JPH08291158A - Production of new 3-methyltetrahydrofuran - Google Patents

Abstract

PURPOSE: To obtain 3-methyltetrahydrofuran which is useful as one of the comonomers for poly(tetramethylene ether)glycol-3-methyltetrahydrofuran copolymer from inexpensively mass-produced starting substances. CONSTITUTION: Propylene, carbon monoxide and an alcohol are allowed to react in the presence of one or more catalyst selected from the elements in the group VII of the perioidic table, e.g. Pd or Pt and/or their compounds to give a methylsuccinic acid diester. The product is separated from the catalyst, then simultaneously subjected to hydrogenation, cyclization and dehydration in the presence of a copper-chromite catalyst and a cocatalyst such as manganese or barium to give the objective compound.

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 an industrially useful substance as a comonomer of a polytetramethylene ether glycol-3-methyltetrahydrofuran copolymer, which is a fiber having a high elasticity, or as a solvent.

[Prior art]

Various methods for producing 3-methyltetrahydrofuran have been disclosed, for example, a method by hydrogenation of citric acid (EP Publication 277562) and 4-hydroxy-2.
There is a method by hydrogenation of methylbutane-1,2-epoxide (US Pat. No. 3,956,318), but it is difficult to secure the 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 (USP 3,859). , 369), and a method of obtaining 3-methyltetrahydrofuran by subjecting this to cyclodehydration in the presence of an acid catalyst. However, 1,
2-butene by partial hydrogenation of 4-butynediol
It has the disadvantages that the selectivity of 1,4-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-isomers having similar boiling points are used. Generation of a body is unavoidable, and a large amount of energy is required for its separation, which is not an industrially advantageous method. Further, unsaturated hydrocarbon, carbon monoxide, and alcohol are reacted in the presence of molecular oxygen,
A method for producing a diester of a dicarboxylic acid having 2 more carbon atoms than an unsaturated hydrocarbon as a raw material is widely known, and relates to a method for producing dimethyl succinate or dimethyl methylsuccinate in, for example, JP-A-54-82111. Despite the description, it does not mention the method for producing 3-methyltetrahydrofuran.

[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. To provide.

[Means for Solving the Problems]

As a result of earnest studies to solve these problems, the present inventors have found that in the production of 3-methyltetrahydrofuran (step 1), methylsuccinic acid is produced by the reaction of propylene with carbon monoxide and alcohol. Step of synthesizing diester, (Step 2) A completely novel method of producing 3-methyltetrahydrofuran, which comprises a step of producing 3-methyltetrahydrofuran by cyclization dehydration of methylsuccinic acid diester obtained in the above-mentioned step at the same time as hydrogenation Therefore, the present invention has been completed and the present invention has been completed.

The method of the present invention will be described in detail below. Propylene, which is the starting material of the present invention, is industrially produced in large quantities as a raw material for polypropylene, which is a general-purpose plastic, and is available at low cost. In addition, various alcohols used in the present invention are produced in large quantities by fermentation methods and hydration reactions of olefins. In particular, methanol is industrially produced in large quantities from natural gas,
It is easily available. Further, carbon monoxide is industrially produced in large quantities using natural gas, coal, and coke as raw materials, and is easily available. As described above, in any of the methods of the present invention, it becomes possible to produce 3-methyltetrahydrofuran with a high selectivity by using inexpensive and easily available raw materials, which has an extremely high industrial significance. 3 according to the invention
-Scheme of the manufacturing method of methyltetrahydrofuran (Chemical formula 1)
Shown in

[0008]

Embedded image In the chemical formula 1, R represents an alkyl group having 1 to 8 carbon atoms, [I]
Is dimethyl methylsuccinate, and [II] is 3-methyltetrahydrofuran.

The reaction of propylene with carbon monoxide and alcohol in the step 1 of the present invention is one selected from elements belonging to Group 8 of the Periodic Table or compounds thereof,
Alternatively, a mixture of a plurality of catalysts is used as a catalyst.
For the purpose of promoting this reaction, it is also effective to coexist a substance containing a Group 1a element such as copper, a halogen atom such as chlorine, bromine and iodine, and a nitrogen atom such as nitric acid and nitrite. Further, coexistence of oxygen, particularly molecular oxygen, is effective for maintaining the catalytic species in an active state.

