Synthesis method of MIBT

Abstract

To provide a process (100) for synthesis of MIBT capable of producing an alkyl-substituted aromatic hydrocarbon in a highly selective and high yield with an excellent conversion rate of an aromatic hydrocarbon as a reaction substrate.SOLUTION: The process employs a catalyst slurry that includes a catalyst carrier, an alkali metal catalyst, and an organic solvent. The side-chain alkylation of m-xylene has been carried out using propylene in the presence of a catalyst slurry.SELECTED DRAWING: Figure 1

Description

Cross - reference to related applications and priority

[0001] This application claims priority to Indian Patent Application No. 202221044199, filed on August 2, 2022.

Technical Field

[0002] The disclosure of the present invention relates to a method for alkylating aromatic compounds. More specifically, the present disclosure relates to a method for synthesizing m - isobutyltoluene (MIBT).

Background Art

[0003] Alkyl - substituted aromatic hydrocarbons such as m - isobutyltoluene (MIBT) are useful as intermediate raw materials for organic compounds such as pharmaceuticals and fragrances, and methods for introducing an alkyl group into an aromatic hydrocarbon to produce an alkyl - substituted aromatic hydrocarbon have been studied. In the alkylation method, a series of reactions occur, whereby the alkylation product contains a mixture of mono, di, and tri - alkylated compounds in which the hydrogen atoms in the substitutable range on the ring are substituted. Since the introduction of the original alkyl group activates the ring for further substitution, monoalkylbenzene is further alkylated to some extent depending on the catalyst, olefinic alkylating agent, and reaction conditions.

[0004] Known methods for producing alkyl - substituted aromatic hydrocarbons such as MIBT selectively include the side - chain alkylation of m - xylene using propylene on a solid catalyst. In the known knowledge of the art, the known methods are also troubled by the formation of undesirable hydrocarbon by - products and catalyst residues, thus substantially increasing the reaction time for the alkylation of m - xylene and further reducing the yield.

[0005] The adverse effect on the downstream process due to the presence of free - radical reaction inhibitors in the m - xylene stream has been found to be reduced by treating the catalyst in an inert atmosphere and a reducing atmosphere, whereby undesirable catalyst impurities that are considered to generate free - radical reaction inhibitors can be reduced.

[0006] However, the available methods have various drawbacks. The available methods do not use a specific catalyst for promoting the production of MIBT, a carrier drying process for improving the coating, optimization of the ratio of starting materials, a process for removing trace amounts of catalyst that affect the recovery of the product, and a purification process for MIBT. The recovery of important by-products obtained during the process has also been found to be very important in any biochemical industrial process.

[0007] Therefore, there has been a long-standing desire for a method for producing an alkyl-substituted aromatic hydrocarbon that can achieve an excellent conversion rate of the aromatic hydrocarbon as a reaction substrate and obtain m-isobutyltoluene in a high selective yield. Summary of the Invention Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a method for synthesizing an m-isobutyltoluene (MIBT) composition having a good yield.

[0009] Another object of the present invention is to shorten the overall reaction time of a process that incorporates reactants in an appropriate ratio to shorten the reaction time and thereby obtain an optimized MIBT yield in the side-chain alkylation of aromatic compounds. Means for Solving the Problems

[0010] The description herein is not intended to identify the essential features of the claimed subject matter, nor is it intended to be used to determine or limit the scope of the claimed subject matter. The description herein is provided to introduce concepts related to the composition of a catalyst for the alkylation of aromatic hydrocarbons, and the concepts are further explained in the following detailed description.

[0011] The present disclosure relates to a method for synthesizing m-isobutyltoluene (MIBT) including various steps. The method may include adding a first amount of dried m-xylene and a K2CO3 carrier to a first reactor to form a slurry mixture. The method may include adding a predetermined molten sodium metal catalyst and a suspending agent to the slurry mixture within a certain period of time. The method may include transferring the slurry mixture containing the sodium metal catalyst to a second reactor, and then adding a predetermined amount of propylene and an excess of dried m-xylene to the second reactor heated within a predetermined temperature range. The method may include reacting the slurry mixture, propylene, and m-xylene to obtain a crude MIBT product. The method may include removing the sodium catalyst from the crude MIBT by enabling water washing in a neutralization device, and further recovering propane gas. The method may include separating an aqueous layer and an organic layer containing the crude MIBT and hydrocarbon by-products in a separation device. The method may further include recovering purified MIBT having a purity of 99.9% and a yield of up to 40% by a distillation mechanism.

