Method for preparing paraphthaloyl chloride through light quantity control

Abstract

The present invention relates to a method for preparing paraphthaloyl chloride, which can improve the purity of hexachloroparaxylene, which is an intermediate raw material, by introducing a photochlorination method instead of a radical initiator, and has the advantage of high yield by controlling the light amount of illumination to less than 2000 lux, thereby reducing the occurrence of side reactions of hexachloroparaxylene. Also provided is a method for producing paraphthaloyl chloride in which the chlorine gas is not discharged to the outside by being introduced into a circulation system.

Description

Technical Field

[0001] The present invention relates to a method for preparing terephthaloyl chloride by light quantity control. Background Art

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

[0003] In addition, the terephthaloyl chloride, as a compounding agent for high molecular weight polymers, has broad development and application prospects, such as application in pesticides, intermediates in the pharmaceutical industry, etc.

[0004] As the monomer used in preparing the terephthaloyl chloride, terephthalic acid (TPA) or p-xylene is mainly used.

[0005] However, in the case of preparing terephthaloyl chloride using terephthalic acid as a raw material, toxic solvents such as highly toxic phosgene and dichloromethane are used, and there are problems in that the treatment and purification process of by-products generated during the reaction are difficult.

[0006] Furthermore, when paraxylene is used as a raw material to produce terephthaloyl chloride, an intermediate step of producing hexachloroparaxylene from paraxylene is included, and when chlorine gas used in the intermediate step does not react and is discharged to the outside, it may have an impact on the human body or the environment.

[0007] Furthermore, the intermediate step is performed by a radical reaction, and a radical initiator used in the radical reaction may contain impurities, which may cause problems in preparing high-purity terephthaloyl chloride. Summary of the invention

[0008] Technical issues

[0009] The present invention aims to provide hexachloroparaxylene with very low impurity content by introducing a light irradiation reaction to replace a free radical initiator when preparing hexachloroparaxylene from paraxylene.

[0010] Furthermore, the present invention aims to provide high-purity hexachloroparaxylene with less side reactions and high yield by controlling the amount of light used in the photo-irradiation reaction.

[0011] Furthermore, the present invention aims to provide a method for synthesizing hexachloroparaxylene in which unreacted chlorine gas is not discharged but circulated in different reactors to be consumed, thereby preventing chlorine gas from being discharged to the outside.

[0012] Furthermore, the present invention aims to provide a method for producing hexachloroparaxylene capable of maintaining a relatively high chlorine solubility within an appropriate viscosity by controlling the photoreaction temperature inside a reactor when producing hexachloroparaxylene.

[0013] Furthermore, it is intended to react the produced hexachloroparaxylene with terephthalic acid to provide terephthaloyl chloride.

[0014] Technical Solutions

[0015] The invention relates to a method for preparing hexachloroparaxylene. The method for preparing hexachloroparaxylene comprises the following steps: allowing paraxylene to react with chlorine gas to produce hexachloroparaxylene. The amount of light input into the photoreaction is less than 2000 lux.

[0016] According to an aspect of the present invention, a plurality of reactors may be connected in parallel in the method for preparing hexachloroparaxylene.

[0017] According to one aspect of the present invention, the plurality of reactors may be reactors in which a first reactor and a second reactor are connected in parallel, chlorine gas may be continuously fed into the first reactor filled with para-xylene to carry out a reaction, and the reaction may be started while the hydrochloric acid gas as a side reaction product according to the conversion of hexachloropara-xylene is discharged to the outside, and at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the first reactor at the start of the reaction begins to be discharged as an unreacted product, the unreacted chlorine gas continuously fed into the first reactor and not participating in the reaction is not discharged to the outside, but is transported to the second reactor so that it begins to react with the hydrochloric acid gas filled in the second reactor. The p-xylene in the reactor undergoes a first reaction, the reaction of the first reactor is terminated, and the chlorine gas continuously fed into the first reactor is connected to the second reactor to start being continuously fed into the second reactor. In a state where the first reactor from which the product is discharged is filled with p-xylene, 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, the unreacted chlorine gas is transported to the first reactor to start a first reaction with the p-xylene in the first reactor, and the above process can be repeated to generate hexachloroparaxylene without discharging the unreacted chlorine gas to the outside.

