JP2002155025A - Method for producing methacrylates - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing industrially important methacrylates from hydroxyisobutyric acid or hydroxyisobutyric acid esters such as methyl hydroxyisobutyrate. SOLUTION: The hydroxyisobutyric acid and/or hydroxyisobutyric acid esters are reacted with alcohols in the presence of a solid catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing methacrylates (methacrylic esters). Methacrylates are industrially very important raw materials widely used as raw materials for synthetic resins and synthetic fibers.

[0002]

2. Description of the Related Art Representative methods for producing methacrylates include an esterification reaction between methacrylic acid and alcohol and a transesterification reaction between methacrylate and alcohol. In order to produce their esters from α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid, and strongly acidic ion exchange resins, solid phosphoric acids and solids such as silica-titania In many cases, esterification or transesterification is performed in a liquid phase or a gas phase using an acid as a catalyst.

For example, as a liquid phase method, a method for producing hydroxyalkyl acrylates using a mineral acid such as sulfuric acid or hydrochloric acid as an esterification catalyst (DE 1518572), or using di-n-butyltin oxide or stannoxane or distanoxane as a transesterification catalyst Method (JP-A-46-39)
848, JP-A-52-153913, JP-A-7-973
87) as solid phase phosphoric acid (Japanese Patent Publication No. 42-5 / 1972).
222), molybdenum sulfide (JP-B-44-9885),
A method using a silica-titania (JP-B-55-33702) catalyst is exemplified. However, both the liquid phase method and the gas phase method have problems such as lowering of selectivity and low productivity due to addition reaction to double bond, dehydration condensation of alcohols, formation of dimer ester by intermolecular dehydration, and the like. In addition, the liquid phase method has a problem at the time of mass production, such as production mainly by a batch method.

Methacrylic acid and its derivatives, methacrylic esters, can also be produced from hydroxyisobutyric acid or hydroxyisobutyric esters. For example, a method for producing methyl methacrylate from methyl α-hydroxyisobutyrate using faujasite-type zeolites as a gas phase dehydration catalyst (Japanese Patent Laid-Open No. 8-188)
555). This method is an excellent method in which acetone cyanohydrin is converted into α-hydroxyisobutyrate and then dehydrated to produce methyl methacrylate without producing ammonium sulfate. However, commercially available methods for obtaining methacrylates from hydroxyisobutyric acid or an ester of hydroxyisobutyric acid are not sufficient in selectivity and yield except when producing methyl methacrylate. It was still insufficient to apply to the industrial production of a wider range of methacrylates from the esters.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily producing industrially important methacrylates from hydroxyisobutyric esters such as hydroxyisobutyric acid and methyl hydroxyisobutyrate. . In particular, methacrylates that were conventionally difficult to produce, that is,
An object of the present invention is to provide a method for producing esters from two or more carbon atoms or polyfunctional alcohols and methacrylic acid in one step.

[0006]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that hydroxyisobutyric acid and / or hydroxyisobutyrate esters and alcohols are present in the presence of a solid catalyst. The inventors have found that methacrylates can be easily obtained by performing the reaction below, and have reached the present invention.

That is, the present invention relates to a method for producing methacrylates by reacting hydroxyisobutyric acid and / or hydroxyisobutyrate with alcohols in the presence of a solid catalyst.

[0008]

DETAILED DESCRIPTION OF THE INVENTION One of the raw materials used in the present invention is hydroxyisobutyric acid and / or esters thereof, for example, α-hydroxyisobutyric acid, β-hydroxyisobutyric acid, and α- or β-hydroxy acid. Isobutyric acid methyl ester, ethyl ester, n-propyl ester, isopropyl ester, allyl ester, glycidyl ester, n-butyl ester, isobutyl ester, sec
-Butyl ester, tert-butyl ester, hexyl ester, octyl ester, 2-ethylhexyl ester, lauryl ester, stearyl ester, cyclohexyl ester, benzyl ester, 2-hydroxyethyl ester, 2-hydroxypropyl ester,
3-hydroxypropyl ester and 4-hydroxybutyl ester. Among them, particularly preferred are α-hydroxyisobutyric acid, β-
Hydroxyisobutyric acid, methyl α-hydroxyisobutyrate,
methyl β-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, ethyl β-hydroxyisobutyrate, 2-ethylhexyl α-hydroxyisobutyrate, and 2-ethylhexyl β-hydroxyisobutyrate. The above compounds can be used alone or in combination of two or more. Even if methacrylic acid or methacrylic acid esters are present in the first raw material, they have almost no adverse effect on the reaction results, and thus may be contained.

