Method for producing terephthaloyl chloride by controlling the amount of light

Abstract

The present invention relates to a method for producing terephthaloyl chloride, in which the purity of the intermediate raw material hexachloroparaxylene can be improved by introducing a photochlorination method instead of a radical initiator, and by controlling the light intensity of the light irradiation to less than 2000 lux, the occurrence of side reactions of hexachloroparaxylene is reduced and the yield is high.The present invention also provides a method for producing terephthaloyl chloride that introduces a circulation system and does not discharge chlorine gas to the outside.

Description

[Technical Field]

[0001] The present invention relates to a method for producing terephthaloyl chloride by controlling the amount of light. [Background technology]

[0002] Terephthaloyl chloride (TPC) is a white solid or colorless needle-shaped crystal, and is primarily used as a polymer monomer for poly(paraphenylene terephthamide) and polysulfonamide.

[0003] Furthermore, terephthaloyl chloride has a wide range of applications, such as as an additive for polymers and as an intermediate in the agricultural chemical and pharmaceutical industries.

[0004] The monomers used in the production of terephthaloyl chloride are mainly terephthalic acid (TPA) or paraxylene.

[0005] However, when producing terephthaloyl chloride from terephthalic acid as a raw material, toxic solvents such as highly toxic phosgene and methylene chloride are used, and the treatment and purification processes of by-products generated during the reaction are complicated.

[0006] Furthermore, when terephthaloyl chloride is produced using paraxylene as a raw material, an intermediate step of converting paraxylene into hexachloroparaxylene is included. If the chlorine gas used in the intermediate step does not react and is released to the outside, it may have an adverse effect on the human body or the environment.

[0007] In addition, the intermediate step is carried out by a radical reaction, and impurities may act on the radical initiator used in the radical reaction, which may cause problems when producing high-purity terephthaloyl chloride. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide hexachloroparaxylene with an extremely low impurity content by introducing a photoirradiation reaction instead of a radical initiator when producing hexachloroparaxylene from paraxylene.

[0009] Another object of the present invention is to provide high-purity hexachloroparaxylene with low side reactions and high yield by controlling the amount of light used in the photoirradiation reaction.

[0010] Another object of the present invention is to provide a method for synthesizing hexachloroparaxylene in which chlorine gas is not discharged to the outside by circulating unreacted chlorine gas through a different reactor and consuming it without discharging the unreacted chlorine gas.

[0011] Another object of the present invention is to provide a method for producing hexachloroparaxylene, which can maintain a relatively high chlorine gas solubility within an appropriate viscosity range by controlling the photoreaction temperature inside a reactor when producing hexachloroparaxylene.

[0012] Another object of the present invention is to provide terephthaloyl chloride by reacting the hexachloroparaxylene produced above with terephthalic acid. [Means for solving the problem]

[0013] The present invention relates to a method for producing hexachloroparaxylene by photoreacting paraxylene with chlorine gas, in which the amount of light input to the photoreaction is less than 2,000 Lux.

[0014] According to one embodiment of the present invention, the method for producing hexachloroparaxylene may include a plurality of reactors connected in parallel.

[0015] According to one embodiment of the present invention, the plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and chlorine gas is continuously introduced into the first reactor filled with paraxylene to react, and the reaction is initiated while discharging hydrochloric acid gas, which is a by-product of the conversion of hexachloroparaxylene, to the outside. When the chlorine gas continuously introduced into the first reactor after the reaction has started, begins to be discharged as an unreacted product, the unreacted chlorine gas that is continuously introduced into the first reactor and does not participate in the reaction is transferred to the second reactor without being discharged to the outside, and the paraxylene filled in the second reactor is The first reactor is then connected to the second reactor to start a first reaction, the reaction in the first reactor is terminated, and the chlorine gas continuously introduced into the first reactor is connected to the second reactor and continuous introduction into the second reactor is started. In a state where the first reactor, from which the product has been discharged, is filled with paraxylene, the unreacted chlorine gas is transferred to the first reactor at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor begins to be discharged as an unreacted product, and the unreacted chlorine gas is then transferred to the first reactor to start a first reaction with the paraxylene in the first reactor. By repeating this process, hexachloroparaxylene can be produced without discharging unreacted chlorine gas to the outside.

