Method for preparing terephthaloyl chloride through temperature control

Abstract

The present invention relates to a method for preparing terephthaloyl chloride and, specifically, to a method for preparing terephthaloyl chloride, the method comprising: preparing hexachloro-p-xylene by performing a reaction in a plurality of temperature sections, specifically, in the fourth or higher temperature sections, according to the conversion rate; and reacting the prepared hexachloro-p-xylene with phthalic acid so as to prepare terephthaloyl chloride.

Description

Method for producing terephthaloyl chloride through temperature control

[0001] The present invention relates to a method for producing terephthaloyl chloride through temperature control.

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

[0003] In addition, the above terephthaloyl chloride has a wide range of development application prospects, such as being used as a polymer admixture and as a thickener in the agricultural and pharmaceutical industries.

[0004] As described above, a method for producing terephthaloyl chloride, which has various uses, is known to be a method in which paraxylene and chlorine gas undergo a photoreaction step using ultraviolet rays, and hexachloroparaxylene produced by the photoreaction is reacted with terephthalic acid in the presence of a catalyst to produce terephthaloyl chloride (also called terephthaloyl dichloride).

[0005] However, as the concentration of hexachloroparaxylene generated in the above photoreaction increases, the viscosity increases, which may cause a problem in that the reaction rate decreases. Accordingly, when reacting at a high temperature to lower the viscosity, the solubility of chlorine gas within the liquid paraxylene becomes very low, and as a result, the time for participating in the reaction becomes very short, which may cause a problem in that the chlorine gas is released to the outside before reacting with paraxylene.

[0006] In addition, when paraxylene and chlorine gas are photoreacted, there are persistent problems such as unreacted chlorine gas being discharged together with hydrochloric acid, a side product, causing environmental pollution. In other words, while hydrochloric acid, a side product as mentioned above, can be easily removed by dissolving it in water, unreacted chlorine gas requires excessive facilities for recovery or storage when discharged externally. Therefore, a new method is required to completely circulate it in the reaction and consume it during the reaction.

[0007] The present invention has been devised to solve the above-described problem, and provides a method for producing hexachloroparaxylene, which can maintain a relatively high chlorine gas solubility within an appropriate viscosity by controlling the photoreaction temperature inside a reactor when producing hexachloroparaxylene.

[0008] In addition, the present invention aims to provide a method for producing hexachloroparaxylene in which chlorine gas is not discharged to the outside by consuming it entirely in the reaction without discharging unreacted chlorine gas to the outside.

[0009] In addition, it is intended to provide terephthaloyl chloride by reacting the above-mentioned manufactured hexachloroparaxylene with terephthalic acid.

[0010] The present invention provides a method for producing hexachloroparaxylene by photoreacting paraxylene and chlorine gas, wherein the photoreaction is carried out in a plurality of temperature sections of four or more stages according to an increase in the melting point of an intermediate product produced according to the conversion rate of hexachloroparaxylene.

[0011] According to one aspect of the present invention, the method for producing hexachloroparaxylene may have a plurality of reactors connected in parallel.

[0012] According to one aspect of the present invention, the plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and the reaction is started by continuously introducing chlorine gas into the first reactor filled with paraxylene to cause a reaction, and the reaction is started by discharging hydrochloric acid gas, which is a side product resulting from the conversion of hexachloroparaxylene, to the outside, and at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor where the reaction is started is 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, thereby initiating an initial reaction with the paraxylene filled in the second reactor, and after the reaction in the first reactor is completed, the chlorine gas continuously introduced into the first reactor is connected to the second reactor to start continuous introduction into the second reactor, and in a state where the first reactor that has discharged the product is filled with paraxylene, at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor is discharged as an unreacted product, A method for producing hexachloroparaxylene without discharging unreacted chlorine gas to the outside may be included by repeating the process of transferring unreacted chlorine gas to the first reactor to initiate an initial reaction with paraxylene in the first reactor.