[0018] According to one aspect of the present invention, in a method for preparing terephthaloyl chloride by reacting hexachloroparaxylene with terephthalic acid, the method may include: a step of injecting chlorine gas into paraxylene to prepare hexachloroparaxylene; and a step of reacting the hexachloroparaxylene with terephthalic acid in the presence of a Lewis acid catalyst to prepare terephthaloyl chloride, and the amount of light input in the step of preparing the hexachloroparaxylene may be less than 2000 lux.

[0019] According to an aspect of the present invention, a plurality of reactors may be connected in parallel in the method for preparing hexachloroparaxylene.

[0020] According to one aspect of the present invention, the plurality of reactors may be reactors in which a first reactor and a second reactor are connected in parallel, chlorine gas may be continuously fed into the first reactor filled with para-xylene to carry out a reaction, and the reaction may be started while the hydrochloric acid gas as a side reaction product according to the conversion of hexachloropara-xylene is discharged to the outside, and at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the first reactor at the start of the reaction begins to be discharged as an unreacted product, the unreacted chlorine gas continuously fed into the first reactor and not participating in the reaction is not discharged to the outside, but is transported to the second reactor so that it begins to react with the hydrochloric acid gas filled in the second reactor. The p-xylene in the reactor undergoes a first reaction, the reaction of the first reactor is terminated, and the chlorine gas continuously fed into the first reactor is connected to the second reactor to start being continuously fed into the second reactor. In a state where the first reactor from which the product is discharged is filled with p-xylene, 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, the unreacted chlorine gas is transported to the first reactor to start a first reaction with the p-xylene in the first reactor, and the above process can be repeated to generate hexachloroparaxylene without discharging the unreacted chlorine gas to the outside.

[0021] According to one aspect of the present invention, the preparation of the hexachloroparaxylene may further include a purification step.

[0022] According to one aspect of the present invention, the purification step may be performed by a distillation column.

[0023] According to an aspect of the present invention, the distillation column may purify hexachloroparaxylene at a distillation temperature of 100 to 300° C. at the bottom, 100 to 250° C. at the top, and 1 to 20 Torr at the pressure.

[0024] According to one aspect of the present invention, the Lewis acid catalyst may be one or more selected from aluminum chloride, zinc chloride and ferric chloride.

[0025] According to one aspect of the present invention, the preparation of the terephthaloyl chloride may further include a purification step.

[0026] According to one aspect of the present invention, the purification step may be performed by a distillation column.

[0027] According to an aspect of the present invention, the distillation column may purify hexachloroparaxylene at a controlled distillation temperature of 75 to 250° C. and a pressure of 1 to 20 torr.

[0028] Effects of the Invention

[0029] The present invention provides hexachloroparaxylene by replacing a free radical initiator with light, thereby providing hexachloroparaxylene with a low impurity content.

[0030] Furthermore, the present invention has the advantage that the side reaction of hexachloroparaxylene is less and the yield thereof is higher by controlling the light intensity of the light irradiation to less than 2000 lux.

[0031] In addition, the present invention controls the reaction temperature by dividing the photoreaction into a plurality of intervals and gradually raising the reaction temperature in each interval, thereby maintaining a relatively high chlorine solubility within an appropriate viscosity, thereby providing a high yield of hexachloroparaxylene.

[0032] The present invention introduces a chlorine circulation system for circulating unreacted chlorine through the first reactor and the second reactor when preparing hexachloroparaxylene as an intermediate raw material, thereby preparing hexachloroparaxylene without discharging toxic chlorine to the outside. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram showing the preparation steps for preparing terephthaloyl chloride is shown.