The other raw material is alcohols. However, when hydroxyisobutyrate is used as the first raw material, alcohols are different from alcohols constituting the ester portion of the hydroxyisobutyrate. The alcohols have 1 to 24 carbon atoms, preferably 2 to 24 carbon atoms.
Twelve alcohols, glycols and polyols are preferred. For example, methanol, ethanol, n-propanol, isopropyl alcohol, allyl alcohol, n-
Butanol, isobutyl alcohol, tert-butyl alcohol, hexanol, octanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,3-propanediol, and 1,
4-butanediol is preferred. Preferred are methanol, ethanol, propanol, butanol, allyl alcohol, ethylene glycol and cyclohexanol, and particularly preferred are butanol, allyl alcohol, ethylene glycol and cyclohexanol.
The above alcohols can be used alone or in combination of two or more.

In the present invention, a solid catalyst is used. Specifically, silica, alumina, titania, zirconia, silicalite, heteropolyacid, mesoporous silica (for example,
Mesoporous compounds such as MCM-41); crystalline aluminosilicates; crystalline silicoaluminophosphates;
Examples include naturally occurring clay minerals such as kaolinite, montmorillonite, sepiolite, and mica.
Among them, silica, silicalite, crystalline aluminosilicate, and crystalline silicoaluminophosphates are preferred.

The solid catalyst used in the present invention preferably contains Cs as an active ingredient. Usually, Cs is preferably supported on a solid catalyst in the form of a carbonate, hydroxide or nitrate such as cesium carbonate, cesium hydroxide or cesium nitrate. Since it is difficult for Cs salts to exist in the form of oxides even when calcined, such carbonates, hydroxides,
And nitrates are preferably contained in the solid catalyst.

[0012] The method for incorporating Cs into the solid catalyst includes an impregnation method, a coprecipitation method, a sol-gel method, an ion exchange method, a physical mixing method, a thermal decomposition method, a chemical deposition method, a mechanochemical method and a synthesis method. And a method of adding a Cs compound during the production of molecular sieves, and the method can be appropriately selected and employed. The amount of Cs carried is not particularly limited, but is preferably 0.1 to 20% by weight in terms of Cs metal relative to the solid catalyst.

In some cases, the activity and selectivity can be further improved by using Cs together with other metal species. For this purpose, Na,
K, Rb, Mg, Ca, La, Ce, Sr, Ba, Y,
Ti, Zr, V, Nb, Ta, Cr, Fe, Ru, C
o, Ir, Ni, Pd, Pt, Cu, Ge, In, S
It is preferable to use at least one metal selected from the group consisting of n and Sb in combination with Cs. For example, a Cs compound and a compound of a metal selected from the above-mentioned group are compounded by a general impregnation method, a coprecipitation method, an ion exchange method, a physical mixing method, a chemical deposition method, a thermal decomposition method, or a compound serving as a precursor. It is supported on a solid catalyst by a method of adding and calcining. The loading amount of other metal species is preferably 0.01 to 50% by weight in terms of metal based on the solid catalyst. The solid catalyst of the present invention, the solid catalyst containing Cs alone or together with other metal species, may be used as it is, or as a binder, for example, silica, alumina, titania, various clay compounds, and the like.
After baking at 00 to 700 ° C. for 1 to 24 hours, it can be subjected to compression molding, tablet molding, or the like, and put to practical use.