[0013] According to one aspect of the present invention, a method for producing terephthaloyl chloride by reacting hexachloroparaxylene and terephthalic acid may include the steps of producing hexachloroparaxylene by photoreacting paraxylene and chlorine gas in a temperature range of four or more stages depending on the melting point of the intermediate product; and the step of producing terephthaloyl chloride by reacting the hexachloroparaxylene and terephthalic acid in the presence of a Lewis acid catalyst.

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

[0015] According to one aspect of the present invention, the plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and the reaction is started by continuously introducing chlorine gas into the first reactor filled with paraxylene to cause a reaction, and the reaction is started by discharging hydrochloric acid gas, which is a side product resulting from the conversion of hexachloroparaxylene, to the outside, and at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor in which the reaction is started is 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, thereby starting an initial reaction with the paraxylene filled in the second reactor, and after the reaction in the first reactor is completed, the chlorine gas continuously introduced into the first reactor is connected to the second reactor to start continuous introduction into the second reactor, and in a state where the first reactor that has discharged the product is filled with paraxylene, at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor is discharged as an unreacted product, By repeating the process of transferring unreacted chlorine gas to the first reactor and initiating an initial reaction with paraxylene in the first reactor, it is possible to produce hexachloroparaxylene without discharging unreacted chlorine gas to the outside.

[0016] According to one aspect of the present invention, the manufactured hexachloroparaxylene may further include a purification step.

[0017] According to one aspect of the present invention, the purification step may be purification using a distillation tower.

[0018] According to one aspect of the present invention, the distillation tower may include a distillation temperature of a bottom temperature of 100 to 300°C, a tower temperature of 100 to 250°C, and a pressure of 1 to 20 torr for purifying hexachloroparaxylene.

[0019] According to one aspect of the present invention, the Lewis acid catalyst may include one or more selected from aluminum trichloride, zinc chloride, and ferric trichloride.

[0020] According to one aspect of the present invention, the manufactured terephthaloyl chloride may further include a purification step.

[0021] According to one aspect of the present invention, the purification step may be purification using a distillation tower.

[0022] According to one aspect of the present invention, the distillation tower may purify hexachloroparaxylene at a controlled distillation temperature of 75 to 250°C and a pressure of 1 torr to 20 torr.

[0023] The present invention can provide hexachloroparaxylene with a low impurity content by providing hexachloroparaxylene by irradiating it with light instead of a radical initiator.

[0024] In addition, the present invention controls the reaction temperature during the photoreaction by dividing it into multiple sections and gradually increasing the reaction temperature in each section, thereby maintaining a relatively high chlorine gas solubility within an appropriate viscosity, thereby providing a high yield of hexachloroparaxylene.

[0025] The present invention has the advantage of being able to produce hexachloroparaxylene without emitting toxic chlorine gas to the outside by introducing a chlorine gas circulation system that circulates unreacted chlorine gas to the first reactor and the second reactor when producing hexachloroparaxylene, which is an intermediate raw material.

[0026] Figure 1 is a schematic diagram showing the manufacturing steps for producing terephthaloyl chloride.

[0027] Figure 2 is a schematic diagram showing the manufacturing steps of hexachloroparaxylene.

[0028] The present invention is further described in detail below through specific examples or embodiments, including the attached 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 may be implemented in various forms.

[0029] Additionally, 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 invention pertains. The terminology used herein is merely for the purpose of effectively describing specific embodiments and is not intended to be limiting of the invention.

[0030] Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0031] Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0032] In addition, the chlorinated intermediate product described later in the present invention may be monochloroparaxylene, dichloroparaxylene, trichloroparaxylene, tetrachloroparaxylene, or pentachloroparaxylene.

[0033] Hexachloroparaxylene, the final product produced by the chlorination reaction of the present invention, is produced by irradiating chlorine gas with ultraviolet rays and causing a chlorine radical to undergo a substitution reaction with the hydrogen of the methyl group of paraxylene.

