WO2005040088A1

WO2005040088A1 - Method for producing (meth)acrylic ester

Info

Publication number: WO2005040088A1
Application number: PCT/JP2003/013602
Authority: WO
Inventors: Satomi Sugano; Shuhei Otsuka; Akira Ogawa
Original assignee: Mitsubishi Rayon Co., Ltd.
Priority date: 2003-10-24
Filing date: 2003-10-24
Publication date: 2005-05-06

Abstract

A method for producing a (meth)acrylic ester wherein the (meth)acrylic ester is produced through the transesterification reaction of another (meth)acrylic ester with an alcohol, characterized in that it comprises pressurizing the gas phase in a reactor with an oxygen-containing gas, to thereby carry out the transesterification reaction in a reaction mixture containing the another (meth)acrylic ester, the alcohol and dissolved oxygen. The method allows more effective inhibition of the polymerization of a (meth)acrylic ester, resulting in the production of the objective (meth)acrylic ester with improved selectivity.

Description

Specification

(Meth) Acrylic ester production method

The present invention relates to a method for producing a (meth) acrylate by a transesterification reaction. Background art

Conventionally, a method for producing a (meth) acrylic ester of an alcohol by a transesterification reaction between the (meth) acrylic ester and the alcohol has been known, and many proposals have been made.

For example, Japanese Patent Application Laid-Open No. 57-93930 discloses a method for producing methyl acrylate using an inorganic weak acid salt of an alkali metal (such as a carbonate) as a transesterification catalyst. I have. This catalyst is described in the same publication as having high catalytic activity and low side reactions. The publication also states that the transesterification is carried out under normal pressure or reduced pressure.

Japanese Patent Application Laid-Open No. 6-256620 describes that, during the production of a (meth) acrylic acid ester, Z and the remaining by-products are recovered by distillation and added to the next reaction. A method for producing an acrylate ester is disclosed. According to the publication, it is possible to suppress the generation of by-products and improve the selectivity of raw materials to products. In this publication, the transesterification reaction is performed under a reduced pressure of 300 Torr.

JP-A-3-118352 also discloses that in a transesterification reaction between a (meth) acrylic acid ester and a dialkylamino alcohol, a saturated hydrocarbon which is inert to the reaction is converted to a by-product alcohol. The reaction is carried out under pressurized conditions (usually at a pressure of 1.5 to 4.0 atm) while removing the azeotrope of by-product alcohol and azeotropic agent from the system using a distillation column. A method for producing an acrylic monomer is disclosed. The In this method, the gas phase during the reaction is occupied by by-product alcohol, azeotropic agent, raw material ester, and raw material alcohol, and oxygen is substantially absent. According to this publication, the reaction time is significantly shortened, side reactions are less likely to occur, and the raw material (meth) acrylic acid ester can be used in a smaller number of times in this method. . The publication also states that when the reaction is not performed under pressure, the reaction time is long and the reaction yield is poor.

However, the effect of preventing polymerization of (meth) acrylic acid ester is not always sufficient in the conventional method, and a method of preventing polymerization more effectively and producing (meth) acrylic acid ester with high selectivity is desired. I have.

Further, in the method using an azeotropic agent described in the above-mentioned Japanese Patent Application Laid-Open No. 3-118352, the cost of raw materials is increased, and separation from the azeotropic agents is necessary when considering the recycling of raw materials. There is also a problem that equipment costs are high. Disclosure of the invention

The present invention is intended to more effectively prevent the polymerization of (meth) acrylic acid ester in the transesterification reaction between (meth) acrylic acid ester and alcohol, and achieve the desired (meth) acrylic acid ester at a high selectivity. It is intended to provide a method for producing the same.

The present invention relates to a method for producing a (meth) acrylic acid ester of an alcohol by a transesterification reaction between a (meth) acrylic acid ester and an alcohol, wherein the (meth) acrylic acid ester is contained in a reactor. There is a liquid phase sound 15 which is a reaction liquid containing alcohol, and a gas phase part.

The present invention relates to a method for producing a (meth) acrylic acid ester, wherein the gas exchange portion is pressurized with an oxygen-containing gas to dissolve oxygen in the reaction solution, and the ester exchange reaction is performed.

