Preparation process of 2, 3-dichlorooctafluorobutane

Abstract

The invention relates to the technical field of dichlorooctafluorobutane, and provides a preparation process of 2, 3-dichlorooctafluorobutane, and the preparation process comprises the following steps: S100, adding a fluorine phase into a polar phase, and carrying out shearing treatment to obtain a microemulsion; s200, carrying out photoelectric synergistic activation treatment on the microemulsion to obtain 2, 3-dichlorooctafluorobutane; wherein the polar phase comprises a solvent, an electrolyte, a photocatalyst and a stabilizer; the fluorine phase comprises a fluorine-containing substrate, an inert fluorine solvent and a fluorine-containing surfactant. According to the preparation method, the fluorine phase is added into the polar phase containing the photocatalyst and the electrolyte, a stable micro-emulsion system with a nanoscale interface is formed through high-speed shearing, and then photoelectric synergistic activation is implemented, so that precise regulation and control on a perfluoro-2-butene chloride addition reaction path are realized, and the synthesis efficiency and selectivity of the 2, 3-dichlorooctafluorobutane are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of dichlorooctafluorobutane technology, and more particularly to a preparation process for 2,3-dichlorooctafluorobutane. Background Technology

[0002] Fluorine-containing fine chemicals are widely used in electronic chemicals, semiconductor lithography materials, fluorochemical new materials, and high-end refrigerants due to their excellent thermal stability, chemical inertness, and dielectric properties. Among fluorine-containing compound systems, 2,3-dichlorooctafluorobutane is an important class of fluorinated halogenated compounds, which can be used as fluorine-containing intermediates, monomers for fluorinated functional materials, and components in special working condition formulations, and has high industrial value.

[0003] The preparation of 2,3-dichlorooctafluorobutane typically employs a photochlorination route. Using perfluoro-2-butene (CF3-CFCl-CFCl-CF3, also known as W12) as a fluorinated olefin feedstock, chlorine radicals are added to both sides of the double bond via a photoinduced free radical reaction in the presence of chlorine gas, thereby generating 2,3-dichlorooctafluorobutane. A typical process includes: mixing perfluoro-2-butene with chlorine gas in a specific ratio, reacting under specific wavelength light source irradiation and catalytic conditions, followed by crude distillation, washing, rectification, and drying to obtain the target product. The typical reaction is shown below: CF3-CF=CF-CF3+Cl2→CF3-CFCl-CFCl-CF3 Although the above-mentioned photochlorination method can achieve the preparation of addition products, this type of process generally belongs to the gas phase free radical reaction system, which has disadvantages such as a wide variety of free radicals, complex reaction paths, and easy occurrence of side reactions. It may lead to: (1) limited regioselectivity of chlorine free radical addition, with the risk of generating isomers such as 1,4-addition; (2) the reaction depends on strong light and chlorine gas, which may cause equipment corrosion and low light efficiency; (3) the product often contains impurities, requiring more distillation and purification steps, resulting in higher energy consumption and cost.

[0004] Therefore, there is an urgent need to develop novel preparation methods with mild reaction conditions, high selectivity, and the ability to suppress the formation of byproducts. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of this application is to provide a preparation process for 2,3-dichlorooctafluorobutane.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: This application constructs a polar phase and a fluorine phase microemulsion system and introduces a photoelectric synergistic activation method to generate chlorine free radicals in a directional and mild manner at the microemulsion interface, thereby significantly improving the 2,3-position addition selectivity for perfluoro-2-butene, and finally obtaining high-purity 2,3-dichlorooctafluorobutane, which is easier to separate, has a higher yield, and is suitable for industrialization.

[0007] This application provides a process for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. A fluorine phase is added to the polar phase, and shearing is performed to obtain a microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes solvents, electrolytes, photocatalysts, and stabilizers; The fluorinated phase includes fluorinated substrates, inert fluorinated solvents, and fluorinated surfactants.

[0008] In an optional implementation, S200 includes: S210. Electrolyze the microemulsion to obtain a microemulsion containing active chlorine products; S220. Photo-treating microemulsions containing active chlorine products yields 2,3-dichlorooctafluorobutane.

[0009] In an optional implementation, S200 includes: S230. Electrolyze the microemulsion and simultaneously irradiate it with light to obtain 2,3-dichlorooctafluorobutane.

[0010] In one alternative embodiment, the voltage for electrolytic treatment is 1.5-5.0V; and / or the wavelength for light irradiation treatment is 420-520nm.

[0011] In one alternative embodiment, the mass ratio of the polar phase to the fluorine phase is (0.7-1.5):1.

[0012] In one alternative embodiment, the mass ratio of solvent, electrolyte, photocatalyst and stabilizer in the polar phase is 1:(0.01-0.2):(0.0005-0.07):(0.01-0.1); and / or the mass ratio of fluorinated substrate, inert fluorinated solvent and fluorinated surfactant in the fluorinated phase is 1:(0.01-0.5):(0.001-0.1).