[0034] However, there is a problem that as the concentration of hexachloroparaxylene increases through the above photoreaction, the viscosity also increases, resulting in a decrease in the reaction rate.

[0035] On the other hand, when reacting at high reaction temperatures, the viscosity is low, but the solubility of chlorine gas in liquid paraxylene is very low. Consequently, the reaction time is very short, which can lead to problems such as chlorine gas being released before it even reacts with paraxylene.

[0036] Accordingly, in order to solve the above problem that occurs when the reaction is performed by increasing the reaction temperature as described above, the present invention achieves this by dividing the step of performing the reaction by increasing the reaction temperature between the melting point start temperature and the melting point end temperature of the mixture containing the intermediate product formed when the melting point of the product increases by increasing the chlorination degree of paraxylene and raising the reaction temperature between the melting point start temperature and the melting point end temperature of the intermediate product formed, into 4 or more steps, preferably 10 or more steps.

[0037] As the conversion rate of the above intermediate product increases, when the product is recovered and the melting point is measured, the steps between the melting point start point where melting begins and the melting point end point where it is completely melted are divided as many times as possible, so that the solubility of chlorine gas increases as the multi-stage reaction is performed, thereby inducing the participation of chlorine gas as much as possible in the reaction, thereby adopting a means for reacting in an environmentally friendly manner without or minimizing the leakage of all chlorine gas to the outside.

[0038] Specifically, during the above reaction, chlorination of the methyl group of paraxylene occurs, generating chlorinated products. These chlorinated products have a higher melting point than paraxylene, and as chlorination of paraxylene progresses further, the melting points of the chlorinated products also increase. For example, the melting point of trichloroparaxylene is higher than that of monochloroparaxylene, and the melting point of pentachloroparaxylene is higher than that of trichloroparaxylene.

[0039] Accordingly, the present invention recognizes that the melting point of a mixture of various forms of chlorinated intermediate products or final products produced according to the conversion rate of paraxylene by chlorination of paraxylene increases, and provides a method for producing a new environmentally friendly hexachloroparaxylene that can be used in the reaction without external discharge of chlorine by continuously increasing the reaction temperature according to the increase in the melting point and proceeding with the entire reaction.

[0040] The present invention divides the temperature section into at least 3-stage sections, 4-stage sections, 5-stage sections, 6-stage sections, 7-stage sections, 8-stage sections, 9-stage sections, or 10-stage sections from low temperature to high temperature and reacts while increasing the temperature, thereby controlling the solubility of chlorine gas while maintaining the viscosity at a constant level, thereby fastening the reaction speed and allowing chlorine to participate in the reaction as much as possible without external leakage, thereby achieving a high yield of 95% or more.

[0041] According to one specific example of the present invention, the reaction is initiated by raising the reaction temperature from 13°C to 20°C for 4 hours, and as the conversion rate progresses, the reaction is conducted at 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, so that 95% or more of the product is converted, preferably 98% or more of the product is converted, and the reaction can be conducted without external leakage of chlorine gas.

[0042] In addition, the present invention adopts a means for preventing or minimizing external leakage of chlorine gas by combining a step of circulating unreacted chlorine gas from the first reactor to the second reactor or from the second reactor to the first reactor along with a multi-stage reaction temperature according to the melting point of the product.

[0043] By the means of the above invention, the inventors of the present invention have solved the problem of proceeding with the photoreaction immediately by raising the temperature to a temperature at which all chlorinated intermediate products or final products can be melted, as in the prior art.

[0044] That is, it was found that the present invention can eliminate or minimize the problem of difficulty in controlling the reaction due to high temperature, particularly the problem of the solubility of chlorine gas used in the reaction being low, thereby lowering the efficiency of the reaction, and the problem of having to discharge unreacted chlorine to the outside.

[0045] The present invention has been able to achieve the above object by using a multi-stage reaction temperature means for gradually increasing the temperature from the paraxylene melting point to the melting point of the chlorinated product and / or by reacting with chlorine gas introduced from one reactor in the first and second reactors connected in parallel and circulating unreacted chlorine gas to another reactor to participate in the reaction.