[0034] Figure 2 A schematic diagram showing the preparation steps for hexachloroparaxylene is shown.

[0035] Description of Reference Numerals

[0036] 100: first reactor 110: first discharge pipe

[0037] 120: first cross-transfer pipe 200: second reactor

[0038] 210: Second discharge conveying pipe 220: Second cross conveying pipe

[0039] 300: Paraxylene supply unit 400: Chlorine gas supply unit

[0040] 500: Inert gas supply unit 600: Incinerator

[0041] 700: Hydrochloric acid preparation facilities DETAILED DESCRIPTION

[0042] Hereinafter, the present invention will be described in more detail by specific examples or embodiments with reference to the accompanying drawings. However, the following specific examples or embodiments are only a reference for describing the present invention in detail, and the present invention is not limited thereto and can be implemented in various forms.

[0043] In addition, unless otherwise defined, all technical terms and scientific terms have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used for explanation in the present invention are only used to effectively record specific examples and are not intended to limit the present invention.

[0044] Furthermore, unless the context specifically indicates otherwise, singular expressions used in the specification and the appended claims may be intended to include the plural forms as well.

[0045] Furthermore, when a specific portion is referred to as “comprising” a specific constituent element, it does not mean that other constituent elements are excluded, but other constituent elements may also be included unless otherwise specifically described to the contrary.

[0046] Furthermore, in the present invention, the chlorinated intermediate product described later may be monochloroparaxylene, dichloroparaxylene, trichloroparaxylene, tetrachloroparaxylene or pentachloroparaxylene.

[0047] Although hexachloroparaxylene has been provided by adding a radical initiator in the past, there is a disadvantage that it is difficult to provide high-purity hexachloroparaxylene due to impurities caused by the addition.

[0048] To solve this problem, hexachloroparaxylene has been prepared by irradiating a mixture of paraxylene and chlorine gas with light. However, there are disadvantages in that side reactions frequently occur and the yield of hexachloroparaxylene is low.

[0049] In this regard, the present invention provides a method for preparing hexachloroparaxylene, and the method for preparing hexachloroparaxylene prepares hexachloroparaxylene by reacting paraxylene with chlorine, and the amount of light input in the reaction is less than 2000 lux, thereby solving the problem.

[0050] The hexachloroparaxylene is prepared by mixing paraxylene with chlorine and irradiating it with UV light. Although the light intensity input in the irradiation is 2000 lux or more to carry out the reaction, side reactions may occur within the light intensity range, and there is a disadvantage of low yield of hexachloroparaxylene.

[0051] Chlorine radicals are generated by irradiating the chlorine gas with UV, and the generated chlorine radicals undergo a substitution reaction with hydrogen of p-xylene methyl groups to prepare hexachlorop-xylene.

[0052] Conventionally, the reaction is carried out by irradiating the above-mentioned UV light amount of 2000 lux or more and 30000 lux or more. However, there are disadvantages in that side reactions occur and the yield of hexachloroparaxylene is low within the above-mentioned light amount range.

[0053] In this regard, the present inventors have found that hexachloroparaxylene can be produced even if the light intensity range of the irradiation is controlled to be less than 2000 lux, less than 1900 lux, less than 1800 lux, less than 1700 lux, less than 1500 lux, more than 100 lux, more than 200 lux, more than 300 lux, more than 400 lux, or more than 500 lux, preferably controlled to 100 to 1900 lux, and preferably controlled to 100 to 1800 lux. Moreover, it has been found that when the production is carried out within the light intensity range, there are fewer side reactions and a higher yield.

[0054] Furthermore, when the reaction is carried out within the above light intensity range, since the reaction heat generated by the reaction is low, there is an advantage that the reaction rate can be controlled while being very suitable for temperature control.

[0055] Furthermore, the illumination area is not limited as long as it allows the reaction to proceed smoothly, but specifically, the illumination area is 30 cm 2 Below, preferably 20cm 2 Below, more preferably 10cm 2 When the reaction temperature is less than 0.1%, the reaction can proceed more smoothly.