The present invention can be carried out in any of a gas phase, a liquid phase, a normal pressure and a pressurized batch system, a semi-batch system, and a continuous flow system. Therefore, it is preferable to select an appropriate reaction system in consideration of the properties of the raw materials, the apparatus, and the like, but a gas phase circulation system using a fixed bed is simple. For example, in a liquid phase batch reaction, hydroxyisobutyric acid or its esters and alcohols are mixed in a solvent or without using a solvent at a ratio of 1: 0.1 to 1:10.
At room temperature to 200 ° C. for 1 to 24 hours in the presence of a solid catalyst. It is not necessary to use a solvent, but hydrocarbons such as hexane and heptane, or aromatic hydrocarbons such as benzene, toluene and xylene can be used as appropriate. The solid catalyst is preferably used in an amount of 0.1 to 50% by weight based on the raw material mixture. In the gas-phase flow reaction, 200 to 400 ° C., 0.01 to 1 MPa
Then, a mixed gas of hydroxyisobutyric acid or its ester and alcohols in a ratio of 1: 0.1 to 1:10 (molar ratio) is
It is preferably fed at a gas reference space velocity of 10,000 h ^-1 to the reactor in which the solid catalyst is arranged. In any of the reaction systems, the reaction between hydroxyisobutyric acid and / or its esters and alcohols proceeds in the presence of a solid catalyst, and methacrylates, particularly methacrylates having 2 to 12 carbon atoms in the ester portion, are reacted with one another. Manufactured in stages.

[0015]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these. In the following Examples and Comparative Examples, the reaction was performed using a raw material tank, a raw material supply pump, a mass flow controller for introducing an inert gas, a quartz reaction tube (inner diameter 13 mm).
(φ, length 250 mm) using a flow reactor equipped with a sampling tank. Two to four hours after the reaction reached a steady state, the reaction solution was collected over about one hour and analyzed by FID detection type gas chromatography to determine the composition distribution of the reaction product.

Catalyst Preparation Example Catalyst 1 64.5 g of a silica sol and 5.76 g of a 10 wt% cesium nitrate aqueous solution were mixed and stirred at room temperature, and concentrated nitric acid was added thereto.
H was kept between 6.7 and 7.3. Next, 10wt%
0.56 g of ammonium nitrate was added to gel. The gelled product was crushed, formed into granules, and calcined at 500 ° C. for 4 hours to obtain Catalyst 1. As a result of thermal analysis, it was confirmed that cesium did not exist as an oxide, and that nitrate remained.

Catalyst 2 Commercially available silicalite (MFI300 manufactured by UOP, Si / A
20 mol was ion-exchanged three times with 500 ml of a 10 wt% cesium nitrate aqueous solution.
Dried for hours. Calcination was performed at 500 ° C. for 4 hours to obtain Catalyst 2.

Catalyst 3 Commercial silicalite (MFI300 manufactured by UOP, Si / A
(1 mol ratio = 300), 20 g of cesium carbonate and 0.5 g of titanium oxide were mixed, and 40 g of water was added thereto, followed by stirring. Next, the resultant was dried at 120 ° C. for 2 hours and calcined at 500 ° C. for 4 hours to obtain Catalyst 3.

Catalyst 4 40 g of a 10 wt% cesium carbonate aqueous solution was mixed with silica gel 2
5 g and left for 2 hours. Next, water was distilled off under reduced pressure, and then dried at 120 ° C. for 18 hours to obtain Catalyst 4.

Example 1 3 ml of the catalyst 1 was charged into a reaction tube, and α-hydroxyisobutyric acid (HBA) and ethylene glycol (E) were used as raw materials.
After evaporating a 1 to 6 molar mixed solution of G), the mixture is supplied at a gas-based space velocity (GHSV) of 500 h ^-1 under a pressure of 0.
A synthesis reaction of 2-hydroxyethyl methacrylate (2-HEMA) was performed at 1 MPa and a temperature of 320 ° C. The reaction results were as follows. HBA conversion: 98.9 mol% 2-hydroxyethyl methacrylate yield: 85.9 m
ol%

