KR102482504B1 - Method for the preparation of t-butyl methacrylate - Google Patents

Abstract

The present invention relates to a method for producing t-butyl methacrylate, and a solution containing t-butyl methacrylate and a solution containing unreacted methacrylic acid by adding water during the manufacturing process of t-butyl methacrylate By including a step of separating the target product, t-butyl methacrylate, and methacrylic acid, a reactant that can be recycled, in high purity and high efficiency, can be obtained and recovered, and furthermore, by-products that form azeotropes with methacrylic acid can also be separated, making it easy to purify each of t-butyl methacrylate and methacrylic acid.

Description

Method for preparing t-butyl methacrylate {Method for the preparation of t-butyl methacrylate}

The present invention relates to a process for preparing t-butyl methacrylate.

t-Butyl methacrylate is widely used as a starting material for polymers used in various industrial fields such as adhesives, coating resins or paint dispersions. Such t-butyl methacrylate is not easy to synthesize through the esterification method of acid and alcohol, which is a method of synthesizing a general ester compound, or the transesterification method, so addition of methacrylic acid and isobutylene is usually performed using a strong acid catalyst. A method of synthesis by reaction has been used, and the method is disclosed in US Patent Registration No. 3031495 and US Patent Registration No. 3082246.

In addition, as an acid catalyst, a homogeneous catalyst such as sulfuric acid may be used as described above, but in addition, soluble acids such as mineral acids, alkyl sulfonic acids, aryl sulfonic acids, or insoluble catalysts such as sulfonic acid group-containing ion exchange resins may be used. Methods of doing so have also been proposed.

The synthesis method specifically reacts methacrylic acid and isobutylene under strong acid conditions to prepare a mixed solution containing a product and unreacted methacrylic acid, and distills the mixed solution through a distillation process using a difference in boiling point to obtain the final product, t- It goes through a step of separating and purifying butyl methacrylate, unreacted methacrylic acid, and impurities, and at this time, unreacted methacrylic acid can be recycled back to the reaction system for use.

However, in addition to t-butyl methacrylate, which is a product in the reaction process of synthesizing t-butyl methacrylate using a conventional synthesis method, diisobutylene (DIBs) and triisobutylene (TIBs) are used as by-products. There is a problem in that a lot of isobutylene oligomers such as ) are produced. In particular, triisobutylene has a higher boiling point than the target product t-butyl methacrylate, but since it forms an azeotrope with unreacted methacrylic acid, the distillation process is required. It is not easy to separate even if passed through, which causes a problem in that the yield and recovery of t-butyl methacrylate and methacrylic acid are lowered. That is, when the distillation process is applied to the mixed solution, when trying to increase the purity and yield of t-butyl methacrylate, which is a reaction product, the purity of methacrylic acid to be recycled to the reactor may decrease or the recovery rate may decrease, and conversely, methacrylic acid In order to increase the purity and recovery rate of the acid, the content of by-products such as methacrylic acid and triisobutylene in the product t-butyl methacrylate increases, resulting in low purity or low yield.

Among them, when the recovery rate of methacrylic acid is increased, as described above, methacrylic acid in t-butyl methacrylate may increase, and the increase in methacrylic acid in t-butyl methacrylate may increase the acid content (Acid content) can lead to problems.

In addition, when the yield of t-butyl methacrylate is increased, the content of triisobutylene in methacrylic acid to be recycled to the reactor may increase as described above, and the content of impurities in methacrylic acid to be recycled to the reactor In order to lower it, a process for removing the triisobutylene may be additionally introduced. However, since the triisobutylene removal process requires high temperature conditions, when the triisobutylene removal process is performed, the time for methacrylic acid to be exposed to high temperatures may be prolonged, and thus, even in the presence of a polymerization inhibitor During the distillation process, a problem in which polymers of methacrylic acid are produced may occur. When methacrylic acid is polymerized, it not only reduces the recovery rate of methacrylic acid to be recycled to the reactor, but also causes problems such as contamination of distillation column conduits, pumps, columns, etc., polymer deposits with scale and blockage, and coating of distillation column trays. can In addition, when the concentration of triisobutylene in methacrylic acid increases, methacrylic acid is lost due to azeotrope in the methacrylic acid purification process.

As such, the conventional synthesis method causes a large amount of loss in the process of recovering the target product and unreacted material after the reaction, and may contaminate the distillation tower device, resulting in a decrease in the efficiency of the manufacturing process of t-butyl methacrylate, In terms of cost, there is also a problem of high cost.

Therefore, it solves the above problems and facilitates the separation of the target product t-butyl methacrylate and unreacted methacrylic acid after the reaction to recover high-purity t-butyl methacrylate and methacrylic acid with high efficiency, respectively There is a need for research on how to do this.

