A continuous method for the preparation of high purity chloroamines

Abstract

The application relates to the technical field of fine chemical synthesis, and discloses a continuous preparation method of high-purity chloroamine, which comprises the following steps: preparing an organic phase raw material solution, a non-gas-bound acid agent, a phase transition inducer and a liquid reducing agent; synchronously obtaining an acetonitrile-water-free hydroxylamine ternary homogeneous solution through hydroxylamine sulfate reaction; pumping the homogeneous solution, the raw material solution and the acid agent into a first micro-channel reactor to generate an intermediate through substitution reaction, and then pumping the intermediate and the liquid reducing agent into a second micro-channel reactor to generate a full-liquid-phase reduction clear liquid through reduction cracking; injecting the phase transition inducer to trigger phase separation, discharging waste water and collecting an organic light phase; pumping the organic light phase and pure water into a countercurrent extraction tower for normal-temperature extraction, and extracting acetonitrile into the water phase; and continuously distilling a toluene-chloroamine solution at the top of the tower to obtain high-purity products. The application realizes full closed loop of the solvent and continuous production of high-purity products through micro-channel series connection, inhibition of side reactions, rapid demulsification by using salting-out effect and decoupling of the solvent system through normal-temperature extraction.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis technology, specifically to a continuous preparation method for high-purity chloroamines. Background Technology

[0002] Chlorinated amines are a class of high-value-added fine chemical intermediates, widely used in the synthesis and manufacture of pharmaceuticals, pesticides, and specialty polymers. Their molecular structure contains both reactive halogen atoms and amino functional groups, a bifunctional characteristic that endows them with significant chemical transformation potential. Industrially, chloroamines are typically prepared by nucleophilic substitution reactions between corresponding haloalkanes and hydroxylamine compounds. Because free hydroxylamines are extremely reactive under normal conditions, stabilization and dissolution in specific polar solvents are essential for actual production.

[0003] Existing processes for preparing chloroamines primarily rely on traditional batch reactors. In actual production, the reaction substrate, a haloalkane, is typically dissolved in a nonpolar solvent such as toluene. Then, an aqueous solution of free hydroxylamine is added for multiphase mixing. The stability of the free hydroxylamine often requires the participation of a polar co-solvent such as acetonitrile. As the amination reaction proceeds, hydrogen chloride is continuously generated as a byproduct. Carbonates are commonly added to the reaction solution as a conventional acid-binding agent for neutralization. After the reaction, a large amount of water is injected into the reactor, and the mixture is allowed to stand for an extended period to allow for physical separation of the aqueous and organic phases. The separated organic phase contains the target product and various mixed solvents. This crude liquid is then directly fed into a high-temperature distillation section, where the boiling point difference is used to heat and vaporize the liquid to remove toluene and the polar co-solvents, thus obtaining crude chloroamine at the bottom of the distillation column.

[0004] However, in actual operation, this traditional batch process suffers from a small heat transfer area per unit volume of the reactor, resulting in the inability to instantly dissipate the intense exothermic reaction during amination. This easily leads to the formation of localized hot spots within the reactor, which promotes the thermal degradation of free hydroxylamine and triggers various side reactions of the substrate. The carbonate neutralization process continuously releases carbon dioxide, and the churning of bubbles creates a chaotic gas-liquid-solid multiphase state in the reaction system, severely interfering with effective collisions and mass transfer between the liquid phase substrates. The post-processing separation stage frequently faces severe emulsification problems. The intermingling of polar solvents, inorganic salts, and amine products with certain surface activity easily forms a stable microemulsion layer at the oil-water interface. This not only results in extremely slow and blurred separation upon standing, but forced separation also causes some organic products to be lost with the aqueous phase. Therefore, this invention provides a continuous preparation method for high-purity chloroamines to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a continuous preparation method for high-purity chloroamines, which solves the problems of low mass transfer efficiency, difficulty in controlling reaction temperature leading to numerous side reactions, easy emulsification of the system after reaction making separation difficult, and high energy consumption for multi-component solvent separation in existing batch processes.

[0006] To achieve the above objectives, the present invention provides a continuous preparation method for high-purity chloroamines, comprising the following steps: S1. Prepare organic phase feed solution containing reaction substrate and toluene solvent, gas-free acid binder, phase change inducer and liquid reducing agent respectively; simultaneously carry out continuous reaction and physical filtration of hydroxylamine sulfate aqueous solution and strong base aqueous solution in the presence of acetonitrile solvent to obtain acetonitrile-water-free hydroxylamine ternary homogeneous solution; S2. The prepared acetonitrile-water-free hydroxylamine ternary homogeneous solution, the organic phase raw material liquid, and the gas-free acid-binding agent are continuously pumped into the first microchannel reactor to carry out a mixed substitution reaction to generate a clear liquid containing chloroalkyl hydroxylamine intermediate and potassium chloride. S3. The outflowing liquid-phase reaction solution and the liquid reducing agent are continuously pumped into the second microchannel reactor to carry out a reduction and cracking reaction, so that the NO bond of the intermediate is broken and the hydroxyl group is removed, generating a liquid-phase reduced solution containing the target product chloroamine. S4. The clear liquid of the whole liquid phase reduction is introduced into the mixing tank, the phase change inducer is pumped in to mix and trigger phase separation, the lower layer of wastewater containing inorganic salts is discharged, and the upper layer of toluene-acetonitrile-target chloroamine ternary organic light phase is collected. S5. The toluene-acetonitrile-target chloroamine ternary organic light phase and pure water are continuously pumped into a countercurrent extraction tower for liquid-liquid extraction. The pure water extracts the acetonitrile in the organic phase to the aqueous phase. The acetonitrile-water biphase solution is discharged from the bottom of the tower and the toluene-chloroamine solution is discharged from the top of the tower. S6. The discharged toluene-chloroamine solution is pumped into a continuous distillation column for distillation and solvent removal. The toluene liquid condensed at the top of the column is recycled as a raw material solvent, and the high-purity chloroamine product is continuously collected from the bottom of the column.