Brief Description of the Drawings

[0012] The detailed description of the drawings is described with reference to the accompanying drawings. In the figures, the leftmost digit of the reference number identifies the figure in which the reference number first appears. Throughout the drawings, the same numbers are used to refer to like features and components.

[0013]

Figure 1

Embodiments for Carrying Out the Invention

[0014] References throughout this specification to "various embodiments", "some embodiments", "an embodiment", or "an implementation" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in various embodiments", "in some embodiments", "in an embodiment", or "in an implementation" throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] The words "comprising", "containing", "including", and "having", and other forms thereof, are used interchangeably and are intended to be open-ended terms. It is not intended that any such terms following any of these words be construed to mean that the list of items following such terms is an exclusive list of only those items, nor that the list of items following such terms is limited to only those items.

[0016] It should also be noted that, unless otherwise indicated herein, the singular forms "a", "an", and "the" include plural references. Any methods similar or equivalent to those described herein can be used in the practice or testing of the embodiments of this specification, although exemplary methods are described. The disclosed embodiments are merely illustrative of the present disclosure and can be embodied in various forms. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles described herein can be applied to other embodiments. However, those skilled in the art will readily recognize that the present disclosure is not limited to the illustrated embodiments, but rather will be given the broadest scope consistent with the principles and features described herein. The present invention will be described in detail below with reference to the accompanying drawings.

[0017] The present invention relates to an alkylation method for producing an alkyl-substituted aromatic hydrocarbon by alkylating the meta-position of an aromatic hydrocarbon using a catalyst coated on a carrier material. Specific solid bases, alkaline earth metal compounds, and alkali metal hydrides exhibit extremely high alkylation activity, and the target alkyl-substituted aromatic hydrocarbon can be efficiently obtained using a small amount of catalyst. The catalyst is easily separated from the reaction product and has been found to be destroyed when dissolved in water.

[0018] In one embodiment, referring to FIG. 1, the present disclosure relates to a method (100) for synthesizing m-isobutyltoluene (MIBT). As shown, the method includes a step (101) of adding a first amount of dried m-xylene and a K2CO3 carrier to a first reactor to form a slurry mixture.

[0019] The method (100) may further include a step (102) of adding a predetermined molten sodium metal catalyst and a suspending agent to the slurry mixture over a certain period of time. The method (100) may further include a step (103) of transferring the slurry mixture containing the sodium metal catalyst to a second reactor. After the transferring step (103), a step (104) of adding a predetermined amount of propylene and excess dried m-xylene to the second reactor follows. Further, the method (100) may include a step (105) of heating the second reactor to a predetermined temperature range and reacting the slurry mixture, propylene, and m-xylene to obtain a crude MIBT product. The method may further include a step (106) of removing the sodium catalyst from the crude MIBT by enabling water washing in a neutralization device and further recovering propane gas. The method may include a step (107) of separating an aqueous layer and an organic layer in a separation device, and such an organic layer includes crude MIBT and hydrocarbon by-products. The method may further include a step (108) of recovering purified MIBT having a purity of 99.9% and a yield of up to 40% by a distillation mechanism.

[0020] Furthermore, the present disclosure relates to a novel method for the side-chain alkylation of alkyl-substituted aromatic hydrocarbons with aliphatic monoolefins. In particular, a high conversion rate of the side-chain alkylation of m-xylene with propylene is obtained. The present disclosure aims to provide a novel method for efficiently synthesizing m-isobutyltoluene.

[0021] In one embodiment, the method (100) may include a step of drying m-xylene in a vacuum dryer, and the initial water content of m-xylene ranges from 70 to 140 PPM, preferably from 90 to 120 PPM, and more preferably from 100 to 125 PPM. In an embodiment, in the step of drying water, the water contained in m-xylene is removed by a vacuum dryer equipped with a molecular sieve adsorber having a controlled flow rate, and dried m-xylene is obtained.