Example 2 The procedure of Example 1 was repeated except that 3 ml of the catalyst 2 was charged. The reaction results were as follows. HBA conversion: 98.6 mol% 2-hydroxyethyl methacrylate yield: 78.9 m
ol%

Example 3 The procedure of Example 1 was repeated, except that methyl α-hydroxyisobutyrate (HBM) was used instead of α-hydroxyisobutyric acid, and the reaction temperature was 330 ° C. The reaction results were as follows. HBM conversion: 99.6 mol% 2-hydroxyethyl methacrylate yield: 62.9 m
ol%

Example 4 Cyclohexanol (C
H) was carried out in the same manner as in Example 1 except that the reaction temperature was changed to 350 ° C. The reaction results were as follows. HBA conversion: 100 mol% Cyclohexyl methacrylate (CHM) yield: 58.
4mol%

Example 5 2-ethylhexyl α-hydroxyisobutyrate (HBO) was used instead of α-hydroxyisobutyric acid, and the reaction temperature was 3
The procedure was performed in the same manner as in Example 1 except that the temperature was changed to 40 ° C. The reaction results were as follows. HBO conversion: 98.1 mol% 2-hydroxyethyl methacrylate yield: 58.7 m
ol%

Example 6 The procedure of Example 1 was repeated except that the catalyst 2 was used and ethyl α-hydroxyisobutyrate (HBE) was used instead of α-hydroxyisobutyric acid. The reaction results were as follows. HBE conversion: 94.0 mol% 2-hydroxyethyl methacrylate yield: 54.9 m
ol%

Example 7 The procedure of Example 1 was repeated, except that n-butanol (NB) was used instead of ethylene glycol. The reaction results were as follows. HBA conversion: 96.8 mol% n-butyl methacrylate (NBA) yield: 42.9 m
ol%

Example 8 The same procedure as in Example 1 was carried out except that the catalyst 3 was used.
The reaction results were as follows. HBA conversion: 99.6 mol% 2-hydroxyethyl methacrylate yield: 90.4 m
ol%

Example 9 The procedure of Example 1 was repeated, except that a 90 wt% aqueous solution of α-hydroxyisobutyric acid was used instead of α-hydroxyisobutyric acid. The reaction results were as follows. HBA conversion: 99.5 mol% 2-hydroxyethyl methacrylate yield: 89.2 m
ol%

Example 10 A reaction was conducted in the same manner as in Example 1 except that the catalyst 4 was used.
The reaction results were as follows. HBA conversion: 99.6 mol% 2-hydroxyethyl methacrylate yield: 88.0 m
ol%

Example 11 A catalyst 5 was prepared in the same manner as in the preparation of the catalyst 1 except that sodium carbonate was used instead of cesium nitrate. Using the catalyst 5, the same procedure as in Example 1 was performed.
The reaction results were as follows. HBA conversion: 97.4 mol% 2-hydroxyethyl methacrylate yield: 23.4 m
ol%

Example 12 As the catalyst 6, Na-substituted X-type zeolite (MS13X
(Manufactured by Aldrich) and the reaction temperature was set to 300 ° C., except that the reaction was carried out in the same manner as in Example 1. The reaction results were as follows. HBA conversion: 98.3 mol% 2-hydroxyethyl methacrylate yield: 38.0 m
ol%

Example 13 As a catalyst 7, a Na-substituted Y-type zeolite (HSZ-32) was used.
0NAA Tosoh Corporation) at a reaction temperature of 300 ° C.
The procedure was performed in the same manner as in Example 1 except that a 1: 4 molar mixed solution of α-hydroxyisobutyric acid and ethylene glycol was used as a raw material. The reaction results were as follows. HBA conversion: 98.4 mol% 2-hydroxyethyl methacrylate yield: 9.4 mo
1%