[0007] By adopting the above technical solution, and combining microchannel continuous reaction technology with phase change-induced liquid-liquid extraction and room-temperature countercurrent extraction decoupling processes, the effects of improved product purity and yield, reduced distillation energy consumption, and closed-loop material circulation are achieved. Specifically, the following mechanisms of action are employed: The material is continuously pumped into a microchannel reactor equipped with a static mixing component. Within the limited pipe diameter, the fluid undergoes high-intensity alternating dispersion and mixing, resulting in a significant increase in interphase mass transfer area. The acetonitrile-water-free hydroxylamine ternary homogeneous solution undergoes a rapid nucleophilic substitution reaction with the substrate in the organic phase. The microchannel structure provides an extremely high specific surface area, rapidly transferring the heat released from the reaction to the heat exchange pipes, maintaining temperature uniformity throughout the system, thereby suppressing the thermal decomposition of free hydroxylamine and other heat-sensitive side reactions. A chloroalkyl hydroxylamine intermediate dissolved in the organic phase is generated with high conversion rate within a short time. Subsequently, the system continuously enters a second microchannel reactor and mixes with a liquid reducing agent, undergoing a quantitative reductive cleavage reaction. This rapidly cleaves the NO bond in the intermediate and removes the hydroxyl group, ultimately generating the target product, chloroamine. This two-step cascade reaction maintains full liquid-phase flow, with the byproduct potassium chloride dissolving in the aqueous phase, preventing microchannel blockage due to solid salt precipitation.

[0008] After the clear liquid from the all-liquid reaction enters the mixing tank, a phase change initiator is injected. The phase change initiator ionizes and dissociates in the aqueous phase, causing a sharp increase in the ionic strength of the aqueous phase. These strongly ionized ions capture water molecules to form hydrated ions, displacing trace amounts of organic matter originally dissolved in the aqueous phase, resulting in salting out. The high ionic strength increases the relative density of the aqueous phase, widening the density difference between the organic and aqueous phases, and increasing the interfacial tension between the two phases. This promotes rapid aggregation and demulsification of the mixture, which was originally in an emulsion-particle state. This achieves clear separation of the toluene-acetonitrile-target chloroamine ternary organic light phase from the inorganic brine phase, avoiding the prolonged emulsification problems associated with conventional water washing.

[0009] Pure water enters from the top of the extraction column, while the light organic phase enters from the bottom. Acetonitrile, as a polar aprotic solvent, exhibits strong hydrogen bonding with pure water, while toluene is low in polarity and insoluble in water. Utilizing the high affinity of pure water, acetonitrile in the organic phase is selectively transferred into the aqueous phase, forming an acetonitrile-water biphase solution. This step achieves the initial decoupling and separation of acetonitrile from toluene and chloroamine at room temperature, avoiding the significant heat consumption associated with directly separating the ternary azeotropic system using distillation, and mitigating the risk of degradation of the heat-sensitive target product at high temperatures. The remaining toluene-chloroamine solution is a single-phase system, which can be separated into high-purity product and toluene recovery liquid by subsequent single-stage distillation.

[0010] Preferably, in step S1, the organic phase feed solution is prepared by dissolving 12 to 18 parts by weight of the reaction substrate in 80 to 120 parts by weight of toluene, and the reaction substrate is 1,3-dichloropropane or 1,4-dichlorobutane. The gas-free acid binder is prepared by dissolving 9 to 12 parts by weight of potassium hydroxide solid in 40 to 50 parts by weight of deionized water, and the phase change inducer is prepared by dissolving 10 to 15 parts by weight of sodium chloride in 25 to 35 parts by weight of deionized water; in step S4, the amount of pure water used is 60 to 90 parts.

[0011] By employing the above technical solution, potassium hydroxide is used as a gas-free acid-binding agent to absorb the hydrogen chloride generated in the amination reaction, thus shifting the reaction equilibrium to the forward direction. This process does not produce gases such as carbon dioxide, maintaining the stability of the fluid system pressure within the tube and avoiding interference from multiphase flow of gas, liquid, and solid on the microchannel mixing effect. Sodium chloride, as a phase change initiator, has strong dissociation ability and low cost, providing sufficient salting-out effect. The above ratio ensures that the reaction system has appropriate material concentrations and liquid-liquid density differences.

[0012] Preferably, in step S2, the acetonitrile-water-free hydroxylamine ternary homogeneous solution is obtained by the following preparation method: hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution are independently pumped into a continuous flow crystallization reactor, and acetonitrile is continuously injected into the reactor simultaneously to carry out the crystallization reaction; the reaction solution is continuously overflowed and discharged, and the precipitated potassium sulfate solid crystals are physically filtered out, and the centrifuged mother liquor is collected to obtain the acetonitrile-water-free hydroxylamine ternary homogeneous solution.

[0013] Preferably, in the preparation process of the acetonitrile-water-free hydroxylamine ternary homogeneous solution: the feed mass flow rates of hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution are adjusted to maintain the pH value of the reaction mixture at 6.5 to 7.0; the steady-state temperature in the continuous flow crystallization reactor is controlled at 15 to 20°C, and the average residence time of the fluid in the reactor is controlled at 20 to 30 minutes.

[0014] By employing the above technical solution, hydroxylamine sulfate reacts with a strong alkali to release free hydroxylamine. Free hydroxylamine readily undergoes disproportionation decomposition in pure water. By simultaneously injecting acetonitrile, acetonitrile molecules participate in the solvation process of free hydroxylamine, forming a stable acetonitrile-water-free hydroxylamine ternary eutectic system, thus improving the chemical stability of free hydroxylamine. The pH value is controlled between 6.5 and 7.0 to prevent accelerated degradation of hydroxylamine under excessively alkaline conditions. The reaction temperature is controlled within a low range and the reaction time is short to suppress its thermodynamic decomposition tendency. The generated byproduct, potassium sulfate crystals, are continuously physically filtered out to obtain a clear, solid-free feed mother liquor, eliminating the risk of blockage in downstream microchannel reactions.

[0015] Preferably, the microchannel reactor is a silicon carbide tubular microchannel reactor with static mixing components, and the material is continuously pumped in by a high-pressure metering pump; the system back pressure of the microchannel reactor is set to 0.1 to 0.2 MPa, the fluid temperature of the entire pipeline is controlled to be 40 to 45°C, and the total flow rate is adjusted to control the residence time of the liquid phase fluid in the pipe to be 3 to 6 minutes.

[0016] By adopting the above technical solution, silicon carbide material possesses high thermal conductivity and corrosion resistance, making it suitable for long-term operation in chloride-containing salt water systems. Setting a system back pressure prevents localized boiling and vaporization of the low-boiling-point solvent acetonitrile in the reaction pipeline, ensuring a continuous and homogeneous fluid morphology. A temperature of 40 to 45°C combined with a residence time of 3 to 6 minutes meets the substrate conversion kinetics requirements while preventing the induction of thermosensitive side reactions.

[0017] Preferably, in step S3, the lower layer of wastewater containing inorganic salts specifically includes potassium chloride and sodium chloride, and the wastewater is discharged to the environmental protection treatment unit.

[0018] By adopting the above technical solution, the reaction byproduct potassium chloride and the added inducing salt sodium chloride are concentrated in the lower aqueous phase for removal, thereby reducing the load on subsequent organic phase washing and extraction.