[0016] According to one aspect of the present invention, there is provided a method for producing terephthaloyl chloride by reacting hexachloroparaxylene with terephthalic acid, the method comprising the steps of: injecting chlorine gas into para-xylene to produce hexachloroparaxylene; and reacting the hexachloroparaxylene with terephthalic acid in the presence of a Lewis acid catalyst to produce terephthaloyl chloride, wherein the amount of light input in the step of producing hexachloroparaxylene is less than 2,000 Lux.

[0017] In the method for producing hexachloroparaxylene according to one embodiment of the present invention, a plurality of reactors may be connected in parallel.

[0018] According to one embodiment of the present invention, the plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and chlorine gas is continuously introduced into the first reactor filled with paraxylene to react, and the reaction is initiated while discharging hydrochloric acid gas, which is a by-product of the conversion of hexachloroparaxylene, to the outside. When the conversion of hexachloroparaxylene reaches a conversion rate at which the chlorine gas continuously introduced into the first reactor after the reaction has started to be discharged as an unreacted product, the unreacted chlorine gas that has been continuously introduced into the first reactor and does not participate in the reaction is transferred to the second reactor without being discharged to the outside, and the paraxylene filled in the second reactor is then reacted with the chlorine gas. The first reactor is then connected to the second reactor and continuous feeding of chlorine gas into the second reactor is initiated; the reaction in the first reactor is terminated; the chlorine gas continuously fed into the first reactor is connected to the second reactor and continuous feeding into the second reactor is initiated; and in a state where the first reactor, from which the product has been discharged, is filled with paraxylene, the unreacted chlorine gas is transferred to the first reactor at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously fed into the second reactor begins to be discharged as an unreacted product, and the unreacted chlorine gas is then transferred to the first reactor and the first reaction is initiated with the paraxylene in the first reactor. By repeating this process, hexachloroparaxylene can be produced without discharging unreacted chlorine gas to the outside.

[0019] According to one embodiment of the present invention, the hexachloroparaxylene produced may further include a purification step.

[0020] According to one embodiment of the present invention, the purification step can be carried out in a distillation column.

[0021] According to one embodiment of the present invention, the distillation column can purify hexachloroparaxylene at a distillation bottom temperature of 100 to 300°C, a top temperature of 100 to 250°C, and a pressure of 1 to 20 torr.

[0022] According to one embodiment of the present invention, the Lewis acid catalyst may be any one or more selected from aluminum trichloride, zinc chloride, and ferric trichloride.

[0023] According to one embodiment of the present invention, the terephthaloyl chloride produced may further include a purification step.

[0024] According to one embodiment of the present invention, the purification step can be carried out in a distillation column.

[0025] According to one embodiment of the present invention, the distillation column can purify hexachloroparaxylene at a controlled distillation temperature of 75 to 250° C. and a pressure of 1 torr to 20 torr. [Effects of the Invention]

[0026] The present invention can provide hexachloroparaxylene with a low impurity content by providing hexachloroparaxylene by performing light irradiation instead of using a radical initiator.

[0027] Furthermore, the present invention has the advantage of reducing the occurrence of side reactions of hexachloroparaxylene by controlling the light intensity of light irradiation to less than 2000 lux.

[0028] In addition, the present invention controls the reaction temperature during the photoreaction in multiple sections and gradually increases the reaction temperature in each section, thereby maintaining a relatively high chlorine gas solubility within an appropriate viscosity range and providing hexachloroparaxylene in a high yield.