[0013] In an optional embodiment, the solvent includes at least one of deionized water, alcohols, polar aprotic solvents, or ionic liquids; and / or the electrolyte includes at least one of sodium chloride, potassium chloride, lithium chloride, or quaternary ammonium chloride; and / or the photocatalyst includes at least one of copper chloride, iron chloride, cobalt chloride, or nickel chloride; and / or the stabilizer includes at least one of fluorinated surfactants, ionic liquids, buffers, or metal complexing agents; and / or the fluorinated substrate includes perfluoro-2-butene; and / or the inert fluorinated solvent includes at least one of perfluorohexane, perfluoropentane, perfluorotributylamine, or HFE solvent; and / or the fluorinated surfactant includes at least one of fluorocarbonate, fluorocarbon sulfonate, or fluorinated ether surfactant.

[0014] In an optional implementation, in S100, the shearing speed is 1000-3000 rpm.

[0015] In an optional implementation, S100 and S200 further include: S110. Allow the microemulsion to stand.

[0016] In an optional embodiment, the preparation method further includes: S300 and 2,3-dichlorooctafluorobutane were sequentially centrifuged and purified. Refining processes include distillation and drying.

[0017] The beneficial effects of this application include at least the following: (1) By adding the fluorine phase into the polar phase containing the photocatalyst and electrolyte, a stable microemulsion system with a nanoscale interface is formed by high-speed shearing, and then photoelectric synergistic activation is carried out, which realizes the precise control of the perfluoro-2-butene chloro addition reaction pathway and significantly improves the synthesis efficiency and selectivity of 2,3-dichlorooctafluorobutane. (2) By adding the fluorine phase to the polar phase and subjecting it to high-speed shearing, an emulsion system with a stable microstructure is constructed. Then, photoelectric synergistic activation is performed on the microemulsion system to achieve precise control of the selective chlorination reaction pathway of fluorinated olefins. (3) The photoelectric synergistic activation strategy is adopted. First, the photocatalyst is excited to generate electron-hole pairs, and then an external electric field is used to further promote the efficient cracking of chlorine molecules into Cl· at the interface, thereby realizing the directional generation of chlorine free radicals. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0019] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0020] The preparation of 2,3-dichlorooctafluorobutane typically employs a photochlorination process, where, under a chlorine atmosphere, light-induced free radical reactions cause chlorine radicals to add to both sides of the double bond in perfluoro-2-butene. A typical process involves mixing perfluoro-2-butene with chlorine in a specific ratio, reacting under irradiation with a specific wavelength light source in the presence of a catalyst, and then purifying the product through steps such as crude distillation, washing, rectification, and drying to finally obtain the target product. However, this gas-phase free radical reaction system suffers from problems such as the variety of free radicals, complex pathways, and susceptibility to side reactions, leading to certain limitations in the process. On the one hand, the regioselectivity of chlorine radical addition is poor, posing a risk of generating isomers such as 1,4-addition products; on the other hand, the reaction relies on strong light irradiation and the introduction of chlorine gas, which can easily cause equipment corrosion and result in low light energy utilization efficiency; furthermore, the product contains many impurities, often requiring multi-step rectification and purification, leading to higher overall energy consumption and increased costs.

[0021] To address the shortcomings of existing technologies, this application provides a process for preparing 2,3-dichlorooctafluorobutane.

[0022] This application provides a process for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. A fluorine phase is added to the polar phase, and shearing is performed to obtain a microemulsion. S200 was used to perform photoelectro-co-activation treatment on the microemulsion to obtain 2,3-dichlorooctafluorobutane.

[0023] Preferably, this application constructs an emulsion system with a stable microstructure by adding a fluorine phase to a polar phase and subjecting it to high-speed shearing. Subsequently, photoelectric synergistic activation is performed on this microemulsion system to achieve precise control of the selective chloroaddition reaction pathway of fluorinated olefins. The core of this approach lies in constructing a highly dispersed, interface-uniform microemulsion reaction environment, confining the free radical collision process, which would otherwise occur freely and randomly in traditional gas-phase reactions, to a microscale interfacial region. This confined reaction space not only significantly enhances the regioselectivity of the free radical reaction and effectively suppresses side reactions, but also improves mass transfer and energy transfer efficiency, thereby enhancing the overall controllability and process safety of the reaction.