[0056] Furthermore, as a light source used in the photoirradiation reaction used in the present invention, an LED lamp is used.

[0057] Although mercury lamps have been used in the past, the short-wavelength light of the low-pressure mercury lamp may induce other photochemical side reactions and reduce the purity of the product, and the long-wavelength light of the high-pressure mercury lamp may not be sufficient to induce the chlorine free radical reaction and consume more energy. In addition, when the mercury lamp is used, more heat is generated, so there may be a problem that a cooling device needs to be additionally introduced to reduce the heat.

[0058] In this regard, the present invention overcomes the disadvantages of the mercury lamp by using an LED lamp. By using the LED lamp, the wavelength band suitable for the reaction can be controlled, thereby reducing the photochemical side reaction, and even if used for a long time, no heat is generated compared to the mercury lamp, so there is an advantage that no additional cooling device is required. In addition, the LED lamp has a low power consumption and thus has the advantage of high energy efficiency.

[0059] Through the photoreaction, hydrochloric acid gas (HCl) is discharged as a by-product.

[0060] However, there is a problem that part of the unreacted chlorine gas is also mixed with the hydrochloric acid gas and discharged through the photoreaction. In particular, as the photoreaction proceeds, the reaction rate of the generated chlorine gas is reduced due to steric hindrance and the content of the unreacted chlorine gas discharged to the outside increases.

[0061] In view of this, the present invention proposes a novel method for producing hexachloroparaxylene, which can consume all the unreacted chlorine gas without being discharged to the outside.

[0062] The novel method for preparing hexachloroparaxylene is a method in which a plurality of reactors are connected in parallel and unreacted chlorine gas sequentially discharged from the plurality of reactors is transported to other reactors for circulation.

[0063] In addition, the plurality of reactors may be 2 or 3 or more, but is not limited thereto.

[0064] Hereinafter, a more specific description will be given using a reactor in which two reactors are connected in parallel.

[0065] The present invention first continuously feeds chlorine into a first reactor filled with p-xylene to react, and starts the reaction while discharging hydrochloric acid gas as a side reaction product according to the conversion of hexachloro-p-xylene to the outside. At this time, the chlorine fed in quantitatively reacts with the p-xylene and is consumed. Then, at the conversion rate of hexachloro-p-xylene that the chlorine fed in continuously in the first reactor begins to be discharged as an unreacted substance, at the time point when the unreacted chlorine fed in continuously in the first reactor and not participating in the reaction is discharged from the first reactor, the discharged unreacted chlorine is not discharged to the outside, but is transported to the second reactor to start the first reaction with the p-xylene filled in the second reactor. The circulating chlorine stops the feeding of chlorine into the first reactor at the moment when the reaction of the first reactor ends, and the chlorine fed in the first reactor is connected to the second reactor to be continuously fed into the second reactor, so that it participates in the reaction.

[0066] Next, in a state where the first reactor from which the product has been discharged is again filled with paraxylene as a starting material, 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, the unreacted chlorine gas is circulated to the first reactor to start a first reaction with the paraxylene in the first reactor, and the above process is repeated to generate hexachloroparaxylene without discharging the unreacted chlorine gas to the outside.

[0067] Below, refer to Figure 2 , the preparation method of hexachloroparaxylene is divided into various steps for more detailed description.

