoes etherification reaction with the initial condensation liquid after process water washing, the etherified product contained in the etherification reaction kettle includes: 270.96 kg of etherification product, 175.67 kg of potassium phenolate, 2587.25 kg of toluene, 0.8 kg of 2-chloro-4-trifluoromethylphenol, 3.2 1kg of inert organic solvent, 28.05kg of potassium hydroxide, 237.22kg of ethanol, 7.83kg of nitrate and 13.49kg of process water. The waste gas G2 includes 0.12kg of ethanol. Among them, the waste gas G2 usually refers to the organic heavy components separated by rapid cooling and acid washing and the evaporation concentrate produced by multiple-effect evaporation in the waste gas treatment process. These substances are hazardous wastes; toluene is left over from the extraction of the initial condensation liquid. The 0.12kg of ethanol is transported to the high-efficiency organic waste gas treatment equipment for waste gas treatment.

[0061] It should be noted that the method for recovering the by-product of oxyfluorfen in the present application has the following beneficial effects: (1) Based on the efficient recovery of by-product phenols in the microchannel of oxyfluorfen continuously and the technical development of co-production of oxyfluorfen, the discharge of waste liquid is effectively reduced and the high-value utilization of by-product phenol waste liquid is realized; (2) It breaks through the technical bottleneck of efficient recovery and co-production of by-product phenols in the microchannel of oxyfluorfen continuously, and provides key common technical support for the industry; (3) It effectively avoids the major dangerous process of preparing oxyfluorfen by nitration reaction, solves the inherent safety problem of production, makes safety supervision and approval easier, and effectively reduces the safety production risks in this field; (4) It improves the oxyfluorfen industry chain and significantly reduces costs and increases efficiency; (5) It effectively promotes technological upgrading and innovation in the field of fine chemicals.

[0062] In some embodiments, in the microchannel continuous preparation of oxyfluorfen, DMF is used as an inert solvent, the temperature of the condensation reaction kettle is precisely controlled below 38°C, and 2-chloro-4-trifluoromethylphenol and potassium carbonate are added dropwise to successfully prepare potassium phenolate. After keeping warm at 38±2°C for 1h, 2,4-difluoronitrobenzene is added, and the kettle temperature is raised to 75°C for keeping warm for 3h, and the initial condensation liquid is obtained through a series of reactions. The initial condensation liquid is washed with process water and then flows to the etherification kettle. In the etherification kettle, we use ethanol and potassium hydroxide to prepare potassium alcohol solution, and react with the condensation liquid to react with etherification reaction. The temperature is controlled at 37-48°C and kept warm for 4h to react to generate oxyfluorfen. This technology breaks through the limitations of traditional preparation processes, improves the quality and yield of products, and provides strong support for the large-scale production of oxyfluorfen.

[0063] In the related art, oxyfluorfen is prepared by fully automatic continuous flow microchannel technology. 2-chloro-4-trifluoromethylphenol is a by-product in the production process of oxyfluorfen. The by-product 2-chloro-4-trifluoromethylphenol generated in this process cannot be recycled. Since a large amount of 2-chloro-4-trifluoromethylphenol contained in the waste process water is unstable, the trifluoromethyl group is easily hydrolyzed in the process, which may produce hydrogen fluoride and a strong irritating odor, which has a great impact on the environment. It is difficult for a large amount of waste process water to meet the discharge standards.

[0064] Therefore, the method for recovering oxyfluorfen byproducts provided by an embodiment of the present invention comprises the following steps: extracting 2-chloro-4-trifluoromethylphenol from the byproduct phenol waste liquid under the continuous production conditions of oxyfluorfen microchannel by means of supergravity bed vacuum distillation technology; adding an inert organic solvent to a condensation reaction kettle, and adding potassium carbonate to the condensation reaction kettle during the stirring of the inert organic solvent; dripping 2-chloro-4-trifluoromethylphenol into the condensation reaction kettle, and controlling the dripping temperature of 2-chloro-4-trifluoromethylphenol to be below 38° C., so that 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate to obtain potassium phenolate, wherein the potassium phenolate is 2 -Chloro-4-trifluoromethylphenol potassium salt; control the kettle temperature of the condensation reaction kettle between 30 and 45 ° C, keep warm for 1 hour, and then add 2,4-difluoronitrobenzene to the condensation reaction kettle to make 2,4-difluoronitrobenzene and potassium phenol salt undergo condensation reaction, the kettle temperature of the condensation reaction kettle rises to 68-82 ° C, keep warm for 3 hours, obtain the initial condensation liquid, and wash the initial condensation liquid with process water before transporting it to the etherification kettle; add ethanol and potassium hydroxide to the potassium alcoholate preparation kettle to prepare potassium alcoholate solution; add the potassium alcoholate solution to the etherification kettle, so that the potassium alcoholate solution and the initial condensation liquid after process water washing undergo etherification reaction to obtain the target oxyfluorfen. Through this method, the present application can achieve low-cost and efficient recovery of by-product phenol under continuous flow microchannel process conditions, which not only effectively reduces the discharge of production waste process water, but also realizes the high-value utilization of phenol-containing waste process water.

