Method for producing isobutyl vinyl ether and method for purifying isobutyl vinyl ether

Abstract

Provided is a method for producing isobutyl vinyl ether from isobutyl alcohol and acetylene at high purity and with excellent efficiency.　The present invention is a method for producing isobutyl vinyl ether using isobutyl alcohol as a raw-material alcohol, the production method including the following steps A1, A2, and A3.　(Step A1) A vinyl ether synthesis step for reacting isobutyl alcohol and acetylene to obtain a mixture that includes unreacted isobutyl alcohol and isobutyl vinyl ether (Step A2) An acetalization step for reacting the unreacted isobutyl alcohol and isobutyl vinyl ether within the mixture in the presence of an acid catalyst to achieve conversion to acetaldehyde diisobutyl acetal (Step A3) A distillation step for removing the acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in step A2

Description

[Technical Field]

[0001] The present invention relates to a method for producing isobutyl vinyl ether and a method for purifying isobutyl vinyl ether. [Background technology]

[0002] The addition reaction of alcohol to acetylene is widely known as a method for producing vinyl ethers. However, if the raw material alcohol remaining in the obtained crude vinyl ether forms an azeotrope with the target vinyl ether, it becomes difficult to purify the vinyl ether by distillation. Known examples of alcohols and corresponding vinyl ethers that form an azeotrope include a combination of 2-ethylhexanol and 2-ethylhexyl vinyl ether, and a combination of cyclohexanol and cyclohexyl vinyl ether. Therefore, a method has been proposed in which unreacted 2-ethylhexanol or cyclohexanol contained in a mixture obtained by addition reaction of 2-ethylhexanol or cyclohexanol with acetylene is reacted with 2-ethylhexyl vinyl ether or cyclohexyl vinyl ether produced by the addition reaction in the presence of an acid catalyst to convert the unreacted 2-ethylhexanol or cyclohexanol into an acetal, which is then removed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5312133 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there have been few reports on the production of isobutyl vinyl ether from isobutyl alcohol and acetylene, and it has not been known that the combination of isobutyl alcohol and isobutyl vinyl ether forms an azeotrope. Under these circumstances, the present inventors have conducted research and found that a combination of isobutyl alcohol and isobutyl vinyl ether forms an azeotropic mixture.

[0005] An object of the present invention is to provide a method for efficiently producing highly pure isobutyl vinyl ether from isobutyl alcohol and acetylene. [Means for solving the problem]

[0006] The object of the present invention is to provide the following <1> ~ <6> was resolved by the following means. <1> A method for producing isobutyl vinyl ether using isobutyl alcohol as a raw material alcohol, the method comprising the following steps A1, A2, and A3: (Step A1) A vinyl ether synthesis step in which isobutyl alcohol is reacted with acetylene to obtain a mixture containing unreacted isobutyl alcohol and isobutyl vinyl ether. (Step A2) An acetalization step in which unreacted isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step A3) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step A2. <2> A method for producing isobutyl vinyl ether using isobutyl alcohol as a raw material alcohol, the method comprising the following steps A1, A2, A2-2, and A3. (Step A1) A vinyl ether synthesis step in which isobutyl alcohol is reacted with acetylene to obtain a mixture containing unreacted isobutyl alcohol and isobutyl vinyl ether. (Step A2) An acetalization step in which unreacted isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step A2-2) A step of performing a treatment selected from neutralizing the acid catalyst and removing the acid catalyst (Step A3) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step A2-2.

[0007] <3> Step A2-2 is a step of neutralizing the acid catalyst using a basic compound. <2> The manufacturing method described in <4> Step A1 is carried out in the presence of an alkali metal alcoholate catalyst. <1> ~ <3> 1. The manufacturing method according to any one of the preceding claims. <5> The distillation pressure in step A3 is 40 kPaA to atmospheric pressure. <1> ~ <4> 1. The manufacturing method according to any one of the preceding claims.

