JP4539808B2 - Method for producing methacrylates - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing methacrylates (methacrylic acid esters).
Methacrylates are industrially very important raw materials widely used as raw materials for synthetic resins and synthetic fibers.
[0002]
[Prior art]
Typical methods for producing methacrylates include esterification reaction of methacrylic acid and alcohol, and ester exchange reaction of methacrylate and alcohol. To produce esters thereof from α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, solids such as sulfuric acid, phosphoric acid, paratoluenesulfonic acid, strongly acidic ion exchange resins, solid phosphoric acid and silica-titania In many cases, an acid is used as a catalyst for esterification or transesterification in a liquid phase or gas phase.
[0003]
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 (DE1518572) or a method using di-n-butyltin oxide or stannoxane or distanoxane as a transesterification catalyst (special JP-A-46-39848, JP-A-52-153913, JP-A-7-97387), and solid phase phosphoric acid (JP-B 42-5222), molybdenum sulfide (JP-B 44-9885), silica-titania ( JP-B-55-33702) includes a method using a catalyst. However, both the liquid phase method and the gas phase method have problems such as reduction of selectivity and low productivity due to addition reaction to double bonds, dehydration condensation of alcohols, formation of dimer ester by intermolecular dehydration, etc. In addition, the liquid phase method has a problem in mass production such as production mainly by a batch method.
[0004]
Methacrylic acid and its derivatives, methacrylic acid esters, can also be produced from hydroxyisobutyric acid or hydroxyisobutyric acid esters. For example, there is a method for producing methyl methacrylate from methyl α-hydroxyisobutyrate using a faujasite type zeolite as a gas phase dehydration catalyst (Japanese Patent Laid-Open No. 8-188555). This method is an excellent method in which an ammonium cyanohydrin is induced to methyl α-hydroxyisobutyrate and then dehydrated to produce an ammonium sulfate to produce methyl methacrylate. However, industrially available methods of obtaining methacrylates from hydroxyisobutyric acid or esters of hydroxyisobutyric acid are not sufficient in selectivity and yield except when methyl methacrylate is produced. It was still insufficient to apply to the industrial production of a wider range of methacrylates from the ester.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for easily producing industrially important methacrylates from hydroxyisobutyric acid esters such as hydroxyisobutyric acid and methyl hydroxyisobutyrate. In particular, the present invention provides a method for producing methacrylates, which have been difficult to produce in the past, that is, esters of two or more carbon atoms or polyfunctional alcohols and methacrylic acid in one step.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have made methacrylates react by reacting hydroxyisobutyric acid and / or hydroxyisobutyric acid esters with alcohols in the presence of a solid catalyst. Knowing that it can be easily obtained, the present invention has been achieved.
[0007]
That is, the present invention relates to a process for producing methacrylates in which hydroxyisobutyric acid and / or hydroxyisobutyric acid esters are reacted 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 methyl ester of α- or β-hydroxyisobutyric acid, 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, β-hydroxyisobuty, which are easily available industrially. Ethyl butyrate, 2-ethylhexyl α-hydroxyisobutyrate, and 2-ethylhexyl β-hydroxyisobutyrate. The above compounds can be used alone or in admixture of two or more. Even if methacrylic acid or methacrylic acid esters are present in the first raw material, there is almost no adverse effect on the reaction results, so these may be contained.
[0009]
The other raw material is alcohol. However, when hydroxyisobutyric acid ester is used as the first raw material, the alcohol is different from the alcohol constituting the ester portion of the hydroxyisobutyric acid ester. As the alcohols, alcohols having 1 to 24 carbon atoms, preferably 2 to 12 carbon atoms, glycols, and polyols are preferable. 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 are 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 admixture of two or more.