[0065] It should be noted that the chemical formula of 2-chloro-4-trifluoromethylphenol is: C7H4CLF3O, the chemical formula of potassium carbonate is K2CO3, the chemical formula of carbonic acid is H2CO3, the chemical formula of 2,4-difluoronitrobenzene is C6H3FN2O4, the chemical formula of potassium phenolate is C7H4CLF3KO, the chemical formula of potassium fluoride is KF, the chemical formula of ethanol is C2H5OH, the chemical formula of potassium hydroxide is KOH, and the chemical formula of oxyfluorfen is C 15 H 11 CLF3NO4, wherein the reaction process of 2-chloro-4-trifluoromethylphenol and potassium carbonate to obtain potassium phenolate, the reaction process of condensation reaction of 2,4-difluoronitrobenzene and potassium phenolate, and the reaction process of etherification reaction of potassium alcoholate solution and initial condensation liquid after process water washing are as follows:

[0066]

[0067] Embodiment 2:

[0068] Reference Figures 2 to 4 , Figures 2 to 4 Another method for recovering oxyfluorfen byproducts provided by an embodiment of the first aspect of the present invention is shown, the method comprising the following steps:

[0069] Step S210, extracting 2-chloro-4-trifluoromethylphenol from the by-product phenol waste liquid under the oxyfluorfen microchannel continuous production conditions by using supergravity bed vacuum distillation technology.

[0070] This step can be done using Figure 1 The description of step S110 of the embodiment will not be repeated here.

[0071] Step S220, adding an inert organic solvent into the condensation reaction kettle, and adding potassium carbonate into the condensation reaction kettle during the process of stirring the inert organic solvent.

[0072] This step can be done using Figure 1 The description of step S120 of the embodiment will not be repeated here.

[0073] Step S230, 2-chloro-4-trifluoromethylphenol is added dropwise to the condensation reaction kettle, and the dropping temperature of 2-chloro-4-trifluoromethylphenol is controlled to be below 38° C., so that 2-chloro-4-trifluoromethylphenol reacts with potassium carbonate to obtain potassium phenolate.

[0074] In this step, the phenol potassium salt is 2-chloro-4-trifluoromethylphenol potassium salt. Figure 1 The description of step S130 of the embodiment will not be repeated here.

[0075] Step S240, controlling the temperature of the condensation reaction kettle between 30 and 45°C, keeping the temperature for 1 hour, then adding 2,4-difluoronitrobenzene to the condensation reaction kettle to make 2,4-difluoronitrobenzene and potassium phenolate undergo condensation reaction, raising the temperature of the condensation reaction kettle to 68 to 82°C, keeping the temperature for 3 hours, and obtaining an initial condensation liquid.

[0076] This step can be done using Figure 1 The description of step S140 of the embodiment will not be repeated here.

[0077] Step S241, performing reduced pressure distillation on the inert organic solvent, controlling the distillation temperature to 120° C. and the vacuum degree to -0.095 MPa, and then ending the distillation.

[0078] In this step, the inert organic solvent is distilled under reduced pressure, the distillation temperature is controlled to 120° C., and when the vacuum degree is -0.095 MPa, substantially no fraction slips out, and the distillation is finished.