The alcohol used in the present invention is not particularly limited, but one having 1 to 8 carbon atoms is preferable. The alcohol used in the present invention includes methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl alcohol, sec-
Examples thereof include butyl alcohol, tert-butyl alcohol, pentanol, n-hexanol, 2-ethyl-hexanol, and n-octanol, but are not limited to those exemplified. Particularly preferred are methanol, isopropanol, n-butanol and the like because they are inexpensive and easily available.

In the embodiment of the step 1 of the present invention, even in a liquid phase homogeneous system, a heterogeneous system of a fixed bed or a suspension bed using a solid catalyst in which a catalyst species is supported on a carrier such as activated carbon, silica, alumina or diatomaceous earth. However, it can be implemented. The elements of Group 8 of the periodic table used as catalysts include palladium, platinum, iron, cobalt, nickel, ruthenium, rhodium, osmium, iridium, etc., and the elements of Group 1a include copper, silver, etc. The catalyst may be used alone or in combination of two or more. Of these, palladium and copper are particularly suitable as the catalyst component. In addition, halogen atoms such as chlorine and bromine are effective as elements having the effect of promoting the reaction or increasing the selectivity, but these are the chlorides of the metals serving as the main catalyst, salts of alkali metals, and halogenated salts. It is effective to introduce it into the reaction system in the form of an alkyl or ammonium salt.

The amount of the element of Group 8 of the periodic table used as a catalyst in (Step 1) of the present invention is as follows:
It is in the range of 0.0001 to 200 mmol, more preferably in the range of 0.001 to 100 mmol.

Step 1 of the method of the present invention is atmospheric pressure to 300 kg.
/ Cm ² (gauge pressure), preferably 5-200 Kg / c
High methylsuccinate diester yields are achieved by carrying out the reaction under m ² (gauge pressure) carbon monoxide pressure. Carbon monoxide used in the method of the present invention preferably has a high purity, but carbon monoxide containing methane, hydrogen, nitrogen or the like can be used as long as the partial pressure of carbon monoxide is secured. Furthermore, in step 1 of the method of the present invention, it is possible to improve the selectivity of the target methyl succinic acid diester by introducing molecular oxygen into the reaction system.

In carrying out step 1 of the method of the present invention,
Although it can be carried out without solvent, it is also possible to use a reaction solvent. The reaction solvent is not particularly limited as long as it is stable in the reaction system and does not hinder the intended reaction, and includes aliphatic hydrocarbons, aromatic hydrocarbons, ethers, ketones, esters, alcohols, amides and the like. You can choose from.
In particular, it is preferable to use alcohol, which is one of the reaction raw materials, or methyl succinate diester, which is a reaction product, as a reaction solvent without complicating the reaction system. The reaction temperature in the method of the present invention is in the range of 30 to 200 ° C., but especially 5
The range of 0 to 150 ° C. is preferable.

The reaction product, methylsuccinic acid diester, in step 1 of the present invention is separated from the catalyst component by operations such as distillation, extraction, and filtration.
And subjected to a dehydration cyclization reaction.

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. The reaction conditions of the hydrogenation and dehydration cyclization reaction of (Step 2) in the present invention differ depending on the catalyst component used, but the reaction temperature is generally 100 to 3
The reaction is carried out at a temperature of 00 ° C. and a reaction pressure of 20 to 200 kg / cm ² (gauge pressure). Particularly suitable copper as a catalyst for this reaction
Chromite preferably has a reaction temperature of 150 to 280 ° C. and a reaction pressure 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 the 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.

[0018] (1), (2) copper obtained by a method of - chromium - barium (or manganese) weight ratio of each component contained in the catalyst is _{CuO: Cr 2 O 3: MnO} 2 ( or BaO) 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 solution containing 3-methyltetrahydrofuran produced by the hydrogenation and dehydration cyclization reactions can be separated and purified by a conventional distillation operation to easily obtain the desired 3-methyltetrahydrofuran. it can.

[0020]

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.