[0008] <6> A method for purifying isobutyl vinyl ether from a mixture containing isobutyl alcohol and isobutyl vinyl ether, comprising the following steps B1 and B2: (Step B1) An acetalization step in which isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step B2) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step B1. [Effects of the Invention]

[0009] According to the production method of the present invention, isobutyl vinyl ether can be produced efficiently from isobutyl alcohol and acetylene with high purity. Furthermore, according to the purification method of the present invention, isobutyl vinyl ether can be efficiently purified to a high purity from a mixture containing isobutyl alcohol and isobutyl vinyl ether. [Brief explanation of the drawings]

[0010] [Figure 1] This is a vapor-liquid equilibrium diagram for isobutyl vinyl ether and isobutyl alcohol at 80 kPaA and 15 kPaA. [Figure 2] FIG. 1 is a schematic diagram showing the configuration of an apparatus used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Method for producing vinyl ether] The production method of the present invention is a method for producing isobutyl vinyl ether using isobutyl alcohol as a raw material alcohol, and includes the above-mentioned steps A1, A2, and A3. Specifically, after step A1 (vinyl ether synthesis step), a mixture containing the unreacted raw material alcohol and isobutyl vinyl ether obtained in step A1 (a mixture further containing a catalyst when the vinyl ether synthesis is performed in the presence of a catalyst) is subjected to step A1-2 (catalyst removal step) as needed, followed by step A2 (acetalization step) and step A3 (distillation step).

[0012] (Step A1: Vinyl ether synthesis step) Step A1 is a vinyl ether synthesis step in which isobutyl alcohol (boiling point: 108°C) is reacted with acetylene to obtain a mixture containing unreacted raw material alcohol and isobutyl vinyl ether (boiling point: 83°C). Isobutyl vinyl ether is a vinyl ether with a low boiling point, and the production method of the present invention makes it possible to produce isobutyl vinyl ether, which is such a low boiling point vinyl ether, with high purity.

[0013] Step A1 is preferably carried out in the presence of a catalyst, preferably an alkali metal alcoholate catalyst from the viewpoint of reaction efficiency. The alkali metal alcoholate catalyst is an alkali metal alcoholate of an alkali metal hydroxide and isobutyl alcohol, and from the viewpoint of handling, it is preferable that it is soluble in isobutyl alcohol. Specific examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, and these may be used alone or in combination of two or more.

[0014] In step A1, an organic solvent may be used, and preferred organic solvents are aprotic polar solvents that are miscible with isobutyl alcohol and dissolve the alkali metal alcoholate catalyst. Examples of the organic solvent include amide solvents such as dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone; sulfur-containing compound solvents such as sulfolane and dimethyl sulfoxide; and glycol dialkyl ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether. These solvents may be used alone or in combination.

[0015] The reaction temperature in step A1 is usually in the range of 60 to 200°C, and from the viewpoints of reaction rate and suppression of side reactions, a range of 80 to 150°C is more preferable. The higher the reaction pressure, the faster the reaction rate, but to prevent decomposition explosion of acetylene, it is preferable to keep the pressure at 0.3 MPa or less. The reaction time in step A1 is usually about 10 minutes to 48 hours.

[0016] (Process A1-2 Catalyst removal process) In the production method of the present invention, when the vinyl ether synthesis is carried out in the presence of a catalyst, the catalyst and the like may be removed from the reaction mixture obtained in step A1 prior to step A2. The catalyst and other components can be removed by known methods such as solvent extraction, distillation, filtration, and other solid-liquid separation methods (in the case of a solid catalyst or a supported catalyst). Among these methods, distillation is preferred because it facilitates catalyst separation and allows the raw material alcohol to be reduced in advance. Furthermore, distillation can also remove the organic solvent used in step A1. Even when the catalyst is removed by a method other than distillation, distillation may be further performed to reduce the raw material alcohol in the reaction mixture. The distillation column used for distillation to remove a catalyst or the like or for concentration after catalyst removal (hereinafter also referred to as "pre-distillation") may be any of a packed column, a plate column, a bubble cap column, etc., and the number of plates in the distillation column is, for example, 1 to 100 theoretical plates, preferably 5 to 50 theoretical plates. The preliminary distillation can be carried out under any of normal pressure, elevated pressure, and reduced pressure, preferably normal pressure or reduced pressure. Specifically, the pressure is usually 0.7 to 13.3 kPa, preferably 1.3 to 6.7 kPa. The distillation method may be any of batch, semi-batch, and continuous.