[0079] Exemplarily, 398.49 kg of nitrate obtained by condensation reaction, 90.29 kg of potassium fluoride, 9.21 kg of potassium phenolate, 6.4 kg of 2-chloro-4-trifluoromethylphenol, 2.38 kg of potassium carbonate, 450 kg of inert organic solvent, 14.37 kg of process water, and 1.25 kg of 2,4-difluoronitrobenzene are subjected to reduced pressure distillation to obtain fractions including: 444.34 kg of inert organic solvent, 13.29 kg of process water, 5.6 kg of 2-chloro-4-trifluoromethylphenol, and 1.25 kg of 2,4-difluoronitrobenzene. The residue includes: 398.49 kg of nitrate, 90.29 kg of potassium fluoride, 9.21 kg of potassium phenolate, 0.8 kg of 2-chloro-4-trifluoromethylphenol, 2.38 kg of potassium carbonate, 1.25 kg of 2,4-difluoronitrobenzene, 3.21 kg of inert organic solvent, and the waste gas G1 includes: 2.45 kg of inert organic solvent and 1.08 kg of process water; the waste gas G1 is transported to the high-efficiency organic waste gas treatment equipment for waste gas treatment, the distillate is applied, and the residue is extracted.

[0080] Step S242, controlling the temperature of the condensation reaction kettle to drop to 100°C, adding toluene into the condensation reaction kettle to extract the initial condensation liquid obtained through the condensation reaction, and then washing the extracted initial condensation liquid with process water and transferring it to the etherification kettle.

[0081] In a possible implementation, the residue in the condensation reactor is extracted and dissolved with process water, and then potassium fluoride, a by-product of the condensation reaction, is recovered.

[0082] Exemplarily, the residue obtained by vacuum distillation: 398.49 kg of nitrate, 90.29 kg of potassium fluoride, 9.21 kg of potassium phenolate, 0.8 kg of 2-chloro-4-trifluoromethylphenol, 2.38 kg of potassium carbonate, 1.25 kg of 2,4-difluoronitrobenzene, 3.21 kg of inert organic solvent are extracted with 2600 kg of toluene, and the obtained extract includes: 391.38 kg of nitrate, 2587.25 kg of toluene, 0. 8kg of 2-chloro-4-trifluoromethylphenol and 3.21kg of inert organic solvent are used for extraction, and the obtained extract includes 391.38kg of nitrate, 2587.25 of toluene, 0.8kg of 2-chloro-4-trifluoromethylphenol and 3.21kg of inert organic solvent, and the residue includes: 90.29kg of potassium fluoride, 9.21kg of potassium phenolate, 2.38kg of potassium carbonate, 1.25kg of 2,4-difluoronitrobenzene and 12.75kg of toluene. The extract is transported to an etherification kettle to participate in the etherification reaction, and the potassium fluoride in the residue is recovered.

[0083] Step S250, transporting the initial condensation liquid from the condensation reaction kettle to the condensation process water washing kettle, adding the first process water to the condensation process water washing kettle, stirring the initial condensation liquid and the first process water, standing for 30 minutes to separate the layers, and transporting the target condensation liquid in the lower layer to the etherification kettle.

[0084] Step S260, adding ethanol and solid potassium hydroxide into the interior of the potassium alcohol preparation kettle, passing ice salt process water into the jacket of the potassium alcohol preparation kettle to cool the potassium alcohol preparation kettle to 10° C., stirring the ethanol and solid potassium hydroxide until the potassium hydroxide is completely dissolved to obtain a potassium alcohol solution.

[0085] Step S270, adding the potassium alcohol solution dropwise into the etherification kettle to allow the potassium alcohol solution to react with the initial condensation liquid after process water washing to undergo an etherification reaction, controlling the kettle temperature of the etherification kettle between 37 and 48° C., keeping the temperature for 4 hours, sampling and testing the material in the etherification kettle until the sampling and testing results meet the preset stop conditions to obtain an etherification product.

[0086] In this step, the etherification product contains oxyfluorfen.

[0087] Specifically, steam is first introduced into the jacket of the etherification kettle to start to evaporate toluene, 1 / 3 of the toluene is evaporated, and the evaporated toluene flows into the toluene receiving tank; the steam valve of the etherification kettle is closed, the circulating water valve of the etherification kettle is opened, the etherification kettle is cooled to 40°C and then the circulating water valve is closed, and then the potassium alcohol solution is dripped into the etherification kettle to allow the potassium alcohol solution to react with the initial condensation liquid after the process water washing to undergo an etherification reaction, the kettle temperature of the etherification kettle is controlled between 37 and 48°C, and after keeping the temperature for 4 hours, the material in the etherification kettle is sampled and tested until the sampling test result meets the preset stop condition to obtain the etherification product.

[0088] Step S271, add toluene and the second process water into the etherification process water washing kettle, pass ice salt process water into the jacket of the etherification process water washing kettle to cool the potassium alcohol preparation kettle to 10°C, transfer the etherification product in the etherification kettle to the etherification process water washing kettle, stir for 10 minutes, let it stand for 30 minutes to separate the layers, and obtain a first upper oil phase and a lower alkaline solution.