[0046] By adopting the above temperature range and the circulating reaction means of the reaction chlorine gas in this reaction, there is an advantage in that paraxylene can maintain the reactivity of the chlorination reaction at a high level even when using the above chlorine and hydrochloric acid mixed gas generated as a reaction by-product.

[0047] The above chlorine gas circulation is described in detail.

[0048] The above photoreaction for producing hexachloroparaxylene using paraxylene has a problem in that as the reaction progresses, the reaction rate of chlorine gas gradually increases due to steric effects of the methyl group substituted with chlorine, so that the additional chlorine substitution reaction rate gradually decreases, resulting in an increase in the content of unreacted chlorine gas.

[0049] Accordingly, the present invention adopts a means for connecting multiple reactors in parallel and transferring unreacted chlorine gas sequentially discharged from the multiple reactors to another reactor and circulating the unreacted chlorine gas so that it does not discharge the unreacted chlorine gas to the outside but is transferred to another reactor to participate in the reaction.

[0050] The above-mentioned plurality of reactors may be two or three or more, but this is not limited.

[0051] Below, a more detailed explanation is provided using a reactor in which two reactors are connected in parallel.

[0052] The present invention first starts the reaction by continuously introducing chlorine gas into a first reactor filled with paraxylene to react, and then discharging hydrochloric acid gas, which is a by-product resulting from the conversion of hexachloroparaxylene, to the outside. At this time, the introduced chlorine gas reacts quantitatively with paraxylene and is consumed. Next, at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor begins to be discharged as an unreacted product, at a point in time when the unreacted chlorine gas continuously introduced into the first reactor and not participating in the reaction is discharged from the first reactor, the discharged unreacted chlorine gas is not discharged to the outside but is transferred to a second reactor to initiate an initial reaction with the paraxylene filled in the second reactor. As for the circulating chlorine gas, at the moment 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, and is continuously introduced into the second reactor to participate in the reaction.

[0053] Next, the first reactor that discharged the product is filled again with paraxylene, which is the starting material, and at a conversion rate of hexachloroparaxylene where 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 initiate an initial reaction with the paraxylene in the first reactor, thereby producing hexachloroparaxylene without discharging unreacted chlorine gas to the outside.

[0054] The above method for producing hexachloroparaxylene is explained in more detail step by step with reference to Figure 2 below.

[0055] According to one aspect of the present invention, the hexachloroparaxylene production step comprises:

[0056] S1) Step of filling the first reactor (100) and the second reactor (200) with para-xylene;

[0057] S2) A step of continuously introducing chlorine gas into the first reactor (100), the introduced chlorine gas reacting 100% with para-xylene, and transferring the hydrochloric acid gas, which is a by-product discharged from the reaction, to an incinerator (600) through the first transfer pipe (110) to recover the hydrochloric acid;

[0058] S3) When the reaction of chlorine gas in the first reactor (100) decreases to 100% or less and unreacted chlorine gas is generated, a step of blocking the first discharge pipe (110);

[0059] S4) After blocking the first discharge transfer pipe (110), the unreacted chlorine gas and residual hydrochloric acid gas in the first reactor (100) are transferred to the second reactor (200) through the first cross transfer pipe (120) so that they are reacted for the first time in the second reactor (200), thereby simultaneously producing hexachloroparaxylene in the first reactor (100) and the second reactor (200);

[0060] S5) A step of transporting hydrochloric acid gas generated as a by-product in the second reactor (200) to an incinerator (600) through a second discharge transport pipe (210) at the top of the second reactor (200);

[0061] S6) When the reaction of the first reactor (100) is completed, the first cross-transfer pipe (120) is blocked, and the chlorine gas being fed into the first reactor (100) is changed to be fed into the second reactor (200);

