JPH08217770A - New production of 3-methyltetrahydrofuran - Google Patents

Abstract

PURPOSE: To obtain the subject compound useful as a comonomer component of a copolymer for fiber, a solvent, etc., in high yield at a low cost by reacting methyl methacrylate with a formic acid ester, forming a methylsuccinic acid diester, hydrogenating and cyclodehydrating the resultant diester. CONSTITUTION: Methyl methacrylate and a formic acid ester (e.g. methyl formate) are added to an autoclave, made of stainless steel and equipped with a thermometer and a pressure indicator. An element belonging to group VIII of the periodic table (e.g. ruthenium) is used as a catalyst and benzene. etc., are used as a solvent. Carbon monoxide gas is filled therein and the reaction is carried out at 200 deg.C for 24hr to form a methylsuccinic acid diester of formula I (R is an alkyl), which is then hydrogenated and cyclodehydrated using a copper-chromite catalyst at 150-200 deg.C to industrially and advantageously afford the objective 3-methyltetrahydrofuran of formula II usable as a comonomer component of a copolymer which is a raw material for fibers rich in elasticity, a solvent, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for producing 3-methyltetrahydrofuran. 3-Methyltetrahydrofuran is a substance useful as a comonomer of a polytetramethylene ether glycol / 3-methyltetrahydrofuran copolymer, which is a fiber having a high elasticity, or as a solvent in a specific application.

[Prior art]

Various methods for producing 3-methyltetrahydrofuran are disclosed, for example, a method by hydrogenation of citric acid (EP Publication 277562) and 4-hydroxy-.
There is a method by hydrogenation of 2-methylbutane-1,2-epoxide (US Pat. No. 3,956,318), but it is difficult to secure a starting material and it is difficult to carry out industrially. Further, a method by hydrogenation of methylmaleic acid or methylsuccinic acid (JP-A-49-9463) is also disclosed. However, not only is it difficult to obtain starting materials, but also the hydrogenation conditions are harsh, so that industrial implementation Is obviously difficult.

Further, 2-methyl-1,4-butanediol obtained by hydroformylating and hydrogenating 2-butene-1,4-diol obtained by partially hydrogenating 1,4-butynediol is obtained (USP3859369). There is a method of obtaining 3-methyltetrahydrofuran by subjecting this to cyclodehydration in the presence of an acid catalyst. However, 1,4-
2-Butene-1,4 by partial hydrogenation of butynediol
It has the disadvantage that the selectivity of the diol is not high enough and that the hydroformylation yield for internal olefins such as 2-butene-1,4-diol is not high enough.

Further, 3-methyltetrahydrofuran or 2-by the hydrogenation of β-formylisobutyric acid ester
Method for obtaining methyl-1,4-butanediol
No. 219981) is disclosed. The starting material β-formylisobutyric acid ester in this method is synthesized by a known method of hydroformylation of methacrylic acid ester (Bull. Chem. Soc. Japan 50 (1977) 2351), but α-isomerization with a close boiling point is performed. Generation of the body is unavoidable, and a large amount of energy is required for its separation, which is not an industrially advantageous method.

[Problems to be Solved by the Invention]

The problem to be solved by the present invention is to solve the above-mentioned problems in various methods for producing 3-methyltetrahydrofuran and to provide a method for producing 3-methyltetrahydrofuran by an industrially advantageous method. There was to offer.

[Means for Solving the Problems]

As a result of intensive studies to solve these problems, the present inventors have found that in the production of 3-methyltetrahydrofuran (step 1), a methyl succinate diester is formed by reacting methyl methacrylate with a formate ester. And a step of producing 3-methyltetrahydrofuran, which comprises the step of producing 3-methyltetrahydrofuran by cyclizing and dehydrating the methylsuccinic acid diester obtained in the above step (step 2) The present invention has been completed.