[0024] Preferably, this application incorporates a fluorine phase into a polar phase containing a photocatalyst and electrolyte, forming a stable microemulsion system with a nanoscale interface through high-speed shearing. This allows for photoelectro-co-activation, enabling the regulation of the perfluoro-2-butene chloroaddition reaction pathway and significantly improving the synthesis efficiency and selectivity of 2,3-dichlorooctafluorobutane. In the microemulsion system, the hydrophobic and polar perfluoroolefin is mainly distributed within the fluorine phase droplets or at the interface, while photoactive chlorine radicals (Cl·) are generated in the polar phase and preferentially contact the substrate at the interface. This structure makes the 2,3-positions of the double bond more easily exposed to the attack range of Cl·, while the distal carbons at the 1,4-positions are shielded by the interfacial space, thus effectively suppressing the formation of byproducts such as 1,4-addition and significantly improving regioselectivity. The mass ratio of polar phase to fluorine phase is (0.7-1.5):1, aiming to form a microemulsion system with a high interfacial area and stable structure. If the polar phase is too large, it is difficult to form a continuous conductive phase, resulting in insufficient electrolyte concentration and decreased conductivity, affecting the electrochemical activation efficiency of chlorine. At the same time, the microemulsion droplet size increases, and the effective interfacial area decreases, which is not conducive to the realization of 2,3-addition regioselectivity. If there is too much polar phase, the fluorine phase is over-diluted, the substrate concentration is too low, and chlorine radicals can easily diffuse into the bulk phase to trigger non-selective side reactions. The microemulsion structure may also undergo a phase inversion. Under the specified ratio, the microemulsion interface can effectively restrict the generation and reaction of chlorine radicals to the interfacial region, prompting Cl· to preferentially attack the 2,3-positions of the double bond, significantly improving the main product selectivity. Shearing treatment transforms the originally immiscible fluorine phase into microemulsions of 10-500 nm in size with the polar phase, significantly increasing the contact area between the two phases. This promotes the rapid diffusion of photogenerated free radicals to the reaction interface, thereby improving mass transfer efficiency and reaction rate, resulting in more complete chlorine addition and significantly reduced energy consumption. A shearing treatment speed of 1000-3000 rpm is sufficient to obtain uniform microemulsions with a particle size distribution of 50-300 nm. Below this range, the droplets become coarse, resulting in insufficient interfacial area and decreased reaction efficiency and selectivity. Excessive rotation speed introduces too much mechanical energy, leading to localized overheating, which may trigger side reactions and damage the microemulsion structure. Unlike traditional photochlorination that relies on high-intensity ultraviolet light, this application employs a photoelectro-photocatalyst synergistic activation strategy. First, photoexcitation of the photocatalyst generates electron-hole pairs, and then an external electric field further promotes the efficient decomposition of chlorine molecules into Cl· at the interface, achieving the directional generation of chlorine free radicals. This method not only reduces chlorine consumption but also makes the reaction conditions milder, reduces side reactions, and mitigates the risks of equipment corrosion and free radical runaway. In addition, the electrolytes and stabilizers introduced into the polar phase can enhance the interfacial charge density and microemulsion structure stability, prevent droplet aggregation, ensure that the reaction system remains homogeneous during continuous operation, and further improve product purity and yield.