[0068] According to one aspect of the present invention, the preparation step of hexachloroparaxylene may include:

[0069] S1) a step of introducing and filling paraxylene into the first reactor 100 and the second reactor 200;

[0070] S2) continuously feeding chlorine gas into the first reactor 100, so that the chlorine gas fed reacts with 100% of para-xylene, and as a step of transporting the hydrochloric acid gas as a by-product removed by the reaction to an incinerator 600 through a first transport pipe 110 to recover the hydrochloric acid;

[0071] S3) when the reaction rate of chlorine in the first reactor 100 is reduced to below 100% and unreacted chlorine is generated, blocking the first discharge delivery pipe 110;

[0072] S4) after blocking the first discharge delivery pipe 110, transporting the unreacted chlorine gas and the residual hydrochloric acid gas in the first reactor 100 to the second reactor 200 through the first cross delivery pipe 120 to perform a first reaction in the second reactor 200, thereby simultaneously producing hexachloroparaxylene in the first reactor 100 and the second reactor 200;

[0073] S5) a step of transporting the hydrochloric acid gas produced as a by-product in the second reactor 200 to the incinerator 600 through the second discharge transport pipe 210 above the second reactor 200;

[0074] S6) when the reaction of the first reactor 100 is finished, the first cross-transfer pipe 120 is blocked, and the chlorine gas previously fed into the first reactor 100 is changed to be fed into the second reactor 200;

[0075] S7) discharging hexachloroparaxylene as a product in the first reactor 100 and adding new paraxylene;

[0076] S8) when the chlorine reaction in the second reactor 200 is reduced to below 100% and unreacted chlorine is generated, the second discharge delivery pipe 210 is blocked, and the unreacted chlorine and residual hydrochloric acid in the second reactor 200 are fed into the first reactor 100 through the second cross delivery pipe 220, so that the step of reacting to produce hexachloroparaxylene is simultaneously performed in the second reactor 200 and the first reactor 100;

[0077] S9) after the reaction in the second reactor 200 is finished, the chlorine gas introduced into the second reactor 200 is introduced into the first reactor 100 for reaction, and the first exhaust delivery pipe 110 is opened to deliver the hydrochloric acid as a by-product to the incinerator 600 to recover the hydrochloric acid; and

[0078] S10) discharging the hexachloroparaxylene in the second reactor 200 and adding new paraxylene; and repeating the steps S2 to S10 to continuously prepare hexachloroparaxylene.

[0079] In the step of preparing hexachloroparaxylene, chlorine gas and paraxylene are photo-reacted to prepare hexachloroparaxylene. The chlorine gas is decomposed into chlorine radicals by the photoreaction, and the chlorine radicals replace the hydrogen of the methyl group of paraxylene to prepare hexachloroparaxylene, and hydrochloric acid is discharged as a by-product.

[0080] Through the method for preparing hexachloroparaxylene, chlorine gas can be completely consumed in the reaction, thereby preventing chlorine gas that is fatal to human body or environment from being released to the outside.

[0081] In particular, the mixed gas of chlorine gas and hydrochloric acid gas introduced into the reactor through the cross-conveying pipe is more likely to undergo side reactions under high light intensity than single chlorine gas, and thus the problem of reduced reactivity may occur.

[0082] In contrast, the present invention irradiates the light at an amount less than 2000 lux, which can reduce the reactivity of the side reaction and thereby obtain a high yield of hexachloroparaxylene.

[0083] In addition, the viscosity may increase as the content of hexachloroparaxylene produced by the reaction increases. Therefore, when the temperature is increased to reduce the viscosity, the solubility of chlorine gas in liquid paraxylene may decrease, resulting in a problem of a decrease in reaction rate.

[0084] In view of this, the present invention improves the above-mentioned problem by performing the reaction at a plurality of temperature ranges according to the conversion rate of hexachloroparaxylene.

[0085] Specifically, the present invention divides the temperature interval from low temperature to high temperature into at least 3 step intervals, 4 step intervals, 5 step intervals, 6 step intervals, 7 step intervals, 8 step intervals, 9 step intervals or intervals of more than 10 steps to carry out the reaction while the temperature is increased, thereby controlling the solubility of chlorine gas while maintaining the viscosity at a certain level, so that the reaction speed is fast, and chlorine can be allowed to participate in the reaction to the maximum extent without leaking to the outside, thereby achieving a high yield of more than 95%.

