JP2003034666A - Method for producing allyl methacrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing allyl methacrylate by a continuous reaction. SOLUTION: The allyl methacrylate is produced by subjecting 2-allyl hydroxyisobutyrate to continuous dehydration in gas phase, usually at 100-400 deg.C and at an atmospheric pressure using a phosphate of a rare-earth element as a catalyst. The catalyst phosphate of the rare-earth element is prepared by precipitation after mixing an aqueous solution of salts of the rare-earth element with almost same number of moles of phosphoric acid as the salts.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing allyl methacrylate by dehydrating allyl 2-hydroxyisobutyrate. Allyl methacrylate is used as a silane coupling agent, a resin raw material, an intermediate in various organic syntheses, and the like. [0002] Allyl methacrylate has been produced by various methods. Allyl methacrylate is produced by, for example, an esterification reaction between allyl alcohol and methacrylic acid, a method of reacting allyl chloride with methacrylic acid salt as disclosed in Japanese Patent Publication No. 43-27849. . Also, West German Patent Publication No. 193
No. 3536 discloses a process for producing an allyl ester by reacting a methyl or ethyl ester of a corresponding acid with an allyl acetate in the presence of a metal methoxide such as sodium methylate. Further, French Patent No. 2088971 discloses a method for producing allyl methacrylate by transesterification of methyl methacrylate with allyl alcohol. [0003] In any of the methods, the production efficiency is low due to the batch operation, and in addition, large-scale production requires a large-sized apparatus and the investment amount is large. . The present invention provides a method for industrially and advantageously producing allyl 2-hydroxyisobutyrate by a continuous process. SUMMARY OF THE INVENTION The present inventors have studied to establish an industrial technique with respect to the above object, and as a result, have found that industrial production of allyl 2-hydroxyisobutyrate from 2-hydroxyisobutyric acid and propylene and oxygen can be considered. Although it has been filed as a production method (Japanese Patent Application No. 2001-215559), the present inventors have intensively studied a method for industrially and advantageously producing allyl methacrylate using allyl 2-hydroxyisobutyrate as a raw material. And completed the present invention. Hereinafter, the present invention will be further described. Hereinafter, a method for producing allyl methacrylate of the present invention will be described. In this reaction, a catalyst comprising one or more rare earth phosphates is used. Any rare earth phosphate can be used regardless of its state or concentration, as long as it can be obtained by a known preparation method, and is a phosphate containing at least one element selected from rare earth elements. is there. La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. For the preparation of the rare earth phosphate, for example, an aqueous solution of the rare earth salt is mixed with approximately equimolar phosphoric acid and reacted to obtain a slurry containing precipitate. This is aged as it is or after neutralization with an aqueous ammonia solution.
The obtained precipitate is washed with water by a decantation method or the like, filtered as it is or dried, and / or calcined to obtain a rare earth phosphate. Rare earth salts include, but are not particularly limited to, nitrates, hydrochlorides, acetates, and the like. The temperature at which the precipitate is obtained is not particularly limited, but it is preferable to carry out the reaction at a constant temperature. The drying and firing temperatures are not particularly limited, but the drying is preferably performed at 60 to 200 ° C. It is preferable to perform firing at 200 to 600 ° C. The rare earth phosphate can be used by being supported on a carrier, and the activity of the catalyst can be increased by using a carrier having a relatively large surface area such as silica. The concentration of the rare earth phosphoric acid in the carrier and the rare earth phosphate is 95 to
A range of 5% is preferable, and a range of 10 to 70% is preferable. As the carrier, titanium dioxide, alumina, silica,
Examples of the zeolite include zeolite Y, zeolite Y, alkali metal exchanged zeolite Y, and M
Examples include FI zeolite and alkali metal exchanged MFI zeolite, but are not particularly limited thereto. The reaction system according to the present invention may be any of a gas phase method and a liquid phase method, but a gas phase is preferable, and the reaction can be carried out by any method such as a fixed bed system and a fluidized bed system. The reaction temperature of the present invention is usually 100 to 400 ° C, preferably 15 to
0-300 ° C. The reaction pressure may be usually atmospheric pressure,
It can be under pressure or under reduced pressure. The feed rate of allyl 2-hydroxyisobutyrate (LHSV) in the range of 0.005 to 10 hr ^-1 is usually sufficient. The starting material for the reaction may be allyl hydroxyisobutyrate alone, or a diluent may be used. Preferably, the selectivity can be increased by diluting with a solvent inert to the reaction. As the diluent, solvents such as water, aliphatic hydrocarbons, and aromatic hydrocarbons, and gases such as nitrogen, argon, and helium can be used. Even if these diluents are mixed and used, there is no problem. Absent. The method of the present invention will be described in detail below with reference to examples and comparative examples. still. The present invention is not limited to the scope of the following examples. 4 g of the catalyst prepared in each of the examples was filled in a glass reaction tube having an inner diameter of 15 mm, and the reaction was performed under each reaction condition. Example 1 67.37 g of sodium hydrogen phosphate (Na ₂ HPO ₄ ) (0.