[0017] (Step A2 Acetalization step) Step A2 is an acetalization step in which the unreacted raw material alcohol in the mixture obtained in step A1 or step A1-2 is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. As will be described in the Examples below, it has been found that the combination of the raw material alcohols isobutyl alcohol and isobutyl vinyl ether forms an azeotrope. However, even though the raw material alcohol and the target vinyl ether form an azeotrope, by carrying out step A2, the unreacted raw material alcohol is acetalized, and the isobutyl vinyl ether can be easily purified to a high degree by distillation.

[0018] Examples of the acid catalyst used in step A2 include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid; organic acids such as carboxylic acids and organic sulfonic acids; and solid acid catalysts such as acidic zeolites, heteropolyacids, and strongly acidic ion exchange resins. These may be used alone or in combination of two or more. Among these, from the viewpoint of suppressing side reactions (particularly suppressing the polymerization reaction of vinyl ether), phosphoric acid, organic sulfonic acid, and sulfonic acid-type strongly acidic ion exchange resins (strongly acidic ion exchange resins having sulfonic acid groups in the molecule) are preferred, and organic sulfonic acids are more preferred. Examples of organic sulfonic acids include aromatic sulfonic acids such as p-toluenesulfonic acid, o-toluenesulfonic acid, benzenesulfonic acid, p-xylene-2-sulfonic acid, dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, and dinonylnaphthalenedisulfonic acid; aliphatic sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, and trifluoromethanesulfonic acid; and aromatic sulfonates such as pyridinium p-toluenesulfonate and quinolinium p-toluenesulfonate. Examples of strongly acidic ion exchange resins include sulfonic acid-type strongly acidic ion exchange resins and mixtures of sulfonic acid-type strongly acidic ion exchange resins and amine-type weakly basic ion exchange resins. A commercially available sulfonic acid-type strongly acidic ion exchange resin is Amberlyst 15DRY manufactured by Organo Corporation, and a commercially available mixture of sulfonic acid-type strongly acidic ion exchange resins and amine-type weakly basic ion exchange resins is Amberlyst MSPS2-1 DRY manufactured by Organo Corporation.

[0019] From the viewpoint of the purity of isobutyl vinyl ether, the amount of the acid catalyst used is usually 0.00001 to 5 parts by mass, preferably 0.0001 to 1 part by mass, more preferably 0.001 to 0.1 part by mass, and even more preferably 0.001 to 0.01 part by mass, relative to 100 parts by mass of isobutyl vinyl ether. The method for adding the acid catalyst to the mixture obtained in step A1 or step A1-2 may be selected appropriately depending on the type of acid catalyst. For example, in the case of an inorganic acid or an organic acid, the acid may be added to the mixture obtained in step A1 or step A1-2 either as is or after dissolving in an appropriate solvent (preferably isobutyl alcohol). In addition, in the case of a solid acid catalyst, the acid catalyst may be added directly to the mixture obtained in step A1 or step A1-2, or the solid acid catalyst may be packed in a column container or the like and the mixture obtained in step A1 or step A1-2 may be passed through the column container.

[0020] The reaction temperature in step A2 is preferably in the range of 0 to 80°C, more preferably in the range of 10 to 60°C, from the viewpoints of the reaction rate and suppression of side reactions. The reaction time in step A2 is usually about 10 minutes to 48 hours. The acetal obtained in step A2 is acetaldehyde diisobutyl acetal (boiling point: 171°C).

[0021] Furthermore, in order to suppress the production of heavy products in step A3, the production method of the present invention preferably includes, after step A2 and prior to step A3, a step (step A2-2) of carrying out a treatment selected from neutralization of the acid catalyst and removal of the acid catalyst. When an inorganic or organic acid is used as the acid catalyst, neutralization of the acid catalyst is preferred in step A2-2. The neutralization of the acid catalyst may be carried out using a basic compound. Examples of basic compounds include alkali metal compounds such as alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates, and alkali metal hydrogencarbonates; basic ion exchange resins, etc. Examples of the alkali metals include sodium and potassium. From the viewpoint of purity of isobutyl vinyl ether, the amount of the basic compound used is usually 1 to 1,000 molar equivalents, preferably 5 to 100 molar equivalents, more preferably 10 to 100 molar equivalents, and particularly preferably 20 to 100 molar equivalents relative to the acid catalyst used in step A2. When the amount of the basic compound used is 20 molar equivalents or more, isobutyl vinyl ether can be obtained particularly efficiently. When an alkali metal compound is used as the basic compound, it may be added directly or dissolved in a suitable solvent (preferably water) to the acetal-containing mixture obtained in step A2. When a basic ion exchange resin is used, it may be added directly to the acetal-containing mixture obtained in step A2, or the acetal-containing mixture obtained in step A2 may be passed through a column filled with the basic ion exchange resin. If solids or precipitates are present in the liquid after neutralization, they may be subjected to solid-liquid separation by filtration, centrifugation, or the like, as necessary.

