JPH08291157A - Production of new 3-methyltetrahydrofuran - Google Patents

Abstract

PURPOSE: To produce 3-methyltetrahydrofuran in high yield by using inexpensively mass-produced compounds as starting substances. CONSTITUTION: The production process comprises the first step whereby methyl 3-cyanoisobutyrate is formed from hydrogen cyanide and methyl methacrylate, the second step whereby methyl 3-cyanoisobutyrate is hydrated to give methyl 3-carbamoylisobutyrate, the third step whereby a methylsuccinate ester and formamide are obtained from methyl 3-carbamoylisobutyrate and a formate ester, the fourth step whereby the methylsuccinate ester is catalytically hydrogenated to give 3-methyltetrahydrofuran and the fifth (final) step whereby the formamide formed in the third step is decomposed into ammonia and carbon monoxide.

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 used as a comonomer of polyether glycol which is a raw material for spandex fibers.

[0002]

2. Description of the Related Art 3-Methyltetrahydrofuran can be produced by various methods. JP-A-63-218669
According to the publication, 3-methyltetrahydrofuran is formed with 3- and 4-methylbutyrolactone by hydrogenation of citric acid, but its selectivity is about 70%. According to US Pat. No. 3,956,318, it is produced by catalytic hydrogenation of epoxide in the liquid phase in the presence of a protonic acid, but the raw material epoxide is expensive. According to JP-A-2-62835, a diol obtained by catalytic hydrogenation of 4-hydroxybutyraldehyde or 2-hydroxytetrahydrofuran in the presence of an aldehyde is produced by cyclization, but the raw material is also expensive, and a by-product of tetrahydrofuran is produced. Accompany. Further, a method by hydrogenation of methylmaleic acid or methylsuccinic acid (JP-A-49-9463) is also disclosed, but it is difficult to obtain starting materials and the hydrogenation conditions are severe, and industrial implementation is difficult. That is clear.

According to Japanese Patent Laid-Open No. 48-22405, 1,4
-Hydroformylating butenediol, and after the catalyst separation the hydroformylated product (2-formyl-1,
(Estimated to be 4-butanediol) is subjected to catalytic hydrogenation, and the resulting 2-methyl-1,4-butanediol is cyclized to obtain 3-methyltetrahydrofuran. According to JP-A-5-117258 and JP-B-4-55179, diol obtained by catalytic hydrogenation of 1,4-butynediol or 1,4-butenediol in the presence of aldehyde is cyclized to give 3-methyltetrahydrofuran. Is getting However, 1,4-butenediol and 1,4-butynediol, which are raw materials in these methods, are expensive because they are obtained from acetylene, and in these methods, tetrahydrofuran is a by-product.

According to JP-A-6-219981, itaconic acid, 3-formyl-2-methyl-propionic acid or their esters are catalytically hydrogenated to give 2-methyl-1,4.
-Produced with butanediol, the starting materials itaconic acid and 3-formyl-2-methyl-propionic acid are expensive. In the above manufacturing method, the raw materials are expensive,
-Because of its low selectivity to methyltetrahydrofuran,
Not industrially satisfactory.

[0005]

An object of the present invention is to provide a method for producing 3-methyltetrahydrofuran having high selectivity by using an inexpensive raw material which does not have the above-mentioned drawbacks. To this end, (1) a first step for producing methyl 3-cyanoisobutyrate from hydrocyanic acid and methyl methacrylate,
(2) A second step of reacting the methyl 3-cyanoisobutyrate obtained in the above step with water and sulfuric acid, and then reacting the same reaction product with an alcohol to produce a methylsuccinate, (3) obtained in the above step The method for producing 3-methyltetrahydrofuran, which comprises the third step of producing 3-methyltetrahydrofuran by catalytic hydrogenation of methyl succinate, has been investigated. However, this method has a drawback in that a large amount of ammonium salt is produced as a by-product, and this treatment puts a strain on the production cost of 3-methyltetrahydrofuran.