[0025] Preferably, the polar phase includes a solvent, an electrolyte, a photocatalyst, and a stabilizer. The polar solvent, as the continuous phase, not only provides a conductive medium for the electrolyte and promotes the electrochemical activation of chlorine gas to generate chlorine radicals (Cl·), but also provides a uniformly dispersed and photo-excited reaction field for the photocatalyst, thereby constructing a microenvironment capable of photoelectrochemical synergistic reactions. The solvent includes at least one of deionized water, alcohols, polar aprotic solvents, or ionic liquids. On the one hand, these solvents possess sufficient polarity to dissolve the electrolyte and provide high conductivity, ensuring the smooth electrochemical activation of chlorine gas. On the other hand, they exhibit significant immiscibility with the fluorine phase, thus providing a prerequisite for the formation of a stable microemulsion structure. Ionic liquids can also play multiple roles as solvent-surfactant-electrolyte, effectively regulating interfacial tension. The introduction of the electrolyte can significantly improve the system's conductivity, promoting the efficient conversion of Cl2 to Cl· under lower applied voltages and guiding the directional migration of free radicals to the interface, effectively reducing the incidence of side reactions. The electrolyte includes at least one of sodium chloride, potassium chloride, lithium chloride, or quaternary ammonium chloride, and its primary function is to provide chloride ions (Cl·). -Under the influence of an electric field, these salts are efficiently converted into active chlorine free radicals. Furthermore, these salts can regulate the ionic strength of the polar phase, affecting the interfacial curvature and stability of the microemulsion. Quaternary ammonium salt electrolytes also have interfacial modification functions, promoting mass transfer between the two phases. The photocatalyst participates in the activation of chlorine gas through electron-hole pairs under light irradiation, and in synergy with the electric field, enhances the interfacial generation efficiency of chlorine free radicals, thereby confining the reaction site to the microemulsion interface and improving the 2,3-addition selectivity. The stabilizer, by regulating the interfacial tension and enhancing the stability of the emulsion, prevents phase separation or droplet aggregation during the reaction, ensuring that the reaction always takes place in a controllable interfacial region and avoiding the generation of byproducts caused by free radical diffusion. The photocatalysts include at least one of copper chloride, iron chloride, cobalt chloride, or nickel chloride, which can effectively generate active chlorine species under light irradiation through the ligand-to-metal charge transfer (LMCT) mechanism. In synergy with the electrochemical system, they can construct a photoelectric cycle, realizing the rapid regeneration of metal valence states and the continuous and directional generation of chlorine free radicals, thereby improving the reaction efficiency and suppressing non-selective side reactions. The mass ratio of solvent, electrolyte, photocatalyst, and stabilizer is 1:(0.01-0.2):(0.0005-0.07):(0.01-0.1). Within this range, the electrolyte provides sufficient conductivity to activate the cleavage of chlorine molecules while avoiding excessive ionic strength that could damage the microemulsion stability. If the photocatalyst concentration is too low, the light absorption efficiency will be insufficient, and the free radical yield will decrease; if it is too high, it may trigger non-photoinduced side reactions or introduce metal ions that could damage the interfacial structure. The stabilizer is used to maintain the nanoscale structure of the microemulsion and prevent phase separation, but excessive addition can hinder the interfacial mass transfer of chlorine free radicals. Therefore, this ratio ensures that Cl· is directionally generated at the interface and efficiently utilized. The stabilizer includes at least one of fluorinated surfactants, ionic liquids, buffers, or metal complexing agents. Fluorinated surfactants are stabilizers... The key to the fluorinated / polar phase interface is its ability to significantly reduce interfacial tension and form nanoscale microemulsions. Buffers maintain pH stability and prevent catalyst hydrolysis, while metal complexing agents stabilize the catalyst's metal centers through complexation, maintaining its catalytic activity. These components together ensure the long-term stability of the microemulsion structure during operation and prevent reaction runaway caused by phase separation. For example, fluorinated surfactants can be any of perfluoroalkyl sulfonates, perfluorocarboxylate salts, fluorinated quaternary ammonium salt surfactants, or nonionic fluorinated surfactants. Ionic liquids can be fluorinated ionic liquids such as BMIM-BF4 or ionic liquids with strong halogen coordination ability such as BMIM-Cl. Buffers can be borate buffers or phosphate buffers, and metal complexing agents can be pyridine metal complexing agents or imidazole metal complexing agents.

[0026] Preferably, the fluorinated phase comprises a fluorinated substrate, an inert fluorinated solvent, and a fluorinated surfactant. The fluorinated substrate includes perfluoro-2-butene because its molecular structure determines that the double bond at the 2,3-position is the sole target site for the chlorination addition reaction, making it a direct precursor for the total synthesis route. The inert fluorinated solvent not only effectively dissolves fluorinated olefins, but its high chemical inertness also prevents attack by chlorine free radicals, thus ensuring reaction specificity and reducing the formation of non-target chlorination byproducts. The inert fluorinated solvent includes at least one of perfluorohexane, perfluoropentane, perfluorotributylamine, or HFE solvent, primarily due to their extremely high chemical inertness, making them difficult to attack by chlorine free radicals, thereby ensuring reaction specificity. Furthermore, their immiscibility with the polar phase is the basis for microemulsion formation, and their properties can regulate the size and stability of the microemulsion droplets. Fluorinated surfactants significantly reduce the interfacial energy between the fluorinated phase and the polar phase, promoting the formation of nanoscale microemulsion structures after high-speed shearing. This increases the interfacial area and modulates the orientation of substrate molecules at the interface, ensuring that the 2,3-positions of the double bonds are fully exposed to the attack range of chlorine radicals, further enhancing regioselectivity. Fluorinated surfactants include at least one of fluorocarbonates, fluorocarbon sulfonates, or fluorinated ethers. Due to the excellent compatibility of their perfluorinated segments with the fluorinated phase, they can efficiently adsorb onto the interface, significantly reducing the interfacial energy, and are indispensable components for the formation and stabilization of nanoemulsion structures. Their structure directly affects the arrangement and orientation of substrate molecules at the interface, which is crucial for achieving high 2,3-regioselectivity. The mass ratio of fluorinated substrate, inert fluorinated solvent, and fluorinated surfactant is 1:(0.01-0.5):(0.001-0.1). The inert fluorinated solvent can adjust the viscosity of the fluorinated phase, promote the formation of uniformly sized microemulsion droplets, and ensure the orderly arrangement of substrate molecules at the interface. The fluorinated surfactant is the key to building a stable interface. Too little surfactant will lead to an unstable microemulsion structure, while too much surfactant will hinder the interfacial diffusion of chlorine radicals. Within this ratio range, it can ensure that the fluorinated microdroplets are of moderate size and have a clear interfacial orientation, providing favorable spatial conditions for 2,3-addition.