[0089] In this step, 200 kg of the second process water is added to the etherification process water washing kettle, and then the etherification product obtained by the etherification reaction: 270.96 kg of etherified product, 175.67 kg of potassium phenolate, 2587.25 kg of toluene, 0.8 kg of 2-chloro-4-trifluoromethylphenol, 3.21 kg of inert organic solvent, 28.05 kg of potassium hydroxide, 237.22 kg of ethanol, 7.83 kg of nitrate and 13.49 kg of process water are transported to the etherification process water washing kettle for process water washing, and the obtained product is allowed to stand for stratification. The separated aqueous phase, i.e. the lower alkaline solution, includes 211.44 kg of process water, 235.53 kg of ethanol, 28.05 kg of potassium hydroxide, 13.55 kg of etherate, 51.75 kg of toluene and 175.67 kg of potassium phenolate. The separated organic phase, i.e. the first upper oil phase, includes 2535.5 kg of toluene, 257.41 kg of etherate, 1.69 kg of ethanol, 2.05 kg of water, 7.83 kg of nitrate, 0.8 kg of 2-chloro-4-trifluoromethylphenol and 3.21 kg of inert organic solvent.

[0090] Step S272, pump the lower alkaline solution into the neutralization kettle, add toluene into the neutralization kettle so that the toluene extracts the lower alkaline solution, control the kettle temperature of the neutralization kettle at 10°C, stir for 10 minutes, let stand for 30 minutes to separate the layers, and obtain the second upper oil phase and the first lower water phase, and transport the first lower water phase to the transfer tank.

[0091] In this step, 100 kg of toluene is added to the neutralization kettle, and the lower alkaline solution: 211.44 kg of process water, 235.53 kg of ethanol, 28.05 kg of potassium hydroxide, 13.55 kg of etherate, 51.75 kg of toluene and 175.67 kg of potassium phenolate are transported to the neutralization kettle, so that the lower alkaline solution is treated with toluene to obtain an extracted organic phase, i.e., the second upper oil phase, including: 150.42 kg of toluene, 1.58 kg of process water, 13.55 kg of etherate, 0.06 kg of potassium phenolate, 0.09 kg of ethanol, and the obtained extracted aqueous phase, i.e., the first lower aqueous phase, includes: 209.86 kg of water, 235.44 kg of ethanol, 28.05 kg of potassium hydroxide, 175.61 kg of potassium phenolate, and 1.33 kg of toluene.

[0092] In a possible implementation, the first lower aqueous phase in the transfer tank is pumped into the neutralization kettle, waste sulfuric acid is added to the neutralization kettle for acidification adjustment until the pH value is between 3 and 4, the mixture is allowed to stand for 30 minutes for stratification, and the second lower aqueous phase after stratification is transported to an etherification acidification centrifuge for centrifugation to obtain filter cake potassium fluoride and the first centrifuged mother liquor; alkali solution is added to the neutralization kettle, the pH value of the second upper aqueous phase in the neutralization kettle is adjusted to between 9 and 10, and the second upper aqueous phase after pH adjustment is transported to an ethanol recovery kettle for ethanol recovery.

[0093] Step S273, pump the second upper oil phase back to the etherification process water washing kettle, add the third process water into the etherification process water washing kettle, wash the first upper oil phase and the second upper oil phase with process water, let them stand for 30 minutes to separate the layers, and transport the separated third upper oil phase to the desolventizing kettle for desolventizing treatment.

[0094] Exemplarily, the second upper oil phase and the first upper oil phase, namely: 150.42 kg of toluene, 1.58 kg of process water, 13.55 kg of etherified product, 0.06 kg of potassium phenolate, 0.09 kg of ethanol, 2535.5 kg of toluene, 257.41 kg of etherified product, 1.69 kg of ethanol, 2.05 kg of water, 7.83 kg of nitrated product, 0.8 kg of 2-chloro-4-trifluoromethylphenol and 3.21 kg of inert organic solvent are conveyed to the etherification water washing kettle, and 150 kg of the third process water is additionally added to the etherification water washing kettle. The second upper oil phase and the first upper oil phase are washed with water, and the washed organic phase obtained after standing and stratification (i.e., the third upper oil phase) includes: 2684.71 kg of toluene, 270.79 kg of etherified product, 0.12 kg of process water, 7.83 kg of nitrated product, 3.21 kg of inert organic solvent and 0.8 kg of 2-chloro-4-trifluoromethylphenol, and the washed aqueous phase (i.e., the third lower aqueous phase) includes: 1.78 kg of ethanol, 153.51 kg of water, 0.17 kg of etherified product, 1.21 kg of toluene and 0.06 kg of potassium phenolate.

