JPH1067764A - Production of 3-methyltetrahydrofuran - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing 3-methyltctrahydrofuran from an inexpensive raw material in a high yield and also without an unnecessary byproduct. SOLUTION: This method for producing 3-methyltetrahydrofuran is to produce methyl 3-cyanoisobutyrate from hydrocyanic acid with methylmethacrylate, methyl 3-carbamoylisobutyrate by hydrating the obtained methyl 3- cyanoisobutyrate, methyl succinate and formamide from the obtained methyl 3-carbamoylisobutyrate with an aliphatic alcohol and carbon monoxide, and 3-methyltetrahydrofuran by catalytic hydrogenation of the obtained methylsuccinate and also hydrocyanic acid by dehydrating the obtained formamide for using by a recirculation, or ammonia and carbon monoxide by a decomposing the formamide for a utilization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel process for producing 3-methyltetrahydrofuran. 3-Methyltetrahydrofuran is used as a comonomer of polyether glycol, which is a raw material of spandex fiber.

[0002]

2. Description of the Related Art 3-Methyltetrahydrofuran can be produced by various methods. JP-A-63-218669
According to No. 3, hydrogenation of citric acid produces 3-methyltetrahydrofuran with 3- and 4-methylbutyrolactone, with a selectivity of about 70%. U.S. Patent No.
According to 3956318, epoxides are produced by catalytic hydrogenation in the liquid phase in the presence of a protonic acid, but the raw epoxides are expensive. According to JP-A-2-62835, 4-hydroxybutyraldehyde or 2-hydroxybutyraldehyde is used in the presence of an aldehyde.
Cyclization of the diol obtained by catalytic hydrogenation of hydroxytetrahydrofuran is produced, but its raw material is expensive and involves by-product tetrahydrofuran. A method of hydrogenating methyl maleic acid or methyl succinic acid (Japanese Patent Application Laid-Open No. 49-9463) is also disclosed, but not only is it difficult to obtain starting materials, but also the conditions for hydrogenation are severe and industrial practice has been difficult. The difficulty is obvious.

According to JP-A-48-22405, 1,4-butenediol is hydroformylated, and after the catalyst is separated, the hydroformylated product (estimated as 2-formyl-1,4-butenediol) is produced. The 2-methyl-1,4-butenediol obtained by catalytic hydrogenation of the aqueous solution is cyclized to give 3-
Methyl tetrahydrofuran is obtained. In addition, JP-A-5-11
According to JP 7258 and JP-B 4-55179, 1,4-butynediol or 1,4-butenediol is catalytically hydrogenated in the presence of an aldehyde to cyclize the resulting diol to give 3-methyltetrahydrofuran. However, 1,4-butenediol and 1,4-butynediol used as raw materials in these methods are expensive because they are obtained from acetylene, and are accompanied by by-products of tetrahydrofuran. According to Japanese Patent Application Laid-Open No. 6-219881, catalytic hydrogenation of itaconic acid, 3-formyl-2-methylpropionic acid or esters thereof gives 2-methyl-1,4.
It is formed with butanediol, but its raw material, itaconic acid, 3-formyl-2-methylpropionic acid is expensive. As mentioned above, the existing methods for producing 3-methyltetrahydrofuran are not industrially satisfactory, because the raw materials are expensive and the selectivity to 3-methyltetrahydrofuran is low.

[0004]

An object of the present invention is to provide a process for producing highly selective 3-methyltetrahydrofuran using inexpensive raw materials which do not have the above-mentioned disadvantages. For this purpose, (1) a step of producing methyl 3-cyanoisobutyrate from hydrocyanic acid and methyl methacrylate, (2) a reaction of the methyl 3-cyanoisobutyrate obtained in the above step with water and sulfuric acid, and then the reaction product Is also reacted with an alcohol to produce methyl succinate, and (3) a process for producing 3-methyltetrahydrofuran comprising the step of catalytically hydrogenating the methyl succinate obtained in the above step to produce 3-methyltetrahydrofuran. I went. However, in this method, a large amount of ammonium salt is produced as a by-product.
There is a disadvantage that the production cost of tetrahydrofuran is reduced.