[0029] The present invention has the advantage that, by introducing a chlorine gas circulation system that circulates unreacted chlorine gas into the first reactor and the second reactor during the production of hexachloroparaxylene, an intermediate raw material, hexachloroparaxylene can be produced without discharging toxic chlorine gas to the outside. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram of the manufacturing steps for producing terephthaloyl chloride. [Figure 2] FIG. 1 is a schematic diagram of steps for producing hexachloroparaxylene. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described in more detail below with reference to specific examples or embodiments including the accompanying drawings. However, the following specific examples or embodiments are merely references for describing the present invention in detail, and the present invention is not limited thereto and can be realized in various forms.

[0032] Furthermore, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in describing the present invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0033] Also, as used in the specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0034] Furthermore, when a part is described as "comprising" a certain component, this does not mean that it excludes other components, but that it may further include other components, unless otherwise specified to the contrary.

[0035] The chlorinated intermediate product described later in this invention may be monochloroparaxylene, dichloroparaxylene, trichloroparaxylene, tetrachloroparaxylene or pentachloroparaxylene.

[0036] Conventionally, hexachloroparaxylene has been produced by adding a radical initiator, but this method has the disadvantage of making it difficult to produce high-purity hexachloroparaxylene due to impurities.

[0037] To solve this problem, hexachloroparaxylene was produced by irradiating a mixture of paraxylene and chlorine gas with light, but this method had the disadvantage of frequent side reactions and a low yield of hexachloroparaxylene.

[0038] Therefore, the present invention solves the above problem by providing a method for producing hexachloroparaxylene by reacting paraxylene with chlorine, in which the amount of light input to the reaction is less than 2,000 Lux.

[0039] Hexachloroparaxylene is produced by mixing paraxylene and chlorine gas and irradiating the mixture with UV light. Conventionally, the reaction was carried out at a light intensity of 2,000 lux or more, but this range of light intensity can cause side reactions, resulting in a low yield of hexachloroparaxylene.

[0040] The chlorine gas is irradiated with UV light to generate chlorine radicals, which then undergo a substitution reaction with hydrogen in the paraxylene methyl group to produce hexachloroparaxylene.

[0041] Conventionally, the reaction has been carried out by irradiating the UV light at a level of at least 2,000 lux or more, and often at a level of at least 30,000 lux or more. However, this light intensity range has the disadvantage of causing side reactions and resulting in a low yield of hexachloroparaxylene.

[0042] Therefore, the present inventors have found that hexachloroparaxylene can be produced even when the light intensity is controlled to a range of less than 2,000 Lux, 1,900 Lux or less, 1,800 Lux or less, 1,700 Lux or less, 1,500 Lux or less, 100 Lux or more, 200 Lux or more, 300 Lux or more, 400 Lux or more, or 500 Lux or more, preferably 100 to 1,900 Lux, and preferably 100 to 1,800 Lux, and that production within the above ranges results in fewer side reactions and a higher yield.

[0043] Furthermore, within the above range of light intensity, the heat of reaction generated during the reaction is low, which is very favorable for controlling the temperature, and there is also the advantage that the reaction rate can be controlled.

[0044] The area of ​​light irradiation is not limited as long as the reaction proceeds smoothly. 2 Less than 20cm, preferably 2 Less than 10cm, preferably 2 You can respond more smoothly when:

[0045] In addition, an LED lamp is used as the light source used in the photoirradiation reaction of the present invention.

[0046] Mercury lamps have been used in the past, but the short wavelength light of low-pressure mercury lamps can cause other photochemical side reactions and reduce the purity of the product, and the long wavelength light of high-pressure mercury lamps is not sufficient to cause a chlorine radical reaction and can consume more energy. Furthermore, when using mercury lamps, more heat is generated, which can lead to problems such as the need to install an additional cooling device to reduce the heat.