[0095] Step S274, control the kettle temperature of the desolventizing kettle to between 95 and 110°C to perform desolventizing treatment on the third upper oil phase. When the kettle temperature of the desolventizing kettle rises to 115°C, change the normal pressure distillation to the reduced pressure distillation until the pressure in the desolventizing kettle reaches 0.095Mpa. When the kettle temperature of the desolventizing kettle rises to 145°C and there is no distillate, stop the distillation.

[0096] Step S275, exhaust the nitrogen in the desolventizing kettle, control the kettle temperature of the desolventizing kettle to drop to 90°C, add ethanol to the desolventizing kettle, stir the inside of the desolventizing kettle until the kettle temperature of the desolventizing kettle drops to 60°C, and obtain the desolventizing material.

[0097] Exemplarily, the third upper oil phase: 2684.71 kg of toluene, 270.79 kg of etherified product, 0.12 kg of process water, 7.83 kg of nitrated product, 3.21 kg of inert organic solvent and 0.8 kg of 2-chloro-4-trifluoromethylphenol are transported to a desolventizing kettle for desolventizing treatment, the evaporated solvent includes 2683.93 kg of toluene, 0.12 kg of process water and 3.21 kg of inert organic solvent, the residue, i.e., the desolventizing material includes 0.43 kg of toluene, 270.79 kg of etherified product, 0.8 kg of 2-chloro-4-trifluoromethylphenol and 7.83 kg of nitrated product, and the waste gas G3: 0.35 kg of toluene is sent for waste gas treatment, and the evaporated solvent is sent for application.

[0098] Step S276, conveying the desolventized material to a crystallization kettle, controlling the kettle temperature of the crystallization kettle to slowly drop to 10° C., and obtaining a crystallized material.

[0099] Exemplarily, the desolventizing material including 0.43 kg of toluene, 270.79 kg of etherate, 0.8 kg of 2-chloro-4-trifluoromethylphenol and 7.83 kg of nitrate is transported to a crystallization kettle for crystallization filtration to obtain a crystallization material and a filtrate. The crystallization material includes: 270.79 kg of etherate and 10.23 kg of ethanol, and the filtrate includes 7.83 kg of nitrate, 0.8 kg of 2-chloro-4-trifluoromethylphenol, 0.43 kg of toluene and 289.77 kg of ethanol, and the filtrate is sent to scraper desolventizing.

[0100] Step S277, conveying the crystallized material to a first centrifuge for centrifugal treatment to obtain a filter cake etherified product and a second centrifugal mother liquor.

[0101] Step S278, conveying the filter cake etherified product to a dryer, and drying the filter cake etherified product under reduced pressure until the temperature of the dryer drops to 45-60° C. and the pressure in the dryer is 0.09 MPa, then stopping the drying to obtain the target oxyfluorfen.

[0102] In some embodiments, the filter cake etherate is conveyed to a dryer, and the filter cake etherate is dried under reduced pressure until the temperature of the dryer drops to 45°C and the pressure in the dryer is 0.09Mpa, then the drying is stopped to obtain the target oxyfluorfen; in other embodiments, the filter cake etherate is conveyed to a dryer, and the filter cake etherate is dried under reduced pressure until the temperature of the dryer drops to 50°C and the pressure in the dryer is 0.09Mpa, then the drying is stopped to obtain the target oxyfluorfen; in other embodiments, the filter cake etherate is conveyed to a dryer, and the filter cake etherate is dried under reduced pressure until the temperature of the dryer drops to 60°C and the pressure in the dryer is 0.09Mpa, then the drying is stopped to obtain the target oxyfluorfen.

[0103] Exemplarily, after being dried in a dryer under reduced pressure, 270.79 kg of the target oxyfluorfen was obtained.

[0104] In a possible implementation, the second centrifuged mother liquor is transported to an ethanol recovery kettle for ethanol recovery.

[0105] In the related art, oxyfluorfen is prepared by fully automatic continuous flow microchannel technology. 2-chloro-4-trifluoromethylphenol is a by-product in the production process of oxyfluorfen. The by-product 2-chloro-4-trifluoromethylphenol generated in this process cannot be recycled. Since a large amount of 2-chloro-4-trifluoromethylphenol contained in the waste process water is unstable, the trifluoromethyl group is easily hydrolyzed in the process, which may produce hydrogen fluoride and a strong irritating odor, which has a great impact on the environment. It is difficult for a large amount of waste process water to meet the discharge standards.