[0086] Looking at a specific example according to the present invention, the reaction starts with reacting for 4 hours under the condition of raising the reaction temperature from 13°C to 20°C, and as the conversion rate progresses, reacting at 47°C to 60°C for 4 hours, at 63°C to 67°C for 4 hours, at 67°C to 83°C for 14 hours, at 87°C to 99°C for 2 hours, and at 106°C to 113°C for 2 hours, thereby converting to more than 95% of the product, preferably converting to more than 98% of the product, and the reaction can also be carried out without chlorine gas leaking to the outside.

[0087] Furthermore, since the reactor temperature is controlled to be within the temperature range under the photoreaction conditions, there is an advantage that the reactivity can be maintained at a high level even when the mixed gas of chlorine and hydrochloric acid is used.

[0088] According to an aspect of the present invention, terephthaloyl chloride may be prepared by reacting the prepared hexachloroparaxylene with terephthalic acid.

[0089] Specifically, the preparation steps of terephthaloyl chloride include: a step of preparing hexachloroparaxylene from paraxylene; a step of purifying the prepared hexachloroparaxylene; a step of reacting the purified paraxylene with terephthalic acid under an acid catalyst to prepare terephthaloyl chloride; and a step of purifying the prepared terephthaloyl chloride.

[0090] First, the purification step of the hexachloroparaxylene may include recrystallization, rectification, distillation, etc., and the distillation method may include vacuum distillation or molecular distillation, etc.

[0091] The distillation method in the purification step may be performed using a distillation column, and the distillation column is not limited as long as it is a device that generally distills compounds.

[0092] The distillation column may purify hexachloroxylene under the conditions of a distillation temperature of 100 to 300° C. at the bottom, 100 to 250° C. at the top, and 1 to 20 Torr at the pressure, but is not limited thereto.

[0093] Furthermore, the catalyst used in the step of reacting the purified hexachloroxylene with terephthalic acid in the presence of an acid catalyst to prepare terephthaloyl chloride may be an acid catalyst.

[0094] The acid catalyst may be a Lewis acid catalyst, and the Lewis acid catalyst may include one or more selected from aluminum chloride, zinc chloride, and ferric chloride, but is not limited as long as it is a catalyst generally used in the synthesis.

[0095] In the synthesis of the terephthaloyl chloride, 30 to 300 parts by weight of terephthalic acid may be input relative to 100 parts by weight of the hexachloroparaxylene, preferably 40 to 200 parts by weight of terephthalic acid may be input, and more preferably 45 to 130 parts by weight of terephthalic acid may be input, but is not limited thereto.

[0096] In addition, relative to 100 parts by weight of the hexachloroparaxylene, the acid catalyst may be included in an amount of 0.001 to 10 parts by weight, preferably 0.003 to 1 parts by weight, and more preferably 0.005 to 0.01 parts by weight, but is not limited thereto.

[0097] In addition, according to one aspect of the present invention, the prepared terephthaloyl chloride may further include a purification step, and the purification step of the terephthaloyl chloride may include recrystallization, rectification, distillation, etc., and the distillation method may include vacuum distillation or molecular distillation, etc.

[0098] The distillation method in the purification step of terephthaloyl chloride may be performed using a distillation column, and the distillation column is not limited as long as it is an apparatus that generally distills compounds.

[0099] The distillation column may purify terephthaloyl chloride at a controlled distillation temperature of 75 to 250° C. and a pressure of 1 to 20 torr, but is not limited thereto.

[0100] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are only examples for describing the present invention in more detail, and the present invention is not limited to the following Examples and Comparative Examples.

[0101] [Example 1]

[0102] 1) Preparation steps of hexachloro-p-xylene

[0103] After 100 parts by weight of para-xylene are respectively fed into the first reactor 100 and the second reactor 200 from the para-xylene supply unit 300, and after nitrogen is injected into the first reactor 100 from the nitrogen supply unit 500 to remove the air inside, chlorine is injected into the first reactor 100 from the chlorine supply unit 400 and a photoreaction is performed to prepare hexachloropara-xylene.