[0027] Furthermore, S200 includes: S210. Electrolyze the microemulsion to obtain a microemulsion containing active chlorine products; S220. Photo-treating microemulsions containing active chlorine products yields 2,3-dichlorooctafluorobutane.

[0028] Furthermore, the S200 includes: S230. Electrolyze the microemulsion and simultaneously irradiate it with light to obtain 2,3-dichlorooctafluorobutane.

[0029] Preferably, in this application, step S200 can be performed using two methods for photoelectric synergistic activation. In actual operation, those skilled in the art can choose to perform steps S210 and S220, or they can choose to perform step S230. It should be noted that steps S210-S220 and step S230 are parallel; this numbering is used only for convenience and does not mean that step S230 is a supplement to steps S210-S220. In step S210, electrochemical oxidation is used to achieve the activation of Cl in the system. - Direct oxidation generates Cl2 or short-lived coordination / polarized chlorine species on the anode surface. These species can be considered precursors of Cl· or active substances for chlorine addition. Electrolysis provides a stable and controllable flux of active chlorine generation, while enriching active chlorine in the polar phase and interfacial region within the microemulsion system. However, active chlorine may accumulate at high local concentrations near the electrode. If it cannot be decomposed or consumed in time, it can easily lead to overchlorination, side reactions, or loss due to evaporation. Step S220 relies on the LMCT of metal halides or photoinduced electronic transitions to allow the M-Cl bond to enter a high-energy state and break down, directly generating Cl· or promoting the formation of Cl·. It has advantages such as more uniform spatial activity and controllable light flux. However, if there is no electrochemical action to restore the catalyst valence state, the photocatalyst may gradually deactivate due to the accumulation of reduced states. For the above reasons, electrolysis and light irradiation can be carried out in stages, with electrolysis first followed by light irradiation. A certain amount of active chlorine can be accumulated first, and then rapidly decomposed by light irradiation to induce addition, which is beneficial for segmented optimization of current and light intensity. Although stepwise operation has some value in the research stage or when fine-tuning of process parameters is required, this mode often leads to temporary accumulation of active species or failure of the system to reach steady-state equilibrium, thus being inferior to the synchronous mode in terms of reaction efficiency, selectivity and energy consumption.

[0030] In step S230, the temporal and spatial coupling of the two forms a typical optoelectronic synergistic system, which is the optimal choice for this process. When electrolysis and illumination are performed simultaneously, Cl is continuously replenished during electrolysis. -The high oxidation flux maintains the catalyst's valence state cycle, while continuous light irradiation excites M-Cl to generate Cl·. Together, they establish a low-concentration, high-flux stable state of active chlorine, preventing its accumulation in peak form and instead ensuring its immediate consumption by the substrate at a stable rate in the interfacial region. This significantly reduces the probability of non-target reactions such as overchlorination and 1,4-addition. Photovoltaic synergy also forms a closed-loop valence state in the catalyst: subsequently, it decomposes to generate active chlorine radicals Cl·, while simultaneously reducing the metal center from its high valence state to a low valence state. Immediately afterwards, electrolysis immediately re-oxidizes the low-valence metal center to a highly active high valence state and replenishes chloride ions, keeping the catalyst continuously cyclic without the need for additional chemical oxidants, fundamentally improving catalytic efficiency and reducing deactivation. In the microemulsion system, the photoelectrochemical synergistic effect is further amplified by interfacial kinetics: active chlorine generated by electrochemical oxidation in the polar phase and Cl· formed by photoexcitation are both generated near the polar / fluorine phase interface, while the substrate is enriched in the fluorine phase, resulting in high co-localization of the active species and substrate at the interface. Cl· can be captured by the substrate at the moment of formation, preventing it from diffusing into the bulk phase and causing side reactions. Under simultaneous conditions, the active species can also proceed along the 2,3-addition pathway, significantly improving selectivity. Photoelectrochemical synergy can achieve higher conversion rates and better selectivity with lower light intensity and lower current density, reducing energy consumption, decreasing the generation of free Cl2, and improving safety. Therefore, achieving closed-loop catalyst valence state circulation, steady-state supply of active chlorine, and efficient interfacial addition through simultaneous electrolysis and photoexcitation is the optimal implementation method for the preparation of 2,3-dichlorooctafluorobutane in this process.

[0031] Preferably, in steps S210-S220 or step S230, the current density of the electrolysis treatment is controlled at 10-50 mA / cm². 2 The voltage is 1.5-5.0V; the illumination wavelength is 420-520nm, and the light intensity range is 10-100mW / cm². 2 The amount of catalyst used is 1-10 mol% of the molar amount of the fluorine-containing substrate. The temperature is controlled at 40-80°C, and the pH environment is kept neutral to weakly acidic to facilitate the stable reaction.