[0019] Preferably, the liquid-liquid extraction is carried out at room temperature, pure water is continuously pumped in from the top of the countercurrent extraction column, and the upper organic light phase collected in step S3 is continuously pumped in from the bottom of the column.

[0020] By adopting the above technical solution, the density of the aqueous phase is greater than that of the organic phase, forming a cross-flow contact network between the aqueous phase dripping from the top of the column and the organic phase rising from the bottom. Droplets continuously break up and merge between the trays, resulting in a high interface renewal rate. Operation at room temperature reduces energy consumption, eliminates violent mechanical shearing, and prevents secondary emulsification.

[0021] Preferably, in step S5, the absolute system pressure of the continuous distillation column is 0.08 to 0.095 MPa.

[0022] By adopting the above technical solution, toluene solvent is evaporated and separated under a slight negative pressure, reducing the operating bottom temperature in the distillation column and preventing high-purity chloroamine products from undergoing self-polymerization or discoloration due to prolonged heating at the bottom of the column.

[0023] Preferably, the method further includes a recycling process for the acetonitrile-water two-phase solution generated in step S4: the acetonitrile-water two-phase solution discharged from the bottom of the column in step S4 is pumped into an atmospheric distillation column, the top of the column is controlled to condense and collect the acetonitrile-water azeotrope at the azeotropic point temperature, and the collected acetonitrile-water azeotrope is fully recycled to the upstream desalination unit to remove wastewater from the column bottom.

[0024] By adopting the above technical solution, the solvent is recovered under normal pressure by utilizing the azeotropic properties of acetonitrile and water. The condensed azeotrope is directly reused in the preparation process of the front-end reaction reagents, realizing a closed-loop circulation of acetonitrile solvent, reducing the consumption of new solvent and lowering the total organic load in wastewater discharge.

[0025] This invention provides a continuous preparation method for high-purity chloroamines. It has the following beneficial effects: 1. This invention employs microchannel continuous reaction technology to react a pre-prepared acetonitrile-water-free hydroxylamine ternary homogeneous solution with the reaction substrate in an acid-free system. This method utilizes the large specific surface area of ​​the microchannel structure to achieve rapid heat removal and uniform mass transfer between the two phases, effectively suppressing the thermal decomposition of free hydroxylamine and related thermosensitive side reactions. The acid-free system avoids gas generation in the reaction pipeline, ensuring stable flow of the entire liquid phase, thereby improving the conversion rate and product purity of the target chloroamine.

[0026] 2. This invention introduces a phase change initiator into the clear liquid of the all-liquid reaction, which generates a salting-out effect by significantly increasing the ionic strength of the aqueous phase, squeezing out trace amounts of organic matter dissolved in the aqueous phase, and expanding the density difference and interfacial tension between the aqueous and organic phases. This promotes rapid aggregation and demulsification of the emulsion-laden mixture after the reaction, achieving clear separation between the inorganic saline phase and the toluene-acetonitrile-target chloroamine ternary organic light phase, solving the severe emulsification and separation difficulties that easily occur in conventional intermittent water washing processes.

[0027] 3. This invention employs a room-temperature countercurrent extraction process to decouple a complex solvent system. Utilizing the affinity of pure water for polar acetonitrile, acetonitrile is selectively transferred from the organic light phase to the aqueous phase at room temperature. This non-thermal separation step avoids the significant heat consumption associated with high-temperature distillation of the ternary mixture and reduces the risk of degradation and discoloration of the heat-sensitive chloroamine products at high temperatures. The extracted toluene solvent and acetonitrile-water azeotrope are recovered through low-pressure and atmospheric-pressure distillation, respectively, and fully recycled to the upstream stages of the reaction and batching processes. This achieves a closed-loop solvent circulation within the system, reducing production costs and wastewater discharge load. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 The following is a distribution chart of the core evaluation indicators of the embodiments and comparative examples of the present invention, wherein (a) is a comparison chart of the residual sulfate concentration in the free solution, and (b) is a comparison chart of the target substrate conversion rate and the purity of the final extracted product in the microchannel reaction stage. Figure 3 This is a graph showing the change in inlet and outlet pressure difference of the microchannel reactor of the present invention over operating time. Figure 4 This is a graph showing the attenuation of the emulsion layer thickness of the present invention as a function of standing time. Figure 5 The diagram shows a comparison of desalination energy consumption and solvent recovery efficiency in this invention. (a) is a comparison of desalination energy consumption for each test object in the unit inorganic salt precipitation process, and (b) is a correlation diagram of the distribution of toluene purity recovered at the top of the distillation system and the maximum effective closed-loop cycle number. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0031] The CAS number for hydroxylamine sulfate is 10039-54-0; The CAS number for potassium hydroxide is 1310-58-3; Acetonitrile's CAS number is 75-05-8; Toluene's CAS number is 108-88-3; The CAS number for 1,4-dichlorobutane is 110-56-5; The CAS number for 1,3-dichloropropane is 142-28-9; Sodium chloride has the CAS number 7647-14-5.

[0032] Preparation Example 1: This preparation example provides a method for preparing a homogeneous ternary solution of acetonitrile-water-free hydroxylamine, including the following steps: Prepare an aqueous solution of hydroxylamine sulfate by completely dissolving 25 parts of hydroxylamine sulfate in 70 parts of deionized water, and prepare an aqueous solution of potassium hydroxide by completely dissolving 15 parts of potassium hydroxide in 35 parts of deionized water. In a continuous flow crystallization reactor equipped with a cooling jacket, the above-mentioned hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution are pumped in independently by a horizontal flow pump, and the feed mass flow rate of the two fluids is adjusted to keep the pH value of the reaction mixture stable at 6.5. Simultaneously inject 30 parts of acetonitrile into the reactor, control the steady-state temperature in the crystallization reactor to 15℃, and control the average residence time of the fluid in the reactor to 20 minutes. The reaction solution was continuously overflowed and discharged into a continuous sedimentation centrifuge to physically filter out the precipitated potassium sulfate solid crystals. The centrifuged mother liquor was collected to obtain a clear acetonitrile-water-free hydroxylamine ternary homogeneous solution.

[0033] Preparation Example 2: This preparation example provides a method for preparing a homogeneous ternary solution of acetonitrile-water-free hydroxylamine, including the following steps: Prepare an aqueous solution of hydroxylamine sulfate by completely dissolving 28 parts of hydroxylamine sulfate in 78 parts of deionized water, and prepare an aqueous solution of potassium hydroxide by completely dissolving 16 parts of potassium hydroxide in 40 parts of deionized water. In a continuous flow crystallization reactor equipped with a cooling jacket, the above-mentioned hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution are pumped in independently by a horizontal flow pump, and the feed mass flow rate of the two fluids is adjusted to keep the pH value of the reaction mixture stable at 6.8. Simultaneously, 40 parts of acetonitrile were continuously injected into the reactor, and the steady-state temperature in the crystallization reactor was controlled at 18℃. The average residence time of the fluid in the reactor was controlled at 25 minutes. The reaction solution was continuously overflowed and discharged into a continuous sedimentation centrifuge to physically filter out the precipitated potassium sulfate solid crystals. The centrifuged mother liquor was collected to obtain a clear acetonitrile-water-free hydroxylamine ternary homogeneous solution.