US 3031495A US 3082246A

The present invention has been made to solve the problems of the prior art, and in the process of preparing t-butyl methacrylate, the target product t-butyl methacrylate and unreacted methacrylic acid are easily separated to obtain high purity t - To provide a method for producing t-butyl methacrylate capable of recovering butyl methacrylate and methacrylic acid with high efficiency.

The present invention is to solve the above problems, 1) reacting isobutylene and methacrylic acid under acidic conditions to produce a crude product containing t-butyl methacrylate, isobutylene oligomer, and methacrylic acid obtaining; 2) adding water to the crude product to separate the crude product into an aqueous layer and an organic layer; And 3) distilling the organic layer to obtain t-butyl methacrylate; provides a method for producing t-butyl methacrylate that includes.

In the method for producing t-butyl methacrylate of the present invention, isobutylene and methacrylic acid are reacted to produce a crude product, and then water is added before distillation to separate the crude product into an aqueous layer and an organic layer. As a result, the mixture of the organic layer containing t-butyl methacrylate and triisobutylene and the mixture of the aqueous layer containing methacrylic acid can be subjected to a distillation process separately, thereby reducing the amount of loss of the target product and the reactant can be minimized, and high-purity t-butyl methacrylate (target product) and methacrylic acid (unreacted material to be recycled) can be recovered with high efficiency. In addition, since the amount of loss of the target product and the reactant can be minimized as described above, there is an effect of improving efficiency in the manufacturing process, and there is an effect of reducing manufacturing cost in terms of economy.

In addition, according to the production method of the present invention, the content of methacrylic acid in t-butyl methacrylate is low, so the acid concentration of t-butyl methacrylate (target product) can be minimized, and mixed with methacrylic acid Since the content of isobutylene oligomers such as triisobutylene and diisobutylene is low, there is no need to add a by-product removal process such as triisobutylene when refining methacrylic acid, reducing the time exposed to high temperatures in the distillation process. Polymerization of acrylic acid can be prevented.

1 is a diagram schematically showing steps 2) to 3) according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

Terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

The present invention provides a method for producing t-butyl methacrylate capable of obtaining or recovering high-purity t-butyl methacrylate and high-purity methacrylic acid with high efficiency. , preferably by a continuous method. When the production method of the present invention is performed according to a continuous method, process efficiency can be further improved by recycling unreacted methacrylic acid to the reactor to participate in the reaction again.

The method for producing t-butyl methacrylate according to an embodiment of the present invention,

1) reacting isobutylene with methacrylic acid under acidic conditions to obtain a crude product containing t-butyl methacrylate, isobutylene oligomer and methacrylic acid;

2) adding water to the crude product to separate the crude product into an aqueous layer and an organic layer; and

3) distilling the organic layer to obtain t-butyl methacrylate;

includes

Hereinafter, each step will be described in detail.

Step 1)

Step 1) of the present invention is a step of reacting isobutylene with methacrylic acid under acidic conditions to obtain a crude product containing t-butyl methacrylate, isobutylene oligomer, and methacrylic acid, A crude product containing the desired product, t-butyl methacrylate, can be obtained by the addition reaction of methacrylic acid.

In the present invention, 'isobutylene' may mean isobutylene in monomeric form unless specifically described as 'isobutylene oligomer' or 'isobutylene polymer'.

The reaction of methacrylic acid and isobutylene according to an embodiment of the present invention may be performed by a conventionally known reaction, and for example, the reaction may be performed with a liquid phase, or a gaseous and liquid reactant.

The acidic condition in step 1) may be created using an acid catalyst or an acidic ion exchange resin. In this case, the acid catalyst is not particularly limited, but examples include inorganic or organic strong acids such as sulfuric acid, phosphoric acid, and polyphosphoric acid. , sulfonic acid, aryl sulfonic acids such as p-toluene sulfonic acid and benzene sulfonic acid, alkyl sulfonic acids such as dodecyl benzene sulfonic acid and methane sulfonic acid, or mixtures thereof, and when acidic ion exchange resins are applied It is not particularly limited as long as it is a porous resin with a large surface area in order to obtain an appropriate reaction rate, but, for example, an ion exchange resin containing a sulfonic acid group can be applied. The ion exchange resin is not particularly limited, such as a dry type or a water-containing type, and may be used after dehydration in order to improve the yield of the reaction product. A known method may be used as the dehydration method, and for example, a method of heating under reduced pressure, a method of azeotropic dehydration using a hydrocarbon-based solvent, or a method of washing with a polar solvent may be applied, but is not limited thereto, Any method capable of effectively lowering the water content of the ion exchange resin is possible.