[0062] S7) A step of discharging the product hexachloroparaxylene into the first reactor (100) and introducing new paraxylene;

[0063] 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 blocked and the unreacted chlorine gas and residual hydrochloric acid in the second reactor (200) are injected into the first reactor (100) through the second cross transfer pipe (220) to simultaneously perform the hexachloroparaxylene production reaction in the second reactor (200) and the first reactor (100);

[0064] S9) After the reaction in the second reactor (200) is completed, the chlorine gas fed into the second reactor (200) is fed into the first reactor (100) to react, and the first exhaust pipe (110) is opened to transport the byproduct hydrochloric acid to the incinerator (600) to recover the hydrochloric acid; and

[0065] S10) A step of discharging hexachloroparaxylene into the second reactor (200) and introducing new paraxylene; and a step of continuously producing hexachloroparaxylene by repeating steps S2 to S10 may be included.

[0066] In the above hexachloroparaxylene manufacturing step, chlorine gas and paraxylene are manufactured into hexachloroparaxylene through a photoreaction. The chlorine gas is decomposed into chlorine radicals due to the photoreaction, and the chlorine radicals are substituted for the hydrogen of the methyl group of paraxylene to manufacture hexachloroparaxylene, and hydrochloric acid is discharged as a byproduct.

[0067] The above method for producing hexachloroparaxylene can completely consume chlorine gas in the reaction, thereby preventing chlorine gas, which is fatal to the human body or the environment, from being released to the outside.

[0068] In addition, in the above hexachloroparaxylene manufacturing method, there is an advantage in that the reactivity can be maintained at a high level even when the above chlorine and hydrochloric acid mixed gas is used when reacting within the range of the above multiple temperature sections.

[0069] Additionally, according to one aspect of the present invention, the photoreaction may include an ultraviolet light intensity range of less than 2000 LUX, specifically, 100 to 1,800 LUX, specifically 100 to 1,500 LUX.

[0070] The amount of light input into the photoreaction was a high-energy amount of light in the range of 2,000 LUX to 50,000 LUX ultraviolet rays. However, in the above light amount range, side reactions may occur and the yield of hexachloroparaxylene is low.

[0071] Accordingly, the inventors of the present invention found that hexachloroparaxylene can be produced even when the light intensity range being investigated is controlled to ultraviolet rays of less than 100 to 1,500 LUX, and that when produced in the light intensity range, side reactions are low and the yield is high.

[0072] In addition, when reacting in the above light range, the reaction heat generated according to the reaction is low, so it is very good for temperature control, and at the same time, it has the advantage of being able to control the reaction speed.

[0073] In addition, the irradiation area of ​​the photoreaction is not limited as long as the reaction proceeds smoothly, but specifically, 5 to 30 cm per kg of paraxylene. 2 , specifically, 10 to 20 cm 2 , specifically, 10 to 15 cm 2 It could be.

[0074] Mercury lamps were previously used as light sources for photoreactions. However, the short-wavelength light of low-pressure mercury lamps can cause other photochemical side reactions, lowering the purity of the product. In addition, the long-wavelength light of high-pressure mercury lamps is not sufficient to cause chlorine radical reactions, which can result in more energy consumption. Furthermore, the use of mercury lamps can cause problems such as generating more heat, requiring additional cooling devices to reduce this heat.

[0075] The present invention overcomes the shortcomings of mercury lamps by using LED lamps. By using LED lamps, the wavelength range appropriate for the reaction can be controlled, thereby reducing photochemical side reactions. Furthermore, compared to mercury lamps, they do not generate heat even after long-term use, eliminating the need for additional cooling devices. Furthermore, LED lamps have the advantage of low power consumption, making them highly energy efficient.

[0076] In particular, in the case of a mixed gas of chlorine gas and hydrochloric acid gas fed into the reactor through the first cross-transfer pipe or the second cross-transfer pipe, the probability of occurrence of side reactions is higher than that of single chlorine gas at high light levels, and thus, a problem of reduced reactivity may occur.