[0034] Preparation Example 3: This preparation example provides a method for preparing a homogeneous ternary solution of acetonitrile-water-free hydroxylamine, including the following steps: Prepare an aqueous solution of hydroxylamine sulfate by completely dissolving 30 parts of hydroxylamine sulfate in 85 parts of deionized water, and prepare an aqueous solution of potassium hydroxide by completely dissolving 18 parts of potassium hydroxide in 45 parts of deionized water. In a continuous flow crystallization reactor equipped with a cooling jacket, the above-mentioned hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution are independently pumped in by a horizontal flow pump, and the feed mass flow rate of the two fluids is adjusted to keep the pH value of the reaction mixture stable at 7.0. Simultaneously inject 50 parts of acetonitrile into the reactor, control the steady-state temperature in the crystallization reactor to 20℃, and control the average residence time of the fluid in the reactor to 30 minutes. The reaction solution was continuously overflowed and discharged into a continuous sedimentation centrifuge to physically filter out the precipitated potassium sulfate solid crystals. The centrifuged mother liquor was collected to obtain a clear acetonitrile-water-free hydroxylamine ternary homogeneous solution.

[0035] See attached document Figure 1 Example 1: This embodiment provides a continuous preparation method for high-purity chloroamines, including the following steps: S1. Prepare the organic phase feed solution by completely dissolving 12 parts of 1,3-dichloropropane in 80 parts of toluene; prepare the gas-free acid-binding agent by completely dissolving 9 parts of potassium hydroxide solid in 40 parts of deionized water; prepare the phase change initiator by completely dissolving 10 parts of sodium chloride in 25 parts of deionized water; simultaneously prepare the liquid reducing agent by completely mixing 8 parts of hydrazine hydrate aqueous solution in 20 parts of deionized water; and simultaneously obtain the acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 1.

[0036] S2. Using a silicon carbide tubular microchannel reactor with a static mixing component, all the acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 1, the prepared organic phase raw material liquid, and the gas-free acid-binding agent were continuously pumped into the first microchannel reactor via a three-channel high-pressure metering pump. The system back pressure of the first microchannel reactor was set to 0.1 MPa, the temperature of the fluid in the entire section of the heat exchange circulation control pipeline was turned on at 40°C, and the total flow rate was adjusted to control the residence time of the liquid phase fluid in the tube to 3 minutes, generating a clear liquid containing chloroalkyl hydroxylamine intermediate and potassium chloride.

[0037] S3. The clear liquid from the first microchannel reactor and the liquid reducing agent prepared in step S1 are continuously pumped into a second microchannel reactor equipped with a static mixing component. The system back pressure of the second microchannel reactor is set to 0.1 MPa, the fluid temperature throughout the pipeline is controlled at 60°C, and the total flow rate is adjusted to control the residence time of the fluid in the pipe to 5 minutes. The reduction and pyrolysis reaction is carried out, causing the NO bond of the intermediate to break and remove the hydroxyl group, generating a clear liquid containing the target product chloroamine.

[0038] S4. The clear liquid from the second microchannel reactor is introduced into a volumetric phase change triggered mixing tank, while the prepared phase change initiator is continuously pumped in through a branch to mix and induce phase separation. The mixed fluid enters a continuous separator. The lower layer, containing potassium chloride, sodium chloride, and reduction byproducts, is discharged to the environmental treatment unit, while the upper layer, a ternary organic light phase of toluene-acetonitrile-target chloroamine, is collected.

[0039] S5. The organic light phase collected in step S4 and 60 parts of pure water are continuously pumped into the countercurrent extraction tower from the bottom and top of the tower, respectively. Liquid-liquid extraction is carried out at room temperature. The pure water completely extracts the acetonitrile in the organic phase into the aqueous phase. The acetonitrile-water biphase solution is discharged from the bottom of the tower and the toluene-chloroamine solution is discharged from the top of the tower.

[0040] S6. The toluene-chloroamine solution discharged from the top of the column is pumped into a continuous distillation column. The absolute pressure of the control system is maintained at 0.08 MPa for distillation. The toluene liquid collected from the top of the column is fully recycled as the raw material solvent, and the high-purity chloroamine product is continuously collected from the bottom of the column. The acetonitrile-water two-phase solution discharged from the bottom of the column is pumped into an atmospheric distillation column. The acetonitrile-water azeotrope is collected from the top of the column at the azeotropic temperature and fully recycled to the desalination unit. Wastewater is removed from the bottom of the column.

[0041] Example 2: This embodiment provides a continuous preparation method for high-purity chloroamines, including the following steps: S1. Prepare the organic phase feed solution by completely dissolving 15 parts of 1,4-dichlorobutane in 100 parts of toluene; prepare the gas-free acid-binding agent by completely dissolving 10 parts of potassium hydroxide solid in 45 parts of deionized water; prepare the phase change initiator by completely dissolving 12 parts of sodium chloride in 30 parts of deionized water; simultaneously prepare the liquid reducing agent by completely mixing 10 parts of hydrazine hydrate aqueous solution in 25 parts of deionized water; and simultaneously obtain the clear acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 2.

[0042] S2. Using a silicon carbide tubular microchannel reactor with a static mixing component, the entire acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 2, the prepared organic phase raw material solution, and the gas-free acid-binding agent were continuously pumped into the first microchannel reactor via a three-channel high-pressure metering pump. The system back pressure of the first microchannel reactor was set to 0.15 MPa, the heat exchange circulation was turned on, the fluid temperature of the entire pipeline was controlled at 42°C, and the total flow rate was adjusted to control the residence time of the liquid phase fluid in the tube to 4.5 minutes, resulting in a nucleophilic substitution reaction that produces a clear liquid containing a chloroalkyl hydroxylamine intermediate and potassium chloride.