In order to achieve the above-mentioned object, the present inventor has made earnest studies and, as a result, found a manufacturing method by the route of Chemical formula 1 and applied for it (Japanese Patent Application No. 7-22807). The present invention is
It is a further development of the method of the prior application shown in Figure 3 and is a method for producing 3-methyltetrahydrofuran by the route shown in Chemical formula 2. Since the production of hydrocyanic acid by dehydration of formamide shown in Chemical formula 1 is carried out under a high temperature gas phase of 450 to 600 ° C., evaporation of formamide under high temperature is required. However, this evaporation is accompanied by the formation of tar of formamide and the formation of polymer, and it is usually difficult to operate stably for a long period of time, and expensive equipment is required to avoid this.

[0007]

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[0008]

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On the other hand, the decomposition of formamide shown in Chemical formula 2 into ammonia and carbon monoxide does not require high temperature and is 300 ° C.
It can be carried out under the following conditions. Especially, if it is carried out in the presence of a catalyst in a liquid phase reaction, the reaction will proceed even at 200 ° C or lower, so there will be no formation of tallamide of formamide or formation of a polymer, and long-term stable Can drive. That is, according to the present invention, the formamide produced in the third step is dehydrated to hydrocyanic acid as shown in Chemical formula 1 and is recycled to the reaction system. Instead, the formamide is decomposed into ammonia and carbon monoxide as shown in Chemical formula 2 and used. To do.

The ammonia recovered here is converted to hydrocyanic acid by utilizing the conventional hydrocyanic acid production method as it is, and is recycled in the reaction system. That is, a conventional industrial process for producing hydrocyanic acid, such as An
Prussic acid is synthesized from ammonia, methane, and air by the drussow method. Further, the carbon monoxide recovered here may be recycled to the reaction system together with methanol as it is, or may be previously reacted with methanol to form methyl formate and recycled to the reaction system. The method of the present invention will be described in detail below.

In the present invention, the first step for producing methyl 3-cyanoisobutyrate from hydrocyanic acid and methyl methacrylate is carried out by a known method. The solvent is a lower alkyl-substituted pyrrolidone or dimethyl sulfoxide solvent and an alkali metal cyanide compound. Is used as a catalyst at about 40 to 130 ° C.

The production of methyl 3-carbamoylisobutyrate in the present invention (second step) is carried out by catalytically 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 applied, and a strong acid such as sulfuric acid is also used, but a metal catalyst or a metal oxide catalyst is preferable from the economical point of view including treatment. Specifically, manganese, copper,
Nickel or an oxide thereof is effective, and manganese oxide is particularly preferable. The proper weight ratio of methyl 3-cyanoisobutyrate to water is 2: 98-98: 2. It is also possible to coexist with methyl methacrylate, which is a raw material of methyl 3-cyanoisobutyrate, and ketones such as alcohol and acetone, as a solvent in this system.
When manganese oxide is used as a catalyst, the reaction temperature is 20-150.
C is the preferred range, with 30-100 C being especially preferred. The reaction time is preferably 0.3-6 hours, especially 0.5-
4 hours is preferred. The reaction can be carried out batchwise or continuously. Methyl 3-carbamoylisobutyrate can be obtained from this reaction solution by distilling off water, a solvent and the like by a conventional method.

In the present invention, methyl succinate and formamide are produced by the reaction of methyl 3-carbamoylisobutyrate and formate (third step) by using a mixture of methyl 3-carbamoylisobutyrate and formate without a catalyst. Although it is possible to use a heating method, it is effective to perform it in the presence of a solvent and a catalyst. When methyl formate is used as the formate ester, methanol and carbon monoxide can be used instead of methyl formate. This reaction is an equilibrium reaction, and the yield of methyl succinate depends on the charged molar ratio of methyl 3-carbamoylisobutyrate to formic ester, and the charged formate ester / 3-methyl 3-carbamoylisobutyrate (molar ratio) is 1- 10 is preferable, and 2-6 is particularly preferable. Addition of a solvent has the effect of increasing the solubility of methyl 3-carbamoylisobutyrate and increasing the selectivity of the reaction. The solvent used is preferably an alcohol corresponding to the ester group of the formate ester, and the charged molar ratio of the alcohol to methyl 3-carbamoylisobutyrate is preferably 1-10, particularly 2-6.
Alkali metal alcoholates, alkaline earth metal oxides and strongly basic ion exchange resins are extremely excellent catalysts for this reaction. 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 oxides of alkaline earth metals 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, 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 used is appropriately 0.001-0.30 mol. The reaction products in this step are separated and recovered by operations such as distillation,
Unreacted materials are returned to the raw material system.