[0106] Therefore, the method for recovering oxyfluorfen byproducts provided by an embodiment of the present invention comprises extracting 2-chloro-4-trifluoromethylphenol from the byproduct phenol waste liquid under the continuous production conditions of oxyfluorfen microchannel by using the supergravity bed vacuum distillation technology; adding an inert organic solvent to a condensation reaction kettle, and adding potassium carbonate to the condensation reaction kettle during the stirring of the inert organic solvent; dripping 2-chloro-4-trifluoromethylphenol into the condensation reaction kettle, and controlling the dripping temperature of 2-chloro-4-trifluoromethylphenol. The temperature of the condensation reaction kettle is controlled to be between 30 and 45°C, and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to make 2,4-difluoronitrobenzene and potassium phenolate undergo condensation reaction, and the temperature of the condensation reaction kettle is raised to 68-82°C, and the temperature is kept for 3 hours to obtain an initial condensation solution; the inert organic solvent is subjected to reduced pressure distillation, and the distillation temperature is controlled to 120°C and the vacuum degree is -0.095Mpa, end the distillation; control the kettle temperature of the condensation reaction kettle to drop to 100°C, add toluene to the condensation reaction kettle to extract the initial condensation liquid obtained by the condensation reaction, and wash the extracted initial condensation liquid with process water and then transport it to the etherification kettle; transport the initial condensation liquid from the condensation reaction kettle to the condensation process water washing kettle, add the first process water to the condensation process water washing kettle, stir the initial condensation liquid and the first process water, let it stand for 30 minutes to separate the layers, and transport the target condensation liquid in the lower layer to the etherification kettle; add ethanol and solid potassium hydroxide to the interior of the potassium alcohol preparation kettle, pass ice salt process water into the jacket of the potassium alcohol preparation kettle to cool the potassium alcohol preparation kettle to 10°C, stir the ethanol and solid potassium hydroxide Stir until the potassium hydroxide is completely dissolved to obtain a potassium alcohol solution; add the potassium alcohol solution dropwise to the etherification kettle to allow the potassium alcohol solution to react with the initial condensation liquid after the process water washing to undergo an etherification reaction, control the kettle temperature of the etherification kettle between 37 and 48°C, keep warm for 4 hours, sample and test the material in the etherification kettle until the sampling test result meets the preset stop condition to obtain an etherification product; add toluene and the second process water to the etherification process water washing kettle, pass ice salt process water into the jacket of the etherification process water washing kettle to cool the potassium alcohol preparation kettle to 10°C, transport the etherification product in the etherification kettle to the etherification process water washing kettle, stir for 10 minutes, let stand for 30 minutes to separate the layers, and obtain a first upper oil phase and a lower alkaline solution; pump the lower alkaline solution to the neutralization The kettle is in the middle, toluene is added to the neutralization kettle to make the toluene extract the lower alkaline solution, the kettle temperature of the neutralization kettle is controlled at 10°C, stirred for 10 minutes, and allowed to stand for 30 minutes to separate layers, to obtain the second upper oil phase and the first lower water phase, and the first lower water phase is transported to the transfer tank; the second upper oil phase is pumped back to the etherification process water washing kettle, the third process water is added to the etherification process water washing kettle, the first upper oil phase and the second upper oil phase are washed with process water, allowed to stand for 30 minutes to separate layers, and the third upper oil phase after separation is transported to the desolventizing kettle for desolventizing treatment; the kettle temperature of the desolventizing kettle is controlled to be between 95 and 110°C to carry out desolventizing treatment on the third upper oil phase, and when the kettle temperature of the desolventizing kettle rises to 115°C, the atmospheric distillation is changed to the reduced pressure distillation. , until the pressure in the desolventizing kettle is 0.095Mpa, the kettle temperature of the desolventizing kettle rises to 145℃, and the distillation is stopped when there is no distillate; the nitrogen in the desolventizing kettle is emptied, the kettle temperature of the desolventizing kettle is controlled to drop to 90℃, ethanol is added to the desolventizing kettle, and the inside of the desolventizing kettle is stirred until the kettle temperature of the desolventizing kettle drops to 60℃ to obtain the desolventizing material; the desolventizing material is transported to the crystallization kettle, and the kettle temperature of the crystallization kettle is controlled to slowly drop to 10℃ to obtain the crystallized material; the crystallized material is transported to the first centrifuge for centrifugal treatment to obtain the filter cake etherified product and the second centrifugal mother liquor; the filter cake etherified product is transported to the dryer, and the filter cake etherified product is dried under reduced pressure until the temperature of the dryer drops to 45-60℃ and the pressure in the dryer is 0.09Mpa, stop drying and obtain the target oxyfluorfen. This application can achieve low-cost and high-efficiency recovery of by-product phenol under continuous flow microchannel process conditions through this method, which not only effectively reduces the discharge of production waste process water, but also realizes the high-value utilization of phenol-containing waste process water. .