The acidic conditions formed in step 1) of the present invention may be specifically an environment in which the pH in the reactor is 1 to 3, and the reactivity of methacrylic acid and isobutylene is maximized under the above pH conditions to improve reaction efficiency. .

In addition, in step 1), a solvent may be further added as needed, and at this time, the solvent has excellent compatibility with methacrylic acid and isobutylene, and furthermore, their reaction products, and future reaction products and unreacted materials. It is preferable not to affect the purification, and the reaction product itself can also be used as a solvent. The solvent is not particularly limited, but for example, a low boiling point solvent such as n-hexane, benzene, chloroform, and methylene chloride, and a high boiling point solvent such as isopropyl benzene, diethyl benzene, and amyl benzene may be used. When a solvent is further added in step 1), the reactants can be more uniformly mixed and the reaction can be smoothly performed, and the solidification point of the reactants can be lowered, so that the reaction can be easily performed by preventing the solidification of the reactants even under low temperature conditions. In addition, it is easy to remove the reaction heat, so that the selectivity of the reaction product can be improved.

In addition, according to an embodiment of the present invention, the isobutylene and methacrylic acid may be added at a weight ratio of 1:5 to 1:20 (isobutylene:methacrylic acid) to proceed with the reaction. When the weight ratio of isobutylene is lower than the above range, the content of isobutylene as a reactant is too small, and the absolute amount of t-butyl methacrylate crude product produced as a reaction product is reduced, and the weight ratio of isobutylene is greater than the above range. If the reaction ratio between isobutylene is high, the selectivity of the reaction product may decrease, and the conversion rate of the reactant may decrease due to the increase in unreacted methacrylic acid.

In addition, step 1) may be performed at a temperature of -20 to 50 °C, preferably -10 to 20 °C, and the reaction time may be 0.1 to 6 hours, preferably 0.2 to 4 hours. During the reaction, the reaction may be freely performed under any conditions such as normal pressure, reduced pressure, or overpressure, but may preferably be overpressure. Here, the overpressure may specifically mean a pressure exceeding normal pressure (1 atm). In the above step 1) of the present invention, the reaction efficiency can be improved under the above reaction conditions.

In addition, according to one embodiment of the present invention, in order to avoid or reduce the polymerization of methacrylic acid or t-butyl methacrylate, if necessary, a polymerization inhibitor may be additionally added to carry out the polymerization in the presence of a polymerization inhibitor, and the polymerization Inhibitors include, for example, hydroquinone, hydroquinone monomethyl ether, p-benzoquinone, p-nitrosophenol, phenothiazine, N-oxyl compounds, 4-hydroxy-2,2,6,6-tetramethyl-1 -Oxyl-piperidine and methylene blue may be used.

After the reaction of step 1), a crude product can be obtained. As described above, the crude product is derived from t-butyl methacrylate (TBMA), which is a target color, and isobutylene (IB), which is a by-product. It may include isobutylene oligomer (IB oligomer) and methacrylic acid (MAA), which is a kind of unreacted material that did not participate in the reaction of step 1). Among them, the isobutylene oligomer may include, for example, diisobutylene (DIBs), triisobutylene (TIBs), or a mixture thereof. In addition to the above compounds, t-butanol may be produced as a by-product and included in the crude product, and methacrylic acid and isobutylene may also be included in the crude product as unreacted substances not participating in step 1).

Step 2)

Step 2) according to an embodiment of the present invention is a step of adding water to the crude product to separate the crude product into an aqueous layer and an organic layer. Specifically, step 2) is to add water to the crude product, Stirring and standing still to separate the aqueous layer and the organic layer, thereby separating the aqueous layer and the organic layer.

In the present invention, step 2) may be to extract methacrylic acid mixed in the aqueous layer from the crude product and simultaneously extract t-butyl methacrylate mixed in the organic layer.

In this specification, extraction refers to a method of dissolving and separating a specific component in a solid or liquid mixture using a liquid solvent.

According to an embodiment of the present invention, when step 2) is performed before the distillation process for purification, the solution containing methacrylic acid and the solution containing t-butyl methacrylate, the target product, are separated and then individually It may undergo a distillation process, and in this case, the water of step 2) may be applied as an extraction solvent for extracting methacrylic acid.

Furthermore, by-products such as triisobutylene, which formed an azeotrope with methacrylic acid and were not easy to purify when the distillation process was applied, are also included in the organic layer of the crude product containing t-butyl methacrylate, so in step 2) It can be separated from the aqueous layer containing methacrylic acid. Accordingly, unlike when the crude product is directly subjected to a distillation process, it is possible to solve the problem of forming an azeotrope with methacrylic acid, so there is an advantage in that the recovery rate of high-purity methacrylic acid can be increased by effective purification.

