MCPA (2-methyl-4-chlorophenoxyacetic acid) esterification and dehydration equipment and synthetic method

Abstract

The invention discloses 2-methyl-4-chlorophenoxyacetic acid esterification dehydration equipment and a synthesis method, belongs to the technical field of chemical engineering, and solves the problems that when 2-methyl-4-chlorophenoxyacetic acid isooctyl ester is synthesized in the prior art, a catalyst seriously corrodes production equipment, the service life of the equipment is shortened, and the product quality is affected due to the fact that the catalyst is left in a product. The method comprises the following steps: respectively adding 2-methyl-4-chloro-phenoxyacetic acid and isooctyl alcohol into a negative pressure reaction kettle, starting the negative pressure reaction kettle, discharging distilled water through a fraction discharging assembly, and obtaining 2-methyl-4-chloro-phenoxyacetic acid isooctyl ester when no fraction flows out of gas-phase isooctyl alcohol in the negative pressure reaction kettle; in the invention, during synthesis of 2-methyl-4-chloro-isooctyl, a catalyst is not needed to catalyze a raw material reaction, a catalyst-free esterification dehydration method is adopted, a negative pressure forced distillation technology is combined, water generated in the reaction is efficiently removed, and the reaction conversion rate and the product yield are remarkably improved; the problems that the catalyst corrodes reaction equipment and the residual catalyst in the product affects the purity and performance of the product are avoided.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a dimethyltetrachloro esterification and dehydration device and synthesis method. Background Technology

[0002] Dimethyltetrachloroisooctyl ester is an important organic chemical intermediate, widely used in the synthesis of pesticides, pharmaceuticals and other fine chemical products. The traditional synthesis of dimethyltetrachloroisooctyl ester mainly adopts the esterification reaction, that is, dimethyltetrachloro reacts with isooctyl alcohol in the presence of a catalyst to produce dimethyltetrachloroisooctyl ester and water. The esterification reaction is a reversible reaction. In order to improve the conversion rate and product yield, it is usually necessary to remove the water generated in the reaction process to shift the reaction equilibrium towards the formation of ester.

[0003] The traditional synthesis process of dimethyltetrachloroisooctyl ester typically involves the esterification reaction of dimethyltetrachloro and isooctyl alcohol in the presence of a catalyst, such as concentrated sulfuric acid, tin tetrachloride, and p-toluenesulfonic acid. While these catalysts can promote the reaction, they also introduce a series of problems. First, the use of catalysts increases production costs. Catalysts themselves are expensive and may be partially lost during the reaction, requiring regular replenishment, which undoubtedly increases the economic burden of the production process. Second, most existing catalysts are highly corrosive, causing severe corrosion to production equipment, shortening its lifespan, and increasing the cost of equipment maintenance and replacement. For example, concentrated sulfuric acid is a strong acid that can react with many metals, causing corrosion pits on the equipment surface, thus affecting the equipment's sealing and safety. Furthermore, the catalyst needs to be treated in the post-processing stage. Since the catalyst may remain in the product, affecting product quality, additional steps are required to remove the catalyst.

[0004] To address the serious corrosion of production equipment caused by existing catalysts during the synthesis of dimethyltetrachloroisooctyl ester, which shortens the equipment's lifespan and affects product quality due to catalyst residues, we propose a dimethyltetrachloro esterification dehydration device and synthesis method. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a dimethyltetrachloro esterification and dehydration equipment and synthesis method, which solves the problems of severe corrosion of production equipment caused by catalysts during the synthesis of dimethyltetrachloroisooctyl ester, shortening the service life of the equipment, and catalyst residues in the product affecting product quality.

[0006] This invention is achieved through a dimethyltetrachloro esterification dehydration synthesis method, the method comprising: S10, take the pre-prepared dimethyltetrachloro and isooctanol, put the dimethyltetrachloro and isooctanol into the negative pressure reactor respectively, start the negative pressure reactor, and stir the dimethyltetrachloro and isooctanol in the negative pressure reactor. S20, start the vacuum pump of the negative pressure reactor. The vacuum pump evacuates the negative pressure reactor and heats the raw materials inside the negative pressure reactor. Distilled water produced by the reaction is distilled out of the negative pressure reactor. The distilled water is discharged through the fraction discharge component. The content of dimethyltetrachlorine in the gas phase inside the negative pressure reactor is detected by the gas phase sampler. S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor is ≤1%, the vacuum negative pressure pump continues to increase the vacuum treatment of the negative pressure reactor, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor is detected by the gas phase sampler. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor, the negative pressure reactor is cooled to obtain dimethyltetrachloroisooctyl ester.

[0007] Preferably, in step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1-1.5:1.2-1.8. In step S20, when the vacuum negative pressure pump performs vacuum treatment on the negative pressure reactor, the vacuum degree of the negative pressure reactor is -0.060 MPa to -0.065 MPa, and the heating temperature of the raw materials in the negative pressure reactor is maintained at 120-125℃.

[0008] Preferably, in step S30, when the vacuum negative pressure pump continues to increase the vacuum treatment of the negative pressure reactor, the vacuum degree of the negative pressure reactor is -0.098 MPa.

[0009] Preferably, the method for preparing dimethyltetrachloro includes: Place o-cresol and 35% sodium hydroxide solution in a reaction vessel, adjust the temperature of the reaction vessel to 65-70℃, add sodium chloroacetate into the reaction vessel, adjust the temperature of the reaction vessel to 75℃, then stir the reactants in the reaction vessel at a stirring speed of 50-60 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. o-Cresolchloroacetic acid intermediate was mixed with carbon tetrachloride at a ratio of 1:5. The mixture was then added to a reactor, and the reactor was started to stir and mix the reactants. The reactants in the reactor were irradiated with ultraviolet light, and chlorine gas was introduced into the reactor at the same time. The reaction temperature was 35°C, and the stirring speed was 100-120 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. The crude dimethyltetrachloride product was deeply purified to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

[0010] Preferably, the method for deep purification of the crude p-methyltetrachloro product includes: Take crude dimethyltetrachloro product and put it into a melting tank at 83-86℃ for melting treatment for 10 minutes. The crude dimethyltetrachloro product after melting was transferred to a jacketed stainless steel reactor. The stainless steel reactor was evacuated to a vacuum level of -0.1 MPa and a temperature of 110-115°C. Low-boiling-point impurities, such as phenol, were collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. The initial purified dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite purified hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 (composite purified hydrogel to initial purified dimethyltetrachloro product). The dimethyltetrachloro solution was stirred at 50 rpm for 1 h. After stirring, the dimethyltetrachloro solution was filtered to obtain the filtered dimethyltetrachloro solution. Dimethyltetrachloride solution was distilled under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride was then transferred to a melting tank at 110°C, where it was chelated and adsorbed by a modified adsorption resin to obtain highly purified dimethyltetrachloride.

[0011] Preferably, the method for preparing the composite impurity-removing hydrogel includes: Acrylic acid was placed in a reaction vessel, and 0.3 times the volume of deionized water was added to dilute it. The pH of the acrylic acid solution in the reaction vessel was adjusted to 6.5-7 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution. Add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, and stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel. The composite impurity removal hydrogel was frozen at -20℃ for 30 minutes. After freezing, the composite impurity removal hydrogel was removed and set aside for later use.

[0012] On the other hand, the present invention also provides a dimethyltetrachloro esterification dehydration apparatus, the dimethyltetrachloro esterification dehydration apparatus comprising: A negative pressure reactor includes a reactor body and a reactor cover. The reactor body is fixedly mounted on a reactor support. The reactor cover is detachably mounted on the top of the reactor body. A raw material injector is installed on the side wall of the reactor body. A product discharge pipe is provided at the bottom of the reactor body. An esterification dehydration chamber is provided inside the reactor body. The linkage mixing mechanism is located inside the reactor. It is used to stir the raw materials in the esterification and dehydration chamber and assist the fraction discharge component in extracting distilled water and unreacted isooctyl alcohol. The fraction discharge assembly is located on one side of the reactor body and is connected to the esterification dehydration chamber; A liftable gas sampler is installed inside the reactor cover plate. The gas sampler is used to detect the content of gaseous dimethyltetrachloro and gaseous isooctyl alcohol in the negative pressure reactor. The linkage mixing mechanism includes a linkage motor, a mixing linkage unit, and a homogenizing and stirring integrated assembly. The linkage motor is detachably installed inside the kettle cover plate, and the output shaft of the linkage motor is fixedly connected to the mixing linkage unit. The mixing linkage unit is located inside the esterification and dehydration chamber, and the mixing linkage unit is connected to the homogenizing and stirring integrated assembly and the fraction discharge assembly, respectively.