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, hydrated methyl 3-cyanoisobutyrate to form 3-
Methyl carbamoylisobutyrate, and then reacting with an aliphatic alcohol having 2 or more carbon atoms and carbon monoxide to form a methyl succinate ester, and it is found that 3-methyl-tetrahydrofuran can be obtained very efficiently by catalytic hydrogenation. Was. Chemical formulas 1 and 2 schematically show all the steps of the production method of the present invention.

[0006]

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Hereinafter, the method of the present invention will be described in detail. From the hydrocyanic acid and methyl methacrylate in the present invention, 3-
The first step of producing methyl cyanoisobutyrate is carried out by a known method, and is carried out at about 40 to 130 ° C. in the presence of a lower alkyl-substituted pyrrolidone or dimethyl sulfoxide solvent and an alkali metal cyanide as a catalyst.

[0008] The production of methyl 3-carbamoylisobutyrate (second step) in the present invention is carried out by reacting a mixture of methyl 3-cyanoisobutyrate and water in the presence of a catalyst. As the catalyst, a catalyst effective for the hydration reaction of nitriles can be used, and a strong acid such as sulfuric acid is also used, but a metal catalyst or a metal oxide catalyst is preferable from the economic viewpoint including the treatment. Specifically, manganese,
Copper, nickel or their oxides are effective, and manganese oxide is particularly preferred.

The proper weight ratio of methyl 3-cyanoisobutyrate to water is 2: 98-98: 2. In this system, methyl methacrylate, which is a raw material of methyl 3-cyanoisobutyrate, and ketones such as alcohol and acetone can coexist as a solvent. When using manganese oxide as a catalyst, the reaction temperature is preferably in the range of 20 to 150 ° C, and particularly preferably 30 to 100 ° C. The reaction time is preferably 0.3 to 6 hours, particularly preferably 0.5 to 4 hours. The reaction can be carried out in either a batch system or a continuous system.

In the present invention, the production of methyl succinate and formamide by reacting methyl 3-carbamoylisobutyrate with an aliphatic alcohol having 2 or more carbon atoms and carbon monoxide (third step) comprises the steps of: Heating methyl butyrate with aliphatic alcohols and carbon monoxide in the absence of a catalyst is possible, but it is effective to carry out the reaction in the presence of a solvent and a catalyst. As the aliphatic alcohol, an aliphatic alcohol having 2 or more carbon atoms, preferably an aliphatic alcohol having 2 to 8 carbon atoms is used. This reaction is an equilibrium reaction, and the yield of methyl succinate is determined by the molar ratio of the aliphatic alcohol to the methyl 3-carbamoylisobutyrate, and the charged aliphatic alcohol / 3-methyl carbamoylisobutyrate (molar ratio) 1-10
Is preferable, and 2-6 is particularly preferable.

As the solvent, it is preferable to use the alcohol which is the substrate of this reaction as it is, and the molar ratio of the alcohol to methyl 3-carbamoylisobutyrate is 1-.
10 is preferred, and 2-6 is particularly preferred.

As catalysts for this reaction, alkali metal alcoholates, oxides of alkaline earth metals and strongly basic ion exchange resins are extremely excellent. Alkali metal alcoholates are synthesized from lithium, sodium and potassium metals and lower alcohols, and specific examples include sodium and potassium methylates, ethylates or butyrates. Examples of the alkaline earth metal oxide include magnesium oxide, calcium oxide, and barium oxide. When using an alkali metal alcoholate, an alkaline earth metal oxide or a strongly basic ion exchange resin as a catalyst, use a catalyst for 1 mol of methyl 3-carbamoylisobutyrate at a reaction temperature of 20-80 ° C and a reaction time of 0.5-6 hours. The amount is suitably 0.001-0.30 mol. The reaction products in this step are separated and recovered by operations such as distillation, and unreacted products are returned to the raw material system.

With regard to formamide produced simultaneously with the methyl succinate, a hydrocyanic acid is produced by applying a dehydration reaction by thermal decomposition in the presence of a catalyst, and this is recovered and sent to a methyl 3-cyanoisobutyrate production step to be recycled or used. The formamide is decomposed into ammonia and carbon monoxide (fifth step). This ammonia is converted to cyanuric acid again by a method known in the industry, and is recycled to the first step of the reaction. When methane is used as a method for obtaining hydrocyanic acid from ammonia, there are an ammoxidation method such as the Andrussow method and an oxygen-free Degussa method. In the case where a higher alkane is used as a raw material, there is the Shawinnigen method. Further, the recovered ammonia can be supplied to an acrylonitrile manufacturing plant by ammoxidation of propylene by the Sohio method to obtain by-product hydrocyanic acid.