[0104] The chlorine gas is injected at a rate of 30 parts by weight per 100 parts by weight of the p-xylene per hour.

[0105] Regarding the reaction temperature in the photoreaction, as the reaction proceeds in the first reactor 100, an intermediate product is generated according to the conversion rate shown in Table 1 below, and while the melting point of the intermediate mixture rises due to the generation of the intermediate product, the reaction is performed under multi-stage temperature increase conditions according to the temperature and time shown in Table 2. During the reaction, stirring is performed at 300 rpm, and the photoreaction is performed at a rate of 15 cm / kg of raw material. 2 The light area is irradiated with 1000 lux of ultraviolet light.

[0106] In addition, the external chlorine gas introduced into the first reactor quantitatively participates in the reaction at the initial stage of the reaction and is consumed, and at this time, the hydrochloric acid as a by-product is discharged to the incinerator 600 through the first discharge delivery pipe 110. When the production of hexachloroparaxylene reaches 0.1%, the unreacted chlorine gas begins to be discharged to the outside, so at this time, the unreacted chlorine gas is circulated to the second reactor to start the chlorination reaction in the second reactor under the same conditions as the first reactor.

[0107] The reaction was performed in the first reactor under the conditions of Table 1 and Table 2 and the reaction was terminated after 32 hours, and the chlorine gas introduction pipe of the first reactor was connected to the chlorine gas introduction pipe of the second reactor to feed chlorine gas into the second reactor. The conversion rate, reaction temperature and time of the second reactor were reacted according to the conditions of Table 3 and Table 4.

[0108] At the point in time when the production amount of hexachloroparaxylene in the second reactor was 0.1% and unreacted chlorine gas was generated, chlorine gas was supplied to the first reactor to start a chlorination reaction in the first reactor.

[0109]

Table 1

[0110]

[0111]

Table 2

[0112]

[0113]

[0114] 2) Purification steps of hexachloroparaxylene

[0115] The hexachloroparaxylene prepared in the first reactor 100 and the second reactor 200 is transported to the bottom of the first distillation tower. In order to purify the hexachloroparaxylene, the first distillation tower performs purification at a total pressure of 5 Torr, a bottom temperature of 160° C., a top temperature of 150° C., and a stirring speed of 300 rpm. After the hexachloroparaxylene purified to high purity is separated from the hexachloroparaxylene residue, the purified hexachloroparaxylene is transported to the first storage tank for storage.

[0116] 3) Reaction steps of terephthaloyl chloride

[0117] In the hexachloroparaxylene purification step, high-purity hexachloroparaxylene stored in the first storage tank is transported to the third reactor, terephthalic acid and ferric chloride (FeCl3) catalyst are added to the third reactor, and reacted for 5 hours to prepare terephthaloyl chloride.

[0118] In the reaction, 100 parts by weight of terephthalic acid and 0.005 parts by weight of FeCl3 were mixed with 100 parts by weight of high-purity hexachloroparaxylene to carry out the reaction, and the reaction conditions were such that the pressure was maintained at normal pressure at a temperature of 120°C.

[0119] 4) Purification step of terephthaloyl chloride

[0120] The terephthaloyl chloride prepared in the step 3) of reacting terephthaloyl chloride is transferred to a second distillation column and subjected to a first purification. The purification conditions of the second distillation column are as follows: the total pressure of the distillation column is 5 Torr, the bottom temperature is 160° C., the top temperature is 130° C., and the stirring speed is 300 rpm. The terephthaloyl chloride purified to a high purity is transferred to a second storage tank and stored.

[0121] Although the present invention has been described above through specific matters and drawings of limited embodiments, this is only provided to help a more comprehensive understanding of the present invention. The present invention is not limited to the above-mentioned embodiments, and a person skilled in the art of the art to which the present invention belongs can make various modifications and variations from such description.