Further, the present invention relates to the above-mentioned method for producing a (meth) acrylic acid ester, wherein the oxygen-containing gas contains 20% by volume or more of oxygen. In addition, the present invention relates to the above-mentioned (meth) acrylic acid ester production method, wherein the gauge pressure in the gas phase part in the reactor is 0.05 to 0.5 MPa during the transesterification reaction. . BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, the transesterification reaction is performed in a state where the gas phase in the reactor is pressurized with an oxygen-containing gas and oxygen is dissolved in a reaction solution containing a (meth) acrylic ester and an alcohol. By sufficiently dissolving oxygen in the reaction solution, a high polymerization inhibitory effect of (meth) acrylic acid ester can be obtained, and as a result, the desired (meth) acrylic acid ester can be produced with high selectivity. . The dissolved oxygen concentration in the reaction solution at the start of the transesterification reaction is preferably 100 mass ppm or more from the viewpoint that polymerization of the (meth) acrylate ester can be more effectively prevented.

In addition, by performing the transesterification reaction in a state in which the gas phase in the reactor is pressurized with an oxygen-containing gas, the amount of dissolved oxygen in the reaction solution can be kept high, and the polymerization is less likely to occur. High reaction temperatures can be employed. As a result, the reaction speed is improved, and the reaction can be performed more efficiently. During the transesterification reaction, the gage pressure in the gas phase in the reactor is preferably at least 0.05 MPa.

The concentration of dissolved oxygen in the reaction solution at atmospheric pressure varies depending on the combination of raw materials, but is around several tens of ppm with respect to the total mass of the reaction solution at a liquid temperature of around 10. The concentration of dissolved oxygen in the reaction solution under reduced pressure becomes even lower. With such a dissolved oxygen concentration, a sufficient polymerization preventing effect cannot be obtained. In order to obtain a high polymerization inhibitory effect, it is necessary to pressurize to sufficiently dissolve oxygen in the reaction solution.

Further, in the present invention, an azeotropic agent may be added at the time of the ester exchange reaction between the (meth) acrylic acid ester and the alcohol.

Here, “(meth) acrylate” means “acrylic ester” and “methacrylic ester” as commonly used. Gauge pressure is a pressure display that indicates the atmospheric pressure as 0 (reference). Hereinafter, the present invention will be described in detail.

The (meth) acrylate ester of the reaction raw material is not particularly limited as long as it is a transesterification reaction with the raw material alcohol. For example, (meth) methyl acrylate, (methyl) ethyl acrylate and the like can be used. .

The raw material alcohol is not particularly limited, and may be appropriately determined depending on the target (meth) acrylate. As the raw material alcohol, specifically, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n_pentanol, n_hexanol, n-heptanol, n Alkanols such as —octanol, 2-ethylhexanol, tridecanol, lauryl alcohol, stearyl alcohol; alkoxyalkanols such as methoxyethanol, ethoxyethanol, butoxyethanol; aryloxyethanol, etc.

Alkanols such as allyl alcohol and methallyl alcohol; phenoxyal phenols such as phenoxyethanol; cycloalkanols such as cyclohexanol; 3,3,5-trimethylcyclohexanol; -alkylcycloalkanols such as tert-butylcyclohexanol; cycloalkylalkanols such as cyclohexylmethanol; phenylalkanols such as benzyl alcohol and phenylethyl alcohol; alkylphenylalkanols Haloalkanols such as ethanol, etc .; cyanoalkanols such as cyanoethanol; aminoalkanols such as dimethylaminoethanol and ethylaminoethanol; phenol, 4-tert-butylphenol, 4-c Phenols such as mill phenol And the like. Among them, when the reaction is carried out using alkanols, alkanols, cycloalkanols, or phenylalkanols, higher effects of the present invention can be obtained. Further, the carbon number of the starting alcohol is preferably 24 or less. When the number of carbon atoms exceeds 25, the reaction rate becomes very slow, and sometimes the reaction does not proceed. In addition, the (meth) acrylic acid ester produced tends to have a high boiling point, making distillation difficult. The amount of the (meth) acrylic acid ester used as the raw material (mixing ratio) may be appropriately determined, but is preferably 1 mol or more, more preferably 1.2 mol or more, per 1 mol of the raw material alcohol. The amount of the (meth) acrylic acid ester used as a raw material (mixing ratio charged) is preferably 5 mol or less, more preferably 4 mol or less, based on 1 mol of the raw material alcohol.

In the present invention, it is preferable to add a polymerization inhibitor to the reaction solution when performing the transesterification reaction.

The polymerization inhibitor used in the present invention is not particularly limited, and any known one can be used. Examples of the polymerization inhibitor include hydroquinone, hide-mouth quinone monomethyl ether, catechol, phenothiazine, N, N-di-2-naphthyl p-phenylenediamine, nitric acid, nitrate and the like. One type of polymerization inhibitor may be used, or two or more types may be used in combination.