[0107] In the description of the embodiments of the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0108] In the description of the embodiments of the present invention, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0109] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recovering oxyfluorfen byproducts, characterized in that: include: 2-Chloro-4-trifluoromethylphenol was extracted from the by-product phenol wastewater under the conditions of microchannel continuous production of oxyfluorfen by using high gravity bed vacuum distillation technology. Adding an inert organic solvent into the condensation reaction kettle, and adding potassium carbonate into the condensation reaction kettle during the stirring of the inert organic solvent; Adding the 2-chloro-4-trifluoromethylphenol dropwise into the condensation reaction kettle, while controlling the dropping temperature of the 2-chloro-4-trifluoromethylphenol to be below 38° C., so that the 2-chloro-4-trifluoromethylphenol reacts with the potassium carbonate to obtain potassium phenolate, wherein the potassium phenolate is potassium 2-chloro-4-trifluoromethylphenol; The temperature of the condensation reaction kettle is controlled between 30 and 45° C., and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to make the 2,4-difluoronitrobenzene and the potassium phenolate undergo condensation reaction, and the temperature of the condensation reaction kettle is raised to 68 to 82° C., and the temperature is kept for 3 hours to obtain an initial condensation liquid, and the initial condensation liquid is washed with process water and then transported to the etherification kettle; Add ethanol and potassium hydroxide into a potassium alcoholate preparation kettle to prepare a potassium alcoholate solution; The potassium alcohol solution is added dropwise to the etherification kettle, so that the potassium alcohol solution and the initial condensation liquid after process water washing undergo etherification reaction to obtain the target oxyfluorfen.

2. The method for recovering oxyfluorfen byproduct according to claim 1, characterized in that: The kettle temperature of the condensation reaction kettle is controlled between 30 and 45° C., and after keeping the temperature for 1 hour, 2,4-difluoronitrobenzene is added dropwise to the condensation reaction kettle to make the 2,4-difluoronitrobenzene and the potassium phenolate undergo condensation reaction, and the kettle temperature of the condensation reaction kettle is raised to 68 to 82° C. and kept for 3 hours to obtain an initial condensation liquid, comprising: The inert organic solvent is subjected to reduced pressure distillation, and the distillation temperature is controlled to 120° C. and the vacuum degree is -0.095 MPa, and the distillation is terminated; Controlling the temperature of the condensation reaction kettle to drop to 100° C., adding toluene to the condensation reaction kettle to extract the initial condensation liquid obtained through the condensation reaction, and washing the extracted initial condensation liquid with water and then conveying it to the etherification kettle; The residue in the condensation reaction kettle is extracted and dissolved by adding process water, and then potassium fluoride, a by-product of the condensation reaction, is recovered.

3. The method for recovering oxyfluorfen byproduct according to claim 1, characterized in that: The process of washing the initial condensation liquid with water and then conveying it to the etherification kettle comprises: The initial condensation liquid is transported from the condensation reaction kettle to the condensation process water washing kettle, the first process water is added to the condensation process water washing kettle, the initial condensation liquid and the first process water are stirred, and allowed to stand for 30 minutes to separate the layers, and the target condensation liquid in the lower layer is transported to the etherification kettle.

4. The method for recovering oxyfluorfen byproduct according to claim 1, characterized in that: The step of adding ethanol and potassium hydroxide into a potassium alcoholate preparation kettle to prepare a potassium alcoholate solution comprises: Ethanol and solid potassium hydroxide are added into the interior of the potassium alkoxide preparation kettle, and ice salt process water is introduced into the jacket of the potassium alkoxide preparation kettle to cool the potassium alkoxide preparation kettle to 10° C. The ethanol and solid potassium hydroxide are stirred until the potassium hydroxide is completely dissolved to obtain a potassium alkoxide solution.