[0013] Preferably, the mixing linkage unit includes: The first gear is rotatably installed inside the reactor lid, and one side of the first gear is fixedly connected to the output shaft of the linkage motor. The first linkage gear ring installed inside the reactor body rotates, and one side of the first linkage gear ring meshes with the first gear for transmission. At least one set of gear ring support rods, the gear ring support rods are detachably installed on the first linkage gear ring, and the gear ring support rods are fixedly connected to one end of the first linkage gear ring to a second linkage gear ring, at least one set of arc-shaped stirring blades are detachably installed on the second linkage gear ring, and the arc-shaped stirring blades are also connected to the heat-spreading and stirring integrated component. The integrated heating and stirring assembly includes a side stirring section, a variable range stirring section, a spiral stirring paddle, and a bottom heating section. The side stirring section is fixedly connected to the arc-shaped stirring paddle, the side stirring section is connected to the variable range stirring section, the variable range stirring section is fixedly connected to the spiral stirring paddle, the spiral stirring paddle is sleeved on the outside of the bottom heating section, and the bottom heating section is installed inside the reactor body.

[0014] Preferably, the side stirring section includes: A side stirring rod, which is fixedly connected to an arc-shaped stirring paddle; At least one set of side stirring blades, which are detachably mounted on a side stirring rod, are used to stir and mix the raw materials in the esterification and dehydration chamber; The variable-range stirring section includes: A stirring support base, wherein the stirring support base is fixedly connected to the end of the side stirring rod; The third linkage gear ring is disposed on the outside of the stirring support, and the third linkage gear ring is fixedly installed inside the reactor body; The second gear, which is installed in the stirring support, is rotated. A variable-range stirring paddle is fixedly connected to one side of the second gear, and the second gear is also meshed with the third linkage gear ring. The bottom heat equalization section includes: A heat-equalizing support is fixedly installed inside the reactor vessel; A single-headed heating rod is detachably installed inside the heat-equalizing support base, and a spiral heating plate is fitted on the outer wall of the single-headed heating rod.

[0015] Preferably, the fraction discharge assembly includes: The vacuum negative pressure pump is detachably installed on the side wall of the reactor body, and the exhaust port of the vacuum negative pressure pump is fixedly connected to the distillate reflux pipe. At least one set of distillation pipes, one end of which is connected to a vacuum negative pressure pump, and the other end is detachably connected to a negative pressure distillation pipe. The negative pressure distillation pipe is installed on the side wall of the reactor body, and an auxiliary distillation section is provided inside the negative pressure distillation pipe. The auxiliary distillation section is used to help recover distilled water and unreacted isooctyl alcohol produced in the reaction. The auxiliary distillation section includes a third gear, a gear connecting rod, and a negative pressure distillation fan. The gear connecting rod is rotatably connected to the negative pressure distillation pipe. One end of the gear connecting rod is fixedly connected to the negative pressure distillation fan, and the other end of the gear connecting rod is detachably connected to the third gear. The third gear meshes with the second linkage gear ring for transmission.

[0016] Compared with the prior art, the embodiments of this application have the following main advantages: In this embodiment of the invention, the synthesis of dimethyltetrachloroisooctyl ester does not require a catalyst to catalyze the reaction of the raw materials. Instead, a catalyst-free esterification and dehydration method is employed, combined with negative pressure forced distillation technology, to efficiently remove the water generated in the reaction. This promotes a continuous shift in the reaction equilibrium towards the formation of dimethyltetrachloroisooctyl ester, significantly improving the reaction conversion rate and product yield. Furthermore, by precisely controlling the molar ratio of dimethyltetrachloro to isooctyl alcohol and adjusting the vacuum and temperature in stages, efficient and precise control of the reaction process is achieved. In addition, the preparation and purification process of dimethyltetrachloro ensures the high purity of the raw materials from the source, further improving the quality and stability of the final product. This avoids the problems of catalyst corrosion of reaction equipment and residual catalyst in the product affecting its purity and performance.

[0017] In this embodiment of the invention, during the preparation of dimethyltetrachloro, the crude product is first melted and vacuum-sealed to remove low-boiling-point impurities (phenols), then dissolved in ethyl acetate and a composite impurity-removing hydrogel is added. After filtration, the solvent is removed by vacuum distillation. Finally, trace metal ions or other soluble impurities are removed by chelation with modified adsorption resin in the molten state. The composite impurity-removing hydrogel and modified adsorption resin work synergistically to significantly reduce the content of phenols, organic impurities, and metal ions in dimethyltetrachloro. Combined with thin-film evaporator drying, the interference of moisture on the subsequent esterification reaction can be avoided, and finally, high-purity, low-moisture dimethyltetrachloro is obtained, providing high-quality raw materials for the synthesis of dimethyltetrachloroisooctyl ester and directly improving the quality and yield of the target ester product.

[0018] In this embodiment of the invention, during the preparation of the composite impurity-removing hydrogel, controlled free radical polymerization of acrylic monomers is induced under mild reaction conditions to form a three-dimensional cross-linked network structure. The addition of ammonium bicarbonate as an auxiliary reagent, combined with inert gas protection, effectively prevents oxygen inhibition during polymerization, ensuring the integrity and uniformity of the hydrogel structure. Furthermore, freezing at -20°C for 30 minutes induces the formation of differentiated microcrystalline and amorphous regions within the gel. After freezing, a gel with multi-level pores is formed, increasing the specific surface area and improving the gel's mechanical stability and swelling properties. This allows the hydrogel to efficiently capture organic impurities such as phenols during subsequent adsorption with dimethyltetrachloride solution, while maintaining structural integrity and preventing breakage. The resulting hydrogel possesses high adsorption capacity, good pore structure, and mechanical strength, providing a key and efficient adsorption material for the deep removal of crude dimethyltetrachloride products.

[0019] In this embodiment of the invention, a dimethyltetrachloro esterification and dehydration device is provided. The device comprises a linkage mixing mechanism consisting of a linkage motor, a mixing linkage unit, and a homogenizing and stirring integrated assembly. The linkage mixing mechanism is driven by a servo motor to the mixing linkage unit, which in turn synchronously drives the homogenizing and stirring integrated assembly and the fraction discharge assembly, forming a synergistic mechanism of stirring-mass transfer-distillation. The homogenizing and stirring integrated assembly achieves omnidirectional material mixing in both radial and axial directions, ensuring rapid and uniform dispersion of dimethyltetrachloro and isooctyl alcohol in the initial stage of the reaction. The spiral stirring paddle in the homogenizing and stirring integrated assembly works in conjunction with the bottom homogenizing unit to enhance the mixing effect of the bottom material, avoiding uneven reaction caused by localized overheating or undercooling of the raw materials in the esterification and dehydration chamber. Simultaneously, it ensures that the water generated in the reaction evaporates rapidly and is discharged through the fraction discharge assembly, while avoiding high-temperature side reactions.

[0020] In this embodiment of the invention, the integrated heating and stirring assembly comprises a side stirring section, a variable-range stirring section, a spiral stirring paddle, and a bottom heating section. The side stirring section and the arc-shaped stirring paddle work together to achieve thorough stirring of the raw materials. Combined with the radial expansion and angle adjustment of the variable-range stirring paddle in the variable-range stirring section, it can perform all-round, multi-level mechanical stirring of materials at different heights and positions in the esterification and dehydration chamber, promoting the rapid and uniform dispersion of dimethyltetrachloro and isooctyl alcohol, and avoiding uneven reaction caused by local concentration differences. The spiral stirring paddle not only generates axial flow through rotation, enhancing the vertical circulation and mixing effect of the materials, but also forms an integrated stirring and heat transfer structure with the bottom heating section. This allows the heat generated by the heating element to be evenly transferred to the bottom and central areas of the reactor through the rotation of the spiral stirring paddle, avoiding local overheating or undercooling caused by uneven heating in traditional equipment, ensuring the stability and uniformity of the reaction temperature, improving mass transfer efficiency and the degree of positive shift of reaction equilibrium, and ultimately achieving efficient conversion of reactants. Attached Figure Description

[0021] Figure 1 Schematic diagram of performance test results of Embodiments 1-4 and Comparative Examples 1-3 of the present invention.