The method of the present invention will be described in detail below. Methyl methacrylate, which is the starting material of the present invention, is industrially produced in large quantities as a monomer of polymethacrylate and is available at low cost. Among the formate esters as the other raw material, methyl formate is easily available by dehydrogenation of methanol, which is supplied in large quantities and at low cost, or by carbonylation of methanol, and other formate esters are the same as those mentioned above. It can be easily obtained by transesterification reaction with various alcohols. in this way,
According to the method of the present invention, it is possible to produce 3-methyltetrahydrofuran with a high selectivity by using inexpensive and easily available raw materials, which is extremely significant industrially. Chemical formula 1 shows a method for producing 3-methyltetrahydrofuran according to the present invention.

[0008]

Embedded image In the formula (Formula 1), R is an alkyl group, [I] is a methylsuccinic acid diester, and [II] is 3-methyltetrahydrofuran.

The reaction of methyl methacrylate and formic acid ester in (Step 1) of the present invention is carried out by using an element belonging to Group 8 of the periodic table or a compound thereof as a catalyst (Japanese Patent Application No. 5-224590). Further, examples of the formate ester used in this reaction include methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate and the like, and any of them can be used from the viewpoint of reactivity, but formic acid is easily available. Methyl is preferred.

The embodiment of (Step 1) of the present invention is carried out in a liquid phase homogeneous system, in which methyl methacrylate as a raw material, formic acid ester and a catalyst component are mixed and treated at a predetermined temperature for a predetermined time. It is done by The molar ratio of the formate ester to methyl methacrylate is in the range of 0.1 to 20 times by mole, more preferably 0.5 to 10 times by mole. Further, as elements of Group 8 of the periodic table used as catalysts, iron, cobalt, nickel, ruthenium, rhodium,
There are palladium, osmium, iridium, and platinum, and these can be used alone or in combination of two or more as a catalyst. Among these, especially cobalt,
And ruthenium are suitable as catalyst components. Also,
The form of the element of Group 8 of the periodic table used as a catalyst is
There are halides, salts, carbonyl compounds, phosphine coordination compounds and the like, and any of them can be used, but carbonyl compounds are particularly preferable.

The amount of the element of Group 8 of the periodic table used as a catalyst in the present invention is in the range of 0.1 to 200 mmol, preferably in the range of 1 to 50 mmol, per liter of the reaction solution.

In the method of the present invention, carbon monoxide is not consumed, but it is effective for maintaining high activity of the elements of Group 8 of the Periodic Table used as catalysts or these compounds, and usually 1 to 300 kg / cm 3. High methylsuccinate diester yields are achieved by carrying out the reaction under carbon monoxide pressure of ² (gauge pressure), preferably 5-200 kg / cm ² (gauge pressure). The carbon monoxide used in the method of the present invention does not need to be highly pure, and even if it contains methane, hydrogen, nitrogen, etc., there is no problem as long as the partial pressure of carbon monoxide is secured.

It is possible to use reaction solvents in carrying out the process of the invention. As the reaction solvent, it is possible to use the reaction raw material itself as the reaction solvent, but there is no particular limitation as long as it is stable in the reaction system and does not hinder the intended reaction, and aliphatic hydrocarbon, aromatic hydrocarbon It can be selected from hydrogen, ether, ketone, ester, alcohol, amide and the like. The reaction temperature in the method of the present invention is 50 to 3
The temperature is in the range of 50 ° C, but the range of 100 to 250 ° C is particularly preferable.

The methyl succinic acid diester which is the reaction product in (Step 1) of the present invention is separated from the catalyst component by an operation such as distillation or extraction, and is subjected to the next (Step 2) hydrogenation and dehydration cyclization reaction. Be served.