Example 1 (Process 1) A 20 ml stainless steel autoclave equipped with a thermometer and a pressure gauge was used, and 0.7% of 5% Pd-supporting activated carbon was used.
6 g (38 mg as Pd metal), PdCl ₂ 46.7
mg and 10 ml of methanol were charged and the container was sealed, and after cooling the container with ice water, 4.21 g of propylene was press-fitted.
The pressure inside the container was about 11 kg / cm2 when propylene was charged.
(Gauge pressure). Further, the reaction vessel was filled with carbon monoxide gas up to 50 Kg / cm ² (gauge pressure), and further filled with oxygen at 4 Kg / cm ² (gauge pressure). 90 ° C
Load the reaction vessel into the metal clad heater kept at
The reaction solution was stirred with a magnetic stirrer and reacted for 2 hours. Oxygen 5 kg / cm ² (gauge pressure) during the reaction
Press-fitted three times each. When the reaction liquid was analyzed by gas chromatography after the completion of the reaction, the yield of dimethyl methylsuccinate was 3.9 mmol, and in addition thereto, 0.10 mmol of dimethyl oxalate was produced.

Example 2 The same reactor as in Example 1 was charged with 0.0% 5% Pd-supported activated carbon.
82 g (4.1 mg as Pd metal), 61% nitric acid 0.
1 g and 10 ml of methanol were charged, the container was sealed, the container was cooled with ice water, and 2.65 g of propylene was press-fitted.
When propylene was charged, the pressure in the container was about 11 kg /
It was cm ² (gauge pressure). Further, the carbon monoxide gas into the reaction vessel was filled up to 40 Kg / cm ² (gauge pressure), further oxygen 5Kg / cm ² (gauge pressure) was charged. The reaction vessel was loaded into the metal clad heater maintained at 85 ° C, and the reaction solution was stirred with a magnetic stirrer.
The reaction was carried out for 7 hours. Oxygen 5kg / cm during the reaction
² (gauge pressure) was pressed 4 times. After completion of the reaction, the reaction solution was analyzed by gas chromatography to find that the yield of dimethyl methylsuccinate was 4.2 mmol, and in addition to this, 1.28 mmol of dimethyl oxalate was produced.

Example 3 (Step 2) A hydrogenation reactor having an inner diameter of 15 mm and a length of 3
A 00 mm stainless steel reaction tube was used, and a copper-chromite catalyst (Nissan Gadler: G-99) was used as a catalyst.
10 g of C) that had been sized to 10 to 20 mesh was filled. While preventing hot spots according to the usual method, 150 with 0.5 to 5% by volume of hydrogen diluted with nitrogen.
The catalyst was reduced at ˜200 ° C.

The catalyst was filtered from the reaction solution obtained in Example 1 and further distilled, and 70 parts by weight of metaxylene was added to 30 parts by weight of the isolated dimethyl methylsuccinate to carry out hydrogenation and dehydration cyclization reactions. Used as feedstock. The supply gas to the hydrogenation reactor was switched to pure hydrogen, pressure 160Kg
/ Cm ² (gauge pressure), the purge gas SV was 500 h ⁻¹ , and the catalyst layer temperature was 230 ° C. The reaction raw material was supplied from the upper part of the reaction tube at 3.3 g / h. After cooling the reaction solution,
Gas-liquid separation was performed and the liquid phase part was analyzed by GC. 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 93.
The yield of 1% and 2-methyl-butanediol was 0.7%.

[0025]

INDUSTRIAL APPLICABILITY 3-Methyltetrahydrofuran can be produced in high yield from a large amount of raw materials produced at low cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 23/74 B01J 23/74 X 23/86 23/86 X 27/08 27/08 X 27 / 10 27/10 X // C07B 61/00 300 C07B 61/00 300 C07C 69/40 9546-4H C07C 69/40

Claims (8)

[Claims] 1. A process comprising a step 1 of synthesizing a methylsuccinic acid diester by reacting propylene, carbon monoxide, and an alcohol, and a step 2 of hydrogenating and dehydrating cyclization of the methylsuccinic acid diester, which is a product of the step 1. -Method for producing methyltetrahydrofuran. 2. The method according to claim 1, wherein the reaction with propylene, carbon monoxide and alcohol is carried out in the presence of an element belonging to Group 8 of the periodic table. 3. The method according to claim 2, wherein the element belonging to Group 8 of the periodic table is palladium and / or platinum. 4. The method according to claim 1, wherein the method is carried out in the presence of molecular oxygen. 5. The method according to claim 1, wherein the step 2 is carried out in the presence of an element belonging to Groups 7a and 8 of the periodic table and / or copper. 6. The method according to claim 5, wherein in step 2, the hydrogenation catalyst is copper-chromite. 7. The alcohol is methanol.
The method described in. 8. The alcohol produced in step 2,
The method according to claim 1 or 7, which is reused as a raw material in step 1.