[0010]
In the present invention, a solid catalyst is used. Specifically, mesoporous compounds such as silica, alumina, titania, zirconia, silicalite, heteropolyacid, mesoporous silica (for example, MCM-41); crystalline aluminosilicate; crystalline silicoaluminophosphates; naturally occurring clay Minerals such as kaolinite, montmorillonite, sepiolite, mica and the like are exemplified. Of these, silica, silicalite, crystalline aluminosilicate, and crystalline silicoaluminophosphates are preferred.
[0011]
The solid catalyst used in the present invention preferably contains Cs as an active ingredient. Cs is usually preferably supported on a solid catalyst in the form of carbonate, hydroxide or nitrate, such as cesium carbonate, cesium hydroxide, or cesium nitrate. Since it is difficult for Cs salts to be present in the form of oxides even when calcined, it is preferable to contain such carbonates, hydroxides, and nitrates in the solid catalyst.
[0012]
Examples of the method for containing Cs in the solid catalyst include impregnation method, coprecipitation method, sol-gel method, ion exchange method, physical mixing method, thermal decomposition method, chemical deposition method, mechanochemical method and synthesis method such as molecular sieve. There is a method of adding a Cs compound at the time of production, and it can be appropriately selected and adopted. Although there is no restriction | limiting in particular in the load of Cs, The range of 0.1-20 weight% is preferable in conversion of Cs metal with respect to a solid catalyst.
[0013]
The activity and selectivity may 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, Co, Ir, Ni, Pd, Pt It is preferable that at least one metal selected from the group consisting of Cu, Ge, In, Sn, and Sb is used in combination with Cs. For example, a compound that becomes a general impregnation method, coprecipitation method, ion exchange method, physical mixing method, chemical deposition method, thermal decomposition method, or precursor with a Cs compound and a metal compound selected from the above group. It is supported on a solid catalyst by a method of adding and baking. The supported amount of other metal species is preferably 0.01 to 50% by weight in terms of metal with respect to the solid catalyst.
The solid catalyst of the present invention, the solid catalyst containing Cs alone or together with other metal species, is used as it is or as a binder, for example, silica, alumina, titania, various clay compounds, and usually 300 to 700 ° C. After being fired for 1 to 24 hours, it can be put into practical use by performing compression molding or tableting.
[0014]
The present invention can be carried out in a gas phase, a liquid phase, or any of a batch type, a semi-batch type, and a continuous flow type of normal pressure and pressure. Therefore, it is preferable to select an appropriate reaction system in consideration of the properties of the raw materials, equipment, etc., but a gas phase distribution system using a fixed bed is simple.
For example, in a liquid phase batch reaction, hydroxyisobutyric acid or an ester thereof and an alcohol are mixed at a molar ratio of 1: 0.1 to 1:10 at room temperature to 200 ° C. without using a solvent or a solvent. The reaction is carried out in the presence of a solid catalyst for 24 hours. There is no particular need 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, a gas mixture of hydroxyisobutyric acid or its ester and alcohols at a ratio of 1: 0.1 to 1:10 (molar ratio) is 10 to 10,000 h at 200 to 400 ° C. and 0.01 to 1 MPa. ^It is preferred to feed the reactor with the solid catalyst at a gas reference space velocity of ^-1 .
In any reaction system, the reaction of hydroxyisobutyric acid and / or its ester and alcohol proceeds in the presence of a solid catalyst, and methacrylates, in particular, methacrylates having 2 to 12 carbon atoms in the ester moiety are one. Manufactured in stages.
[0015]
【Example】
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.
Reactions in the following examples and comparative examples use a flow reactor equipped with 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 mmφ, length 250 mm), and a sampling tank. I went. Two to four hours after the reaction reached a steady state, the reaction solution was collected over about one hour and analyzed by a FID detection type gas chromatograph to determine the composition distribution of the reaction product.