[0047] Therefore, the present invention uses an LED lamp to overcome the disadvantages of the mercury lamp. The LED lamp can control the wavelength band appropriate for the reaction, reducing photochemical side reactions. It also generates less heat than a mercury lamp, even during long-term use, eliminating the need for additional cooling devices. Furthermore, the LED lamp has the advantage of low power consumption and high energy efficiency.

[0048] The photoreaction produces hydrochloric acid gas (HCl) as a by-product.

[0049] However, there is a problem that some unreacted chlorine gas is mixed with hydrochloric acid gas and discharged together during the light irradiation reaction. In particular, as the light irradiation reaction proceeds, the reaction rate of chlorine gas decreases due to steric effects, which increases the amount of unreacted chlorine gas discharged to the outside.

[0050] Therefore, the present invention provides a new method for producing hexachloroparaxylene, which can consume all of the unreacted chlorine gas without discharging it to the outside.

[0051] The new method for producing hexachloroparaxylene involves connecting multiple reactors in parallel, and transferring unreacted chlorine gas discharged from the multiple reactors in turn to other reactors for circulation.

[0052] The number of reactors may be two or three or more, but is not limited thereto.

[0053] Hereinafter, a more detailed explanation will be given using a reactor in which two or more reactors are connected in parallel.

[0054] In the present invention, chlorine gas is first continuously introduced into a first reactor filled with paraxylene to react with it, and the reaction begins while hydrochloric acid gas, a by-product of the conversion of hexachloroparaxylene, is discharged to the outside. Here, the introduced chlorine gas is quantitatively consumed by reacting with paraxylene. Next, chlorine gas continuously introduced into the first reactor is continuously introduced into the first reactor at a conversion rate of hexachloroparaxylene at which the unreacted chlorine gas begins to be discharged. When the unreacted chlorine gas that did not participate in the reaction is discharged from the first reactor, the discharged unreacted chlorine gas is transferred to the second reactor without being discharged to the outside, and begins to react with the paraxylene filled in the second reactor. When the reaction in the first reactor is completed, the introduction of chlorine gas into the first reactor is stopped, and the chlorine gas introduced into the first reactor is connected to the second reactor, which is then continuously introduced into the second reactor to participate in the reaction.

[0055] Next, with the first reactor from which the product has been discharged being filled again with paraxylene as the starting material, the unreacted chlorine gas is circulated to the first reactor at a conversion rate of hexachloroparaxylene at which chlorine gas continuously introduced into the second reactor begins to be discharged as an unreacted product, and the unreacted chlorine gas is allowed to react with the paraxylene in the first reactor. This process is repeated to produce hexachloroparaxylene without discharging unreacted chlorine gas to the outside.

[0056] The method for producing hexachloroparaxylene will be described in more detail below with reference to FIG. 2, which is divided into steps.

[0057] According to one embodiment of the present invention, the steps for producing hexachloroparaxylene include: S1) adding and filling the first reactor 100 and the second reactor 200 with para-xylene; S2) continuously injecting chlorine gas into the first reactor 100, the injected chlorine gas reacting 100% with para-xylene, and transferring hydrochloric acid gas, a by-product of the reaction, to an incinerator 600 through a first transfer pipe 110, and recovering hydrochloric acid; S3) When the reaction of chlorine gas in the first reactor 100 decreases to 100% or less and unreacted chlorine gas is generated, shutting off the first discharge transfer pipe 110; S4) after blocking the first discharge transfer pipe 110, transferring the unreacted chlorine gas and residual hydrochloric acid gas in the first reactor 100 to the second reactor 200 through the first cross transfer pipe 120, and reacting first in the second reactor 200 to produce hexachloroparaxylene simultaneously in the first reactor 100 and the second reactor 200; S5) transferring the hydrochloric acid gas generated as a by-product in the second reactor 200 to the incinerator 600 through the second discharge transfer pipe 210 at the top of the second reactor 200; S6) When the reaction in the first reactor 100 is completed, the first cross transfer pipe 120 is shut off and the chlorine gas introduced into the first reactor 100 is redirected to the second reactor 200; S7) discharging the product hexachloroparaxylene into the first reactor 100 and introducing new paraxylene; S8) When the chlorine gas reaction in the second reactor 200 decreases to 100% or less and unreacted chlorine gas is generated, the second discharge transfer pipe 210 is shut off, and the unreacted chlorine gas and residual hydrochloric acid in the second reactor 200 are introduced into the first reactor 100 through the second cross transfer pipe 220, and the reaction to produce hexachloroparaxylene is carried out simultaneously in the second reactor 200 and the first reactor 100; S9) After the reaction in the second reactor 200 is completed, the chlorine gas introduced into the second reactor 200 is introduced into the first reactor 100 for reaction, and the first discharge transfer pipe 110 is opened to transfer the by-product hydrochloric acid to the incinerator 600, and the hydrochloric acid is recovered; S10) discharging hexachloroparaxylene into the second reactor 200 and introducing new paraxylene; The method may include a step of continuously producing hexachloroparaxylene by repeating steps S2 to S10.