[0022] On the other hand, when a solid acid catalyst or the like is used as the acid catalyst, removal of the acid catalyst is preferred in step A2-2. Examples of the removal procedure include solid-liquid separation procedures such as filtration and centrifugation. Note that when the solid acid catalyst is used by packing it in a column container, the separation procedure is not necessary.

[0023] (Step A3 Distillation step) Step A3 is a distillation step in which acetaldehyde diisobutyl acetal is removed by distillation from the acetal-containing mixture obtained in step A2 (step A2-2 if step A2-2 was carried out). The distillation apparatus and distillation method used in step A3 are not particularly limited, and simple distillation or distillation with multiple distillation plates may be used. The distillation method may be batch, semi-batch, or continuous. When a distillation column is used, the distillation column may be a packed column, a plate column, a bubble cap column, or the like. The number of theoretical plates in the distillation column is preferably 1 to 30, more preferably 5 to 15. The reflux ratio is preferably in the range of 1 to 15. The temperature at the top of the distillation column is preferably 40 to 100°C, more preferably 50 to 90°C, and the temperature at the bottom of the distillation column is preferably 40 to 180°C, more preferably 50 to 170°C. From the viewpoint of the purity of isobutyl vinyl ether, the distillation pressure in step A3 is preferably 20 to 120 kPaA (A indicates absolute pressure), more preferably 40 kPaA to atmospheric pressure. When a distillation column is used, the target high-purity isobutyl vinyl ether is obtained from the top of the distillation column, and a bottom liquid rich in acetaldehyde diisobutyl acetal is recovered from the bottom of the column. The acetaldehyde diisobutyl acetal contained in the bottom liquid can be recovered and converted into vinyl ether and a raw material alcohol, and can be recycled as a raw material for synthesizing isobutyl vinyl ether.

[0024] (Step A4: Acetal decomposition step) The method for converting acetaldehyde diisobutyl acetal into the starting alcohol and vinyl ether may be appropriately selected from known methods. Specifically, there are methods for thermally decomposing acetaldehyde diisobutyl acetal in the gas phase in the presence of a silica / alumina catalyst carrying an alkali or alkaline earth metal (e.g., Khim. Prom. 48(9)657-660(1972), JP-A-48-78109, JP-A-62-87247, etc.), methods for decomposing acetaldehyde diisobutyl acetal in the gas phase using magnesium oxide as a catalyst (e.g., JP-A-8-268945), methods for decomposing acetaldehyde diisobutyl acetal in the presence of a catalyst containing a noble metal (e.g., Ann., 601 81-84, 1956, German Patent Publication No. 1957680, JP-A-48-76803, etc.), and a method of decomposing using an acid catalyst (for example, J. Org. Chem., 38, 2910, 1973, Helv. Chim. Acta, 1158 (1967), Bull. Chem. Soc. Jpn. 3089 (1976), JP-A-8-277237, etc.).

[0025] [Method for purifying isobutyl vinyl ether] The purification method of the present invention is a method for purifying isobutyl vinyl ether from a mixture containing isobutyl alcohol and isobutyl vinyl ether, and includes the following steps B1 and B2. (Step B1) An acetalization step in which isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step B2) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step B1.

[0026] Step B1 may be carried out in the same manner as step A2 in the production method of the present invention, and step B2 may be carried out in the same manner as step A3 in the production method of the present invention. [Example]