[0022] Figure 2 This is a schematic diagram of the dimethyltetrachloro esterification and dehydration equipment provided by the present invention.

[0023] Figure 3 This is a front view of the dimethyltetrachloro esterification and dehydration equipment provided by the present invention.

[0024] Figure 4 This is a top view of the dimethyltetrachloro esterification and dehydration equipment provided by the present invention.

[0025] Figure 5 yes Figure 4 A sectional view along the AA direction.

[0026] Figure 6 This is a schematic diagram of the linkage mixing mechanism provided by the present invention.

[0027] Figure 7 This is a front view of the linkage mixing mechanism provided by the present invention.

[0028] Figure 8 This is a top view of the linkage mixing mechanism provided by the present invention.

[0029] Figure 9 This is a schematic diagram of the mixing linkage unit provided by the present invention.

[0030] Figure 10 This is a schematic diagram of the integrated heating and stirring assembly provided by the present invention.

[0031] Figure 11This is an isometric view of the integrated heating and stirring assembly provided by the present invention.

[0032] Figure 12 This is a schematic diagram of the fraction discharge assembly provided by the present invention.

[0033] Figure 13 This is a schematic diagram of the auxiliary distillation section provided by the present invention.

[0034] In the diagram: 1-Negative pressure reactor, 11-Reactor body, 111-Esterification and dehydration chamber, 12-Reactor support, 13-Reactor cover, 14-Raw material feeder, 15-Product discharge pipe, 2-Linked mixing mechanism, 21-Linked motor, 22-Mixing linkage unit, 221-First gear, 222-First linkage gear ring, 223-Gear ring support rod, 224-Second linkage gear ring, 225-Arc-shaped stirring paddle, 3-Fraction discharge assembly, 31-Vacuum negative pressure pump, 32-Fraction reflux pipe, 33-Fraction guide pipe, 34-Negative pressure fraction pipe, 35-Auxiliary distillation... Components: 351-Third Gear, 352-Gear Connecting Rod, 353-Negative Pressure Drainage Fan, 4-Integrated Heat Sprinkler Assembly, 41-Side Stirring Section, 411-Side Stirring Rod, 412-Side Stirring Paddle, 42-Variable Range Stirring Section, 421-Stirring Support, 422-Second Gear, 423-Third Linkage Gear Ring, 424-Variable Range Stirring Paddle, 43-Spiral Stirring Paddle, 44-Bottom Heat Sprinkler, 441-Heat Sprinkler Support, 442-Single-Head Heating Rod, 443-Spiral Heating Plate, 5-Gas Phase Sampler, 51-Lifting Cylinder, 52-Gas Phase Sampler Seat. Detailed Implementation

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0036] The existing catalyst used in the synthesis of dimethyltetrachloroisooctyl ester causes severe corrosion to the production equipment, shortening its service life, and the catalyst residue in the product affects its quality. To address these issues, we propose a dimethyltetrachloro esterification and dehydration device and synthesis method. In short, the method involves first adding dimethyltetrachloro and isooctanol to a negative pressure reactor 1, starting the reactor 1, stirring the dimethyltetrachloro and isooctanol, discharging distilled water through a fraction discharge component 3, and detecting the content of dimethyltetrachloro in the gas phase within the reactor 1 using a gas phase sampler 5. When no isooctanol fraction flows out of the reactor 1, the reactor 1 is cooled to obtain dimethyltetrachloroisooctyl ester. In this embodiment of the invention, the synthesis of dimethyltetrachloroisooctyl ester does not require a catalyst to catalyze the reaction of the raw materials. Instead, a catalyst-free esterification and dehydration method is employed, combined with negative pressure forced distillation technology, to efficiently remove the water generated in the reaction. This promotes a continuous shift in the reaction equilibrium towards the formation of dimethyltetrachloroisooctyl ester, significantly improving the reaction conversion rate and product yield. Furthermore, by precisely controlling the molar ratio of dimethyltetrachloro to isooctyl alcohol and adjusting the vacuum and temperature in stages, efficient and precise control of the reaction process is achieved. In addition, the preparation and purification process of dimethyltetrachloro ensures the high purity of the raw materials from the source, further improving the quality and stability of the final product. This avoids the problems of catalyst corrosion of reaction equipment and residual catalyst in the product affecting its purity and performance.

[0037] Example 1 This invention provides a method for synthesizing dimethyltetrachloro via esterification and dehydration, the method specifically comprising: S10, take the pre-prepared dimethyltetrachloro and isooctyl alcohol, put the dimethyltetrachloro and isooctyl alcohol into the negative pressure reactor 1 respectively, start the negative pressure reactor 1, and stir the dimethyltetrachloro and isooctyl alcohol in the negative pressure reactor 1. S20, start the vacuum negative pressure pump 31 of the negative pressure reactor 1, the vacuum negative pressure pump 31 evacuates the negative pressure reactor 1 and heats the raw materials in the negative pressure reactor 1, the distilled water produced by the reaction is distilled out in the negative pressure reactor 1, the distilled water is discharged through the fraction discharge component 3, and the content of dimethyltetrachlorine in the gas phase in the negative pressure reactor 1 is detected based on the gas phase sampler 5. In step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1:1.2. In step S20, when the vacuum negative pressure pump 31 performs vacuum treatment on the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.060 MPa, and the heating temperature of the raw materials in the negative pressure reactor 1 is maintained at 125℃.

[0038] S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor 1 is ≤1%, the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor 1 is detected by the gas phase sampler 5. When the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.098 MPa. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor 1, the negative pressure reactor 1 is cooled down to obtain dimethyltetrachloroisooctyl ester.

[0039] In this embodiment of the invention, the method for preparing dimethyltetrachloro includes: S101, o-cresol and 35% sodium hydroxide solution were placed in a reaction vessel and the temperature of the reaction vessel was adjusted to 70℃. Sodium chloroacetate was added to the reaction vessel and the temperature of the reaction vessel was adjusted to 75℃. Then the reactants in the reaction vessel were stirred at a stirring speed of 50 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. In step S102, o-cresol chloroacetate intermediate was mixed with carbon tetrachloride at a feed-to-liquid ratio of 1:5. The mixture was then fed into a reactor, and the reactor was started to stir and mix the reactants. The reactants in the reactor were irradiated with ultraviolet light. The ultraviolet light irradiation enhanced the reactivity of chlorine gas, selectively introducing chlorine atoms (target sites) at the ortho position of the methyl group of the o-cresol ring, avoiding over-chlorination or side reactions, and significantly improving the synthesis selectivity of dimethyltetrachloro. At the same time, chlorine gas was introduced into the reactor, the reaction temperature was 35°C, and the stirring speed was 100 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. S103 was used to deeply purify the crude dimethyltetrachloride to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

[0040] In this embodiment of the invention, during the preparation of dimethyltetrachloro, the crude product is first melted and vacuum-sealed to remove low-boiling-point impurities (phenols), then dissolved in ethyl acetate and a composite impurity-removing hydrogel is added. After filtration, the solvent is removed by vacuum distillation. Finally, trace metal ions or other soluble impurities are removed by chelation with modified adsorption resin in the molten state. The composite impurity-removing hydrogel and modified adsorption resin work synergistically to significantly reduce the content of phenols, organic impurities, and metal ions in dimethyltetrachloro. Combined with thin-film evaporator drying, the interference of moisture on the subsequent esterification reaction can be avoided, and finally, high-purity, low-moisture dimethyltetrachloro is obtained, providing high-quality raw materials for the synthesis of dimethyltetrachloroisooctyl ester and directly improving the quality and yield of the target ester product.