The catalyst used in the hydrogenation and dehydration cyclization reaction of (Step 2) in the present invention contains copper or an element belonging to Groups 7a and 8 of the periodic table as a main component.
More specifically, copper, cobalt, nickel, iron, rhenium, palladium, ruthenium, platinum and rhodium are effective as the main components of the catalyst of this reaction. Further, as a component forming the co-catalyst, a solid acid component containing chromium, molybdenum, manganese, barium, magnesium, and silicon and aluminum is effective. A particularly suitable catalyst for this reaction is one containing copper as a main component and generally called copper-chromite, and one containing manganese, barium, or the like as a promoter component. In the present invention (step 2)
The reaction conditions for the hydrogenation and dehydration cyclization reaction of are different depending on the catalyst components used, but the reaction temperature is generally 10
The reaction is carried out at a temperature of 0 to 300 ° C. and a reaction pressure of 20 to 200 kg / cm ² (gauge pressure). With copper-chromite, which is particularly suitable as a catalyst for this reaction, the reaction temperature is 150 to 280.
° C., also the reaction pressure is preferably in the range of 50 to 200 kg / cm ² (gauge pressure). The hydrogen used in the reaction is preferably pure hydrogen, but those containing methane, nitrogen, etc. can also be used.

The catalyst used in this catalytic hydrogenation reaction is preferably a copper-chromium-barium (or manganese) catalyst, which is prepared, for example, by the following method. (1) Solid cupric oxide (CuO), chromic oxide (Cr ₂
O ₃ ) and manganese dioxide (MnO ₂ ) (or barium oxide (B
aO)) is mixed, and graphite etc. are added as a lubricant and mixed well, then molded by a general method, calcinated at a high temperature, and crushed the molded product to be used in an appropriate size. (2) Ammonia water is added to an aqueous solution in which ammonium dichromate is dissolved, and cupric nitrate (or cupric sulfate or the like) and manganese nitrate (or manganese sulfate or the like) or barium nitrate that are separately prepared are added to the aqueous solution. Is added dropwise with stirring. The precipitate formed is washed with water, dried and then calcined in the air at a temperature of about 350 ° C. The powdery calcined product thus obtained can be used as it is for the reaction, but it is also possible to add an appropriate binder or lubricant to the calcined product and sufficiently mix it, followed by molding and use.

The weight ratio of each component contained in the copper-chromium-barium (or manganese) catalyst obtained by the above-mentioned methods (1), (2), etc. is CuO: Cr ₂ O ₃ : MnO ₂ (or BaO ₂ ). It is preferable that they are in the range of 20-85: 15-75: 1-15, respectively. The catalyst may be in the form of powder, tablet, or the like, and the most suitable one for the usage is used. Before use, these catalysts are subjected to a suitable activation treatment such as treatment in a hydrogen atmosphere at about 200 ° C. and then subjected to the reaction. The amount of hydrogen used is 4 mol or more, preferably 6 to 60 mol, per 1 mol of the ester.

In the present invention, the reaction liquid containing 3-methyltetrahydrofuran produced by hydrogenation and dehydration cyclization reaction can be separated and purified by a conventional distillation operation to easily obtain the desired 3-methyltetrahydrofuran. it can.

[0019]

The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited by these examples.

(Step 1) Example 1 Methyl methacrylate 1.0 × 10 ^-2 mol, methyl formate 0.1 mol, and Ru ₃ (CO) ₁₂ as a catalyst were placed in a 50 ml stainless steel autoclave equipped with a thermometer and a pressure gauge. 1.2 x 10 ^-5 mo
l, 5.0 ml of benzene was charged as a solvent. After thoroughly replacing the inside of the reaction vessel with carbon monoxide gas, fill the reaction vessel with carbon monoxide gas up to 20 kg / cm ² (gauge pressure), immerse the reaction vessel in an oil bath maintained at 200 ° C, and use a magnetic stirrer to prepare the reaction solution. Was stirred and reacted for 24 hours. When the reaction solution was analyzed by gas chromatography, the conversion rate of methyl methacrylate was 92%, the yield of dimethyl methylsuccinate was 73.2%, and in addition, 4.0% of methyl isobutyrate was produced. .