188 mol) in 500 ml of water.
° C.) with stirring, to which lanthanum nitrate _{(La (NO 3) 3 ·} 6H
₂ O) 37.02 g (0.0855 mol) in 300 m of water
When an aqueous solution dissolved in 1 is dropped, a white precipitate is formed. After this, heating was continued for 1 hour to ripen, and the white precipitate was filtered and washed with water to obtain lanthanum phosphate. Example 2 The lanthanum phosphate obtained in Example 1 was dried at 100 ° C. for 10 hours and calcined at 400 ° C. for 3 hours. A reaction was performed using this catalyst. A solution obtained by diluting allyl 2-hydroxyisobutyrate with 12-fold molar n-hexane was supplied at 8.17 g / hr. At a reaction temperature of 280 ° C., the conversion of allyl 2-hydroxyisobutyrate was 72.3%, the yield of allyl methacrylate was 41.3 mol%, and the yield of methacrylic acid was 19.
It was 5 mol%. EXAMPLE 3 14 g of 5 μm silica powder was added to 53.8 g of the lanthanum phosphate obtained in Example 1, kneaded, dried at 100 ° C. for 10 hours, and calcined at 400 ° C. for 3 hours. A reaction was performed using this catalyst. A solution obtained by diluting allyl 2-hydroxyisobutyrate with 12-fold molar n-hexane was supplied at 8.17 g / hr. At a reaction temperature of 280 ° C., the conversion of allyl 2-hydroxyisobutyrate was 97.5%, the yield of allyl methacrylate was 62.5 mol%, and the yield of methacrylic acid was 26.
It was 5 mol%. Example 4 6 g of 5 μm silica powder was added to 23.0 g of the lanthanum phosphate obtained in Example 1, kneaded, dried at 100 ° C. for 10 hours, and calcined at 400 ° C. for 3 hours. A reaction was performed using this catalyst. A solution obtained by diluting allyl 2-hydroxyisobutyrate with 12-fold molar n-hexane was supplied at 8.17 g / hr. At a reaction temperature of 280 ° C., the conversion of allyl 2-hydroxyisobutyrate was 84.5%, the yield of allyl methacrylate was 56.8 mol%, and the yield of methacrylic acid was 22.
It was 7 mol%. Example 5 Cerium phosphate prepared exactly the same as in Example 1 except that lanthanum nitrate was replaced with cerium nitrate was used.
For 10 hours and calcined at 400 ° C. for 3 hours. A reaction was performed using this catalyst. 7. A solution obtained by diluting allyl 2-hydroxyisobutyrate with 12-fold molar n-hexane is used.
It was fed at 17 g / hr. At a reaction temperature of 280 ° C., the conversion of allyl 2-hydroxyisobutyrate was 70.4%, the yield of allyl methacrylate was 40.9 mol%, and the yield of methacrylic acid was 16.5 mol%. Example 6 Na-Y was added to 23.0 g of the lanthanum phosphate obtained in Example 1.
6 g of zeolite type powder was added, kneaded, dried at 100 ° C. for 10 hours, and calcined at 400 ° C. for 3 hours. A reaction was performed using this catalyst. 12 Allyl 2-hydroxyisobutyrate
A solution diluted with a molar amount of n-hexane was 8.17 g /
hr. At a reaction temperature of 280 ° C., the conversion of allyl 2-hydroxyisobutyrate was 78.5%, the yield of allyl methacrylate was 56.8 mol%, and the yield of methacrylic acid was 19.1 mol%. As is clear from the above examples, according to the present invention, by using a rare earth phosphate as a dehydration catalyst, an allyl methacrylate can be continuously converted from allyl 2-hydroxyisobutyrate by using a continuous reaction. Can be manufactured
Its industrial significance is great.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kazuo Tanaka             Mitsubishi Gas Chemical, 22 Wadai, Tsukuba City, Ibaraki Prefecture             Inside Research Institute Co., Ltd. F-term (reference) 4H006 AA02 AC25 BA08 BA71 BA81                       BB11 BC10 BC18 KA31 KC14                       KD00                 4H039 CA21 CG10

Claims (1)

Claims: 1. A rare earth phosphate is used as a catalyst.
-A method for producing allyl methacrylate, comprising dehydrating allyl hydroxyisobutyrate.