[0041] The method for deep purification of the crude dimethyltetrachloro product includes: S201, take the crude dimethyltetrachloro product and put it into a melting tank at 83°C for 10 minutes to melt it. By melting the crude dimethyltetrachloro product for 10 minutes, the boiling point difference between low-boiling-point impurities and dimethyltetrachloro is utilized, allowing them to preferentially volatilize under subsequent vacuum conditions and be collected at the top, thus achieving the targeted removal of low-boiling-point impurities. This step specifically removes any phenols that may remain in the reaction. S202, the crude dimethyltetrachloro product after molten treatment is transferred to a jacketed stainless steel reactor. The stainless steel reactor is evacuated to a vacuum level of -0.1 MPa and a temperature of 110°C. Low-boiling-point impurities such as phenol are collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. S203, the initial impurity-removed dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite impurity-removing hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 (composite impurity-removing hydrogel to initial impurity-removed dimethyltetrachloro product). The dimethyltetrachloro solution was stirred at 50 rpm for 1 hour. After stirring, the dimethyltetrachloro solution was filtered to obtain a filtered dimethyltetrachloro solution. By dissolving the initial impurity-removed product in ethyl acetate and adding the composite impurity-removing hydrogel, the hydrogen bonding, coordination, or complexation of the carboxyl and hydroxyl functional groups in the hydrogel with the residual organic impurities was utilized to achieve specific adsorption of dissolved organic impurities. After filtration, the gel with adsorbed impurities was removed, significantly reducing the content of organic impurities in the solution and improving the purity of the solution. S204, the dimethyltetrachloride solution is distilled under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride is then transferred to a melting tank at 110°C. The molten dimethyltetrachloride is chelated and adsorbed by a modified adsorption resin to obtain deeply purified dimethyltetrachloride. Subsequently, the molten dimethyltetrachloride is chelated and adsorbed by the modified adsorption resin. The functional groups (such as sulfonic acid groups, amino groups, etc.) on the resin surface combine with trace metal ions or polar impurities to further remove trace impurities that may cause product discoloration, reduced catalytic activity, or storage instability. In this embodiment of the invention, the modified adsorption resin can be a phenolic resin modified resin or a sulfonic acid-phosphoric acid bifunctional resin. Through the chelation adsorption of the modified adsorption resin, the content of metal ions in dimethyltetrachloride can be significantly reduced, the purity and stability of the product can be improved, the interference of metal ions on subsequent reactions can be reduced, and the smooth progress of the dimethyltetrachloride isooctyl ester synthesis reaction and the consistency of product quality can be ensured.

[0042] In this embodiment of the invention, the method for preparing the composite impurity-removing hydrogel includes: S301, place acrylic acid in a reaction vessel, add 0.3 times the volume of deionized water to dilute the acrylic acid, and adjust the pH of the acrylic acid solution in the reaction vessel to 6.5 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution; S302, add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel; S303, place the composite impurity removal hydrogel at -20℃ for 30 minutes to freeze. After freezing, remove the composite impurity removal hydrogel for later use.

[0043] In this embodiment of the invention, during the preparation of the composite impurity-removing hydrogel, controlled free radical polymerization of acrylic monomers is induced under mild reaction conditions to form a three-dimensional cross-linked network structure. The addition of ammonium bicarbonate as an auxiliary reagent, combined with inert gas protection, effectively prevents oxygen inhibition during polymerization, ensuring the integrity and uniformity of the hydrogel structure. Furthermore, freezing at -20°C for 30 minutes induces the formation of differentiated microcrystalline and amorphous regions within the gel. After freezing, a gel with multi-level pores is formed, increasing the specific surface area and improving the gel's mechanical stability and swelling properties. This allows the hydrogel to efficiently capture organic impurities such as phenols during subsequent adsorption with dimethyltetrachloride solution, while maintaining structural integrity and preventing breakage. The resulting hydrogel possesses high adsorption capacity, good pore structure, and mechanical strength, providing a key and efficient adsorption material for the deep removal of crude dimethyltetrachloride products.

[0044] In this embodiment of the invention, the synthesis of dimethyltetrachloroisooctyl ester does not require a catalyst to catalyze the reaction of the raw materials. Instead, a catalyst-free esterification and dehydration method is employed, combined with negative pressure forced distillation technology, to efficiently remove the water generated in the reaction. This promotes a continuous shift in the reaction equilibrium towards the formation of dimethyltetrachloroisooctyl ester, significantly improving the reaction conversion rate and product yield. Furthermore, by precisely controlling the molar ratio of dimethyltetrachloro to isooctyl alcohol and adjusting the vacuum and temperature in stages, efficient and precise control of the reaction process is achieved. In addition, the preparation and purification process of dimethyltetrachloro ensures the high purity of the raw materials from the source, further improving the quality and stability of the final product. This avoids the problems of catalyst corrosion of reaction equipment and residual catalyst in the product affecting its purity and performance.

[0045] Example 2 This invention provides a method for synthesizing dimethyltetrachloro via esterification and dehydration, the method specifically comprising: S10, take the pre-prepared dimethyltetrachloro and isooctyl alcohol, put the dimethyltetrachloro and isooctyl alcohol into the negative pressure reactor 1 respectively, start the negative pressure reactor 1, and stir the dimethyltetrachloro and isooctyl alcohol in the negative pressure reactor 1. S20, start the vacuum negative pressure pump 31 of the negative pressure reactor 1, the vacuum negative pressure pump 31 evacuates the negative pressure reactor 1 and heats the raw materials in the negative pressure reactor 1, the distilled water produced by the reaction is distilled out in the negative pressure reactor 1, the distilled water is discharged through the fraction discharge component 3, and the content of dimethyltetrachlorine in the gas phase in the negative pressure reactor 1 is detected based on the gas phase sampler 5. In step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1:1.8. In step S20, when the vacuum negative pressure pump 31 performs vacuum treatment on the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.065 MPa, and the heating temperature of the raw materials in the negative pressure reactor 1 is maintained at 125℃.

[0046] S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor 1 is ≤1%, the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor 1 is detected by the gas phase sampler 5. When the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.098 MPa. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor 1, the negative pressure reactor 1 is cooled down to obtain dimethyltetrachloroisooctyl ester.

[0047] In this embodiment of the invention, the method for preparing dimethyltetrachloro includes: S101, o-cresol and 35% sodium hydroxide solution were placed in a reaction vessel and the temperature of the reaction vessel was adjusted to 70℃. Sodium chloroacetate was added to the reaction vessel and the temperature of the reaction vessel was adjusted to 75℃. Then the reactants in the reaction vessel were stirred at a stirring speed of 60 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. S102, o-cresol chloroacetate intermediate was mixed with carbon tetrachloride at a ratio of 1:5. The mixture was put into a reactor, the reactor was started and stirred to mix the reactants. The reactants in the reactor were irradiated with ultraviolet light, and chlorine gas was introduced into the reactor at the same time. The reaction temperature was 35°C and the stirring speed was 120 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. S103 was used to deeply purify the crude dimethyltetrachloride to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

[0048] The method for deep purification of the crude dimethyltetrachloro product includes: S201, take crude dimethyltetrachloro product, put the crude dimethyltetrachloro product into a melting tank at 86℃, and melt the crude dimethyltetrachloro product for 10 minutes; S202, the crude dimethyltetrachloro product after molten treatment is transferred to a jacketed stainless steel reactor. The stainless steel reactor is evacuated to a vacuum degree of -0.1MPa and a temperature of 114℃. Low-boiling-point impurities phenol are collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. S203, the initial purified dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite purified hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 of composite purified hydrogel and initial purified dimethyltetrachloro product. The dimethyltetrachloro solution was stirred at a speed of 50 rpm for 1 h. After stirring, the dimethyltetrachloro solution was filtered to obtain the filtered dimethyltetrachloro solution. S204 was used to distill the dimethyltetrachloride solution under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride was then transferred to a melting tank at 110°C, where it was chelated and adsorbed by a modified adsorption resin to obtain highly purified dimethyltetrachloride.

[0049] In this embodiment of the invention, the method for preparing the composite impurity-removing hydrogel includes: S301, place acrylic acid in a reaction vessel, add 0.3 times the volume of deionized water to dilute the acrylic acid, and adjust the pH of the acrylic acid solution in the reaction vessel to 7 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution; S302, add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel; S303, place the composite impurity removal hydrogel at -20℃ for 30 minutes to freeze. After freezing, remove the composite impurity removal hydrogel for later use.