[0058] In the hexachloroparaxylene production step, chlorine gas and paraxylene are photoreacted to produce hexachloroparaxylene, where the chlorine gas is decomposed into chlorine radicals, which are then substituted with hydrogen atoms in the methyl groups of paraxylene to produce hexachloroparaxylene, with hydrochloric acid being discharged as a by-product.

[0059] According to the method for producing hexachloroparaxylene, chlorine gas can be completely consumed in the reaction, and thus chlorine gas, which is fatal to humans or the environment, can be prevented from being released to the outside.

[0060] In particular, the mixed gas of chlorine gas and hydrochloric acid gas introduced into the reactor through the cross-transfer pipe has a higher probability of side reactions occurring than single chlorine gas under high light intensity, which can lead to a problem of reduced reactivity.

[0061] Therefore, in the present invention, by irradiating the reaction system with a light intensity of less than 2,000 Lux, the reactivity can be reduced, and the side reactions can be reduced, thereby enabling hexachloroparaxylene to be obtained in high yield.

[0062] In addition, the viscosity of the hexachloroparaxylene produced by the reaction increases as the content of the hexachloroparaxylene increases. Therefore, if the temperature is increased to reduce the viscosity, the solubility of chlorine gas in the liquid paraxylene decreases, resulting in a decrease in the reaction rate.

[0063] Therefore, the present invention solves the above problem by controlling the reaction temperature in a plurality of temperature ranges depending on the hexachloroparaxylene conversion rate.

[0064] Specifically, in the present invention, the reaction is carried out while increasing the temperature from a low temperature to a high temperature in at least a 3-step section, a 4-step section, a 5-step section, a 6-step section, a 7-step section, an 8-step section, a 9-step section, or a 10-step or more section. This allows the viscosity to be maintained at a constant level while controlling the solubility of chlorine gas, resulting in a high reaction rate and maximum participation of chlorine in the reaction without leakage to the outside, thereby achieving a high yield of 95% or more.

[0065] In one embodiment of the present invention, the reaction is started by increasing the reaction temperature from 13°C to 20°C for 4 hours, and then the reaction proceeds as follows: 47°C to 60°C for 4 hours, 63°C to 67°C for 4 hours, 67°C to 83°C for 14 hours, 87°C to 99°C for 2 hours, and 106°C to 113°C for 2 hours. The reaction is completed by converting the product to 95% or more, preferably 98% or more, without leaking chlorine gas.

[0066] Furthermore, by controlling the reactor temperature within the above temperature range under the above photoreaction conditions, there is an advantage that the reactivity can be maintained at a high level even when a mixed gas of chlorine and hydrochloric acid is used.

[0067] Hexachloroparaxylene produced according to one embodiment of the present invention can be reacted with terephthalic acid to produce terephthaloyl chloride.