[0016]
Catalyst preparation example Catalyst 1
After mixing and stirring 64.5 g of silica sol and 5.76 g of 10 wt% cesium nitrate aqueous solution at room temperature, concentrated nitric acid was added to maintain the pH between 6.7 and 7.3. Next, 0.56 g of 10 wt% ammonium nitrate was added for gelation. The gelled product was crushed and formed into granules and then calcined at 500 ° C. for 4 hours to obtain Catalyst 1. As a result of thermal analysis, it was confirmed that cesium was not present as an oxide and that nitrate radicals remained.
[0017]
Catalyst 2
20 g of commercially available silicalite (MOP300 manufactured by UOP, Si / Al molar ratio = 300) was ion-exchanged three times with 500 ml of a 10 wt% cesium nitrate aqueous solution, and then dried at 120 ° C. for 2 hours. The catalyst 2 was obtained by firing at 500 ° C. for 4 hours.
[0018]
Catalyst 3
2 g of cesium carbonate and 0.5 g of titanium oxide were mixed with 20 g of commercially available silicalite (MFI300 manufactured by UOP, Si / Al molar ratio = 300), and 40 g of water was added, followed by stirring. Subsequently, the catalyst 3 was obtained by drying at 120 ° C. for 2 hours and calcining at 500 ° C. for 4 hours.
[0019]
Catalyst 4
40 g of 10 wt% cesium carbonate aqueous solution was mixed with 25 g of silica gel and allowed to stand for 2 hours. Subsequently, after distilling off water under reduced pressure, the catalyst 4 was obtained by drying at 120 ° C. for 18 hours.
[0020]
Reference example 1
3 ml of catalyst 1 is filled in a reaction tube, and a 1: 6 molar mixed solution of α-hydroxyisobutyric acid (HBA) and ethylene glycol (EG) is vaporized as a raw material, and then a gas-based space velocity (GHSV) of 500 h −1 and a synthesis reaction of 2-hydroxyethyl methacrylate (2-HEMA) was performed at a pressure of 0.1 MPa and a temperature of 320 ° C. The reaction results were as follows.
HBA conversion: 98.9 mol%
2-hydroxyethyl methacrylate yield: 85.9 mol%
[0021]
Reference example 2
The same procedure as in Reference Example 1 was performed except that 3 ml of catalyst 2 was charged. The reaction results were as follows.
HBA conversion: 98.6 mol%
2-hydroxyethyl methacrylate yield: 78.9 mol%
[0022]
Example 1
The same procedure as in Reference Example 1 was performed 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 rate: 99.6 mol%
2-hydroxyethyl methacrylate yield: 62.9 mol%
[0023]
Reference example 3
The same procedure as in Reference Example 1 was performed except that cyclohexanol (CH) was used instead of ethylene glycol and the reaction temperature was 350 ° C. The reaction results were as follows.
HBA conversion rate: 100 mol%
Cyclohexyl methacrylate (CHM) yield: 58.4 mol%
[0024]
Example 2
The same procedure as in Reference Example 1 was conducted except that 2-ethylhexyl (HBO) was used instead of α-hydroxyisobutyric acid and the reaction temperature was 340 ° C. The reaction results were as follows.
HBO conversion: 98.1 mol%
2-hydroxyethyl methacrylate yield: 58.7 mol%
[0025]
Example 3
The same procedure as in Reference Example 1 was conducted except that 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 mol%
[0026]
Reference example 4
The same procedure as in Reference Example 1 was performed 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 mol%
[0027]
Reference Example 5
The same procedure as in Reference Example 1 was performed except that catalyst 3 was used. The reaction results were as follows.
HBA conversion: 99.6 mol%
2-hydroxyethyl methacrylate yield: 90.4 mol%
[0028]
Reference Example 6
The same procedure as in Reference Example 1 was performed except that a 90 wt% α-hydroxyisobutyric acid aqueous solution was used instead of α-hydroxyisobutyric acid. The reaction results were as follows.
HBA conversion: 99.5 mol%
2-hydroxyethyl methacrylate yield: 89.2 mol%
[0029]
Reference Example 7
The same procedure as in Reference Example 1 was performed except that catalyst 4 was used. The reaction results were as follows.