[0050] Example 3 This invention provides a method for synthesizing dimethyltetrachloro via esterification and dehydration, the method specifically comprising: S10, take the pre-prepared dimethyltetrachloro and isooctyl alcohol, put the dimethyltetrachloro and isooctyl alcohol into the negative pressure reactor 1 respectively, start the negative pressure reactor 1, and stir the dimethyltetrachloro and isooctyl alcohol in the negative pressure reactor 1. S20, start the vacuum negative pressure pump 31 of the negative pressure reactor 1, the vacuum negative pressure pump 31 evacuates the negative pressure reactor 1 and heats the raw materials in the negative pressure reactor 1, the distilled water produced by the reaction is distilled out in the negative pressure reactor 1, the distilled water is discharged through the fraction discharge component 3, and the content of dimethyltetrachlorine in the gas phase in the negative pressure reactor 1 is detected based on the gas phase sampler 5. In step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1.5:1.8. In step S20, when the vacuum negative pressure pump 31 performs vacuum treatment on the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.063 MPa, and the heating temperature of the raw materials in the negative pressure reactor 1 is maintained at 123℃.

[0051] S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor 1 is ≤1%, the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor 1 is detected by the gas phase sampler 5. When the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.098 MPa. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor 1, the negative pressure reactor 1 is cooled down to obtain dimethyltetrachloroisooctyl ester.

[0052] In this embodiment of the invention, the method for preparing dimethyltetrachloro includes: S101, o-cresol and 35% sodium hydroxide solution were placed in a reaction vessel and the temperature of the reaction vessel was adjusted to 68℃. Sodium chloroacetate was added to the reaction vessel and the temperature of the reaction vessel was adjusted to 75℃. Then the reactants in the reaction vessel were stirred at a speed of 55 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. S102, o-cresol chloroacetate intermediate was mixed with carbon tetrachloride at a ratio of 1:5. The mixture was put into the reactor, the reactor was started and stirred to mix the reactants. The reactants in the reactor were irradiated with ultraviolet light, and chlorine gas was introduced into the reactor at the same time. The reaction temperature was 35℃ and the stirring speed was 118 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. S103 was used to deeply purify the crude dimethyltetrachloride to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

[0053] The method for deep purification of the crude dimethyltetrachloro product includes: S201, take crude dimethyltetrachloro product, put the crude dimethyltetrachloro product into a melting tank at 85°C, and melt the crude dimethyltetrachloro product for 10 minutes; S202, the crude dimethyltetrachloro product after molten treatment is transferred to a jacketed stainless steel reactor. The stainless steel reactor is evacuated to a vacuum degree of -0.1MPa and a temperature of 114℃. Low-boiling-point impurities phenol are collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. S203, the initial purified dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite purified hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 of composite purified hydrogel and initial purified dimethyltetrachloro product. The dimethyltetrachloro solution was stirred at a speed of 50 rpm for 1 h. After stirring, the dimethyltetrachloro solution was filtered to obtain the filtered dimethyltetrachloro solution. S204 was used to distill the dimethyltetrachloride solution under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride was then transferred to a melting tank at 110°C, where it was chelated and adsorbed by a modified adsorption resin to obtain highly purified dimethyltetrachloride.

[0054] In this embodiment of the invention, the method for preparing the composite impurity-removing hydrogel includes: S301, place acrylic acid in a reaction vessel, add 0.3 times the volume of deionized water to dilute the acrylic acid, and adjust the pH of the acrylic acid solution in the reaction vessel to 6.8 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution; S302, add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel; S303, place the composite impurity removal hydrogel at -20℃ for 30 minutes to freeze. After freezing, remove the composite impurity removal hydrogel for later use.

[0055] Example 4 This invention provides a method for synthesizing dimethyltetrachloro via esterification and dehydration, the method specifically comprising: S10, take the pre-prepared dimethyltetrachloro and isooctyl alcohol, put the dimethyltetrachloro and isooctyl alcohol into the negative pressure reactor 1 respectively, start the negative pressure reactor 1, and stir the dimethyltetrachloro and isooctyl alcohol in the negative pressure reactor 1. S20, start the vacuum negative pressure pump 31 of the negative pressure reactor 1, the vacuum negative pressure pump 31 evacuates the negative pressure reactor 1 and heats the raw materials in the negative pressure reactor 1, the distilled water produced by the reaction is distilled out in the negative pressure reactor 1, the distilled water is discharged through the fraction discharge component 3, and the content of dimethyltetrachlorine in the gas phase in the negative pressure reactor 1 is detected based on the gas phase sampler 5. In step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1:1.2. In step S20, when the vacuum negative pressure pump 31 performs vacuum treatment on the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.065 MPa, and the heating temperature of the raw materials in the negative pressure reactor 1 is maintained at 123.5℃.

[0056] S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor 1 is ≤1%, the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor 1 is detected by the gas phase sampler 5. When the vacuum negative pressure pump 31 continues to increase the vacuum treatment of the negative pressure reactor 1, the vacuum degree of the negative pressure reactor 1 is -0.098 MPa. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor 1, the negative pressure reactor 1 is cooled down to obtain dimethyltetrachloroisooctyl ester.

[0057] In this embodiment of the invention, the method for preparing dimethyltetrachloro includes: S101, o-cresol and 35% sodium hydroxide solution were placed in a reaction vessel and the temperature of the reaction vessel was adjusted to 68.5℃. Sodium chloroacetate was added to the reaction vessel and the temperature of the reaction vessel was adjusted to 75℃. The reactants in the reaction vessel were then stirred at a stirring speed of 52 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. S102, o-cresol chloroacetate intermediate was mixed with carbon tetrachloride at a ratio of 1:5. The mixture was put into the reactor, the reactor was started and stirred to mix the reactants. The reactants in the reactor were irradiated with ultraviolet light, and chlorine gas was introduced into the reactor at the same time. The reaction temperature was 35℃ and the stirring speed was 112 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. S103 was used to deeply purify the crude dimethyltetrachloride to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

[0058] The method for deep purification of the crude dimethyltetrachloro product includes: S201, take the crude dimethyltetrachloro product, put the crude dimethyltetrachloro product into a melting tank at 84°C, and melt the crude dimethyltetrachloro product for 10 minutes; S202, the crude dimethyltetrachloro product after molten treatment is transferred to a jacketed stainless steel reactor. The stainless steel reactor is evacuated to a vacuum degree of -0.1MPa and a temperature of 114℃. Low-boiling-point impurities phenol are collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. S203, the initial purified dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite purified hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 of composite purified hydrogel and initial purified dimethyltetrachloro product. The dimethyltetrachloro solution was stirred at a speed of 50 rpm for 1 h. After stirring, the dimethyltetrachloro solution was filtered to obtain the filtered dimethyltetrachloro solution. S204 was used to distill the dimethyltetrachloride solution under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride was then transferred to a melting tank at 110°C, where it was chelated and adsorbed by a modified adsorption resin to obtain highly purified dimethyltetrachloride.

[0059] In this embodiment of the invention, the method for preparing the composite impurity-removing hydrogel includes: S301, place acrylic acid in a reaction vessel, add 0.3 times the volume of deionized water to dilute the acrylic acid, and adjust the pH of the acrylic acid solution in the reaction vessel to 6.9 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution; S302, add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel; S303, place the composite impurity removal hydrogel at -20℃ for 30 minutes to freeze. After freezing, remove the composite impurity removal hydrogel for later use.

[0060] Comparative Example 1 In this comparative example, the raw materials for the synthesis of dimethyltetrachloroisooctyl ester were dimethyltetrachloro and isooctanol, and the catalyst was concentrated sulfuric acid. The esterification reaction of dimethyltetrachloro and isooctanol was catalyzed by concentrated sulfuric acid. Other raw materials, reaction conditions, and synthesis process were similar to those in Example 4.

[0061] Comparative Example 2 In this comparative example, the raw materials for the synthesis of dimethyltetrachloroisooctyl ester were dimethyltetrachloro and isooctanol, and the catalyst was tin tetrachloride. The esterification reaction of dimethyltetrachloro and isooctanol was catalyzed by tin tetrachloride. Other raw materials, reaction conditions and synthesis process were similar to those in Example 4.

[0062] Comparative Example 3 In this comparative example, the raw materials for the synthesis of dimethyltetrachloroisooctyl ester were dimethyltetrachloro and isooctanol, and the catalyst was p-toluenesulfonic acid. The esterification reaction of dimethyltetrachloro and isooctanol was catalyzed by p-toluenesulfonic acid. Other raw materials, reaction conditions, and synthesis process were similar to those in Example 4.