[0027] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0028] [Reference Example 1: Vapor-liquid equilibrium between isobutyl vinyl ether and isobutyl alcohol (80 kPaA)] Isobutyl vinyl ether and isobutyl alcohol were charged into an Othmer equilibrium distillation apparatus, and the pressure was adjusted to 80 kPaA, and then heating was started. After the reflux started and equilibrium was reached, the vapor phase condensate and the liquid phase were sampled and their compositions were analyzed. Next, isobutyl alcohol was added to the system, and the same operation was carried out. Thereafter, isobutyl alcohol was repeatedly added to the system, and a vapor-liquid equilibrium diagram of isobutyl vinyl ether and isobutyl alcohol at 80 kPaA was prepared. Figure 1 shows the vapor-liquid equilibrium diagram for isobutyl vinyl ether and isobutyl alcohol at 80 kPaA. Note that IBVE in Figure 1 stands for isobutyl vinyl ether. The composition at the intersection of the vapor-liquid equilibrium line and the diagonal line, ie, the azeotropic point, was 96 mass % isobutyl vinyl ether and 4 mass % isobutyl alcohol, and the temperature at that time was 76°C.

[0029] [Reference Example 2: Vapor-liquid equilibrium (15 kPaA) between isobutyl vinyl ether and isobutyl alcohol] The same operation as in Reference Example 1 was carried out, except that the pressure was changed to 15 kPaA. The composition at the azeotropic point was 97% by mass of isobutyl vinyl ether and 3% by mass of isobutyl alcohol, and the temperature at that time was 32° C. The results are shown in FIG.

[0030] The vapor-liquid equilibrium diagram shown in Figure 1 shows that isobutyl vinyl ether forms an azeotrope with the raw material isobutyl alcohol, making it difficult to purify by conventional distillation.

[0031] Example 1: Production of isobutyl vinyl ether (IBVE) (1) (Vinyl etherification process and catalyst removal process) The reactor used was a 10 L stainless steel autoclave, and the continuous distillation column used was a 4 L stainless steel packed continuous distillation column (packing: Sumitomo Heavy Industries, Ltd., Sumitomo / Sulzer Labopacking) with an inner diameter of 50 mm, 12 theoretical plates (7 feed plates), and a kettle capacity of 4 L. A schematic diagram showing the configuration of the apparatus used in the reaction is shown in Figure 2. An autoclave was charged with 6.14 kg of isobutyl alcohol (IBOH), 0.90 kg of potassium hydroxide, and 0.56 kg of tetraglyme. The autoclave conditions were 100°C, 0.03 MPaG, and a maximum oil storage capacity of 5 L. The continuous distillation column conditions were: top 65-68°C, bottom 100-120°C, 17-43 kPa, and a maximum oil storage capacity of 2 L. The reflux ratio was 8, and the circulation rate between the autoclave and the distillation column was 15 kg / hr. The alcoholate catalyst (potassium isobutyl alcoholate) was prepared for 15 hours. During this time, the distillate from the top of the continuous distillation column was 2.04 kg, containing 0.28 kg of water.

[0032] After adding 0.50 kg of isobutyl alcohol and 1.46 kg of tetraglyme, the autoclave conditions were changed to 110°C and 0.06 MPaG, and acetylene and isobutyl alcohol were continuously fed at rates of 105 g / hr and 265 g / hr, respectively. The reaction solution obtained in the above reaction was then continuously fed to a continuous distillation column at a rate of 15.0 kg / hr, and the composition of the reaction solution was 38.4% by mass of isobutyl alcohol, 8.5% by mass of isobutyl vinyl ether, 25.7% by mass of potassium isobutyl alcoholate, 27.1% by mass of tetraglyme, and 0.3% by mass of heavy components.

[0033] Furthermore, the bottoms were extracted from the bottom of the continuous distillation column at a rate of 14.6 kg / hr and supplied to the autoclave under conditions of a reflux ratio of 3 to 4, a column top pressure of 60 kPaA, a column top temperature of 65° C., and a bottoms temperature of 120 to 125° C. The composition of the bottoms from the continuous distillation column was 39.1% by mass of isobutyl alcohol, 6.4% by mass of isobutyl vinyl ether, 26.4% by mass of potassium isobutyl alcoholate, 27.8% by mass of tetraglyme, and 0.3% by mass of heavy components. In this way, crude vinyl ether was continuously synthesized, and crude vinyl ether was obtained from the top of the continuous distillation column at a flow rate of 346 g / hr. Here, the crude vinyl ether had a composition of 95.3 mass% isobutyl vinyl ether and 4.7 mass% isobutyl alcohol.