The hydrogenation of the ester (fourth step) in the present invention can be carried out in a batch mode, but it is preferable to carry out a reaction in a perfusion mode using a fixed-bed catalyst. Is about 0.05-1.0 times the amount of catalyst used by weight. The conditions for this catalytic hydrogenation reaction vary depending on the type of the starting ester and the catalyst, but are generally carried out at a temperature of 100 to 300 ° C. under a pressure of 20 kg / cm ² (gauge pressure) or more. The hydrogen gas used in this reaction does not necessarily need to be high purity, and may contain an inert component such as nitrogen or methane which does not adversely affect the catalytic hydrogenation reaction.

The catalyst used in the hydrogenation reaction of the fourth step in the present invention comprises copper, a copper compound, and the seventh main component of the periodic table.
It contains at least one selected from the group consisting of metals belonging to any of Groups 10 to 10 and the metal compounds. More specifically, copper, cobalt, nickel, iron, rhenium, palladium, ruthenium, platinum, and rhodium are effective as the main components of the catalyst for this reaction. Further, as a component constituting the co-catalyst, a solid acid component containing chromium, molybdenum, manganese, barium, magnesium, and silicon and aluminum is effective. Particularly suitable as a 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 case of copper-chromite, which is particularly suitable as a catalyst for this reaction, the reaction temperature is 150-28.
0 ° C. and the reaction pressure are preferably in the range of 50 to 200 kg / cm ² (gauge pressure).

The catalyst used in the present catalytic hydrogenation reaction is preferably a copper-chromium-barium (or manganese) catalyst, and 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)), add graphite and the like as a lubricant, mix well, form by a general method, and after sintering at high temperature, crush the formed product to an appropriate size before use. (2) Aqueous ammonia is added to an aqueous solution in which ammonium bichromate is dissolved, and cupric nitrate (or cupric sulfate or the like) separately prepared, and manganese nitrate (or manganese sulfate or the like) or barium nitrate are added to the aqueous solution. Is added dropwise while stirring. The resulting precipitate is washed with water, dried and calcined, for example, in air at a temperature of around 350 ° C. The powdered fired product thus obtained can be used for the reaction as it is, but it can also be used after adding an appropriate binder or lubricant to the fired product, thoroughly mixing the resulting product, and then molding.

The weight ratio of each component contained in the copper-chromium-barium (or manganese) catalyst obtained by the above methods (1) and (2) is CuO: Cr ₂ O ₃ : MnO ₂ (or BaO). Are preferably in the range of 20-85: 15-75: 1-15. The form of the catalyst may be any of a powder form and a tablet form, and the form that best suits the form of use is used. These catalysts are subjected to a suitable activation treatment such as treatment at around 200 ° C. in a hydrogen atmosphere before use, and then used in the reaction.

The amount of hydrogen used is 4 per mole of ester.
More than 1 mole, preferably 6-60 moles is suitable. This reaction can be carried out without using a solvent, but preferably a solvent is used. Any one that does not adversely affect the reaction can be used as a solvent. Alcohols and hydrocarbons are exemplified. The catalytic hydrogenation reaction according to the invention is usually subjected to distillation to separate the product 3-methyltetrahydrofuran.

[0019]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples. Example 1 (1) First Step (3-Pyrocyanic Acid and Methyl Methacrylate
Synthesis of methyl cyanoisobutyrate) 500ml inner volume equipped with stirrer, thermometer, 2 dropping funnels
Into the flask, 203 g of N-methylpyrrolidone and 1.35 g of potassium cyanide are charged, and while maintaining the temperature in the flask at 120 ° C., 40 g of hydrocyanic acid and 163 g of methyl methacrylate are added dropwise over 4 hours. After completion of the dropwise addition, the mixture was kept at 120 ° C for 2 hours to complete the reaction. As a result, the conversion of methyl methacrylate was 89.0%,
3 with 98.5% selectivity to reacted methyl methacrylate
-Methyl cyanoisobutyrate was formed. After connecting the flask to a vacuum system and collecting unreacted methyl methacrylate,
167 g of methyl 3-cyanoisobutyrate were obtained. The recovery of methyl 3-cyanoisobutyrate including the middle distillate was quantitative.