[0077] Accordingly, the present invention can obtain hexachloroparaxylene in a high yield while reducing the side reaction by irradiating the light quantity to less than 2,000 LUX.

[0078] In addition, by simultaneously satisfying the above-mentioned light quantity range and the temperature range of the above-mentioned multiple temperature sections, side reactions are very low while at the same time, discharge of hydrochloric acid gas, which is a by-product, is smooth, so that hexachloroparaxylene can be obtained in a very high yield.

[0079] The hydrochloric acid gas discharged above moves to an incinerator, where all unreacted chlorine gas is discharged, and the hydrochloric acid gas enters a hydrochloric acid production facility, where a 35% hydrochloric acid solution is produced.

[0080] Specifically, the hydrochloric acid gas generated from the above incinerator is dissolved in water through a scrubbing system within the hydrochloric acid manufacturing facility and manufactured into hydrochloric acid.

[0081] The 35% hydrochloric acid solution prepared above is transferred to a hydrochloric acid tank and stored.

[0082] According to one aspect of the present invention, terephthaloyl chloride can be produced by reacting the above-produced hexachloroparaxylene with terephthalic acid.

[0083] As an example embodiment, the step of producing terephthaloyl chloride may include a step of producing hexachloroparaxylene from paraxylene; a step of purifying the produced hexachloroparaxylene; and a step of reacting the purified paraxylene and terephthalic acid in the presence of an acid catalyst to produce terephthaloyl chloride.

[0084] In addition, as an embodiment, 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 and terephthalic acid in the presence of a Lewis acid catalyst to produce terephthalyl chloride; and a step of purifying the produced terephthaloyl chloride.

[0085] First, the hexachloroparaxylene purification step 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.

[0086] In the above purification step, the distillation method may be performed using a distillation column, and the distillation column is not limited to a device that generally distills compounds.

[0087] The above distillation tower can purify hexachloroxylene under the 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.

[0088] In addition, 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 a Lewis acid catalyst.

[0089] The above Lewis acid catalyst may include 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 above synthesis.

[0090] The above terephthaloyl chloride synthesis may be carried out by adding 30 to 300 parts by weight of terephthalic acid, preferably 40 to 200 parts by weight, and more preferably 45 to 130 parts by weight, to 100 parts by weight of hexachloroparaxylene, but is not limited thereto.

[0091] In addition, for 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 part by weight, and more preferably 0.005 to 0.01 part by weight, but is not limited thereto.

[0092] In addition, according to one aspect of the present invention, the terephthaloyl chloride produced above may further include a purification step, and the terephthaloyl chloride purification step 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.

[0093] In the above terephthaloyl chloride purification step, the distillation method can be performed using a distillation column, and the distillation column is not limited to a device that generally distills compounds.

[0094] The above distillation tower 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.

[0095]

[0096] The present invention will be described in more detail based on the following examples and comparative examples. However, the following examples and comparative examples are merely illustrative examples for further explaining the present invention, and the present invention is not limited by the following examples and comparative examples.

[0097]

[0098] [Example 1]

[0099] 1) Hexachloro-p-xylene manufacturing step

[0100] After 100 parts by weight of para-xylene was introduced into each of the first reactor (100) and the second reactor (200) from the para-xylene supply unit (300), nitrogen was injected into the first reactor (100) from the nitrogen gas supply unit (500) to remove air inside, and then chlorine gas was injected into the first reactor (100) from the chlorine gas supply unit (400) and photoreacted to produce hexachloropara-xylene.

[0101] The chlorine gas injected above was injected at a rate of 30 parts by weight per hour for 100 parts by weight of the paraxylene.

[0102] In the above photoreaction, as the reaction progressed in the first reactor (100), the intermediate product was generated according to the conversion rate in Table 1 below, and as the intermediate product was generated, the melting point of the intermediate product mixture increased, and the reaction was carried out under multi-stage temperature increase conditions at the temperature and time as shown in Table 2. During the reaction, stirring was performed at 300 rpm, and the photoreaction was performed at 15 cm per 1 kg of raw material. 2 The area of ​​the light was irradiated with 1,000 LUX of ultraviolet light.