[0032] Preferably, S100 and S200 further include: S110. Allow the microemulsion to stand.

[0033] Preferably, a settling process is performed between steps S100 and S200. The core function of this process is to allow the microemulsion system, which is in a high-energy, non-equilibrium state after shearing, to spontaneously relax and restructure towards a thermodynamically stable state, thereby creating a uniform and controllable microenvironment for subsequent reactions. The particle size distribution and interfacial assembly of the microemulsion droplets formed by high-speed shearing are kinetically controlled and may exhibit local inhomogeneities. During the settling process, surfactant molecules have sufficient time to complete orderly arrangement and reach adsorption saturation at the oil / water interface, resulting in a more uniform microemulsion droplet size distribution and the formation of stable W / O or O / W structures. This structural stability and uniformity are the physical basis for ensuring batch-to-batch reproducibility and selectivity. Secondly, during the settling process, electrolyte ions and metal catalyst ions dissolved in the polar phase are more evenly distributed and enriched in the interfacial region of the microemulsion through diffusion. This lays the foundation for the efficient generation of chlorine or chlorine radicals in the subsequent electrolysis step and the effective interfacial reaction in the photocatalysis step, avoiding side reactions caused by excessively high or low local concentrations. Secondly, since high-density fluorinated substrates may aggregate or settle after shearing, the settling process allows larger unstable droplets to break down and recombine, forming smaller, more narrowly distributed stable droplets. This simultaneously ensures sufficient adsorption of the fluorinated surfactant at the interface, resulting in uniform dispersion of the substrate within the fluorinated phase and increasing the probability of interfacial contact between the substrate and active chlorinated species. Furthermore, directly introducing a high-energy unstable microemulsion system into the photoelectrochemical reaction can cause interfacial disturbances that lead to current fluctuations, localized overheating, or uneven light absorption, potentially exacerbating side reactions or even causing safety incidents. The stabilized system after settling provides a more stable electrolysis current, more uniform light absorption, and more controllable free radical generation rates, significantly reducing these risks.

[0034] Preferably, the preparation method further includes: S300 and 2,3-dichlorooctafluorobutane were subjected to centrifugation and purification processes in sequence.

[0035] Preferably, after obtaining 2,3-dichlorooctafluorobutane in step S200, centrifugation and purification are required. The density difference and immiscibility between the polar phase and the fluorine phase are utilized to achieve natural and thorough stratification, separating the fluorine phase rich in the target product 2,3-dichlorooctafluorobutane. Subsequently, the fluorine phase undergoes crude distillation. Depending on the product's boiling point and thermal stability, reduced pressure or atmospheric pressure conditions are selected to remove and recover the inert fluorine solvent for preliminary product concentration. Afterward, deep dehydration can be performed using a desiccant or 4A molecular sieve, followed by purification through distillation to obtain a high-purity product. During this process, the catalyst and ionic liquid contained in the polar phase can be recovered through filtration or centrifugation, and recycled for microemulsion preparation after adjusting the salt concentration or regeneration and activation. Fluorinated surfactants can also be recovered through phase separation, adsorption, or distillation to reduce emissions and costs. To improve separation efficiency, various industrial distillation and energy recovery strategies can be introduced: for example, using distillation column dehydration processes, utilizing the azeotropic properties of materials and water, and heating the column bottom to discharge water and light components from the top; using tubular heat exchangers to recover reaction heat for system heating; achieving static stratification and recovery of materials in the alkali system based on density differences; heating and desorbing 4A molecular sieves adsorbed with fluorides, and condensing and recovering the material; or referencing epoxy distillation processes to return light components to the reaction system for further purification of heavy components. Through these integrated separation, dehydration, recovery, and energy recovery measures, efficient product purification is achieved while maximizing the recovery and utilization of solvents, catalysts, and surfactants, comprehensively improving the economic efficiency and environmental sustainability of the process.

[0036] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0037] Example 1 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 0.7:1, and shearing is performed at a speed of 1000 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes deionized water, sodium chloride, copper chloride, and fluorinated surfactant, with the mass ratio of deionized water, sodium chloride, copper chloride, and fluorinated surfactant being 1:0.01:0.0005:0.01. The fluorine phase includes perfluoro-2-butene, perfluorohexane, and fluorocarbonate, with a mass ratio of 1:0.01:0.001. S200 includes: S210. Electrolyze the microemulsion at a voltage of 1.5V to obtain a microemulsion containing active chlorine products. S220. The microemulsion containing active chlorine products was phototreated with light of wavelength 420nm to obtain 2,3-dichlorooctafluorobutane.