[0063] Performance testing: The present invention's Examples 1-4 and Comparative Examples 1-3 were tested, and the purity, reaction yield, and free water content of the products were tested respectively. Table 1 and Figure 1 The performance test results of Examples 1-4 and Comparative Examples 1-3 of the present invention are shown. In the purity test, gas chromatography (GC) was used for detection. The higher the value, the more effective component of dimethyltetrachloroisooctyl ester in the product. In the yield test, the actual product mass percentage calculated based on the feed amount (dimethyltetrachloro, isooctyl alcohol) reflects the reaction conversion efficiency. In the free water content test, it was detected by a Karl Fischer moisture analyzer. The lower the value, the better the drying effect.

[0064] Table 1 As can be clearly seen from the data in Table 1, the catalyst-free synthesis method of this invention achieves higher product purity and yield compared to the traditional catalyst method used in the comparative example. Furthermore, this method significantly reduces the free water content in the product, effectively avoiding equipment corrosion problems and complex subsequent processing steps that may be caused by the use of catalysts. In summary, this invention demonstrates significant performance advantages in simplifying the process, improving product quality, and reducing production costs.

[0065] Example 5 This invention also provides a dimethyltetrachloro esterification dehydration device, such as... Figures 2-5 As shown, the dimethyltetrachloro esterification dehydration equipment specifically includes: A negative pressure reactor 1 includes a reactor body 11 and a reactor cover 13. The reactor body 11 is fixedly mounted on a reactor support 12, and the reactor cover 13 is detachably mounted on the top of the reactor body 11. A raw material injector 14 is installed on the side wall of the reactor body 11, and a product discharge pipe 15 is provided at the bottom of the reactor body 11. An esterification dehydration chamber 111 is provided inside the reactor body 11. The negative pressure reactor 1 can be a hollow cylindrical tank or cylinder structure. The inner wall of the negative pressure reactor 1 is polished. The negative pressure reactor 1 is also connected to a condensation system. The product collection system is provided. The reactor body 11 and the reactor support 12 are connected by welding or bolts, while the reactor body 11 and the reactor cover plate 13 are connected by a sealing flange and bolts for detachment. The product discharge pipe 15 is equipped with a solenoid valve to control the product discharge. The product discharge pipe 15 is connected to the product collection system. The raw material injector 14 is located on one side of the top of the reactor body 11. The raw material injector 14 is equipped with a feed pump and a solenoid valve. The raw material injector 14 is also connected to a raw material injection pipe and a catalyst (spare) injection pipe. The linkage mixing mechanism 2 is installed inside the reactor body 11. The linkage mixing mechanism 2 is used to stir the raw materials in the esterification dehydration chamber 111 and assist the fraction discharge component 3 in extracting distilled water and unreacted isooctyl alcohol. The fraction discharge assembly 3 is located on one side of the reactor body 11, and the fraction discharge assembly 3 is connected to the esterification dehydration chamber 111. A liftable gas sampler 5 is installed inside the reactor cover plate 13. The gas sampler 5 is used to detect the content of gaseous dimethyltetrachloro and gaseous isooctanol in the negative pressure reactor 1. The gas sampler 5 includes a lifting cylinder 51 and a gas sampling seat 52. The lifting cylinder 51 is fixedly installed on the top of the reactor cover plate 13 by means of snap-fit ​​or plug-in connection. The telescopic end of the lifting cylinder 51 is fixedly connected to the gas sampling seat 52 by means of snap-fit ​​or tenon connection. The gas sampling seat 52 is connected to an online gas chromatograph for real-time monitoring of the content of dimethyltetrachloro / isooctanol in the gas phase. Among them, such as Figures 6-8 As shown, the linkage mixing mechanism 2 includes a linkage motor 21, a mixing linkage part 22, and a homogenizing and stirring integrated assembly 4. The linkage motor 21 is detachably installed inside the kettle cover plate 13, and the output shaft of the linkage motor 21 is fixedly connected to the mixing linkage part 22. The mixing linkage part 22 is located inside the esterification dehydration chamber 111. The mixing linkage part 22 is connected to the homogenizing and stirring integrated assembly 4 and the fraction discharge assembly 3 respectively. The linkage motor 21 is a servo motor, and the linkage motor 21 is detachably installed inside the kettle cover plate 13 by means of clamps or buckles.

[0066] In this embodiment of the invention, a dimethyltetrachloro esterification and dehydration device is provided. The linkage mixing mechanism 2 in the dimethyltetrachloro esterification and dehydration device consists of a linkage motor 21, a mixing linkage part 22, and a homogenizing and stirring integrated assembly 4. The linkage mixing mechanism 2 drives the mixing linkage part 22 via a servo motor, which in turn synchronously drives the homogenizing and stirring integrated assembly 4 and the fraction discharge assembly 3, forming a synergistic mechanism of stirring-mass transfer-distillation. The homogenizing and stirring integrated assembly 4 achieves omnidirectional material mixing in both radial and axial directions, ensuring rapid and uniform dispersion of dimethyltetrachloro and isooctyl alcohol in the initial stage of the reaction. The spiral stirring paddle 43 in the homogenizing and stirring integrated assembly 4 works in conjunction with the bottom homogenizing part 44 to enhance the mixing effect of the bottom material, avoiding uneven reaction caused by local overheating or undercooling of the raw materials in the esterification and dehydration chamber 111. Simultaneously, it ensures that the water generated in the reaction evaporates rapidly and is discharged through the fraction discharge assembly 3, while avoiding high-temperature side reactions.

[0067] In a further preferred embodiment of the present invention, such as Figure 9 As shown, the mixing linkage unit 22 includes: The first gear 221 is rotatably installed inside the lid plate 13, and one side of the first gear 221 is fixedly connected to the output shaft of the linkage motor 21. The first gear 221 and the output shaft of the linkage motor 21 are connected by plug-in or interference fit. The first linkage gear ring 222 is rotatably installed inside the reactor body 11. One side of the first linkage gear ring 222 meshes with the first gear 221 for transmission. The first linkage gear ring 222 is rotatably connected to the reactor body 11 through a bearing or roller. At least one set of gear ring support rods 223 are provided. The gear ring support rods 223 are detachably installed on the first linkage gear ring 222. The gear ring support rods 223 are fixedly connected to one end of the first linkage gear ring 222 to a second linkage gear ring 224. At least one set of arc-shaped stirring paddles 225 are detachably installed on the second linkage gear ring 224. The arc-shaped stirring paddles 225 are also connected to the heat-spreading and stirring integrated assembly 4. The arc-shaped stirring paddles 225 have an arc-shaped or fan-shaped structure. The arc-shaped stirring paddles 225 are fixedly connected to the second linkage gear ring 224 by means of snap-fit ​​or bolt. Among them, such as Figures 10-11 As shown, the integrated heating and stirring assembly 4 includes a side stirring section 41, a variable range stirring section 42, a spiral stirring paddle 43, and a bottom heating section 44. The side stirring section 41 is fixedly connected to the arc-shaped stirring paddle 225, the side stirring section 41 is connected to the variable range stirring section 42, the variable range stirring section 42 is fixedly connected to the spiral stirring paddle 43, the spiral stirring paddle 43 is sleeved on the outside of the bottom heating section 44, and the bottom heating section 44 is installed inside the reactor body 11.