The amount of the polymerization inhibitor used may be appropriately determined, but from the viewpoint of preventing polymerization, it is preferably at least 0.01%, more preferably at least 0.05%, based on the mass of the raw material (meth) acrylate. preferable. Further, the amount of the polymerization inhibitor to be used is preferably 1% or less, more preferably 0.5% or less, based on the mass of the raw material (meth) acrylate from the viewpoint of separation during purification.

To substantially initiate the transesterification reaction, both reactants and the catalyst are contacted. Specifically, a polymerization inhibitor is added to a reaction solution containing (meth) acrylate and alcohol as reaction raw materials, and a gas phase in the reactor is pressurized with an oxygen-containing gas to dissolve a desired amount of oxygen. After the reaction, the catalyst is added to the reaction solution as it is, or dissolved or suspended in an appropriate solvent, and the transesterification reaction is substantially started. As a solvent for dissolving or suspending the catalyst, a (meth) acrylate or alcohol as a reaction raw material may be used.

The catalyst used in the present invention is not particularly limited, and any known catalyst can be used. Examples of the catalyst include sodium carbonate, a basic ion exchange resin, an oxidizing catalyst such as calcium oxide, magnesium oxide and the like, g-n-butyltin oxide, Examples thereof include tin catalysts such as di-n-octyltin oxide, titanium catalysts such as tetra-n-butoxytitanium and tetra-n-methoxytin, and solid catalysts such as calcium oxide containing titanium metal. One type of catalyst may be used, or two or more types may be used in combination.

The amount of the catalyst used may be appropriately determined, but is preferably 0.0001 mol or more, more preferably 0.0004 mol or more, per 1 mol of the starting alcohol. The amount of the catalyst used is preferably 0.5 mol or less, more preferably 0.1 mol or less, per 1 mol of the starting alcohol.

In the present invention, in order to improve the polymerization prevention effect, the gas phase in the reactor is pressurized with an oxygen-containing gas, and oxygen is dissolved in the reaction solution to perform a transesterification reaction. At this time, the reaction solution or the reaction solution and the gas phase of the reactor may be stirred.

The oxygen-containing gas to be used is not particularly limited as long as it preferably contains 20 to 100% by volume of oxygen, but it is preferable to use air in consideration of raw materials and equipment costs.

The dissolved oxygen concentration in the reaction solution at the start of the reaction is preferably 100 mass ppm or more from the viewpoint that a higher polymerization inhibitory effect can be obtained. Excessive pressurization to increase the dissolved oxygen concentration results in high cost reactors and peripheral equipment.

During the reaction, the pressure of the gas phase in the reactor may be appropriately determined depending on the combination of the raw materials, the reaction temperature and the like so that the desired dissolved oxygen concentration in the reaction solution can be obtained. The gauge pressure of the gas phase in the reactor during the reaction is preferably 0.05 MPa or more, more preferably 0.0 IMP a or more, from the viewpoint of obtaining a higher polymerization preventing effect. Further, the gauge pressure of the gas phase in the reactor during the reaction is preferably 0.5 MPa or less, more preferably 0.4 MPa or less, from the viewpoint of the cost of the reaction apparatus and peripheral equipment.

When the gas phase inside the reactor is pressurized with air, if the temperature of the reaction solution is 80 ° C, pressurization at a gauge pressure of 0.04 MPa or more will be performed. At ° C, by applying a gauge pressure of 0.25 MPa or more, the dissolved oxygen concentration in the reaction solution can be increased to 100 ppm or more. The reaction temperature may be appropriately determined according to the combination of the raw materials, but from the viewpoint of the reaction rate,

It is preferably at least 60 ° C, more preferably at least 80 ° C. The reaction temperature is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, from the viewpoint of preventing polymerization of the (meth) acrylyl ester.

The reaction time may be appropriately determined, but is usually about 0.5 to 20 hours.

Since the transesterification reaction of the (meth) acrylic ester is an equilibrium reaction, it is preferable to carry out the reaction while removing the product out of the system in order to progress the reaction. The reactor used in the present invention is not particularly limited as long as the inside of the reactor can be pressurized. For example, a stirred tank batch type, continuous apparatus, a stirred tank batch type having a distillation apparatus, and a continuous apparatus And the like. Among them, a stirred tank type device having a distillation device is preferable because the product can be removed by distillation. The distillation conditions may be determined appropriately.

After the transesterification reaction is performed to produce the (meth) acrylic ester, the (meth) acrylic ester produced is usually purified by a known method such as distillation. Example

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The analysis (measurement of the content of the raw material and the product in the reaction solution) in the examples was performed by gas chromatography. The selectivity was defined as the ratio of the number of moles of the target product (butyl methacrylate) to the number of moles of the starting alcohol (n-butanol) consumed by the reaction. The production of the polymer was confirmed visually.