According to one embodiment of the present invention, a basic compound may be further added in step 2), and specifically, in step 2), water and a basic compound are added to the crude product to separate the crude product into an aqueous layer and an organic layer. It can be done by doing When a basic compound is added together with water, a basic aqueous medium can be formed, so an optimal pH can be formed in terms of the solubility of methacrylic acid in water, and thus the solubility of methacrylic acid can be further increased, so that the extraction efficiency is improved. can be improved In addition, since the amount of water added can be reduced as the extraction efficiency is improved, there is an effect of reducing manufacturing cost.

Here, the basic compound is not particularly limited as long as it is a compound that can increase the pH of water, and examples thereof include sodium hydroxide (NaOH), lithium hydroxide (LiOH), sodium hydrogen carbonate (NaHCO ₃ ), ammonia water (NH ₄ OH), Potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), barium hydroxide (Ba(OH) ₂ ), sodium carbonate (Na ₂ CO ₃ ), magnesium hydroxide (Mg(OH) ₂ ), and amine-type basic compounds such as At least one compound selected from the group consisting of ethylamine (TEA)) may be used.

When the basic compound is further added, the pH of the crude product to which the water and the basic compound are added may be 8 to 14, preferably 12 to 14. Under the above pH condition, the solubility of methacrylic acid in water is maximized, so that the extraction efficiency can be further improved.

In addition, the basic compound may be added in an amount such that the molar ratio (basic compound:methacrylic acid) with methacrylic acid included in the crude product is 0.5:1 to 5.0:1. That is, the molar ratio of the basic compound and methacrylic acid contained in the crude product may be 0.5:1 to 5.0:1, preferably 0.5:1 to 3.0:1, more preferably 1:1 to 5.0:1. It may be 2:1. When the above molar ratio is satisfied, an optimal pH at which the solubility of methacrylic acid can be improved can be formed, which has the effect of further improving extraction efficiency. When the molar ratio of the basic compound and methacrylic acid contained in the crude product is low, the extraction efficiency may be further improved by repeating the number of extractions.

In addition, in step 2), water may be added in an amount of 1 to 30 volume ratio based on 1 volume ratio of the crude product, preferably 8 to 25 volume ratio, and more preferably 10 to 20 volume ratio. It may be added in quantity.

In step 2), when water is added at a volume ratio of less than 1 outside the volume ratio, the amount of water added is too small to sufficiently dissolve methacrylic acid present in the crude product. Problems in the extraction efficiency of methacrylic acid may occur, such as that the ratio of methacrylic acid and methacrylic acid in the organic layer may be at an equal level or the content ratio of methacrylic acid in the aqueous layer may be lower. In addition, when the amount of water added exceeds 30 volume ratio, an excess amount of water is added in excess of the amount in which methacrylic acid can be sufficiently dissolved, which is inefficient, and included in the water layer when performing the distillation process described later for purifying methacrylic acid In order to remove the excessive amount of water, a longer purification time and higher purification costs may occur. That is, a problem of reducing the efficiency of the entire manufacturing process may occur.

In addition, step 2) may be performed at a temperature of 1 to 90 °C, preferably 1 to 60 °C, and more preferably 10 to 45 °C. If the temperature exceeds 90 ℃, it is close to the boiling point of water applied as an extraction solvent, or higher than the boiling point of water, so that water vaporizes, which may cause a problem that it is impossible to dissolve methacrylic acid and extract it, and less than 1 ℃ In the case of solidification lower than the freezing point of water, a problem may occur in which the operation of extracting methacrylic acid becomes impossible. Therefore, when the above numerical range is appropriate, and the preferred numerical range is satisfied, the extraction efficiency is further improved.

On the other hand, the crude product is separated into an aqueous layer and an organic layer by adding water, stirring for 0.5 to 4 hours, and then allowing to stand for 0.5 to 6 hours, and then separating the aqueous layer and organic layer of the crude product. can

At this time, by adding water and mixing through stirring, the compatibility of water and methacrylic acid is improved, and extraction efficiency may be improved, such as increasing the content ratio of methacrylic acid included in the water layer after layer separation. In addition, it is preferable to satisfy the stirring time and stationary time in terms of process efficiency and extraction efficiency.

In addition, the separating step of step 2) may be a step of separating the aqueous layer and the organic layer of the crude product in which the layers are separated through a liquid-liquid separation process. The separation process may be applied without limitation as long as it is a method capable of separating liquid-liquid in general.