[0068] In this embodiment, the side stirring unit 41 includes: A side stirring rod 411 is fixedly connected to an arc-shaped stirring paddle 225. The side stirring rod 411 is fixedly connected to the arc-shaped stirring paddle 225 by means of plugging or snapping. At least one set of side stirring blades 412, the side stirring blades 412 are detachably mounted on the side stirring rod 411, the side stirring blades 412 are used to stir and mix the raw materials in the esterification dehydration chamber 111, the side stirring blades 412 are evenly arranged on the outer wall of the side stirring rod 411 in a circumferential manner, and the shape of the side stirring blades 412 is arc-shaped, fan-shaped or rectangular. The variable-range stirring section 42 includes: A stirring support 421 is fixedly connected to the end of a side stirring rod 411. The third linkage gear ring 423 is disposed on the outside of the stirring support 421. The third linkage gear ring 423 is fixedly installed inside the reactor body 11. It should be noted that the third linkage gear ring 423 is an incomplete gear ring. Its surface is provided with an arc-shaped tooth set, which meshes with the second gear 422 for transmission. The second gear 422 is rotatably installed in the stirring support 421. A variable range stirring paddle 424 is fixedly connected to one side of the second gear 422, and the second gear 422 is also meshed with the third linkage gear ring 423. In this embodiment of the invention, the variable-range stirring paddle 424 is an arc-shaped or semi-circular rod structure. The variable-range stirring paddle 424 is fixedly connected to the second gear 422 by plugging or snapping. During operation, the linkage motor 21 starts and drives the first gear 221 to rotate. The first gear 221 drives the first linkage gear ring 222 to rotate, which in turn drives the gear ring support rod 223, the second linkage gear ring 224, and the arc-shaped stirring paddle 225 to rotate. This causes the arc-shaped stirring paddle 225 to drive the side stirring rod 411 to rotate, and the side stirring rod 411 to drive the side stirring paddle 412 and the stirring support 421 to rotate. The movement of the stirring support 421 enables thorough mixing of the reaction materials at the edge of the esterification and dehydration chamber 111. The rotation of the stirring support 421 drives the second gear 422 and the variable-range stirring paddle 424 to rotate. At the same time, when the second gear 422 rotates, it intermittently meshes with the third linkage gear ring 423, so that the variable-range stirring paddle 424 rotates synchronously around the horizontal central axis of the stirring support 421. This achieves shearing and variable-range mixing of the reaction materials in the esterification and dehydration chamber 111, enhances the mixing efficiency of the materials, and avoids the distilled water generated in the reaction being encapsulated by the materials, effectively improving the efficiency and quality of the esterification and dehydration reaction.

[0069] The bottom heat dissipation section 44 includes: The heat-spreading support 441 is fixedly installed inside the reactor body 11; A single-headed heating rod 442 is detachably installed inside the heat-equalizing support 441, and a spiral heating plate 443 is sleeved on the outer wall of the single-headed heating rod 442.

[0070] The heat-equalizing support 441 is fixedly installed in the inner wall of the reactor body 11 by snap-fit ​​or welding. The single-head heating rod 442 can be an electric heating rod, while the spiral heating plate 443 can be a copper spiral heating plate 443 or a stainless steel spiral heating plate 443, thereby ensuring good thermal conductivity and making the heating process more uniform and stable. The single-head heating rod 442 is connected to an external power source to convert electrical energy into heat energy. The heat is quickly dissipated through the spiral heating plate 443 to heat the reaction raw materials in the reactor body 11, ensuring that the esterification and dehydration reaction proceeds efficiently under suitable temperature conditions, further guaranteeing the quality and efficiency of the dimethyltetrachloro esterification and dehydration synthesis reaction.

[0071] In this embodiment of the invention, the integrated heating and stirring assembly 4 consists of a side stirring section 41, a variable-range stirring section 42, a spiral stirring paddle 43, and a bottom heating section 44. The side stirring section 41 and the arc-shaped stirring paddle 225 work together to achieve thorough stirring of the raw materials. Combined with the radial expansion and angle adjustment of the variable-range stirring paddle 424 in the variable-range stirring section 42, it can perform all-round and multi-level mechanical stirring of materials at different heights and positions in the esterification and dehydration chamber 111, promoting the rapid and uniform dispersion of dimethyltetrachloro and isooctyl alcohol, and avoiding uneven reaction caused by local concentration differences. The spiral stirring paddle 43 not only generates axial flow through rotation, enhancing the vertical circulation and mixing effect of materials, but also forms an integrated stirring and heat transfer structure with the bottom heating section 44. This allows the heat generated by the heating element to be evenly transferred to the bottom and central areas of the reactor through the rotation of the spiral stirring paddle 43, avoiding local overheating or overcooling caused by uneven heating in traditional equipment, ensuring the stability and uniformity of the reaction temperature, improving the mass transfer efficiency and the degree of positive shift of the reaction equilibrium, and ultimately achieving efficient conversion of the reactants.

[0072] In a further preferred embodiment of the present invention, such as Figure 12 As shown, the fraction discharge assembly 3 includes: A vacuum negative pressure pump 31 is detachably installed on the side wall of the reactor body 11, and the exhaust port of the vacuum negative pressure pump 31 is fixedly connected to a distillate reflux pipe 32. The vacuum negative pressure pump 31 is fixedly installed on the side wall of the reactor body 11 by snap-fit ​​or plug-in connection. At least one set of distillation pipes 33, one end of which is connected to a vacuum negative pressure pump 31, and the other end is detachably connected to a negative pressure distillation pipe 34. The negative pressure distillation pipe 34 is installed on the side wall of the reactor body 11, and an auxiliary distillation section 35 is provided inside the negative pressure distillation pipe 34. The auxiliary distillation section 35 is used to assist in the recovery of distilled water and unreacted isooctyl alcohol produced in the reaction; Among them, such as Figure 13 As shown, the auxiliary distillation section 35 includes a third gear 351, a gear connecting rod 352, and a negative pressure diversion fan 353. The gear connecting rod 352 is rotatably connected to the negative pressure distillation pipe 34. One end of the gear connecting rod 352 is fixedly connected to the negative pressure diversion fan 353, and the other end of the gear connecting rod 352 is detachably connected to the third gear 351. The third gear 351 meshes with the second linkage gear ring 224 for transmission.

[0073] In this embodiment, during operation, the vacuum negative pressure pump 31 can quickly extract distilled water in the early stage of the esterification reaction. The third gear 351 in the auxiliary distillation section 35 can be engaged and driven when the second linkage gear ring 224 rotates, thereby driving the gear connecting rod 352 and the negative pressure drainage fan 353 to rotate. On the one hand, this enhances the rapid discharge of distilled water, and on the other hand, it improves the transmission efficiency of the mixing linkage section 22 and the synthesis reaction efficiency of dimethyltetrachloroisooctyl ester.

[0074] In summary, this invention provides a dimethyltetrachloro esterification and dehydration apparatus and synthesis method. In the embodiments of this invention, the synthesis of dimethyltetrachloroisooctyl ester does not require the use of a catalyst to catalyze the reaction of the raw materials. A catalyst-free esterification and dehydration method is adopted, combined with negative pressure forced distillation technology, to efficiently remove the water generated in the reaction. This promotes a continuous shift of the reaction equilibrium towards the formation of dimethyltetrachloroisooctyl ester, significantly improving the reaction conversion rate and product yield. Furthermore, by precisely controlling the molar ratio of dimethyltetrachloro to isooctyl alcohol and adjusting the vacuum degree and temperature in stages, efficient and precise control of the reaction process is achieved. At the same time, combined with the dimethyltetrachloro preparation and purification process, the high purity of the raw materials is guaranteed from the source, further improving the quality and stability of the final product. This avoids the problems of catalyst corrosion of reaction equipment and residual catalyst in the product affecting the purity and performance of the product.

[0075] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

Claims

1. A method for synthesizing dimethyltetrachloro esterification and dehydration, characterized in that, The method includes: S10, take the pre-prepared dimethyltetrachloro and isooctanol, put the dimethyltetrachloro and isooctanol into the negative pressure reactor respectively, start the negative pressure reactor, and stir the dimethyltetrachloro and isooctanol in the negative pressure reactor; S20, start the vacuum pump of the negative pressure reactor. The vacuum pump evacuates the negative pressure reactor and heats the raw materials inside the negative pressure reactor. Distilled water produced by the reaction is distilled out of the negative pressure reactor. The distilled water is discharged through the fraction discharge component. The content of dimethyltetrachlorine in the gas phase inside the negative pressure reactor is detected by the gas phase sampler. S30, when the content of dimethyltetrachloro in the gas phase in the negative pressure reactor is ≤1%, the vacuum negative pressure pump continues to increase the vacuum treatment of the negative pressure reactor, and the unreacted isooctanol is distilled by heating and reducing pressure. The gas phase isooctanol in the negative pressure reactor is detected by the gas phase sampler. S40, when no fraction of gaseous isooctanol flows out of the negative pressure reactor, the negative pressure reactor is cooled to obtain dimethyltetrachloroisooctyl ester.

2. The method for synthesizing dimethyltetrachloro esterification and dehydration as described in claim 1, characterized in that: In step S10, the molar ratio of dimethyltetrachloro to isooctyl alcohol is 1-1.5:1.2-1.

8. In step S20, when the vacuum negative pressure pump evacuates the negative pressure reactor, the vacuum degree of the negative pressure reactor is -0.060 MPa to -0.065 MPa, and the heating temperature of the raw materials in the negative pressure reactor is maintained at 120-125℃.