5. The method for recovering oxyfluorfen byproduct according to claim 1, characterized in that: The step of dripping the potassium alcohol solution into the etherification kettle so that the potassium alcohol solution and the initial condensation liquid after process water washing undergo an etherification reaction comprises: The potassium alcohol solution is added dropwise to the etherification kettle to allow the potassium alcohol solution to undergo an etherification reaction with the initial condensation liquid after process water washing, and the kettle temperature of the etherification kettle is controlled between 37 and 48° C. After keeping the temperature for 4 hours, the material in the etherification kettle is sampled and tested until the sampling test result meets the preset stop condition, thereby obtaining an etherification product, wherein the etherification product contains oxyfluorfen.

6. The method for recovering oxyfluorfen byproduct according to claim 5, characterized in that: After obtaining the etherification product, the method further comprises: Adding toluene and second process water to the etherification process water washing kettle, passing ice salt process water into the jacket of the etherification process water washing kettle to cool the potassium alcohol preparation kettle to 10° C., conveying the etherification product in the etherification kettle to the etherification process water washing kettle, stirring for 10 minutes, standing for 30 minutes to separate layers, and obtaining a first upper oil phase and a lower alkaline solution; The lower alkaline solution is pumped into a neutralization kettle, toluene is added into the neutralization kettle so that the toluene extracts the lower alkaline solution, the kettle temperature of the neutralization kettle is controlled at 10° C., the mixture is stirred for 10 minutes, and allowed to stand for 30 minutes to separate layers, thereby obtaining a second upper oil phase and a first lower aqueous phase, and the first lower aqueous phase is transported to a transfer tank; The first lower aqueous phase in the transfer tank is pumped into the neutralization kettle, waste sulfuric acid is added to the neutralization kettle for acidification adjustment until the pH value is between 3 and 4, and the mixture is allowed to stand for 30 minutes to separate layers. The second lower aqueous phase after separation is transported to an etherification acidification centrifuge for centrifugation to obtain filter cake potassium fluoride and the first centrifugal mother liquor; Alkali solution is added to the neutralization kettle, the pH value of the second upper aqueous phase in the neutralization kettle is adjusted between 9 and 10, and the second upper aqueous phase with pH adjustment is transported to the ethanol recovery kettle for ethanol recovery.

7. The method for recovering oxyfluorfen byproduct according to claim 6, characterized in that: The method further comprises: The second upper oil phase is pumped back to the etherification process water washing kettle, and the third process water is added to the etherification process water washing kettle, and the first upper oil phase and the second upper oil phase are washed with process water. The phases are allowed to stand for 30 minutes to separate, and the third upper oil phase after separation is transported to the desolventizing kettle for desolventizing treatment.

8. The method for recovering oxyfluorfen byproduct according to claim 7, characterized in that: The step of transporting the third upper oil phase after stratification to a desolventizing kettle for desolventizing treatment comprises: When the temperature of the desolventizing kettle is controlled to be between 95°C and 110°C, the third upper oil phase is desolventized. When the temperature of the desolventizing kettle rises to 115°C, the atmospheric distillation is changed to vacuum distillation until the pressure in the desolventizing kettle is 0.095 MPa. When the temperature of the desolventizing kettle rises to 145°C and there is no distillate, the distillation is stopped. The nitrogen in the desolventizing kettle is exhausted, the kettle temperature of the desolventizing kettle is controlled to drop to 90° C., ethanol is added to the desolventizing kettle, and the interior of the desolventizing kettle is stirred until the kettle temperature of the desolventizing kettle drops to 60° C. to obtain a desolventized material; The desolventized material is transported to a crystallization kettle, and the kettle temperature of the crystallization kettle is controlled to slowly drop to 10° C. to obtain a crystallized material; The crystallized material is transported to a first centrifuge for centrifugal treatment to obtain a filter cake etherified product and a second centrifugal mother liquor.

9. The method for recovering oxyfluorfen byproduct according to claim 7, characterized in that: The step of transporting the third upper oil phase after stratification to a desolventizing kettle for desolventizing treatment comprises: The filter cake etherified product is conveyed to a dryer, and the filter cake etherified product is dried under reduced pressure until the temperature of the dryer drops to 45-60° C. and the pressure in the dryer is 0.09 MPa, and then the drying is stopped to obtain the target oxyfluorfen; The second centrifuged mother liquor is transported to the ethanol recovery kettle for ethanol recovery.

Images