The results of Examples 1 to 13 are summarized in Table 1.
Shown in Table 1 Catalyst Raw material Temperature Conversion rate Yield Product ° C mol% mol% Example 1 Catalyst 1 HBA / EG 320 98.9 85.9 2-HEMA Example 2 Catalyst 2 HBA / EG 320 98.6 78.9 2-HEMA Example 3 Catalyst 1 HBM / EG 330 99.6 62.9 2-HEMA Example 4 Catalyst 1 HBA / CH 350 100 58.4 CHM Example 5 Catalyst 2 HBO / EG 340 98.1 58.7 2-HEMA Example 6 Catalyst 2 HBE / EG 320 94.0 54.9 2-HEMA Example 7 Catalyst 1 HBA / NB 320 96.8 42.9 NBA Example 8 Catalyst 3 HBA / EG 320 99.6 90.4 2-HEMA Example 9 Catalyst 1 HBA / EG 320 99.5 89.2 2-HEMA Example 10 Catalyst 4 HBA / EG 320 99.6 88.0 2 -HEMA Example 11 Catalyst 5 HBA / EG 320 97.4 23.4 2-HEMA Example 12 Catalyst 6 HBA / EG 300 98.3 38.0 2-HEMA Example 13 Catalyst 7 HBA / EG 300 98.4 9.4 2-HEMA

[0034]

Industrial Applicability According to the present invention, methacrylates, which are industrially important raw materials, particularly those having 2 carbon atoms, can be easily prepared by reacting hydroxyisobutyric acid and / or its derivatives with alcohols.
It is significant in that it provides a means for producing the above or esters comprising a polyfunctional alcohol and methacrylic acid.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mitsugu Taniguchi 22nd Wadai, Tsukuba-shi, Ibaraki F-term in Mitsubishi Gas Chemical Co., Ltd. Research Laboratory 4H006 AA02 AC13 AC48 BA04 BA09 BA10 BA30 BA33 BA71 BJ20 BN10 KA00 KE20 4H039 CA21 CA66 CG10 CL25

Claims (8)

[Claims] 1. A method for producing methacrylates, comprising reacting hydroxyisobutyric acid and / or hydroxyisobutyrate with alcohols in the presence of a solid catalyst. 2. A solid catalyst comprising silica, alumina, titania,
The methacrylate according to claim 1, which is at least one selected from the group consisting of zirconia, silicalite, heteropolyacid, mesoporous silica, crystalline aluminosilicate, crystalline silicoaluminophosphates, kaolinite, montmorillonite, sepiolite, and mica. Manufacturing method. 3. The method according to claim 1, wherein the hydroxyisobutyric acid is α-hydroxyisobutyric acid and / or β-hydroxyisobutyric acid.
Or the method for producing methacrylates according to 2. 4. The method of claim 1, wherein the hydroxyisobutyrate is methyl ester, ethyl ester, n-propyl ester, isopropyl ester, allyl ester, glycidyl ester, n-butyl ester, isobutyl ester of α-hydroxyisobutyric acid or β-hydroxyisobutyric acid. Ester, se
c-butyl ester, tert-butyl ester, hexyl ester, octyl ester, 2-ethylhexyl ester, lauryl ester, stearyl ester, cyclohexyl ester, benzyl ester, 2-hydroxyethyl ester, 2-hydroxypropyl ester, 3-hydroxypropyl ester The method for producing methacrylates according to claim 1, wherein the methacrylate is at least one ester selected from the group consisting of, and 4-hydroxybutyl ester. 5. The method according to claim 1, wherein the alcohols are methanol, ethanol,
n-propanol, isopropyl alcohol, allyl alcohol, n-butanol, isobutyl alcohol, t
tert-butyl alcohol, hexanol, octanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,3-propanediol, and 1,4-butanediol The method for producing a methacrylate according to any one of claims 1 to 4, which is at least one compound. 6. The method for producing methacrylates according to claim 1, wherein the solid catalyst supports cesium. 7. The method for producing methacrylates according to claim 6, wherein the supported amount of cesium is 0.1 to 20% by weight based on the solid catalyst. 8. Hydroxyisobutyric acid and / or hydroxyisobutyrate esters and alcohols are used in an amount of from 200 to 40.
The method for producing a methacrylate according to any one of claims 1 to 7, wherein the gas phase reaction is performed at 0 ° C.