[0043] S3. The clear liquid reaction solution flowing out of the first microchannel reactor and the liquid reducing agent prepared in step S1 are continuously pumped into a second microchannel reactor equipped with a static mixing component. The system back pressure of the second microchannel reactor is set to 0.15 MPa, the fluid temperature throughout the pipeline is controlled at 65°C, and the total flow rate is adjusted to control the residence time of the fluid in the pipe to 6 minutes. The reduction and pyrolysis reaction is carried out, which causes the NO bond of the intermediate to break and remove the hydroxyl group, generating a clear liquid reduction solution containing the target product chloroamine. S4. The clear liquid from the second microchannel reactor is introduced into a volumetric phase change triggered mixing tank, while the prepared phase change initiator is continuously pumped in through a branch to mix and induce phase separation. The mixed fluid enters a continuous separator. The lower layer, containing potassium chloride, sodium chloride, and reduction byproducts, is discharged to the environmental treatment unit, while the upper layer, a ternary organic light phase of toluene-acetonitrile-target chloroamine, is collected.

[0044] S5. The organic light phase collected in step S4 and 75 parts of pure water are continuously pumped into the countercurrent extraction tower from the bottom and top of the tower, respectively. Liquid-liquid extraction is carried out at room temperature. The pure water completely extracts the acetonitrile in the organic phase into the aqueous phase. The acetonitrile-water biphase solution is discharged from the bottom of the tower and the toluene-chloroamine solution is discharged from the top of the tower.

[0045] S6. The toluene-chloroamine solution discharged from the top of the column is pumped into a continuous distillation column. The absolute pressure of the control system is maintained at 0.085 MPa for distillation. The toluene liquid collected from the top of the column is fully recycled as the raw material solvent, and the high-purity chloroamine product is continuously collected from the bottom of the column. The acetonitrile-water two-phase solution discharged from the bottom of the column is pumped into an atmospheric distillation column. The acetonitrile-water azeotrope is collected from the top of the column at the azeotropic temperature and fully recycled to the desalination unit. Wastewater is removed from the bottom of the column.

[0046] Example 3: This embodiment provides a continuous preparation method for high-purity chloroamines, including the following steps: S1. Prepare the organic phase feed solution by completely dissolving 18 parts of 1,4-dichlorobutane in 120 parts of toluene; prepare the gas-free acid-binding agent by completely dissolving 12 parts of potassium hydroxide solid in 50 parts of deionized water; prepare the phase change initiator by completely dissolving 15 parts of sodium chloride in 35 parts of deionized water; simultaneously prepare the liquid reducing agent by completely mixing 12 parts of hydrazine hydrate aqueous solution in 30 parts of deionized water; and simultaneously obtain the clear acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 3.

[0047] S2. Using a silicon carbide tubular microchannel reactor with a static mixing component, all the acetonitrile-water-free hydroxylamine ternary homogeneous solution obtained in Preparation Example 3, the prepared organic phase raw material solution, and the gas-free acid-binding agent were continuously pumped into the first microchannel reactor via a three-channel high-pressure metering pump. The system back pressure of the first microchannel reactor was set to 0.2 MPa, the heat exchange circulation was turned on, the fluid temperature of the entire pipeline was controlled at 45°C, and the total flow rate was adjusted to control the residence time of the liquid phase fluid in the tube to 6 minutes, resulting in a nucleophilic substitution reaction to generate a clear liquid containing a chloroalkyl hydroxylamine intermediate and potassium chloride.

[0048] S3. The clear liquid from the first microchannel reactor and the liquid reducing agent prepared in step S1 are continuously pumped into a second microchannel reactor equipped with a static mixing component. The system back pressure of the second microchannel reactor is set to 0.2 MPa, the fluid temperature throughout the pipeline is controlled at 70°C, and the total flow rate is adjusted to control the residence time of the fluid in the pipe to 8 minutes. The reduction and pyrolysis reaction is carried out, causing the NO bond of the intermediate to break and remove the hydroxyl group, generating a clear liquid containing the target product chloroamine.

[0049] S4. The clear liquid from the second microchannel reactor is introduced into a volumetric phase change triggered mixing tank, while the prepared phase change initiator is continuously pumped in through a branch to mix and induce phase separation. The mixed fluid enters a continuous separator. The lower layer, containing potassium chloride, sodium chloride, and reduction byproducts, is discharged to the environmental treatment unit, while the upper layer, a ternary organic light phase of toluene-acetonitrile-target chloroamine, is collected.

[0050] S5. The organic light phase collected in step S4 and 90 parts of pure water are continuously pumped into the countercurrent extraction tower from the bottom and top of the tower, respectively. Liquid-liquid extraction is carried out at room temperature. The pure water completely extracts the acetonitrile in the organic phase into the aqueous phase. The acetonitrile-water biphase solution is discharged from the bottom of the tower and the toluene-chloroamine solution is discharged from the top of the tower.

[0051] S6. The toluene-chloroamine solution discharged from the top of the column is pumped into a continuous distillation column. The absolute pressure of the control system is maintained at 0.095 MPa for distillation. The toluene liquid collected from the top of the column is fully recycled as the raw material solvent, and the high-purity chloroamine product is continuously collected from the bottom of the column. The acetonitrile-water two-phase solution discharged from the bottom of the column is pumped into an atmospheric distillation column. The acetonitrile-water azeotrope is collected from the top of the column at the azeotropic temperature and fully recycled to the desalination unit. Wastewater is removed from the bottom of the column.

[0052] Comparative Example 1: Compared with Example 2, the difference is that acetonitrile was not continuously injected in the desalting step of Example 2. Instead, a cryogenic cooling crystallization method was used to physically remove the precipitated potassium sulfate solid crystals by lowering the internal temperature of the continuous flow crystallization reactor to -5°C. All other aspects are the same.

[0053] Comparative Example 2: Compared with Example 2, the difference is that the potassium hydroxide used in preparation Example 2 and step S1 of Example 2 is completely replaced with an equimolar mass of conventional sodium hydroxide solid, converting it into a full sodium salt reaction system, while the rest are the same.

[0054] Comparative Example 3: Compared with Example 2, the difference is that the potassium hydroxide solid used in step S1 of Example 2 to prepare the gas-free acid binder is replaced with an equimolar mass of potassium carbonate solid, and all other aspects are the same.

[0055] Comparative Example 4: Compared with Example 2, the difference is that in step S3, no sodium chloride aqueous solution was prepared and pumped in. The clear liquid of the full liquid phase reaction flowing out of the microchannel reactor was directly introduced into the continuous separator for conventional phase separation. All other aspects are the same.

[0056] Comparative Example 5: Compared with Example 2, the difference is that the pure water decoupling extraction step in step S4 is omitted, and the toluene-acetonitrile-target chloroamine ternary organic light phase collected in step S3 is directly and fully pumped into the continuous distillation column in step S5 for desolvation treatment. All other aspects are the same.

[0057] Test Example 1: Test Description: This test experiment uses the operating system of Examples 1 to 3 as the test benchmark, and simultaneously introduces material samples of Comparative Example 1 and Comparative Example 4 as reference systems. The engineering applicability of the phase change desalination and demulsification decoupling mechanism is verified by extracting fluid indicators of each key process.