[0103] In addition, the external chlorine gas fed into the first reactor quantitatively participated in the reaction at the beginning of the reaction and was consumed, and at this time, the by-product hydrochloric acid was discharged to the incinerator (600) through the first discharge conveyance pipe (110). When the yield of the above hexachloroparaxylene reached 0.1%, unreacted chlorine gas began to be discharged to the outside, so at this time, 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 the first reactor.

[0104] The reaction was carried out in the first reactor under the conditions of Tables 1 and 2, and the reaction was completed after 32 hours. 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 of Tables 3 and 4 for the conversion rate, reaction temperature, and time of the second reactor.

[0105] At the point where unreacted chlorine gas was generated at a 0.1% yield of hexaparaxylene in the second reactor, the chlorine gas was transferred to the first reactor, and the chlorination reaction was initiated in the first reactor.

[0106]

[0107]

[0108]

[0109] 2) Hexachloroparaxylene purification step

[0110] The hexachloroparaxylene produced in the first reactor (100) and the second reactor (200) was transferred to the bottom of the first distillation tower. In order to purify the hexachloroparaxylene, the first distillation tower was purified at a total pressure of 5 torr, a bottom temperature of 160°C, a tower temperature of 150°C, and a stirring speed of 300 rpm, and the hexachloroparaxylene purified to high purity was separated from the hexachloroparaxylene residue. The purified hexachloroparaxylene was then transferred to the first storage tank and stored.

[0111]

[0112] 3) Terephthaloyl chloride reaction step

[0113] In the above hexachloroparaxylene purification step, high-purity hexachloroparaxylene stored in the first storage tank is transferred to the third reactor, and terephthalic acid and iron chloride (FeCl3) catalyst are introduced into the third reactor. The reaction is carried out for 5 hours to produce terephthaloyl chloride.

[0114] The above reaction was carried out by mixing 100 parts by weight of high-purity hexachloro-p-xylene, 100 parts by weight of terephthalic acid, and 0.005 parts by weight of FeCl3, and the reaction conditions were maintained at a temperature of 120°C and atmospheric pressure.

[0115]

[0116] 4) Terephthaloyl chloride purification step

[0117] The terephthaloyl chloride produced in the above 3) terephthaloyl chloride reaction step was transferred to a second distillation tower and subjected to primary purification. The purification conditions of the second distillation tower were as follows: a total pressure of 5 torr, a bottom temperature of 160°C, a tower temperature of 130°C, and a stirring speed of 300 rpm. The terephthaloyl chloride purified to high purity was transferred to a second storage tank and stored.

[0118]

[0119] As described above, the present invention has been described with specific details and limited examples and drawings, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0120] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

[0121]

[0122] [Explanation of symbols]

[0123] 100: Reactor 1

[0124] 110: First discharge pipe

[0125] 120: First cross-transfer pipe

[0126] 200: Second reactor

[0127] 210: Second discharge pipe

[0128] 220: Second cross-transfer pipe

[0129] 300: Paraxylene supply unit

[0130] 400: Chlorine gas supply unit

[0131] 500: Inert gas supply unit

[0132] 600: Incinerator

[0133] 700: Hydrochloric acid manufacturing facility

Claims

1. A method for producing hexachloroparaxylene by photoreacting paraxylene and chlorine gas, wherein the photoreaction is carried out in a plurality of temperature sections of four or more stages according to an increase in the melting point of an intermediate product produced according to the conversion rate of hexachloroparaxylene.

2. In paragraph 1, The above hexachloroparaxylene manufacturing method is a manufacturing method of hexachloroparaxylene in which a plurality of reactors are connected in parallel.