(2) Second step (Synthesis of methyl 3-carbamoylisobutyrate by hydration of methyl 3-cyanoisobutyrate) Preparation of catalyst ; inner volume 1 equipped with stirrer, reflux condenser, thermometer
63.2 g of potassium permanganate and 500 g of water in l flask
And heat to 70 ° C with stirring. Manganese sulfate 9
Add 240 g of an aqueous solution in which 6.2 g is dissolved and 40 g of 15% sulfuric acid.
The reaction was carried out at 3 ° C. for 3 hours. After cooling the contents, the precipitate was filtered and washed with 2.4 l of water. The precipitated cake was dried at 60 ° C for 24 hours to obtain 75 g of active manganese dioxide, which was used as a catalyst for the following reaction. Hydration reaction ; internal volume 5 with stirrer, thermometer, dropping funnel
A 00 ml flask is charged with 80 g of methyl 3-cyanoisobutyrate obtained in Step 1, 250 g of water, 58 g of acetone and 50 g of a catalyst, and a hydration reaction is carried out for 3.5 hours while maintaining the temperature in the flask at 80 ° C. After the reaction mixture was cooled, the filtrate from which the catalyst was removed by filtration was analyzed, and as a result, the conversion of methyl 3-cyanoisobutyrate was 91.1%, and the 3-carbamoylisobutyrate was 98.0% selective for the reacted methyl 3-cyanoisobutyrate. Methyl butyrate was obtained. The filtrate was concentrated under reduced pressure and recrystallized from acetone to obtain 73 g of methyl 3-carbamoylisobutyrate having a purity of 99.5% or more.

(3) Third step (Synthesis of methyl succinate diester and formamide from methyl 3-carbamoylisobutyrate, ethanol and carbon monoxide) In step 2, a 1 l stainless steel autoclave with a stirrer was used. The obtained methyl 3-carbamoylisobutyrate72.
5 g, 250 g of ethanol and 1.1 g of sodium methylate were charged, and carbon monoxide was further injected thereinto at a pressure of 40 kg / cm ² (gauge pressure), and the mixture was heated and stirred to react. When the temperature in the autoclave reached 60 ° C., carbon monoxide was supplied so as to maintain the reaction pressure at 40 kg / cm ² (gauge pressure), and the reaction was continued for 3 hours. Then, the autoclave is cooled, the internal pressure is gradually reduced to normal pressure, and the product is taken out and analyzed. As a result, the conversion of methyl 3-carbamoylisobutyrate was 78.1%.
Thus, methyl methyl succinate has a selectivity of 67.3% with respect to the reacted methyl 3-carbamoylisobutyrate, and methyl ethyl succinate diester has a selectivity of 28.8% with respect to the reacted methyl 3-carbamoyl isobutyrate. Further, formamide was obtained at a selectivity of 95.6% with respect to methyl 3-carbamoylisobutyrate reacted.

(4) Fourth Step (Diester Methyl Succinate)
Hydrogenation of Nissan Gardler G99C (weight composition C)
uO 36%, Cr_TwoO_Three32%, MnO _Two2.4%, BaO 2.2% Shape 1/4 a
Divided into 1/8 inch pellets)
And fill a reaction tube with an inner diameter of 15 mm and a length of 300 mm with 20.0 g.
Medium layer height 97mm), activation treatment by ordinary hydrogen reduction (1-
(Reduced in a nitrogen stream containing 10% hydrogen at 200 ° C or less)
After performing, it was subjected to the reaction. Reaction temperature 230 ℃, reaction pressure 1
60kg / cm^Two(Gauge pressure), the supply amount of hydrogen is 10 at the outlet of the reaction tube.
 l / hr, 30 wt% of methyl succinate obtained in the third step
5 g / hr of pseudocumene solution containing acid diester mixture
WHSV (raw material feed rate divided by catalyst weight)
0.075hr^-1) And hydrogen was supplied from the top of the reaction tube.
As a result of analyzing the obtained reaction solution, unreacted methyl succinic acid
No diester was found and 3-methyltetrahydrofuran
Is 9 based on the methyl succinate diester supplied.
6.2%.