Formamide produced simultaneously with methyl succinate is easily decomposed into ammonia and carbon monoxide by the following method (step 5). That is, this decomposition reaction is carried out by heating formamide in the gas phase or in the liquid phase in the presence of a catalyst or a basic catalyst, but it is preferably carried out at 300 ° C. or lower in order to suppress by-product of hydrocyanic acid. Activated carbon, caustic soda, soda blue, and metal alcoholate are effective catalysts. A preferred example of the reaction is formamide in the liquid phase in the presence of a catalyst.
The decomposition reaction is carried out while heating to 20-220 ° C. and removing the produced gas from the reaction system with stirring. The produced mixed gas of ammonia and carbon monoxide can be recovered as high-purity ammonia and carbon monoxide, respectively, if ammonia is separated by pressure cooling or absorption. The recovered ammonia is converted to hydrocyanic acid again by an industrially known method, and recycled to the first step of this reaction. Andrussow of ammoxidation method when methane is used as a method for obtaining hydrocyanic acid from recovered ammonia
Method, or Degussa method without oxygen. When using high-grade alkanes as a raw material, there is the Shawinnigen method. It is also possible to supply recovered ammonia to the acrylonitrile production plant by Sohio method ammoxidation of propylene to obtain by-product hydrocyanic acid.

The hydrogenation of the methylsuccinate ester in the present invention (the fourth step) can be carried out in a batch system, but it is more preferable to carry out a perfusion solution reaction using a fixed bed catalyst. The amount of the ester to be supplied per unit time is about 0.05 to 1.0 of the amount of the catalyst used by weight. The conditions of the catalytic hydrogenation reaction vary depending on the types of the starting ester and the catalyst, but are generally carried out at a temperature of 100 to 300 ° C. and a pressure of 20 Kg / cm ² (gauge pressure) or more. The hydrogen gas used in this reaction does not necessarily have to be of high purity and may be a substance containing an inert component such as nitrogen or methane, which does not adversely affect the catalytic hydrogenation reaction. The catalyst used in this hydrogenation reaction contains copper as a main component, or an element belonging to Groups 7a and 8 of the periodic table. More specifically, copper, cobalt, nickel, iron, rhenium, palladium,
Ruthenium, platinum and rhodium are effective as the main catalyst components in this reaction. Further, as the co-catalyst component, a solid acid component containing chromium, molybdenum, manganese, barium, magnesium, silicon, and aluminum is effective. Particularly suitable as a catalyst for this reaction is a material containing copper as a main component and generally called copper-chromite, which contains manganese, barium or the like as a co-catalyst. When copper-chromite, which is particularly suitable as a catalyst for this reaction, is used, the reaction temperature is 150-280 ° C., and the reaction pressure is 50-200 Kg /
The range of cm ² (gauge pressure) is preferable.

The copper-chromium-barium or manganese catalyst suitable for this reaction 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 (BaO)
Then, after adding graphite etc. as a lubricant and mixing well, it is molded by a general method, and after high temperature firing, the molded product is crushed to an appropriate size and used. (2) Ammonia water is added to an aqueous solution of ammonium dichromate, and cupric nitrate (or cupric sulfate, etc.) and manganese nitrate (or manganese sulfate, etc.) or barium nitrate prepared separately are dissolved in this aqueous solution. The aqueous solution is added dropwise with stirring. The precipitate formed is washed with water and dried, and then calcined, for example, in air at a temperature of around 350 ° C. The powdery fired product thus obtained can be used for the reaction as it is, but it is also possible to add an appropriate binder and a lubricant to the fired product, mix them sufficiently, and use them after molding. The weight ratio of each component contained in the copper-chromium-barium or manganese catalyst is ₂ in terms of the ratio of CuO, Cr ₂ O ₃ , MnO ₂ or BaO.
It is preferably in the range of 0-85: 15-75: 1-15. The catalyst may be in the form of powder, tablet, or the like, and the one most suitable for the usage is used. Before being used, these catalysts are subjected to an appropriate 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 6-60 mol, per 1 mol of ester. Further, this reaction can be carried out without using a solvent, but preferably a solvent is used. Any substance that does not adversely affect this reaction can be used as a solvent. Examples are alcohols and hydrocarbons. The catalytic hydrogenation reaction solution according to the present invention is usually subjected to distillation to separate the product, 3-methyltetrahydrofuran.