3. In paragraph 2, The above-mentioned plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and the reaction is started by continuously introducing chlorine gas into the first reactor filled with paraxylene to react, and the reaction is started by discharging hydrochloric acid gas, which is a side product resulting from the conversion of hexachloroparaxylene, to the outside, and at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor starts to be discharged as an unreacted product in the first reactor where the reaction is started, the unreacted chlorine gas continuously introduced into the first reactor and not participating in the reaction is not discharged to the outside but is transferred to the second reactor to initiate an initial reaction with the paraxylene filled in the second reactor, and after the reaction in the first reactor is completed, the chlorine gas continuously introduced into the first reactor is connected to the second reactor to start continuous introduction into the second reactor, and in a state where the first reactor that has discharged the product is filled with paraxylene, at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor starts to be discharged as an unreacted product, the unreacted chlorine gas is introduced into the first reactor. A method for producing hexachloroparaxylene, which produces hexachloroparaxylene without emitting unreacted chlorine gas to the outside by repeating the process of transporting and initiating an initial reaction with paraxylene in the first reactor.

4. A method for producing terephthaloyl chloride by reacting hexachloroparaxylene and terephthalic acid, A step of producing hexachloroparaxylene by photoreacting paraxylene and chlorine gas in a temperature range of four or more stages depending on the melting point of the intermediate product; and A method for producing terephthaloyl chloride, comprising the step of producing terephthaloyl chloride by reacting the above hexachloroparaxylene and terephthalic acid under a Lewis acid catalyst.

5. In paragraph 4, The above hexachloroparaxylene manufacturing method is a method for manufacturing terephthaloyl chloride, wherein a plurality of reactors are connected in parallel.

6. In paragraph 5, The above-mentioned plurality of reactors are reactors in which a first reactor and a second reactor are connected in parallel, and the reaction is started by continuously introducing chlorine gas into the first reactor filled with paraxylene to react, and the reaction is started by discharging hydrochloric acid gas, which is a side product resulting from the conversion of hexachloroparaxylene, to the outside, and at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the first reactor starts to be discharged as an unreacted product in the first reactor where the reaction is started, the unreacted chlorine gas continuously introduced into the first reactor and not participating in the reaction is not discharged to the outside but is transferred to the second reactor to initiate an initial reaction with the paraxylene filled in the second reactor, and after the reaction in the first reactor is completed, the chlorine gas continuously introduced into the first reactor is connected to the second reactor to start continuous introduction into the second reactor, and in a state where the first reactor that has discharged the product is filled with paraxylene, at a conversion rate of hexachloroparaxylene at which the chlorine gas continuously introduced into the second reactor starts to be discharged as an unreacted product, the unreacted chlorine gas is introduced into the first reactor. A method for producing terephthaloyl chloride, wherein the process of transporting hexachloroparaxylene and initiating an initial reaction with paraxylene in the first reactor is repeated, thereby producing hexachloroparaxylene without emitting unreacted chlorine gas to the outside.

7. In paragraph 4, A method for producing terephthaloyl chloride, wherein the above-mentioned hexachloroparaxylene further comprises a purification step.

8. In paragraph 7, A method for producing terephthaloyl chloride, wherein the above purification step is performed by purifying using a distillation tower.

9. In paragraph 8, A method for producing terephthaloyl chloride, wherein the distillation tower has a bottom temperature of 100 to 300°C, a top temperature of 100 to 250°C, and a pressure of 1 to 20 torr for purifying hexachloroparaxylene.

10. In paragraph 4, A method for producing terephthaloyl chloride, wherein the Lewis acid catalyst is one or more selected from aluminum trichloride, zinc chloride, and ferric trichloride.

11. In paragraph 4, A method for producing terephthaloyl chloride, wherein the above-mentioned terephthaloyl chloride further comprises a purification step.

12. In paragraph 11, A method for producing terephthaloyl chloride, wherein the above purification step is performed by purifying using a distillation tower.

13. In paragraph 12, A method for producing terephthaloyl chloride, wherein the distillation tower 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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