[0058] Test steps: Start the continuous flow microchannel synthesis equipment and upstream and downstream supporting devices. Adjust the feed flow rate of the metering pumps in each flow path according to the process parameters set in Examples 1 to 3, Comparative Example 1 and Comparative Example 4. After the back pressure inside the system and the temperature distribution of each heat exchange tube section reach the steady-state operating condition, perform continuous sampling operation.

[0059] A sample of free hydroxylamine mother liquor was collected at the outlet of the desalination preparation section. After standing and filtering, a fixed volume was transferred to a volumetric flask and diluted to volume. The volume was then injected into an ion chromatography system, and the concentration of free residual sulfate ions in the mother liquor was quantitatively determined by detecting the elution peak area.

[0060] A clear liquid sample of the reaction was taken from the region at the outlet node of the tubular microchannel reactor before the fluid came into contact with the phase change inducer. An ice-water mixture was added to the sample to rapidly quench the reaction and terminate it. The organic layer was extracted, dried with anhydrous magnesium sulfate, and then injected into a gas chromatograph. The single-pass conversion of the reaction substrate was calculated based on the pre-calibrated standard curve.

[0061] The liquid materials continuously collected from the bottom of the terminal vacuum distillation column of each system were collected, and the chromatographic purity of the final chloroamine product was determined by gas chromatography combined with area normalization. The instrument analysis data of multiple parallel samples were recorded and summarized to eliminate systematic errors.

[0062] The experimental data are shown in Table 1: Table 1: Test results of acetonitrile-induced desalting efficiency and pseudo-homogeneous continuous synthesis performance

[0063] According to the appendix Figure 2 Based on the data in Table 1, observation of the residual sulfate index confirms that acetonitrile triggered a thermodynamic phase reversal during the crystallization and desalination stage. Examples 1 to 3, by introducing highly polar acetonitrile molecules in specific mass ratios, effectively competed for and disrupted the hydration shell network of water molecules on the potassium sulfate surface, causing potassium sulfate to undergo supersaturation precipitation at room temperature. Compared to Comparative Example 1, the residual sulfate concentration in the example groups decreased, eliminating the potential risk of a large amount of inert inorganic salts entering the microchannel pipeline.

[0064] Comparative Example 1 exhibited a conventional liquid-liquid two-phase immiscibility state during the reaction stage, resulting in mass transfer resistance and extremely low substrate conversion. In the Example system, residual acetonitrile, after entering the microchannel with the mother liquor, exhibited amphiphilic co-solvent characteristics, enriching at the interface between the aqueous phase and the nonpolar toluene phase and reducing interfacial tension. This allowed the immiscible fluids to be dispersed into a nanoscale pseudo-homogeneous state under the shear of the static mixing components. The nucleophile and substrate in this hydrodynamic environment completely entered the kinetic control region, achieving near-complete chemical transformation within a very short residence time of a few minutes.

[0065] While Comparative Example 4 maintained a high single-pass reaction conversion rate using acetonitrile, it lacked the saturated sodium chloride initiator injection step at the end of the tube section. Polar droplets formed a long-term stable emulsion interface in the phase separation tank, hindering the physical separation of inorganic wastewater and organic products. Impurities and water entrained in the emulsion phase flowed through the subsequent extraction and distillation systems with the organic phase, triggering local side reactions and azeotropic entrainment, resulting in a decrease in the purity of the product collected from the final column bottom. The high-concentration salting-out targeted demulsification strategy of this invention instantly deprives the free water molecules in the system of their solubility, causing acetonitrile to undergo a phase change and carry the target product to the non-polar phase, ensuring the quality of the product flowing out of the multi-effect dynamic phase change process.

[0066] Test Example 2: Test Description: This test aims to evaluate the differences in hydrodynamic behavior caused by different salt systems and acid-base neutralization mechanisms within the confined space of a microchannel. The material system of Example 2 was used as the test baseline, and Comparative Examples 2 and 3 were simultaneously used as reference groups for parallel operation. The design logic to prevent physical blockage and air resistance pressure buildup was verified by real-time acquisition of the hydrodynamic characteristic parameters of the pipeline.

[0067] Experimental steps: A silicon carbide tubular microchannel reaction test platform with an independent feed pipeline and static mixing components was built. High-precision differential pressure transmitters were connected to the inlet and outlet of the reactor to construct a real-time data acquisition link for recording the pressure drop changes of the fluid system.

[0068] The organic phase raw material liquid, homogeneous solution and corresponding acid-binding agents prepared in Example 2, Comparative Example 2 and Comparative Example 3 are connected to a three-channel high-pressure metering pump. The heat exchange modules of each loop are adjusted to the preset process temperature, and the continuous feeding program of each group is started synchronously according to the set total flow parameters.

[0069] Continuously monitor and record the system back pressure and inlet / outlet pressure difference data of the entire pipe section of the microchannel reactor, extract the pressure drop benchmark value from the start-up to steady-state operation stage of the system, and simultaneously track the peak pressure drop and instantaneous fluctuation variance during operation to quantify the internal flow pattern characteristics of the system.

[0070] To maintain the continuous operation of each system group, a shutdown mechanism is set to be actively triggered when the pipeline pressure difference suddenly rises to more than twice the initial reference value or the flow rate drops sharply to the point where the set residence time cannot be maintained. The limit of fault-free operation time for each test system without abnormal fluctuations or shutdown for clearing blockages is recorded.

[0071] The test data is shown in Table 2: Table 2: Test Results of Microchannel Fluid Dynamics Compatibility and Operational Stability

[0072] According to the appendix Figure 3 Compared with the data in Table 2, in Comparative Example 3, the potassium carbonate continuously released carbon dioxide gas during the neutralization of the byproduct hydrogen chloride inside the pipe. The gas phase volume expanded rapidly within the confined micron-sized space, triggering severe slug flow. The disordered alternation of the gas-liquid interface disrupted the continuity of the pseudo-homogeneous liquid-liquid interface, causing the system pressure drop to oscillate violently at high frequencies within a short period of time. The actual residence time of the fluid deviated from the preset range, ultimately leading to pressure buildup and shutdown. In Example 2, the potassium hydroxide system constructed a neutralization environment without gas release, maintaining the smooth propagation of the pure liquid phase fluid. The system pressure drop was strictly limited to a very small fluctuation range, ensuring that the material maintained an ideal plug flow state within the silicon carbide pipe section.