[0038] Example 2 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 1.5:1, and shearing is performed at a speed of 3000 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes ethanol, potassium chloride, ferric chloride and ionic liquid, with a mass ratio of 1:0.2:0.07:0.1. The fluorine phase includes perfluoro-2-butene, perfluorohexane, and fluorocarbonate, with a mass ratio of 1:0.5:0.1. S200 includes: S210. Electrolyze the microemulsion at a voltage of 5.0V to obtain a microemulsion containing active chlorine products. S220. The microemulsion containing active chlorine products was phototreated with light of wavelength 520nm to obtain 2,3-dichlorooctafluorobutane.

[0039] Example 3 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 1:1, and shearing is performed at a speed of 2000 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes an ionic liquid, lithium chloride, cobalt chloride, and a buffer, with the mass ratio of the ionic liquid, lithium chloride, cobalt chloride, and buffer being 1:0.1:0.01:0.05. The fluorinated phase includes perfluoro-2-butene, perfluorotributylamine, and fluorinated ether surfactants, with a mass ratio of 1:0.1:0.01. S200 includes: S230. The microemulsion is electrolyzed at a voltage of 4.5V. Simultaneously, it is irradiated with light at a wavelength of 450nm to obtain 2,3-dichlorooctafluorobutane.

[0040] Example 4 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 1.2:1, and shearing is performed at a speed of 2500 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes acetonitrile, sodium chloride, copper chloride, and a fluorinated surfactant, with the mass ratio of acetonitrile, sodium chloride, copper chloride, and the fluorinated surfactant being 1:0.05:0.05:0.08. The fluorinated phase includes perfluoro-2-butene, perfluorohexane, and fluorocarbonate, with the mass ratio of perfluoro-2-butene, perfluorohexane, and fluorinated ether surfactants being 1:0.3:0.05. S200 includes: S230. The microemulsion is electrolyzed at a voltage of 4.5V. Simultaneously, it is irradiated with light at a wavelength of 465nm to obtain 2,3-dichlorooctafluorobutane.

[0041] Example 5 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 1.2:1, and shearing is performed at a speed of 2000 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes ethanol, sodium chloride, ferric chloride and ionic liquid, and the mass ratio of ethanol, sodium chloride, ferric chloride and ionic liquid is 1:0.1:0.04:0.05; The fluorine phase includes perfluoro-2-butene, perfluorohexane, and fluorocarbonate, with a mass ratio of 1:0.1:0.01. S200 includes: S210. Electrolyze the microemulsion at a voltage of 4.0V to obtain a microemulsion containing active chlorine products. S220. The microemulsion containing active chlorine products was phototreated with light of wavelength 465nm to obtain 2,3-dichlorooctafluorobutane. Between S100 and S200, there is also: S110. Allow the microemulsion to stand. S300 and 2,3-dichlorooctafluorobutane were sequentially centrifuged and purified. Refining processes include distillation and drying.

[0042] Example 6 This embodiment provides a method for preparing 2,3-dichlorooctafluorobutane, comprising the following steps: S100. Fluorine phase is added to the polar phase at a mass ratio of polar phase to fluorine phase of 1.2:1, and shearing is performed at a speed of 2000 rpm to obtain microemulsion. S200, photoelectro-co-activated microemulsion to obtain 2,3-dichlorooctafluorobutane; The polar phase includes ethanol, sodium chloride, ferric chloride and ionic liquid, and the mass ratio of ethanol, sodium chloride, ferric chloride and ionic liquid is 1:0.1:0.04:0.05; The fluorine phase includes perfluoro-2-butene, perfluorohexane, and fluorocarbonate, with a mass ratio of 1:0.1:0.01. S230. The microemulsion is electrolyzed at a voltage of 4.5V. Simultaneously, it is irradiated with light at a wavelength of 465nm to obtain 2,3-dichlorooctafluorobutane. Between S100 and S200, there is also: S110. Allow the microemulsion to stand. S300 and 2,3-dichlorooctafluorobutane were sequentially centrifuged and purified. Refining processes include distillation and drying.

[0043] Comparative Example This comparative example provides a method for preparing 2,3-dichlorooctafluorobutane, using perfluoro-2-butene and chlorine as raw materials, and photochlorination under catalytic conditions to generate 2,3-dichlorooctafluorobutane. After distillation, washing, further distillation, and drying, the finished product 2,3-dichlorooctafluorobutane is obtained.

[0044] Performance testing Weigh the initial mass m0 of perfluoro-2-butene in Examples 1-6 and the comparative example, and calculate its initial molar amount n0. After the reaction is complete, test the remaining molar amount n1 of the substrate, and calculate the substrate conversion rate according to the following formula. Conversion rate (%) = ×100%; Weigh the mass m of 2,3-dichlorooctafluorobutane prepared in Examples 1-6 and the comparative example.实际 And calculate the theoretical yield m of 2,3-dichlorooctafluorobutane. 理论 Calculate the yield using the following formula: Yield (%) = ×100%; The sum of the molar amounts n of all chlorine-containing products in the mixtures of Examples 1-6 and the comparative reactions was determined by fluorine-19 nuclear magnetic resonance spectroscopy. Cl And measure the molar amount n of the target product. C18 The selectivity of the 2nd and 3rd bits is calculated according to the following formula. Selectivity (%) = ×100%; The results are shown in Table 1.