HBA conversion: 99.6 mol%
2-hydroxyethyl methacrylate yield: 88.0 mol%
[0030]
Reference Example 8
Catalyst 5 was prepared in the same manner as Catalyst 1, except that sodium carbonate was used instead of cesium nitrate in the preparation of Catalyst 1. This catalyst 5 was used in the same manner as in Reference Example 1 . The reaction results were as follows.
HBA conversion: 97.4 mol%
2-hydroxyethyl methacrylate yield: 23.4 mol%
[0031]
Reference Example 9
The same procedure as in Reference Example 1 was conducted except that Na-substituted X-type zeolite (MS13X Aldrich) was used as the catalyst 6 and the reaction temperature was 300 ° C. The reaction results were as follows.
HBA conversion: 98.3 mol%
2-hydroxyethyl methacrylate yield: 38.0 mol%
[0032]
Reference Example 10
Reference example, except that Na-substituted Y-type zeolite (HSZ-320NAA manufactured by Tosoh Corporation) was used as the catalyst 7, the reaction temperature was 300 ° C., and a 1: 4 molar mixed solution of α-hydroxyisobutyric acid and ethylene glycol was used as a raw material. 1 was performed. The reaction results were as follows.
HBA conversion: 98.4 mol%
2-hydroxyethyl methacrylate yield: 9.4 mol%
[0033]
The results of Examples 1 to 3 and Reference Examples 1 to 10 are summarized in Table 1.

Table 1
Catalyst Raw material Temperature Conversion Yield Product
℃ mol% mol%
Reference Example 1 Catalyst 1 HBA / EG 320 98.9 85.9 2-HEMA
Reference Example 2 Catalyst 2 HBA / EG 320 98.6 78.9 2-HEMA
Example 1 Catalyst 1 HBM / EG 330 99.6 62.9 2-HEMA
Reference Example 3 Catalyst 1 HBA / CH 350 100 58.4 CHM
Example 2 Catalyst 2 HBO / EG 340 98.1 58.7 2-HEMA
Example 3 Catalyst 2 HBE / EG 320 94.0 54.9 2-HEMA
Reference Example 4 Catalyst 1 HBA / NB 320 96.8 42.9 NBA
Reference Example 5 Catalyst 3 HBA / EG 320 99.6 90.4 2-HEMA
Reference Example 6 Catalyst 1 HBA / EG 320 99.5 89.2 2-HEMA
Reference Example 7 Catalyst 4 HBA / EG 320 99.6 88.0 2-HEMA
Reference Example 8 Catalyst 5 HBA / EG 320 97.4 23.4 2-HEMA
Reference Example 9 Catalyst 6 HBA / EG 300 98.3 38.0 2-HEMA
Reference Example 10 Catalyst 7 HBA / EG 300 98.4 9.4 2-HEMA
[0034]
【The invention's effect】
The present invention is a methacrylate which is an industrially important raw material simply by reaction of hydroxyisobutyric acid and / or a derivative thereof with an alcohol, in particular, having 2 or more carbon atoms or a polyfunctional alcohol and methacrylic acid. Significant in that it provides a means for producing esters comprising

Claims (3)

At least one ester selected from the following hydroxyisobutyric acid esters and at least one alcohol selected from the following alcohols in the presence of a solid catalyst which is silica supported by cesium or silicalite supported by cesium (provided that , Which is different from the alcohol constituting the ester portion of the hydroxyisobutyric acid ester).

Hydroxyisobutyric ester: alpha-methyl ester of the hydroxy iso butyric acid, 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.

Alcohols: 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. Supported amount of cesium, a manufacturing method of methacrylate of claim 1, wherein from 0.1 to 20% by weight relative to the solid catalyst. The method for producing methacrylate according to claim 1 or 2 , wherein the gas phase reaction is carried out at 200 to 400 ° C.