[0073] In Comparative Example 2, the all-sodium salt system experienced an irreversible surge in pipeline pressure drop at a specific cycle. As the reaction progressed, a large amount of sodium chloride accumulated within the pipe. The presence of high-concentration sodium ions drastically reduced the upper limit of solubility of trace residual sodium sulfate in the free phase. This drastic contraction of the metastable region triggered secondary supersaturated crystallization of the inorganic salt. Micron-sized solid particles adhered and aggregated at the narrow walls of the mixing components, rapidly forming physical blockage sections. Example 2, relying on a specifically designed all-potassium salt ecosystem, utilized the extremely weak solubility of potassium chloride in the same system to displace potassium sulfate, maintaining a broad metastable margin throughout the entire reaction process. This thermodynamically blocked the path of secondary crystallization, endowing the microchannel system with a long-term steady-state operation capability far exceeding that of conventional processes.

[0074] Test Example 3: Test Description: This test experiment aims to investigate the effect of high concentration of inorganic salts on the thermodynamic distribution of strongly polar cosolvents in liquid-liquid multiphase systems, and to compare the emulsion band decay behavior and physical phase separation efficiency of the fluid system after leaving the high-shear environment of the microchannel.

[0075] Experimental steps: The microchannel synthesis systems of Example 2 and Comparative Example 4, which were in a stable and continuous operating state, were selected as parallel test objects to confirm that the feed flow rate and internal reaction temperature of the two devices had reached the set steady-state benchmark.

[0076] Simultaneously collect an equal volume of fresh, fully liquid-phase reaction mixture at the outlet node of the phase change trigger mixing tank or the corresponding direct discharge port. Quickly transfer the collected sample to a standard constant-temperature separatory funnel with high-precision graduations and let it stand. Start the timing program and record the initial total volume of the emulsion mixture layer of the system.

[0077] By maintaining the test environment temperature at room temperature, a high-resolution industrial camera system is used to track the gradient evolution of the light transmittance of the fluid inside the separatory funnel in real time, and to identify and calibrate the shifting position of the upper and lower clear liquid interfaces and the dynamic thickness of the emulsion phase.

[0078] The time required from the start of settling to the complete dissipation of the emulsified intermediate phase and the appearance of a sharp interface at the junction of the aqueous and organic phases was accurately recorded. The final volume occupied by each fluid layer after phase equilibrium was reached was measured. At the same time, the upper organic light phase liquid was extracted and injected into a Karl Fischer water titrator to determine the microscopic water content of the system.

[0079] The test data is shown in Table 3: Table 3: Results of Salting-out Targeted Demulsification and Liquid-Liquid Separation Efficiency Tests

[0080] According to the appendix Figure 4 Compared with the data in Table 3, in Comparative Example 4, after leaving the high shear stress field of the microchannel reactor, the highly dispersed polar droplets inside the system were difficult to spontaneously aggregate, and the amphiphilic acetonitrile molecules enriched at the two-phase interface continued to provide extremely strong emulsifying activity. This interfacial effect in the microscopic spatial dimension led to the formation of a thick emulsion band between the toluene layer and the aqueous phase, which maintained a metastable state for a long time. The physical phase separation process was drastically prolonged, and a large number of micron-sized water droplets were inevitably trapped in the organic light phase layer, resulting in a serious exceedance of water content.

[0081] Example 2 demonstrates how targeted pumping of a sodium chloride aqueous solution at a specific saturation level into the pipe section outlet instantly triggers a thermodynamic behavior shift dominated by the chemical potential gradient. Upon entering the system, sodium and chloride ions, possessing extremely high surface charge densities, plunder the limited free water molecules in the aqueous phase, drastically compressing the solvation space originally provided by the polar hydrogen bond network. Acetonitrile, subjected to salting-out repulsion, undergoes a spontaneous physical phase transition, its solubility in the aqueous phase decreases, and it is forced to carry the dissolved target reaction products in a large-scale reverse migration and diffusion towards the low-polarity toluene organic layer.

[0082] The high-flux extraction of acetonitrile molecules from the aqueous phase interface directly destroys the structural basis for maintaining the stability of the tiny emulsion droplets. The interfacial tension subsequently increases dramatically on a nonlinear scale. The unstable droplets rapidly merge and expand within an extremely short encounter period, strictly adhering to the laws of gravity sedimentation to complete interfacial demulsification. This salting-out demulsification mechanism overcomes the separation difficulties faced by ultrafine dispersion systems under conventional sedimentation conditions, constructing a clear liquid-liquid boundary within tens of seconds. This significantly blocks the permeation path of water to the non-polar side, thus providing a feedstock system with extremely excellent physicochemical properties for downstream countercurrent extraction decoupling and high-vacuum distillation purification.

[0083] Test Example 4: Test Description: This test aims to quantitatively verify the actual role of the room temperature antisolvent mechanism in the overall energy consumption control of the system, and to evaluate the engineering value of pure water countercurrent extraction technology in breaking the organic phase azeotropic system and maintaining the high purity of the solvent in a closed loop, combined with the end separation section.

[0084] Experimental steps: The microchannel continuous production systems of Example 2, Comparative Example 1, and Comparative Example 5, which are of the same production line scale, were selected as parallel test objects. A three-phase power quality analyzer was connected to the power supply end of the system distribution cabinet to record the real-time active power of each core workstation.

[0085] For the front-end desalination process, the power consumption of the ambient temperature delivery metering pump in Example 2 was measured cumulatively. The comprehensive system energy consumption of Comparative Example 1 during the precipitation of inorganic salts per unit mass was calculated simultaneously, and the fluid state inside the cryogenic pipeline was observed.

[0086] The feed from Example 2, after countercurrent extraction with pure water, was collected and fed into the distillation column, along with the ternary mixture from Comparative Example 5, which was directly fed into the distillation column without water washing or extraction. The reboiler heating power and absolute pressure at the top of both systems were kept consistent for continuous distillation operations.

[0087] Samples were taken at fixed time points from the outlet pipeline of the condenser at the top of the continuous distillation column, and the mass fraction of toluene in the recovered solvent was determined using a gas chromatograph equipped with a flame ionization detector. The maximum number of closed-loop cycles of effective substance required to cause a conversion rate decline exceeding 5% due to distortion of the recovered solvent composition was statistically calculated.

[0088] The test data is shown in Table 4: Table 4: Evaluation Results of Solvent Decoupling Loop-Closed-Loop Performance and Overall Desalination Energy Consumption

[0089] According to the appendix Figure 5Compared with the data in Table 4, Comparative Example 1 relied on an extremely low temperature gradient to forcibly reduce the upper limit of potassium sulfate solubility in the aqueous phase. This resulted in the refrigeration compressor group operating at full load, generating high-frequency power output. The power consumption per unit of inorganic salt precipitation increased by orders of magnitude, and uncontrollable icing phase interfaces easily formed inside the pipe section. Example 2, which constructed a polar solvent-induced phase change desalination system, utilized the physicochemical property of a sudden drop in the dielectric constant of the mixed system to trigger crystal nucleation and supersaturated precipitation at normal ambient temperatures. The system setting, which replaced the temperature gradient with chemical potential, avoided the energy burden caused by cryogenic equipment, establishing a low-energy-consumption operating benchmark from the process source.