[0068] Specifically, the step of producing terephthaloyl chloride includes a step of producing hexachloroparaxylene from paraxylene, a step of purifying the produced hexachloroparaxylene, a step of reacting the purified paraxylene with terephthalic acid in the presence of an acid catalyst to produce terephthaloyl chloride, and a step of purifying the produced terephthaloyl chloride.

[0069] First, the purification step of the hexachloroparaxylene may include a recrystallization method, a rectification method, a distillation method, etc., and the distillation method may include a vacuum distillation method or a molecular distillation method, etc.

[0070] In the purification step, distillation can be carried out using a distillation column, and the distillation column is not limited to any particular type as long as it is a device generally used to distill compounds.

[0071] The distillation column can purify hexachloroxylene under distillation conditions of a bottom temperature of 100 to 300°C, a top temperature of 100 to 250°C, and a pressure of 1 to 20 torr, but is not limited thereto.

[0072] The catalyst used in the step of producing terephthaloyl chloride by reacting the purified hexachloroxylene with terephthalic acid in the presence of an acid catalyst may be an acid catalyst.

[0073] The acid catalyst may be a Lewis acid catalyst, and the Lewis acid catalyst may include any one or more selected from aluminum trichloride, zinc chloride, and ferric trichloride, but is not limited thereto as long as it is a catalyst typically used in the synthesis.

[0074] In the synthesis of terephthaloyl chloride, 30 to 300 parts by weight, preferably 40 to 200 parts by weight, and more preferably 45 to 130 parts by weight of terephthalic acid can be added to 100 parts by weight of the hexachloroparaxylene, but the amount is not limited thereto.

[0075] Furthermore, the acid catalyst may be contained in an amount of 0.001 to 10 parts by weight, preferably 0.003 to 1 part by weight, and more preferably 0.005 to 0.01 part by weight relative to 100 parts by weight of hexachloroparaxylene, but is not limited thereto.

[0076] According to one embodiment of the present invention, the prepared terephthaloyl chloride may further include a purification step. The purification step of the terephthaloyl chloride may include a recrystallization method, a rectification method, a distillation method, etc., and the distillation method may include a vacuum distillation method or a molecular distillation method, etc.

[0077] In the purification step of the terephthaloyl chloride, the distillation method may be performed using a distillation column, and the distillation column may be any device generally used for distilling compounds, but is not limited thereto.

[0078] The distillation column can purify terephthaloyl chloride at a controlled distillation temperature of 75 to 250° C. and a pressure of 1 torr to 20 torr, but is not limited thereto.

[0079] The present invention will be described in more detail below with reference to examples and comparative examples, but the following examples and comparative examples are merely illustrative examples for explaining the present invention in more detail, and the present invention is not limited by the following examples and comparative examples.

[0080] [Example 1] 1) Hexachloro-p-xylene manufacturing steps 100 parts by weight of para-xylene was introduced into the first reactor 100 and the second reactor 200 from the para-xylene supply unit 300, and then nitrogen was injected into the first reactor 100 from the nitrogen gas supply unit 500 to remove air therein. Then, chlorine gas was injected into the first reactor 100 from the chlorine gas supply unit 400, and a photoreaction was carried out to produce hexachloroparaxylene.

[0081] The chlorine gas was injected at a rate of 30 parts by weight per hour relative to 100 parts by weight of the paraxylene.

[0082] In the photoreaction, as the reaction proceeded in the first reactor 100, intermediate products were produced according to the conversion rates shown in Table 1 below, and the melting point of the intermediate product mixture increased due to the production of the intermediate products, so the reaction was carried out under multi-stage temperature-raising conditions at temperatures and times shown in Table 2. During the reaction, stirring was carried out at 300 rpm, and the photoreaction was carried out at a rate of 15 cm per 1 kg of raw material. 2 A large area was irradiated with 1,000 lux of ultraviolet light.