Example 2 As in Example 1, except that Co ₂ (CO) ₈ 3.6 × 10 ^-5 mol was used as the catalyst and the carbon monoxide pressure was up to 200 kg / cm ² (gauge pressure). went. As a result of the analysis, the conversion rate of methyl methacrylate was 88%, the yield of dimethyl methylsuccinate was 68.5%, and in addition to this, 3.2% of methyl isobutyrate was produced.

Example 3 Example 1 except that methyl formate was replaced with isopropyl formate.
I went the same way. As a result of the analysis, the conversion rate of methyl methacrylate was 91%, and the combined yield of methyl succinic acid methyl isopropyl ester, dimethyl methyl succinate and diisopropyl methyl succinate was 70.1%. Isopropyl and the like were produced in 4.2%.

(Step 2) Example 4 A reaction tube made of stainless steel having an inner diameter of 15 mm and a length of 300 mm was used as a hydrogenation reactor, and a copper-chromite catalyst (manufactured by Nissan Gardler: G-99C) was used as a catalyst. 1
10 g of the sized 0 to 20 mesh was filled. According to the usual method, while preventing hot spots, the amount of hydrogen diluted with nitrogen was 0.5 to 5% by volume of nitrogen containing 150%.
The catalyst was reduced at ˜200 ° C.

The catalyst component was separated from the reaction solution obtained in Example 1 by a conventional method (vacuum distillation) to isolate dimethyl methylsuccinate. This dimethyl methyl succinate 30
70 parts by weight of mixed xylene was added to parts by weight and used as a feedstock for hydrogenation and dehydration cyclization reactions. The supply gas to the hydrogenation reactor was switched to pure hydrogen, and the pressure was 160 kg / cm ²
(Gauge pressure), the purge gas SV was set to 500 hr ^-1 , and the catalyst layer temperature was set to 230 ° C. 3.3 g of reaction raw material per hour
Was supplied from above the reaction tube. The reaction liquid was cooled, gas-liquid separated, and the liquid phase portion was analyzed by gas chromatography.
After 5 hours had passed from the start of the reaction, the reaction solution was collected for 1 hour and analyzed. As a result, the yield of 3-methyltetrahydrofuran was 95.2% and the yield of 2-methyl-1,4-butanediol was 0. It was 0.4%.

Example 5 The same procedure as in Example 4 was carried out except that methylisopropyl methylsuccinate isolated from the reaction solution obtained in Example 3 was used as the raw material for hydrogenation. When the reaction solution was analyzed in the same manner as in Example 4, the yield of 3-methyltetrahydrofuran was 95.5% and the yield of 2-methyl-1,4-butanediol was 0.5%.

[0026]

INDUSTRIAL APPLICABILITY According to the present invention, since each process proceeds with high yield and 3-methyltetrahydrofuran can be obtained from an inexpensive raw material, the present invention has an extremely high industrial value.

Claims (6)

[Claims] 1. A step 1 in which methyl methacrylate is reacted with a formate ester to synthesize a methyl succinate diester,
A method for producing 3-methyltetrahydrofuran, which comprises the step 2 of hydrogenating and cyclodehydrating the methyl succinic acid diester which is the product of step 1. 2. The method according to claim 1, wherein the reaction of methyl methacrylate with the formate ester is carried out in the presence of an element belonging to Group 8 of the periodic table. 3. An element belonging to Group 8 of the periodic table is cobalt,
The method according to claim 2, which is also ruthenium. 4. The method according to claim 1, wherein the formate ester is methyl formate. 5. The hydrogenation reaction in step 2 is carried out in the presence of at least one of copper, a copper compound, a 7a group metal, a 8 group metal, a 7a group metal compound and a 8 group metal compound. The method according to 1. 6. The method according to claim 5, wherein the hydrogenation catalyst in step 2 is copper-chromite.