In the present invention, the aqueous layer of the crude product may be a solution containing methacrylic acid having excellent compatibility with water, and may include, for example, a large amount of methacrylic acid and a small amount of t-butanol. In addition, the organic layer of the crude product may be a solution containing a large amount of t-butyl methacrylate as the target product and by-products, for example, t-butyl methacrylate and diisobutylene, triisobutylene, etc. An isobutylene oligomer may be included, and a small amount of t-butanol may also be included.

In step 2), by subjecting the aqueous layer and the organic layer to a separation process, the purification efficiency is significantly improved when the water layer and the organic layer are purified through distillation processes, respectively, as in step 3) described later, and high-purity t-butyl methacrylate and Methacrylic acid can be recovered with a high recovery rate.

The schematic steps and each process of the present invention are also shown in FIG. Specifically, the leftmost compounds in FIG. 1 represent the crude product prepared by the reaction of step 1), and when water is added to the crude product, an aqueous layer containing methacrylic acid and t-butanol and t-butyl Layer separation is performed into an organic layer containing methacrylate, isobutylene oligomer, t-butanol, unreacted methacrylic acid, and isobutylene (refer to the intermediate step of FIG. 1). Subsequently, as in step 3) to be described later, the aqueous layer and the organic layer may be subjected to distillation or additional extraction and distillation, respectively, to recover high-purity t-butyl methacrylate and methacrylic acid with high efficiency.

step 3)

Step 3) according to an embodiment of the present invention may be a step of obtaining t-butyl methacrylate by distilling the organic layer of the crude product, and specifically, t-butyl from the organic layer of the crude product through a distillation process. It may be a process of purifying methacrylate.

The distillation method of step 3) can be applied without limitation as long as it is a method known in the field of t-butyl methacrylate production, and for example, it can be introduced into a distillation column to perform distillation under conditions of high temperature and low pressure. The distillation conditions are not particularly limited as long as t-butyl methacrylate can be obtained in optimum yield, but for example, as an upper operating condition of the distillation column, a temperature of 50 to 150 ° C., a pressure range of 4.0 to 101.3 kPa, and a distillation column It may be carried out at a temperature of 80 to 161 ° C. and a pressure range of 4.0 to 101.3 kPa as a lower operating condition.

The bottom liquid generated through the distillation process can substantially obtain t-butyl methacrylate and high-boiling components, and in some cases, through repeated distillation processes, the yield and / or purity can be increased.

In addition, the distillation column that can be applied in the present invention is not particularly limited, and is, for example, a packing column type filled with fillers such as Heripak, Magma Horn, and Cascade mini-ring, or a tray column having trays. A type may be applied, and at this time, as the tray, a sieve tray, a valve tray, a bubble cap tray, a dual flow tray, and the like may be applied.

Step 3a)

According to one embodiment of the present invention, the present invention may further include step 3a) performed after step 2), and step 3a) separates methacrylic acid from the water layer of the crude product after step 2) As a step of recycling to step 1), specifically, the water layer of the crude product may be distilled to recover methacrylic acid, and the recovered methacrylic acid may be recycled to step 1).

The methacrylic acid separation method of step 3a) may preferably apply a distillation process, and in this case, the distillation method described above in step 3) may be equally applied, and the distillation conditions are, for example, the top of the distillation column. It may be carried out at a temperature of 30 to 100 ° C., a pressure range of 4.0 to 101.3 kPa as a standard, and a temperature of 80 to 161 ° C., a pressure range of 4.0 to 101.3 kPa as a lower standard.

The order of step 3) and step 3a) is not particularly limited as long as it is after step 2), and step 3) and step 3a) can be performed simultaneously, and in the case of simultaneous distillation in independent distillation columns, respectively This may be performed, and step 3a) may be performed after step 3) or before step 3). The sequence of the steps may be appropriately selected and performed during the process.

In addition, the aqueous layer of the crude product containing methacrylic acid in step 3a) is not directly distilled as in step 3a-1) to increase the purity of methacrylic acid, but additionally extracted after A distillation process may be performed.

In the case of undergoing an additional extraction process, step 3a) may specifically include: 3a-1) adding a hydrocarbon solvent to the aqueous layer to separate the aqueous layer into a water-soluble fraction and an organic fraction; and 3a-2) distilling the organic fraction to obtain methacrylic acid, and recycling the obtained methacrylic acid to step 1). In the case of using a basic compound in step 2), an acid is added to the aqueous layer to adjust the pH in the range of 1 to 5, followed by extraction with a hydrocarbon solvent.