[0083] In addition, the external chlorine gas introduced into the first reactor participated in the reaction quantitatively and was consumed in the early stage of the reaction, and the by-product hydrochloric acid at this point was discharged to the incinerator 600 via the first discharge transfer pipe 110. When the yield of hexachloroparaxylene reached 0.1%, unreacted chlorine gas began to be discharged to the outside, so the unreacted chlorine gas was circulated to the second reactor, and the chlorination reaction was initiated in the second reactor under the same conditions as in the first reactor.

[0084] The reaction was carried out in the first reactor under the conditions shown in Tables 1 and 2. After 32 hours, the reaction was terminated, and the chlorine gas inlet pipe of the first reactor was connected to the chlorine gas inlet pipe of the second reactor, and chlorine gas was introduced into the second reactor. The reaction was carried out under the conditions shown in Tables 3 and 4 for the conversion rate, reaction temperature, and reaction time of the second reactor.

[0085] When unreacted chlorine gas was generated in the second reactor at a hexaparaxylene yield of 0.1%, the chlorine gas was transferred to the first reactor, and the chlorination reaction was initiated in the first reactor.

[0086] [Table 1]

[0087] [Table 2]

[0088] 2) Hexachloroparaxylene purification step Hexachloroparaxylene produced in first reactor 100 and second reactor 200 was transferred to the bottom of a first distillation column. To purify the hexachloroparaxylene, the first distillation column was operated at a total pressure of 5 torr, a bottom temperature of 160°C, a top temperature of 150°C, and an agitation speed of 300 rpm. After separating the highly purified hexachloroparaxylene from the hexachloroparaxylene residue, the purified hexachloroparaxylene was transferred to a first storage tank and stored.

[0089] 3) Reaction step of terephthaloyl chloride In the hexachloroparaxylene purification step, the high-purity hexachloroparaxylene stored in the first storage tank was transferred to a third reactor, and terephthalic acid and iron chloride (FeCl3) catalyst were added to the third reactor and reacted for 5 hours to produce terephthaloyl chloride.

[0090] The reaction was carried out by mixing 100 parts by weight of high-purity hexachloro-p-xylene with 100 parts by weight of terephthalic acid and 0.005 parts by weight of FeCl3, and the reaction conditions were a temperature of 120°C and atmospheric pressure.

[0091] 4) Purification step of terephthaloyl chloride The terephthaloyl chloride produced in step 3) of reacting terephthaloyl chloride was transferred to a second distillation column for primary purification. The purification conditions in the second distillation column were a total pressure of 5 torr, a bottom temperature of 160°C, a top temperature of 130°C, and a stirring speed of 300 rpm. The purified terephthaloyl chloride with high purity was transferred to a second storage tank and stored.

[0092] As described above, the present invention has been described using specific and limited examples and drawings, but these are provided to facilitate a more general understanding of the present invention, and the present invention is not limited to the above examples. Various modifications and variations can be made from such descriptions by those having ordinary knowledge in the field to which the present invention pertains.

[0093] Therefore, the concept of the present invention should not be limited to the above-described embodiments, and it can be said that not only the scope of the claims described below, but also all modifications that are equivalent to or equivalent to the scope of the claims fall within the scope of the concept of the present invention. [Explanation of symbols]

[0094] 100 First reactor 110 1st discharge transfer pipe 120 First cross transfer pipe 200 Second reactor 210 2nd discharge transfer pipe 220 Second cross transfer pipe 300 Paraxylene supply section 400 Chlorine gas supply unit 500 Inert gas supply unit 600 Incinerator 700 Hydrochloric acid manufacturing facility

Claims

1. A method for producing hexachloroparaxylene by photoreacting paraxylene with chlorine gas, wherein the amount of light input to the photoreaction is less than 2,000 lux.

2. 2. The method for producing hexachloroparaxylene according to claim 1, wherein a plurality of reactors are connected in parallel in the production of hexachloroparaxylene.