(Example 1)

In a 1-liter autoclave of a glass vessel equipped with a stirring blade, a thermometer, a catalyst inlet, and a gas inlet to the gas phase, 496 g (4.995 mol) of methyl methacrylate, n- 22 g (2.97 mol) of bushnol and 0.254 g of hydroquinone were charged. The reaction solution was heated to 120 ° C. while stirring, and air was supplied to pressurize the inside of the glass container to a gauge pressure of 0.2 MPa to dissolve oxygen in the reaction solution. At a reaction temperature of 120 ° (at a gauge pressure of 0.2 MPa, 0.257 g of tetramethyl titanate dissolved in 10 g (0.10 mol) of methyl methacrylate (1.

(49 mmol) was injected into the liquid phase of the reactor with air. Then, the reaction was carried out for 3 hours while maintaining the reaction solution temperature at 120 ° C. and the gauge pressure at 0.2 MPa. During the reaction, the internal reaction solution was taken out at regular intervals and analyzed. The results are shown in Table 1.

(Comparative Example 1)

In a 1 L autoclave similar to that in Example 1, 496 g of methyl methacrylate, 220 g of n-butanol, and 0.254 g of hydroquinone were charged. After degassing for 20 minutes while stirring the reaction solution, the gas phase was pressurized to a gauge pressure of 0.2 MPa with nitrogen, and the reaction solution was heated to 120 ° C.

At a reaction solution temperature of 120 ° (:, gauge pressure: 0.2 MPa, 0.257 g of tetramethylthiocyanate dissolved in 10 g of methyl methacrylate was injected into the liquid phase inside the reactor with nitrogen. The reaction was carried out for 3 hours in the same manner as in Example 1. The results are shown in Table 1. After the reaction, a minute polymer was confirmed in the reactor.

(Example 2)

In a 1 L autoclave similar to that in Example 1, 492 g (4.91 mol) of methyl methacrylate, 218 g (2.94 mol) of n-butanol, 0.2 mol of octahydroquinone

53 g were charged. The reaction solution was heated to 130 ° C. with stirring, and air was supplied to pressurize the inside of the glass container to a gauge pressure of 0.3 MPa, thereby dissolving oxygen in the reaction solution.

At a reaction solution temperature of 130 ° C and a gauge pressure of 0.3 MPa, 0.253 g (1.47 mmol) of tetramethyl titanate dissolved in 10 g (0.10 mol) of methyl methacrylate was dissolved in the reactor with air. Pressed into the phase. Then, the reaction was carried out for 3 hours in the same manner as in Example 1. The results are shown in Table 1. (Comparative Example 2)

Into a 1 L autoclave similar to that in Example 1, 492 g of methyl methacrylate, 218 g of n-butanol, and 0.253 g of hydroquinone were charged. After degassing for 20 minutes while stirring the reaction solution, the gas phase was pressurized to a gauge pressure of 0.3 MPa with nitrogen, and the reaction solution was heated to 130 ° C.

At a reaction liquid temperature of 130 ° C. and a gauge pressure of 0.3 MPa, 0.253 g of tetramethyl titanate dissolved in 10 g of methyl methacrylate was injected into the liquid phase inside the reactor with nitrogen. Then, the reaction was carried out for 3 hours in the same manner as in Example 1. The results are shown in Table 1. After the reaction, a minute polymer was confirmed in the reactor. table 1

In Examples 1 and 2 in which the gas phase in the reactor was pressurized with air to dissolve oxygen in the reaction solution and transesterification was performed, Examples 1 and 2 were compared with Comparative Examples in which the reaction was performed in a nitrogen atmosphere. Product formation was suppressed, and the selectivity for the target product, butyl methacrylate, was high. Industrial applicability

According to the invention, the transesterification of (meth) acrylates with alcohols In the reaction, the polymerization of the (meth) acrylate can be more effectively prevented, and the desired (meth) acrylate can be produced at a high selectivity.

Claims

The scope of the claims

1. A method for producing a (meth) acrylic ester of an alcohol by transesterification of the (meth) acrylic ester with an alcohol,

In the reactor, there are a liquid phase portion, which is a reaction solution containing a (meth) acrylate and an alcohol, and a gas phase portion.

The method for producing a (meth) acrylate ester, wherein the gas exchange portion is pressurized with an oxygen-containing gas to dissolve oxygen in the reaction solution, and the ester exchange reaction is performed.

2. The method for producing a (meth) acrylate according to claim 1, wherein the oxygen-containing gas contains 20% by volume or more of oxygen.

3. The (meth) acrylic ester according to claim 1 or 2, wherein a gauge pressure of a gas phase part in the reactor is 0.05 to 0.5 MPa during the transesterification reaction. Method.