In addition, step 3a-1) is more specifically a step of adding a hydrocarbon solvent to the aqueous layer, stirring, and then allowing the aqueous layer of the crude product to separate into a water-soluble fraction and an organic fraction; It may consist of a step of separating the water-soluble fraction and the organic fraction formed, and in step 3a-2), more specifically, the water-soluble fraction is removed, and the organic fraction is distilled to recover methacrylic acid and recycled to the step 1). steps may be included. In addition, the above step 3a-1) may be performed at least once, and being performed repeatedly is also included in the scope of the present invention. In addition, when step 3a-1) is repeatedly performed, it may be repeatedly performed on an organic fraction containing methacrylic acid among the separated water-soluble fraction and organic fraction.

Here, the hydrocarbon solvent is not particularly limited as long as it is a solvent capable of dissolving methacrylic acid, but pentane, hexane, heptane, octane and nonane may be used as an example.

As in steps 3a-1) and 3a-2), the extraction efficiency of methacrylic acid is further improved by additionally performing an additional extraction process targeting the aqueous layer of the crude product at least once, thereby producing high-purity methacrylic acid with high efficiency. There is an effect that can be recovered, and in some cases, the entire amount of methacrylic acid can be completely extracted, so there is an advantage that very high purity methacrylic acid can be recovered with high efficiency.

The distillation method of step 3a-2) may be performed by the same distillation method as the distillation method described above in step 3), and the distillation conditions are, for example, a temperature of 34 to 151 ° C. and a pressure range of 4.0 to 101.3 kPa based on the upper part. And it may be carried out at a temperature of 80 to 161 ° C. and a pressure range of 4.0 to 101.3 kPa on a lower basis.

Example

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In the following Examples and Comparative Examples, the distillation process according to the present invention was simulated using a commercial process simulation program, ASPEN PLUS. The distillation column used in the simulation was a dual flow tray, and was carried out under the theoretical number of 20 stages and the temperature and pressure conditions described later.

Preparation Example 1

a) Preparation of crude t-butyl methacrylate

Reaction at 8℃ by continuously adding isobutylene and methacrylic acid at a weight ratio of 1:9 to a temperature-controllable double-tube reactor filled with cation exchange resin (Purolite, CT-251) containing a sulfonic acid group The reaction was performed at a temperature and a reaction pressure of 3 kPa (3 ± 1 kPa) with a space residence time of 30 minutes.

b) Separation of crude t-butyl methacrylate

100 ml of water was added to 100 ml of the prepared curde t-butyl methacrylate (crude product), stirred at a temperature of 20 ° C for 1 hour, and then allowed to stand for 1 hour while maintaining the same temperature to separate the aqueous layer and the organic layer. A t-butyl methacrylate solution was prepared. At this time, the t-butyl methacrylate solution is a solution containing both unreacted methacrylic acid and reaction by-products as well as t-butyl methacrylate.

Preparation Example 2

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 1, except that water was added, stirred and allowed to stand at a temperature of 30 °C.

Preparation Example 3

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 1, except that water was added, stirred and allowed to stand at a temperature of 40 °C.

Production Example 4

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 1, except that 500 ml of water was added, and the mixture was stirred and allowed to stand at a temperature of 30 °C.

Preparation Example 5

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 1, except that 1000 ml of water was added.

Preparation Example 6

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 5, except for stirring and standing at a temperature of 30 °C.

Preparation Example 7

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 5, except for stirring and standing at a temperature of 40 °C.

Preparation Example 8

When water was added in Preparation Example 5, the NaOH solution was added in an amount such that the molar ratio of NaOH to methacrylic acid in the crude product prepared after the reaction was 1: 1, in the same manner as t -A butyl methacrylate solution was prepared.

Preparation Example 9

A t-butyl methacrylate solution was prepared in the same manner as in Preparation Example 1, except that 2000 ml of water was added.

Comparative Preparation Example 1

Crude t-butyl methacrylate was prepared in the same manner as in Preparation Example 1 except for omitting step b).

Experimental Example 1: Extraction rate of methacrylic acid (MAA)

The weight of methacrylic acid present in the aqueous layer of the t-butyl methacrylate solutions prepared in Preparation Examples 1 to 9 was measured under the measurement conditions of Table 1 with Agilent's 7890B Gas Chromatography, and the extraction rate of methacrylic acid was It was calculated by the formula and shown in Table 2 below.