[0017]

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-from hydrogen cyanide and methyl methacrylate)
Synthesis of methyl cyanoisobutyrate) Internal volume 500 equipped with stirrer, thermometer, two dropping funnels
To a ml flask, 203 g of N-methylpyrrolidone and 1.35 g of potassium cyanide were charged, and 40 g of hydrocyanic acid and 163 g of methyl methacrylate were added dropwise over 4 hours while maintaining the temperature inside the flask at 120 ° C. 120 ℃ after dropping
As a result of the reaction being completed for 2 hours, the conversion of methyl methacrylate was 88.3%, and methyl 3-cyanoisobutyrate was produced at a selectivity of 98.1% with respect to the reacted methyl methacrylate. The flask was connected to a reduced pressure system and unreacted methyl methacrylate was recovered to obtain 165 g of methyl 3-cyanoisobutyrate. 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: a catalyst having a stirrer, a reflux condenser and a thermometer was added to a flask having an internal volume of 1 L. Charge 63.2 g of potassium manganate and 500 g of water, and heat and stir at 70 ° C. 240 g of an aqueous solution containing 96.2 g of manganese sulfate dissolved therein and 15%
Sulfuric acid 40 g was added, and the mixture was reacted at 70 ° C. for 3 hours. After cooling the contents, the precipitate was filtered and washed with 2.4 L of water. The precipitate cake was dried overnight at 60 ° C. to obtain 74 g of active manganese dioxide, which was used as the following catalyst. Hydration reaction: 80 g of methyl 3-cyanoisobutyrate obtained in the first step, 250 g of water, 58 g of acetone, in a flask having an inner volume of 500 ml equipped with a stirrer, a thermometer, and a dropping funnel,
50 g of the catalyst is charged and the 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 catalyst liquid was removed by filtration to analyze the furnace liquid.
-The conversion of methyl cyanoisobutyrate was 90.7%, which was 98% based on the reacted methyl 3-cyanoisobutyrate.
Methyl 3-carbamoylisobutyrate was obtained with a selectivity. The furnace liquid was concentrated under reduced pressure and recrystallized with acetone to obtain 73 g of methyl 3-carbamoylisobutyrate having a purity of 99.5% or more.

(3) Third Step (Synthesis of Dimethyl Methylsuccinate and Formamide from 3-Carbamoylisobutyrate and Methyl Formate) A 3-liter stainless steel autoclave equipped with a stirrer was used in the second step. Carbamoyl methyl isobutyrate 72.5 g, methyl formate 180 g, methanol 96 g,
Charge 1.1 g of sodium methylate, and add 2 at 60 ° C.
Perform heating reaction for an hour. As a result of analyzing the product after cooling, 3
-The conversion rate of methyl carbamoylisobutyrate was 83.2%, which was 99.8% selectivity for dimethyl methylsuccinate and 9% for the reacted methyl 3-carbamoylisobutyrate.
Formamide was obtained with a selectivity of 8.4%. The sodium methylate in the product solution was neutralized with sulfuric acid and then distilled by a conventional method to recover methyl formate and methanol, and 60 g of dimethyl methylsuccinate having a purity of 99% or more and 16 g of formamide having a purity of 99% were obtained. The recovery rate including the middle distillate was quantitative.