[0045] Table 1 As can be seen from Table 1, the conversion rate, yield, and 2,3-position selectivity of Examples 1-6 are all higher than those of the comparative example, indicating that the photoelectric synergistic activation treatment scheme described in this application can achieve better results. Among them, the conversion rate, yield, and 2,3-position selectivity of Examples 3-4 are better than those of Examples 1-2. This is because Examples 3-4 adopt the method of simultaneous electrolysis and light irradiation, which makes the M-Cl bond cleavage more complete, increases the free radical generation rate, and makes the Cl· concentration in the system stable and controllable, thus achieving higher chlorination efficiency and regioselectivity. The performance of Examples 5-6 is better than that of Examples 1-4. This is because Examples 5-6 additionally perform S300 and S110 steps, which makes the structure of the microemulsion system more stable, the reactant distribution more uniform, and the reaction efficiency of the interface region significantly enhanced, thereby improving the overall chlorination reaction effect. The performance of Example 6 is better than that of Example 5. This is because Example 6 also adopts the strategy of simultaneous electrolysis and light irradiation, which makes the free radical generation at the microemulsion interface more efficient, promotes the formation of the target product and further suppresses by-products, thereby achieving the highest yield and selectivity of this invention.

[0046] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A process for the preparation of 2,3-dichlorooctafluorobutane, characterized in that, The preparation method comprises the following steps: S100, adding a fluorine phase into the polar phase, and performing shearing treatment to obtain a microemulsion; S200, performing photoelectric synergistic activation treatment on the microemulsion to obtain the 2,3-dichlorooctafluorobutane; The polar phase comprises a solvent, an electrolyte, a photocatalyst and a stabilizer; The fluorine phase comprises a fluorine-containing substrate, an inert fluorine solvent and a fluorine-containing surfactant.

2. The manufacturing process according to claim 1, characterized in that, The S200 comprises: S210, performing electrolysis treatment on the microemulsion to obtain a microemulsion containing an active chlorine product; S220, performing light treatment on the microemulsion containing the active chlorine product to obtain the 2,3-dichlorooctafluorobutane.

3. The manufacturing process of claim 1, wherein, The S200 comprises: S230, performing electrolysis treatment on the microemulsion, and simultaneously performing light treatment on the microemulsion to obtain the 2,3-dichlorooctafluorobutane.

4. The preparation method according to claim 2 or 3, wherein the voltage of the electrolysis treatment is 1.5-5.0 V; and / or the wavelength of the light treatment is 420-520 nm.

5. The preparation method according to claim 1, wherein the mass ratio of the polar phase to the fluorine phase is (0.7-1.5):

1.

6. The preparation method according to claim 5, wherein the mass ratio of the solvent, the electrolyte, the photocatalyst and the stabilizer in the polar phase is 1:(0.01-0.2):(0.0005-0.07):(0.01-0.1); and / or the mass ratio of the fluorine-containing substrate, the inert fluorine solvent and the fluorine-containing surfactant in the fluorine phase is 1:(0.01-0.5):(0.001-0.1).

7. The preparation method according to claim 1, wherein the solvent comprises at least one of deionized water, an alcohol, a polar aprotic solvent or an ionic liquid; and / or the electrolyte comprises at least one of sodium chloride, potassium chloride, lithium chloride or a quaternary ammonium chloride salt; and / or the photocatalyst comprises at least one of copper chloride, iron chloride, cobalt chloride or nickel chloride; and / or the stabilizer comprises at least one of a fluorine-containing surfactant, an ionic liquid, a buffer or a metal complexing agent; and / or the fluorine-containing substrate comprises perfluoro-2-butene; and / or the inert fluorine solvent comprises at least one of perfluorohexane, perfluoropentane, perfluorotributylamine or an HFE solvent; and / or the fluorine-containing surfactant comprises at least one of a fluorocarbon carboxylate, a fluorocarbon sulfonate or a fluorine-containing ether surfactant. In the S100, the shearing treatment is performed at a speed of 1000-3000 rpm. The preparation method further comprises: S300, sequentially performing centrifugal treatment and refining treatment on the 2,3-dichlorooctafluorobutane; The refining treatment comprises distillation treatment and drying treatment. ​ ​ ​ ​ ​ ​ ​ ​ 8. The manufacturing process of claim 1, wherein, ​ ​ 9. The manufacturing process of claim 1, wherein, ​ ​ 10. The manufacturing process of claim 1, wherein, ​ ​ ​

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