[0090] Comparative Example 5 omits the pure water washing process before solvent removal. The ternary organic mixture containing acetonitrile, toluene, and chloroamine products is directly exposed to the heated environment of the bottom. Toluene and acetonitrile form a specific minimum azeotropic composition. The gas-liquid phase equilibrium in the distillation column is clamped by this azeotropic thermodynamic boundary. The fraction condensed and recovered at the top of the column is essentially transformed into a mixed azeotropic liquid. The target product layer taken from the bottom of the column simultaneously retains a high concentration of polar solvent impurities.

[0091] The room-temperature water washing decoupling unit deployed in Example 2 utilizes the extreme difference in solubility of a single component in pure water to achieve phase separation. The countercurrent contact of deionized water at the two-phase mass transfer interface quantitatively strips acetonitrile present within the organic stream into the aqueous phase, preemptively eliminating component interference conditions that could trigger subsequent azeotropic distillation. The feed received by the continuous distillation column after separation is transformed into a simple binary fluid of toluene and high-boiling-point chloroamine, allowing the mass transfer process based on the difference in relative volatility to proceed smoothly. The high-purity toluene retained at the top of the column is refluxed to the organic phase feed solution preparation node, while the aqueous acetonitrile discharged from the bottom of the column, after azeotropic concentration, is integrated into the upstream desalination network. The material flow in each independent branch forms a continuous and stable circulating system in the topological dimension.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A continuous preparation method for high-purity chloroamine, characterized in that, Includes the following steps: S1. Prepare organic phase feed solution containing reaction substrate and toluene solvent, gas-free acid binder, phase change inducer and liquid reducing agent respectively; simultaneously carry out continuous reaction and physical filtration of hydroxylamine sulfate aqueous solution and strong base aqueous solution in the presence of acetonitrile solvent to obtain acetonitrile-water-free hydroxylamine ternary homogeneous solution; S2. The prepared acetonitrile-water-free hydroxylamine ternary homogeneous solution, the organic phase raw material liquid, and the gas-free acid-binding agent are continuously pumped into the first microchannel reactor to carry out a mixed substitution reaction to generate a clear liquid containing chloroalkyl hydroxylamine intermediate and potassium chloride. S3. The outflowing liquid-phase reaction solution and the liquid reducing agent are continuously pumped into the second microchannel reactor to carry out a reduction and cracking reaction, so that the NO bond of the intermediate is broken and the hydroxyl group is removed, generating a liquid-phase reduced solution containing the target product chloroamine. S4. The clear liquid of the whole liquid phase reduction is introduced into the mixing tank, the phase change inducer is pumped in to mix and trigger phase separation, the lower layer of wastewater containing inorganic salts is discharged, and the upper layer of toluene-acetonitrile-target chloroamine ternary organic light phase is collected. S5. The toluene-acetonitrile-target chloroamine ternary organic light phase and pure water are continuously pumped into a countercurrent extraction tower for liquid-liquid extraction. The pure water extracts the acetonitrile in the organic phase to the aqueous phase. The acetonitrile-water biphase solution is discharged from the bottom of the tower and the toluene-chloroamine solution is discharged from the top of the tower. S6. The discharged toluene-chloroamine solution is pumped into a continuous distillation column for distillation and solvent removal. The toluene liquid condensed at the top of the column is recycled as a raw material solvent, and the high-purity chloroamine product is continuously collected from the bottom of the column.

2. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, In step S1, the organic phase raw material liquid is prepared by dissolving 12 to 18 parts of the reaction substrate in 80 to 120 parts of toluene by mass, wherein the reaction substrate is 1,3-dichloropropane or 1,4-dichlorobutane.

3. The continuous preparation method of high-purity chloroamine according to claim 2, characterized in that, The gas-free acid binder is prepared by dissolving 9-12 parts of potassium hydroxide solid in 40-50 parts of deionized water by weight, and the phase change inducer is prepared by dissolving 10-15 parts of sodium chloride in 25-35 parts of deionized water by weight. In step S4, the amount of pure water used is 60 to 90 parts.

4. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, In step S2, the acetonitrile-water-free hydroxylamine ternary homogeneous solution is obtained by the following preparation method: Hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution were pumped separately into a continuous flow crystallization reactor, and acetonitrile was continuously injected into the reactor simultaneously to carry out the crystallization reaction. The reaction solution is continuously overflowed and discharged, and the precipitated potassium sulfate solid crystals are physically filtered out. The mother liquor is collected by centrifugation to obtain a homogeneous ternary solution of acetonitrile-water-free hydroxylamine.

5. The continuous preparation method of high-purity chloroamine according to claim 4, characterized in that, The acetonitrile-water-free hydroxylamine ternary homogeneous solution is prepared during the following process: Adjust the feed mass flow rates of hydroxylamine sulfate aqueous solution and potassium hydroxide aqueous solution to maintain the pH value of the reaction mixture at 6.5-7.0; The steady-state temperature inside the continuous flow crystallization reactor is controlled at 15–20°C, and the average residence time of the fluid inside the reactor is controlled at 20–30 minutes.

6. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, Step S2 further includes: The microchannel reactor uses a silicon carbide tubular microchannel reactor with static mixing components, and the material is continuously pumped in by a high-pressure metering pump. The system back pressure of the microchannel reactor is set to 0.1-0.2 MPa, the fluid temperature throughout the pipeline is controlled to be 40-45°C, and the total flow rate is adjusted to control the residence time of the liquid phase fluid in the pipe to be 3-6 minutes.

7. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, In step S3, the lower layer of wastewater containing inorganic salts specifically includes potassium chloride and sodium chloride, and the wastewater is discharged to the environmental protection treatment unit.

8. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, Step S4 further includes: The liquid-liquid extraction is carried out at room temperature, with pure water continuously pumped in from the top of the countercurrent extraction tower, and the upper organic light phase collected in step S3 continuously pumped in from the bottom of the tower.

9. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, In step S5, the absolute system pressure of the continuous distillation column is 0.08 to 0.095 MPa.

10. The continuous preparation method of high-purity chloroamine according to claim 1, characterized in that, The method further includes a recycling process for the acetonitrile-water two-phase solution generated in step S4: The acetonitrile-water two-phase solution discharged from the bottom of the column in step S4 is pumped into an atmospheric distillation column. The acetonitrile-water azeotrope is condensed at the top of the column at the azeotropic temperature and collected. The collected acetonitrile-water azeotrope is then fully recycled to the upstream desalination unit to remove wastewater from the column bottom.

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