Oven Equilibration Time: 1.0 min
# Rate(℃/min) Final Temp.(℃) Hold Time(min) Final Time
Initial 40 6.0 6.0
Ramp 1 10.0 70 1.6 10.6
Ramp 2 25.0 200 5.0 22.0
Off Inlet Mode: Split(10:1)
Heater: 230 ℃
Pressure: 11.541 psi Column HP-INNOWax (19095N-126, 60 m x 530 μm x 1 μm)
Flow: 10 mL/min
Mode: Constant Flow Detector(FID) Heater: 260 ℃
Air Flow: 350 mL/min
H2 Fuel Flow: 35 mL/min
Makeup Flow (Conbined): 25 mL/min
Mode: Column + Makeup = Constant
Makeup Gas Type: He Injector Sample Volume: 10 µL
Syringe Size: 0.2 μL

[Equation 1]

*Crude TBMA: Crude t-butyl methacrylate

*MAA: methacrylic acid

Temperature when stirring and standing after adding water (℃) Crude TBMA: Water Volume Ratio Addition of basic compound MAA extraction rate (%) Preparation Example 1 20 1:1 X 12.0 Preparation Example 2 30 1:1 X 17.8 Preparation Example 3 40 1:1 X 23.5 Preparation Example 4 30 1:5 X 46.0 Preparation Example 5 20 1:10 X 77.7 Preparation Example 6 30 1:10 X 78.3 Preparation Example 7 40 1:10 X 79.0 Preparation Example 8 20 1:10 ○ 99.0 Preparation Example 9 20 1:20 X 91.8 Comparative Preparation Example 1 - - X -

As shown in Table 2 above, before distilling crude t-butyl methacrylate, water may be added to separate t-butyl methacrylate and methacrylic acid, at which time the basic compound is mixed with water It can be seen that the extraction rate of methacrylic acid is excellent compared to the rest of Preparation Examples in which Preparation Example 8 is added and is not added, and it can be confirmed that the extraction rate of methacrylic acid is improved as the volume ratio of water increases.

Examples 1 to 7 and Example 9

The water layer of the t-butyl methacrylate solutions of Preparation Examples 1 to 7 and Preparation Example 9 was separated to simulate the distillation process under conditions of a temperature of 30 ° C and a pressure of 4 kPa at the top of the distillation column, a temperature at the bottom of the distillation column of 105 ° C and a pressure of 12 kPa It was carried out, and the organic layer of the t-butyl methacrylate solutions of Preparation Examples 1 to 7 and 9 was separated to obtain a component with a low boiling point (iso butylene, isobutylene oligomer, t-butanol, etc.) are removed, and t-butyl methacrylate is recovered by distillation under conditions of a temperature of 50.3 ° C. and a pressure of 4.0 kPa at the top of the distillation column, a temperature at the bottom of the distillation column at 99 ° C. and a pressure of 12.0 kPa, , The process of recovering the methacrylic acid remaining in the organic layer under conditions of a temperature of 41 ° C and a pressure of 10.6 kPa at the top of the distillation column, a temperature at the bottom of the distillation column of 99 ° C and a pressure of 10.6 kPa was performed by simulation, and the final result of t-butyl methacrylate and methacrylic acid was obtained. The purity is 99.8% and 99.9%, respectively.

Example 8

The water layer in the t-butyl methacrylate solution of Preparation Example 8 was separated, and the distillation process was simulated under conditions of a temperature of 30 ° C and a pressure of 4.0 kPa at the top of the distillation column, a temperature at the bottom of the distillation column of 105 ° C and a pressure of 12 kPa. In the t-butyl methacrylate solution of 8, the organic layer was separated to obtain components with low boiling points (isobutylene, isobutylene oligomer, t- butanol, etc.) and recovering t-butyl methacrylate by distillation under conditions of a temperature of 50.3 ° C and 4.0 kPa at the top of the distillation tower, a temperature at the bottom of the distillation column of 106.3 ° C and a pressure of 12.0 kPa, and a process of recovering t-butyl methacrylate was performed by simulation, and t-butyl methacrylate The final purity of and methacrylic acid is 99.8% and 99.9%, respectively.

In the case of Example 8, the extraction rate of methacrylic acid in the aqueous layer was remarkably high, and a separate distillation process for additionally recovering methacrylic acid in the organic layer was not performed.

Comparative Example 1

Crude t-butyl methacrylate prepared in Comparative Preparation Example 1 was prepared under the condition that the temperature at the top of the distillation column was 18.7 ° C. and the pressure was 8.0 kPa, and the temperature at the bottom of the distillation column was 93 ° C. and the pressure was 10.6 kPa. butylene oligomer, t-butanol, etc.) is removed, and t-butyl methacrylate is recovered by distillation under conditions of a temperature of 50.3° C. and a pressure of 4.0 kPa at the top of the distillation column, a temperature at the bottom of the distillation column at 99° C. and a pressure of 12.0 kPa, and methacrylic acid is recovered from the distillation column. The distillation process under conditions of an upper temperature of 41 ° C and a pressure of 10.6 kPa, a lower temperature of 99 ° C and a pressure of 10.6 kPa was simulated, and the final purities of t-butyl methacrylate and methacrylic acid were 99.8% and 99.9%, respectively.