(5) Fifth step (synthesis of hydrocyanic acid by dehydration of formamide) Preparation of catalyst : 0.85 g of sodium carbonate dissolved in 30 g of water was added to 51.5 g of manganese carbonate and kneaded for 1 hour. Then 110
Dry at 150 ° C for 15 hours and place in a stream of nitrogen containing 10% hydrogen at 450
After calcining at 5 ° C for 5 hours, 30 g of crushed and sized 10-20 mesh was obtained. Reaction : 3.0 g of manganese oxide obtained by the above method was filled in a quartz reaction tube having a diameter of 10 mm and a length of 300 mm equipped with a thermometer sheath tube,
Heating was performed so that the temperature at the lower part of the catalyst layer was maintained at 400 ° C. The upper 15 cm of the catalyst layer was filled with a 3 x 3 mm quartz Raschig ring and heated to 100-400 ° C to form a formamide evaporator. While keeping the inside of the reaction tube at a vacuum of 100 mmHg, the formamide obtained in the third step was added at 10 g / hr and air was added at 240 ml / hr.
It was introduced into the system at the rate of hr from the top of the reaction tube. From 5 hours after the start of the reaction, the reaction gas was sampled for 1 hour. The hydrocyanic acid collected by absorption in water and NaOH aqueous solution is
It was determined by silver nitrate titration. Ammonia dissolved in water was quantified by ion chromatography, and unreacted formamide was quantified by gas chromatography. As a result, the formamide conversion was 99.6%, the yield of cyanuric acid was 95.0%, and the yield of ammonia was 4.4%. (6) Fifth Step (Decomposition of Formamide into Ammonia and Carbon Monoxide) 180 g of the formamide obtained in the third step and 1 g of calcium oxide as a catalyst are charged into a 300 ml four-necked round bottom flask equipped with a stirrer and a reflux condenser. The mixture was heated to 150 ° C. with a mantle heater while stirring. The generated gas mist was dropped by a brine reflux cooler, ammonia gas was absorbed by a sulfuric acid aqueous solution trap and measured by neutralization titration, and carbon monoxide was measured by gas meter and gas chromatography. As a result, ammonia yield 95.0%, carbon monoxide yield
90.0% was obtained.

Example 2 In step 3 of Example 1, 350 g of pentanol was charged instead of 250 g of ethanol, and carbon monoxide was further added to 40 kg / cm ^2.
(Gauge pressure), and the mixture was heated and stirred to react. When the temperature in the autoclave reached 60 ° C., carbon monoxide was supplied so as to maintain the reaction pressure at 40 kg / cm ² (gauge pressure), and the reaction was continued for 3 hours. Then, the autoclave is cooled, the internal pressure is gradually reduced to normal pressure, and the product is taken out and analyzed. As a result, the conversion of methyl 3-carbamoylisobutyrate was 72.3%, and dipentyl methyl succinate was added to the reacted methyl 3-carbamoylisobutyrate.
With a selectivity of 77.0%, methylpentyl methyl succinate diester was obtained with a selectivity of 19.3% with respect to the reacted methyl 3-carbamoylisobutyrate, and with a selectivity of 96.4% with respect to the reacted methyl 3-carbamoylisobutyrate. Formamide was obtained.

[0025]

According to the present invention, each step proceeds at an extremely high selectivity, and uses methyl methacrylate, an aliphatic alcohol and carbon monoxide as raw materials in high yields, and has disadvantageous secondary substances such as ammonium salts. The present invention is of industrially very high value since 3-methyltetrahydrofuran is produced without any product.

Claims (2)

[Claims] (1) (1) a reaction between hydrocyanic acid and methyl methacrylate
-A first step of producing methyl cyanoisobutyrate, (2) a second step of hydrating the methyl 3-cyanoisobutyrate obtained in the first step to produce methyl 3-carbamoylisobutyrate, (3) A third step of producing methyl succinate and formamide from methyl 3-carbamoylisobutyrate obtained in the two steps, an aliphatic alcohol having 2 or more carbon atoms and carbon monoxide, and (4) a step of producing the methyl succinate and formamide in the third step. The methylamide succinate is subjected to catalytic hydrogenation to produce 3-methyltetrahydrofuran, and (5) the formamide separated from the product obtained in the third step is dehydrated to produce hydrocyanic acid, which is then used or recycled. A fifth step of decomposing formamide into ammonia and carbon monoxide 3
-A process for producing methyltetrahydrofuran. 2. The method according to claim 1, wherein the aliphatic alcohol used in the third step is an aliphatic alcohol having 2 to 8 carbon atoms.