[0022] In one embodiment, the present disclosure relates to a method (100) for synthesizing m-isobutyltoluene (MIBT), which includes a first step (101) of adding a first amount of the dried m-xylene and a potassium carbonate (K2CO3) carrier to a first reactor to form a slurry mixture.

[0023] In one embodiment of the present disclosure, a slurry mixture including a catalyst carrier, an alkali metal catalyst, and an organic solvent is proposed, and the molten alkali metal catalyst is coated on the catalyst carrier and suspended in the organic solvent. The catalyst composition can be used for alkylating aromatic hydrocarbons, and the catalyst composition can be composed of a carrier material and an alkali metal catalyst.

[0024] In one embodiment of the present disclosure, the organic solvent can include, but is not limited to, at least one aromatic hydrocarbon selected from m-xylene, p-xylene, n-propylene, and liquefied isobutene. The organic solvent is used in a catalyst slurry to form a homogeneous mixture of the catalyst and the catalyst support. This solvent is usually inert and does not contribute to the catalytic reaction. However, the solvent may be a starting material in the alkylation reaction of aromatic compounds and is also used as a suspension solvent for the catalyst composition. In one embodiment, m-xylene is selected as the organic solvent, but it is not limited thereto.

[0025] In another embodiment, the solid base used in method (100) is a composition comprising one or more selected from alkaline earth metal compounds such as magnesium oxide, magnesium hydroxide, magnesium carbonate, calcium oxide, calcium hydroxide, and calcium carbonate, potassium compounds including at least one of potassium hydroxide and potassium carbonate, and metallic sodium. Specifically, the solid base is metallic sodium in an inert gas atmosphere.

[0026] In one embodiment of the present disclosure, the alkali metal catalyst includes at least one of sodium, lithium, potassium, rubidium, cesium, NaK, and Na2O. The alkali metal used as the catalyst is a transition metal with high reactivity and electrically positive. These metals tend to easily borrow or receive electrons from other molecules, resulting in an increased reaction rate. Alkali metals are used in the reduction of organic compounds and the production of many commercially available compounds. More preferably, sodium may be selected as the alkali metal catalyst.

[0027] In related embodiments of the present disclosure, the catalyst support includes at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate. The catalyst support is a solid material that is usually inert but is maintained under specific conditions to carry, support, or load a catalyst that can contribute to catalytic activity. Preferably, the catalyst supports potassium carbonate.

[0028] In one embodiment of the method (100), the size of the potassium carbonate is in the range of 0.6 to 1.1 mm, preferably in the range of 0.7 to 1.0 mm, and more preferably in the range of 0.8 to 0.9 mm.

[0029] In one embodiment, the catalyst support is not particularly limited, but can be present in any form of powder, pellet, or granule. More preferably, the catalyst support is in the form of a ground fine powder that provides a larger surface area. A larger surface area provides more surface area for forming active sites and thus leads to greater activity.

[0030] In one embodiment, in the method for synthesizing MIBT, the ratio of the amounts of sodium, potassium carbonate (K2CO3), and the suspending agent can be in the range of 5:40:1 to 10:50:1, preferably in the range of 7:50:1 to 9:60:1, and more preferably at a ratio of 6.2:53:1.

[0031] In a preferred embodiment, in the method for synthesizing MIBT, the suspending agent can be selected from fatty acids such as oleic acid, tall oil, and stearic acid.

[0032] In one embodiment, the method (100) may add a predetermined range of 7.5 to 13.6 moles of molten sodium metal catalyst, preferably 9 to 13 moles of molten sodium metal catalyst and a suspending agent, to the slurry mixture within a range of 5 minutes to 1 hour 30 minutes, preferably 10 minutes to 1 hour 10 minutes, and more preferably 20 minutes to 1 hour.

[0033] In one embodiment, the method (100) may include a step (103) of transferring the slurry mixture containing the sodium metal catalyst to a second reactor.