3. The method for synthesizing dimethyltetrachloro esterification and dehydration as described in claim 2, characterized in that: In step S30, when the vacuum negative pressure pump continues to increase the vacuum treatment of the negative pressure reactor, the vacuum degree of the negative pressure reactor is -0.098 MPa.

4. The method for synthesizing dimethyltetrachloro via esterification and dehydration as described in claim 1, characterized in that: The method for preparing dimethyltetrachloro includes: Place o-cresol and 35% sodium hydroxide solution in a reaction vessel, adjust the temperature of the reaction vessel to 65-70℃, add sodium chloroacetate into the reaction vessel, adjust the temperature of the reaction vessel to 75℃, then stir the reactants in the reaction vessel at a stirring speed of 50-60 rpm for 4 hours to obtain o-cresol chloroacetate intermediate. o-Cresolchloroacetic acid intermediate was mixed with carbon tetrachloride at a ratio of 1:

5. The mixture was then added to a reactor, and the reactor was started to stir and mix the reactants. The reactants in the reactor were irradiated with ultraviolet light, and chlorine gas was introduced into the reactor at the same time. The reaction temperature was 35°C, and the stirring speed was 100-120 rpm. After the reaction was completed, the reaction product was washed with water and alkali to obtain crude dimethyltetrachloro product. The crude dimethyltetrachloride product was deeply purified to obtain purified dimethyltetrachloride. The purified dimethyltetrachloride was then dried using a thin-film evaporator to remove free water, thus obtaining the purified dimethyltetrachloride.

5. The method for synthesizing dimethyltetrachloro esterification and dehydration as described in claim 4, characterized in that: The method for deep purification of crude dimethyltetrachloro product includes: Take crude dimethyltetrachloro product and put it into a melting tank at 83-86℃ for melting treatment for 10 minutes. The crude dimethyltetrachloro product after melting was transferred to a jacketed stainless steel reactor. The stainless steel reactor was evacuated to a vacuum level of -0.1 MPa and a temperature of 110-115°C. Low-boiling-point impurities, such as phenol, were collected at the top of the stainless steel reactor to obtain the pre-purified dimethyltetrachloro product. The initial purified dimethyltetrachloro product was dissolved in 5 times its volume of ethyl acetate to obtain a dimethyltetrachloro solution. The pre-prepared composite purified hydrogel was added to the dimethyltetrachloro solution at a volume ratio of 1:5 (composite purified hydrogel to initial purified dimethyltetrachloro product). The dimethyltetrachloro solution was stirred at 50 rpm for 1 h. After stirring, the dimethyltetrachloro solution was filtered to obtain the filtered dimethyltetrachloro solution. Dimethyltetrachloride solution was distilled under reduced pressure to separate ethyl acetate and dimethyltetrachloride from the solution. The collected dimethyltetrachloride was then transferred to a melting tank at 110°C, where it was chelated and adsorbed by a modified adsorption resin to obtain highly purified dimethyltetrachloride.

6. The method for synthesizing dimethyltetrachloro via esterification and dehydration as described in claim 5, characterized in that: The method for preparing the composite impurity-removing hydrogel includes: Acrylic acid was placed in a reaction vessel, and 0.3 times the volume of deionized water was added to dilute it. The pH of the acrylic acid solution in the reaction vessel was adjusted to 6.5-7 using 35% sodium hydroxide solution to obtain a neutralized acrylic acid solution. Add crosslinking agent MBA and initiator APS to acrylic acid solution, stir at 100 rpm for 20 min, add ammonium bicarbonate to the reaction vessel, and stir the reaction vessel at 65℃ for 3 h under inert gas protection to obtain composite impurity-removing hydrogel. The composite impurity removal hydrogel was frozen at -20℃ for 30 minutes. After freezing, the composite impurity removal hydrogel was removed and set aside for later use.

7. A dimethyltetrachloro esterification and dehydration apparatus for implementing the dimethyltetrachloro esterification and dehydration synthesis method as described in any one of claims 1-6, characterized in that: The dimethyltetrachloro esterification and dehydration equipment includes: A negative pressure reactor includes a reactor body and a reactor cover. The reactor body is fixedly installed on a reactor support. The reactor cover is detachably installed on the top of the reactor body. A raw material injector is installed on the side wall of the reactor body. A product discharge pipe is provided at the bottom of the reactor body. An esterification dehydration chamber is provided inside the reactor body. The linkage mixing mechanism is located inside the reactor. It is used to stir the raw materials in the esterification and dehydration chamber and assist the fraction discharge component in extracting distilled water and unreacted isooctyl alcohol. The fraction discharge assembly is located on one side of the reactor body and is connected to the esterification dehydration chamber; A liftable gas sampler is installed inside the reactor cover plate. The gas sampler is used to detect the content of gaseous dimethyltetrachloro and gaseous isooctyl alcohol in the negative pressure reactor. The linkage mixing mechanism includes a linkage motor, a mixing linkage unit, and a homogenizing and stirring integrated assembly. The linkage motor is detachably installed inside the kettle cover plate, and the output shaft of the linkage motor is fixedly connected to the mixing linkage unit. The mixing linkage unit is located inside the esterification and dehydration chamber, and the mixing linkage unit is connected to the homogenizing and stirring integrated assembly and the fraction discharge assembly, respectively.

8. The dimethyltetrachloro esterification and dehydration equipment as described in claim 7, characterized in that: The mixing linkage unit includes: The first gear is rotatably installed inside the reactor lid, and one side of the first gear is fixedly connected to the output shaft of the linkage motor. The first linkage gear ring installed inside the reactor body rotates, and one side of the first linkage gear ring meshes with the first gear for transmission. At least one set of gear ring support rods, the gear ring support rods are detachably installed on the first linkage gear ring, and the gear ring support rods are fixedly connected to one end of the first linkage gear ring to a second linkage gear ring, and at least one set of arc-shaped stirring blades are detachably installed on the second linkage gear ring, the arc-shaped stirring blades are also connected to the heat-spreading and stirring integrated component. The integrated heating and stirring assembly includes a side stirring section, a variable range stirring section, a spiral stirring paddle, and a bottom heating section. The side stirring section is fixedly connected to the arc-shaped stirring paddle, the side stirring section is connected to the variable range stirring section, the variable range stirring section is fixedly connected to the spiral stirring paddle, the spiral stirring paddle is sleeved on the outside of the bottom heating section, and the bottom heating section is installed inside the reactor body.

9. The dimethyltetrachloro esterification dehydration equipment as described in claim 8, characterized in that: The side stirring section includes: A side stirring rod, which is fixedly connected to an arc-shaped stirring paddle; At least one set of side stirring blades, which are detachably mounted on a side stirring rod, and are used to stir and mix the raw materials in the esterification and dehydration chamber; The variable-range stirring section includes: A stirring support base, wherein the stirring support base is fixedly connected to the end of the side stirring rod; The third linkage gear ring is disposed on the outside of the stirring support, and the third linkage gear ring is fixedly installed inside the reactor body; The second gear, which is installed in the stirring support, is rotated. A variable-range stirring paddle is fixedly connected to one side of the second gear, and the second gear is also meshed with the third linkage gear ring. The bottom heat equalization section includes: A heat-equalizing support is fixedly installed inside the reactor vessel; A single-headed heating rod is detachably installed inside the heat-equalizing support base, and a spiral heating plate is fitted on the outer wall of the single-headed heating rod.

10. The dimethyltetrachloro esterification dehydration equipment as described in claim 9, characterized in that: The fraction discharge assembly includes: The vacuum negative pressure pump is detachably installed on the side wall of the reactor body, and the exhaust port of the vacuum negative pressure pump is fixedly connected to the distillate reflux pipe. At least one set of distillation pipes, one end of which is connected to a vacuum negative pressure pump, and the other end is detachably connected to a negative pressure distillation pipe. The negative pressure distillation pipe is installed on the side wall of the reactor body, and an auxiliary distillation section is provided inside the negative pressure distillation pipe. The auxiliary distillation section is used to help recover distilled water and unreacted isooctyl alcohol produced in the reaction. The auxiliary distillation section includes a third gear, a gear connecting rod, and a negative pressure distillation fan. The gear connecting rod is rotatably connected to the negative pressure distillation pipe. One end of the gear connecting rod is fixedly connected to the negative pressure distillation fan, and the other end of the gear connecting rod is detachably connected to the third gear. The third gear meshes with the second linkage gear ring for transmission.

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