[0034] (Acetalization reaction process and distillation purification process) 679.6 g of crude IBVE obtained in the above step was weighed into a 1000 mL three-neck flask equipped with a stirrer tip, and 1.04 g of a solution of p-toluenesulfonic acid in IBOH (p-toluenesulfonic acid concentration: 2 mass%, 30 ppm of p-toluenesulfonic acid relative to crude IBVE) was added, followed by stirring for 60 minutes in a water bath set at 25°C. After the reaction, the IBOH content in the solution was 0.1 mass% or less, and the IBVE and acetaldehyde diisobutyl acetal contents were 89 mass% and 11 mass%, respectively. The reaction solution was neutralized by adding 0.36 g of an aqueous potassium hydroxide solution (potassium hydroxide concentration: 42.1% by mass, 210 ppm of potassium hydroxide relative to the reaction solution, 22 molar equivalents relative to p-toluenesulfonic acid), and then distilled using a packed column with 10 theoretical plates (internal pressure: 80 kPaA, column bottom temperature setting: 80 to 160°C, refrigerant temperature setting: 5°C), yielding 554.8 g of high-purity IBVE with a purity of 99% by mass or more (recovery rate based on IBVE: 85.7% by mass).

[0035] [Example 2: Production of IBVE (2)] (Acetalization reaction process and distillation purification process) Crude IBVE was obtained by performing the vinyl etherification step and catalyst removal step in the same manner as in Example 1. 791.4 g of the resulting crude IBVE was then weighed into a 2000 mL three-neck flask equipped with a stirrer tip, and 1.2 g of a solution of p-toluenesulfonic acid in IBOH (p-toluenesulfonic acid concentration: 2% by mass, 30 ppm of p-toluenesulfonic acid relative to crude IBVE) was added, followed by stirring for 60 minutes in a water bath set at 25°C. After the reaction, the IBOH content in the solution was 0.1% by mass or less, and the IBVE and acetaldehyde diisobutyl acetal contents were 89% by mass and 11% by mass, respectively. The reaction solution was neutralized by adding 0.08 g of aqueous sodium hydroxide (sodium hydroxide concentration: 34.3 mass%, sodium hydroxide 35 ppm relative to the reaction solution, 5 molar equivalents relative to p-toluenesulfonic acid), and then distilled using a packed column with 10 theoretical plates (internal pressure: 80 kPaA, column bottom temperature setting: 80 to 160°C, refrigerant temperature setting: 5°C), yielding 557.2 g of high-purity IBVE with a purity of 99 mass% or more (recovery rate based on IBVE: 73.7 mass%).

Claims

1. A method for producing isobutyl vinyl ether using isobutyl alcohol as a raw material alcohol, the method comprising the following steps A1, A2, A2-2, and A3, wherein step A2-2 is a step of neutralizing the acid catalyst used in step A2 using a basic compound in an amount of 5 to 100 molar equivalents relative to the acid catalyst used in step A2. (Step A1) A vinyl ether synthesis step in which isobutyl alcohol is reacted with acetylene to obtain a mixture containing unreacted isobutyl alcohol and isobutyl vinyl ether. (Step A2) An acetalization step in which unreacted isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step A2-2) Neutralizing the Acid Catalyst (Step A3) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step A2-2.

2. The manufacturing method described in claim 1, wherein the basic compound is an alkali metal compound.

3. The manufacturing method described in claim 2, wherein step A2-2 comprises dissolving the alkali metal compound in water and adding the resulting solution to the acetal-containing mixture obtained in step A2.

4. The method according to any one of claims 1 to 3, wherein step A1 is carried out in the presence of an alkali metal alcoholate catalyst.

5. The production method according to any one of claims 1 to 4, wherein the distillation pressure in step A3 is from 40 kPaA to atmospheric pressure.

6. A method for purifying isobutyl vinyl ether from a mixture containing isobutyl alcohol and isobutyl vinyl ether, comprising the following steps B1 and B2, in which step B1-2 is a step of neutralizing the acid catalyst used in step B1 using a basic compound in an amount of 5 to 100 molar equivalents relative to the acid catalyst. (Step B1) An acetalization step in which isobutyl alcohol in the mixture is reacted with isobutyl vinyl ether in the presence of an acid catalyst to convert it into acetaldehyde diisobutyl acetal. (Step B1-2) A step of neutralizing the acid catalyst (Step B2) A distillation step for removing acetaldehyde diisobutyl acetal by distillation from the acetal-containing mixture obtained in Step B1-2.

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