[0122] Therefore, the idea of ​​the present invention should not be limited to the illustrated embodiments, and the appended claims and all matters having equivalent or equivalent modifications to the claims should fall within the scope of the idea of ​​the present invention.

Claims

1. A method for preparing hexachloroparaxylene, wherein: The method for preparing hexachloroparaxylene comprises performing a photoreaction between paraxylene and chlorine gas to prepare hexachloroparaxylene, wherein the amount of light input into the photoreaction is less than 2000 lux.

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

3. The method for preparing hexachloroparaxylene according to claim 2, wherein: The plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, chlorine gas is continuously fed into the first reactor filled with para-xylene to react, and the reaction is started while hydrochloric acid gas, which is a side reaction product according to the conversion of hexachloropara-xylene, is discharged to the outside, at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the first reactor at the start of the reaction begins to be discharged as an unreacted product, the unreacted chlorine gas continuously fed into the first reactor and not participating in the reaction is not discharged to the outside, but is transported to the second reactor to start a first reaction with the para-xylene filled in the second reactor, the reaction in the first reactor is terminated, and the chlorine gas continuously fed into the first reactor is connected to the second reactor to start continuous feeding into the second reactor, in a state where para-xylene is filled into the first reactor from which the product is discharged, at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the second reactor begins to be discharged as an unreacted product, the unreacted chlorine gas is transported to the first reactor to start a first reaction with the para-xylene in the first reactor, and the above process is repeated, thereby generating hexachloropara-xylene without the unreacted chlorine gas being discharged to the outside.

4. A method for preparing terephthaloyl chloride, wherein: The preparation method of terephthaloyl chloride comprises reacting hexachloroparaxylene with terephthalic acid to prepare terephthaloyl chloride, and the preparation method of terephthaloyl chloride comprises: The step of injecting chlorine gas into p-xylene to prepare hexachlorop-xylene; and The step of preparing terephthaloyl chloride by reacting the hexachloroparaxylene with terephthalic acid in the presence of a Lewis acid catalyst, The amount of light input in the hexachloroparaxylene preparation step is less than 2000 lux.

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

6. The method for preparing terephthaloyl chloride according to claim 5, wherein The plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, chlorine gas is continuously fed into the first reactor filled with para-xylene to react, and the reaction is started while hydrochloric acid gas, which is a side reaction product according to the conversion of hexachloropara-xylene, is discharged to the outside, at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the first reactor at the start of the reaction begins to be discharged as an unreacted product, the unreacted chlorine gas continuously fed into the first reactor and not participating in the reaction is not discharged to the outside, but is transported to the second reactor to start a first reaction with the para-xylene filled in the second reactor, the reaction in the first reactor is terminated, and the chlorine gas continuously fed into the first reactor is connected to the second reactor to start continuous feeding into the second reactor, in a state where para-xylene is filled into the first reactor from which the product is discharged, at a conversion rate of hexachloropara-xylene at which the chlorine gas continuously fed into the second reactor begins to be discharged as an unreacted product, the unreacted chlorine gas is transported to the first reactor to start a first reaction with the para-xylene in the first reactor, and the above process is repeated, thereby generating hexachloropara-xylene without the unreacted chlorine gas being discharged to the outside.

7. The method for preparing terephthaloyl chloride according to claim 4, wherein The prepared hexachloroparaxylene also includes a purification step.

8. The method for preparing terephthaloyl chloride according to claim 7, wherein The purification step is performed by a distillation column.

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

10. The method for preparing terephthaloyl chloride according to claim 4, wherein: The Lewis acid catalyst is one or more selected from aluminum chloride, zinc chloride and ferric chloride.

11. The method for preparing terephthaloyl chloride according to claim 4, wherein: The prepared terephthaloyl chloride also includes a purification step.

12. The method for preparing terephthaloyl chloride according to claim 11, wherein The purification step is performed by a distillation column.

13. The method for preparing 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 to 20 torr.

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