3. The plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and chlorine gas is continuously introduced into the first reactor filled with paraxylene to cause a reaction, and the reaction is initiated while discharging hydrochloric acid gas, which is a by-product of the conversion of hexachloroparaxylene, to the outside of the plurality of reactors. At a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor where the reaction has started, begins to be discharged as an unreacted product, the unreacted chlorine gas continuously introduced into the first reactor and not participating in the reaction is transferred to the second reactor without being discharged to the outside, and an initial reaction is initiated with the paraxylene filled in the second reactor.

3. The method for producing hexachloroparaxylene according to claim 2, wherein the process of: completing the reaction in the first reactor; connecting the chlorine gas continuously introduced into the first reactor to the second reactor and starting continuous introduction into the second reactor; and, in a state where the first reactor from which the product has been discharged is filled with paraxylene, transferring the unreacted chlorine gas to the first reactor at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor begins to be discharged as an unreacted product, and starting the initial reaction with the paraxylene in the first reactor is repeated, thereby producing hexachloroparaxylene without discharging unreacted chlorine gas to the outside.

4. A method for producing terephthaloyl chloride by reacting hexachloroparaxylene with terephthalic acid, comprising: injecting chlorine gas into paraxylene to produce hexachloroparaxylene; and reacting the hexachloroparaxylene with terephthalic acid in the presence of a Lewis acid catalyst to produce terephthaloyl chloride, The method for producing terephthaloyl chloride, wherein the amount of light input in the step of producing hexachloroparaxylene is less than 2,000 lux.

5. 5. The method for producing terephthaloyl chloride according to claim 4, wherein a plurality of reactors are connected in parallel in the production of hexachloroparaxylene.

6. The plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and chlorine gas is continuously introduced into the first reactor filled with paraxylene to cause a reaction, and the reaction is initiated while discharging hydrochloric acid gas, which is a by-product of the conversion of hexachloroparaxylene, to the outside of the plurality of reactors. At a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor where the reaction has started, begins to be discharged as an unreacted product, the unreacted chlorine gas continuously introduced into the first reactor and not participating in the reaction is transferred to the second reactor without being discharged to the outside, and an initial reaction is initiated with the paraxylene filled in the second reactor.

6. The method for producing terephthaloyl chloride according to claim 5, wherein the reaction in the first reactor is terminated, the chlorine gas continuously introduced into the first reactor is connected to the second reactor and continuous introduction into the second reactor is initiated, and in a state where the first reactor from which the product has been discharged is filled with paraxylene, the unreacted chlorine gas is transferred to the first reactor at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor begins to be discharged as an unreacted product, and the unreacted chlorine gas is transferred to the first reactor to initiate the initial reaction with the paraxylene in the first reactor, thereby producing hexachloroparaxylene without discharging unreacted chlorine gas to the outside.

7. 5. The method for producing terephthaloyl chloride according to claim 4, further comprising a step of purifying hexachloroparaxylene.

8. The method for producing terephthaloyl chloride according to claim 7, wherein the purification step is carried out in a distillation column.

9. 9. The method for producing terephthaloyl chloride according to claim 8, wherein the distillation column purifies hexachloroparaxylene at a bottom distillation temperature of 100 to 300°C, a top temperature of 100 to 250°C, and a pressure of 1 to 20 torr.

10. 5. The method for producing terephthaloyl chloride according to claim 4, wherein the Lewis acid catalyst is any one or more selected from aluminum trichloride, zinc chloride, and ferric trichloride.

11. 5. The method for producing terephthaloyl chloride according to claim 4, further comprising a step of purifying terephthaloyl chloride.

12. The method for producing terephthaloyl chloride according to claim 11, wherein the purification step is carried out using a distillation column.

13. 13. The method for producing terephthaloyl chloride according to claim 12, wherein the distillation column purifies hexachloroparaxylene at a controlled distillation temperature of 75 to 250°C and a pressure of 1 torr to 20 torr.

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