(4) Fourth step (hydrogenation of dimethyl methylsuccinate) Commercially available Nissan Gardler G99C (weight composition CuO 3
6%, Cr ₂ O ₃ 32%, MnO 2.4%, BaO 2.2% Shape 1/4 inch × 1/4 inch pellet) 1/8
The reaction tube having an inner diameter of 15 mm and a length of 300 mm is filled with 20.0 g (catalyst layer height of 97 mm) and activated by ordinary hydrogen reduction (in a nitrogen stream containing 1-10% hydrogen,
It is subjected to the reaction after the reduction). The reaction temperature is 230 ° C., the reaction pressure is 160 kg / cm ² (gauge pressure), the hydrogen supply rate is 10 L / hr at the outlet of the reaction tube, and the pseudocumene solution of 30 wt% dimethyl methylsuccinate as a raw material is at a rate of 5 g / hr (raw material supply weight rate). Was divided by the catalyst weight to obtain a WHSV of 0.075 / hr), which was supplied together with hydrogen from the upper part of the reaction tube. As a result of analyzing the obtained reaction solution, unreacted dimethyl methylsuccinate was not observed, and the yield of 3-methyltetrahydrofuran was 95.5% with respect to the supplied dimethyl methylsuccinate.

(5) Step 5 (decomposition of formamide into ammonia and carbon monoxide) A 300 ml four-neck round bottom flask equipped with a stirrer and a reflux condenser was charged with 180 g of formamide and 1 g of calcium oxide as a catalyst and stirred. 1 at the mantle heater
Heated to 50 ° C. The generated gas mist was dropped by a brine reflux condenser, ammonia gas was absorbed by a sulfuric acid solution trap and measured by neutralization titration, and carbon monoxide was measured by a gas meter and gas chromatography analysis. As a result, an ammonia yield of 94% and a carbon monoxide yield of 89% were obtained.

Example 2 Example 1 except that ethyl formate was used instead of methyl formate as a raw material.
The reaction was performed in the same manner as in the third step. As a result, the conversion rate of methyl 3-carbamoylisobutyrate was 83.7%, which was 99.8 relative to the reacted methyl 3-carbamoylisobutyrate.
Dimethyl methyl succinate was obtained with a% selectivity and formamide was obtained with a 98.6% selectivity.

Example 3 In the third step of Example 1, 180 g of methyl formate and 200 g of methanol were charged in place of 96 g of methanol, carbon monoxide was further introduced under pressure of 40 Kg / cm ² (gauge pressure), and the mixture was heated and stirred. It was made to react. When the temperature in the autoclave reached 60 ° C., carbon monoxide was supplied so that the reaction pressure was maintained at 40 Kg / cm ² (gauge pressure), and the reaction was continued for 3 hours. After that, 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 rate of methyl 3-carbamoylisobutyrate was 8
It was 1.4%, and dimethyl methylsuccinate was obtained with a selectivity of 95.7% and formamide was obtained with a selectivity of 94.4% with respect to the reacted methyl 3-carbamoylisobutyrate.

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, each step proceeds with extremely high selectivity, and high yields of methyl methacrylate and formic acid ester are used as raw materials and there is no inconvenient by-product such as ammonium salt. Since it is manufactured, the present invention has an extremely high industrial value.

Claims (5)

[Claims] (1) 3 from cyanide and methyl methacrylate
A first step of producing methyl cyanoisobutyrate, (2) a second step of producing methyl 3-carbamoylisobutyrate by hydrating the methyl 3-cyanoisobutyrate obtained in the first step,
(3) Third step of producing methylsuccinate and formamide from methyl 3-carbamoylisobutyrate obtained in the second step and formate, (4) catalytic hydrogenation of methylsuccinate obtained in the third step A method for producing 3-methyltetrahydrofuran, which comprises a fourth step of producing 3-methyltetrahydrofuran, and (5) a fifth step of decomposing the formamide obtained in the third step into ammonia and carbon monoxide. 2. The method according to claim 1, wherein the formate ester in the third step 3 is methyl formate. 3. The method according to claim 2, wherein methanol and carbon monoxide are used in place of methyl formate in the third step. 4. The method according to claim 1, wherein hydrocyanic acid is synthesized by an ammoxidation method using hydrocarbon and air using ammonia recovered in the fifth step, and is reused in the first step. 5. The method according to claim 1, wherein the carbon monoxide recovered in the fifth step is used for carbonylation of methanol to synthesize methyl formate, which is recycled in the third step. .