Experimental Example 2: Recovery of methacrylic acid (MAA) and t-butyl methacrylate (TBMA)

The recoveries of t-butyl methacrylate and methacrylic acid after performing the distillation process in Examples 1 to 9 and Comparative Example 1 were calculated by Equations 2 and 3 below, respectively, and are shown in Table 3 below.

In Equations 2 and 3 below, the weights of MAA and TBMA were determined by the above-mentioned organic layer, aqueous layer, t-butyl methacrylate after purification and methacrylic acid after purification by the analysis method of Table 1 using Agilent's 7890B Gas Chromatography. It was calculated by quantification.

[Equation 2]

[Equation 3]

Temperature when stirring and standing after adding water (℃) Crude TBMA: Water Volume Ratio Addition of basic compound MAA recovery rate (%) TBMA recovery rate (%) Example 1 20 1:1 X 94.88 94.64 Example 2 30 1:1 X 95.41 96.30 Example 3 40 1:1 X 95.82 97.17 Example 4 30 1:5 X 95.38 96.20 Example 5 20 1:10 X 96.95 98.47 Example 6 30 1:10 X 96.98 98.50 Example 7 40 1:10 X 97.01 98.52 Example 8 20 1:10 ○ 98.00 98.97 Example 9 20 1:20 X 97.64 98.85 Comparative Example 1 - - X 93.10 78.80

As shown in Table 3, prior to distillation and purification of crude t-butyl methacrylate, water was added to first separate t-butyl methacrylate and methacrylic acid, followed by distillation and purification, respectively. Example 1 It can be seen that the recoveries of methacrylic acid (MAA) and t-butyl methacrylate (TBMA) are remarkably excellent compared to Comparative Example 1 in which the to 9 did not undergo the process of adding water.

Furthermore, referring to Examples 1 to 3, it can be confirmed that the recovery rate of MAA and TBMA increases as the temperature when stirring and standing still under the same conditions, that is, the extraction temperature of MAA increases, and Examples 2, 4, 6 and 9 Referring to, it can be confirmed that the recovery rate of MAA and TBMA increases when the volume ratio of the added water is high.

In addition, it can be confirmed that the recovery rate of MAA and TBMA is higher in Example 8, in which the basic compound is added, compared to other Examples and Comparative Examples in which the basic compound is not added.

Claims (10)

1) reacting isobutylene with methacrylic acid under acidic conditions to obtain a crude product containing t-butyl methacrylate, isobutylene oligomer and methacrylic acid;
2) adding water to the crude product to separate the crude product into an aqueous layer and an organic layer; and
3) distilling the organic layer to obtain t-butyl methacrylate;
A method for producing t-butyl methacrylate in which a basic compound is further added in step 2).
delete According to claim 1,
The molar ratio of the basic compound and methacrylic acid in the crude product (basic compound: methacrylic acid) is 0.5: 1 to 5.0: 1. Method for producing t-butyl methacrylate.
According to claim 1,
The basic compound is sodium hydroxide (NaOH), lithium hydroxide (LiOH), sodium hydrogen carbonate (NaHCO ₃ ), ammonia water (NH ₄ OH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), barium hydroxide (Ba (OH) ₂ ), sodium carbonate (Na ₂ CO ₃ ), magnesium hydroxide (Mg (OH) ₂ ) and at least one compound selected from the group consisting of amine basic compounds Preparation of t-butyl methacrylate method.
According to claim 1,
The isobutylene oligomer is a method for producing t-butyl methacrylate comprising at least one of diisobutylene and triisobutylene.
According to claim 1,
In step 2), the water is added in an amount of 1.0 to 30.0 volume ratio based on 1 volume ratio of the crude product.
According to claim 1,
In step 2), the water is added in an amount of 8.0 to 25.0 volume ratio based on 1 volume ratio of the crude product.
According to claim 1,
The step 2) is a method for producing t-butyl methacrylate that is carried out at a temperature of 1 to 90 ℃.
According to claim 1,
After step 2) above,
3a) separating methacrylic acid from the aqueous layer and recycling it to step 1); a method for producing t-butyl methacrylate that further comprises.
According to claim 9,
In step 3a),
3a-1) adding a hydrocarbon solvent to the aqueous layer to separate the aqueous layer into a water-soluble fraction and an organic fraction; and
3a-2) distilling the organic fraction to obtain methacrylic acid, and recycling the obtained methacrylic acid to step 1).

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