[0034] The aromatic hydrocarbon in this embodiment is an aromatic hydrocarbon having an alkyl group with a hydrogen atom at the α position. The α position in this embodiment is the carbon position on the alkyl group and is the position adjacent to the carbon on the aromatic hydrocarbon ring to which the alkyl group is bonded.

[0035] Examples of the aromatic hydrocarbon include toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, o-xylene, m-xylene, p-xylene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, mesitylene, pseudocumene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, 1-methylnaphthalene, 2-methylnaphthalene, dimethylnaphthalene, tetrahydronaphthalene, indane, 2-methylpyridine, 4-methylpyridine, and the like. These aromatic hydrocarbons may be used alone or in combination of two or more. In one embodiment, preferably m-xylene can be used as the starting material and solvent.

[0036] The alkylation in this embodiment means that the hydrogen atom at the meta position of the alkyl group of the aromatic hydrocarbon is substituted with an alkyl group by reaction with an alkene. Examples of the alkene in this embodiment include linear or branched alkenes having 2 to 20 carbon atoms. Specifically, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, octene, nonene, 3-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-pentene, 3-methyl-2-pentene, and the like can be mentioned. These alkenes may be used alone or in combination of two or more. Among these alkenes, propylene is preferred.

[0037] In one embodiment, this process may include step (104) of adding a predetermined amount of propylene and excess dried m-xylene to a second reactor.

[0038] In these coupling reactions, the molar ratio of the alkene to the aromatic hydrocarbon varies depending on the specific reactants used and the desired product, since the aromatic hydrocarbon may have one or more active hydrogens. It may be desirable to react the alkene with only one or two or more active hydrogens in the aromatic hydrocarbon. It is often preferred to use the reactants in stoichiometric amounts appropriate for the preparation of the desired product. However, either reactant can be used in excess.

[0039] In one embodiment, the ratio of the amounts of m-xylene and propylene is from 1:1 to 15:1. In a preferred embodiment, the ratio of the amounts of m-xylene and propylene is from 2:1 to 10:1. In a more preferred embodiment, the ratio of the amounts of m-xylene and propylene is from 0.2 to 1.2, preferably from 0.4 to 0.9.

[0040] In one embodiment, method (100) further includes heating a second reactor to a temperature range of 180 to 220 °C and reacting the slurry mixture, propylene and m-xylene to obtain a crude MIBT product in a crude MIBT stream (step 105).

[0041] In one embodiment, the crude MIBT stream of the reactor comprises a mixture of unreacted m-xylene, propane, crude MIBT, lower hydrocarbons (LHC) and higher hydrocarbons (HHC) formed within the reaction system.

[0042] In another embodiment, method (100) includes removing the sodium catalyst from the crude MIBT by enabling water washing in a neutralization device and further recovering the propane gas to public facilities through a gas holder (step 106).

[0043] In one embodiment, the method (100) for synthesizing MIBT further includes separating an aqueous layer and an organic layer in a separation device (step 107), and the organic layer includes crude MIBT and hydrocarbon by-products by an overflow mechanism.

[0044] In one aspect of this embodiment, at least one organic stream rich in MIBT that does not contain a catalyst or has few catalyst impurities may be separated by a separation device.

[0045] In one embodiment, the separated aqueous layer is sent from the separation device to a wastewater tank, and the separated organic layer is transferred to an LHC column.

[0046] In one embodiment, method (100) includes a step (108) of recovering purified MIBT having a purity of 99.9% and a yield of up to 40% by a distillation mechanism.

[0047] In another embodiment, MIBT is inspected in an internal inspection tank before being stored in an MIBT storage tank.

[0048] In the present disclosure related to the method (100) for synthesizing MIBT, the aromatic hydrocarbon is preferably m-xylene, and the alkene is preferably propylene. Also, in the production method of this embodiment, the alkyl-substituted aromatic hydrocarbon is preferably m-isobutyltoluene, and the alkene is preferably propylene.

[0049] In one embodiment, the present disclosure can improve the conversion rate of the aromatic hydrocarbon as a reaction substrate and obtain the target alkyl-substituted aromatic hydrocarbon with high selectivity and high yield, and can be advantageously produced industrially. Also, by the production method of the present disclosure, an alkyl-substituted aromatic hydrocarbon useful as an intermediate raw material for pharmaceuticals, fragrances, etc. can be obtained.

Examples

[0050] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0051] Experimental Example 1: Yield of m-isobutyltoluene (MIBT) using different ratios of propylene and m-xylene with a catalyst slurry

[0052]

Table 1

[0053] Referring to Table 1, it is clear that the organic solvent (m-xylene), the catalyst support (K2CO3), and the alkali metal catalyst take on defined forms as discussed in various embodiments of the present disclosure. The recovery rate of the MIBT product is improved when the ratio of m-xylene to propylene is varied with the catalyst slurry. In particular, it was observed that the ratio of the number of moles of m-xylene: the number of moles of propylene was in the range of 0.4 to 0.9. A clear difference was observed in the yield of MIBT. Referring to Example 1, within the range of the ratio of the number of moles of m-xylene: the number of moles of propylene being 0.4 to 0.9, the total yield of MIBT with respect to m-xylene reached 40%.

[0054] Experimental Example 2: Yield of m-isobutyltoluene (MIBT) using different catalyst suspensions and additives

[0055]

Table 2

[0056] In one embodiment of the present disclosure, a predetermined ratio of m-xylene and propylene that improves the yield of the alkylation product of the aromatic hydrocarbon is added to the catalyst slurry.

[0057] In another embodiment of the present disclosure, the method (100) according to the present disclosure may have the following advantages, but is not limited thereto. · Improvement of the MIBT synthesis method. · Improvement in the quality and quantity of the resulting MIBT. · Improvement in product yield, such as MIBT being recovered at a yield of up to 40%.

[0058] Embodiments used in the synthesis of alkylated aromatic hydrocarbons are described in terms of structural features and / or language specific to the process, but it should be understood that the appended claims are not necessarily limited to the specific features or processes described. Rather, the specific features and processes are disclosed as examples of catalyst compositions implemented for the synthesis of alkylated aromatic hydrocarbons.

Claims

1. A method (100) for synthesizing m-isobutyltoluene (MIBT), comprising: adding a predetermined amount of dry m-xylene and potassium carbonate carrier free of moisture to a first reactor to form a slurry mixture (step 101); adding a predetermined molten sodium metal catalyst and a suspending agent to the slurry mixture within a certain period of time (step 102); transferring the slurry mixture containing the sodium metal catalyst to a second reactor (step 103); adding a predetermined amount of propylene and an excess of dry m-xylene free of moisture to the second reactor (step 104); heating the second reactor to a predetermined temperature range and reacting the slurry mixture, the propylene and the m-xylene to obtain a crude MIBT product (step 105); removing the sodium metal catalyst from the crude MIBT and further recovering propane gas by enabling water washing in a neutralization device (step 106); separating an aqueous layer and an organic layer containing the crude MIBT and hydrocarbon by-products in a separation device (step 107); recovering purified MIBT having a purity of 99.9% and a yield of up to 40% by a distillation mechanism (step 108).

2. The method according to claim 1, wherein the molar ratio of the amounts of m-xylene and propylene added to the second reactor in step (104) is 0.2 to 1.

2.

3. The method according to claim 1, wherein the molar ratio of the amounts of the sodium metal catalyst, the potassium carbonate and the suspending agent is 7:50:1 to 9:60:

1.

4. The method according to claim 1, wherein the sodium metal catalyst is added within the range of 20 minutes to 1 hour.

5. The method according to claim 1, wherein the second reactor is heated to a temperature range of 180 to 220 °C.

6. The method according to claim 1, wherein the propane gas is recovered from the neutralization device through a gas holder to public facilities.

7. The method according to claim 1, wherein the suspending agent is selected from fatty acids such as oleic acid, tall oil, stearic acid.

8. The method according to claim 1, wherein the initial water content of the m-xylene before drying is in the range of 100 to 125 PPM.

9. The method according to claim 1, wherein the water contained in the m-xylene is removed by a vacuum dryer equipped with a molecular sieve adsorber having a controlled flow rate, and the dried m-xylene is obtained.

10. The method according to claim 1, wherein the potassium carbonate is in the form of a pulverized powder.

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