JP4019670B2 - Method for producing ketal and / or acetal - Google Patents

Description

【００４５】
このように、反応系中の水分量が２０ｗｔ％以下であれば、Ｐｄブラックの生成も無く、顕著な反応成績の低下は見られない。２０ｗｔ％以上になると、Ｐｄの析出が見られ、選択率も大きく低下する。また、水分量が２０ｗｔ％以下であっても、水分量の増加にともない、少しずつ活性、選択率は低下してくる。しかし、実施例１に示したように、例えば、ケイ酸エチルを添加し、生成してくる水を除去する事によりシクロヘキサノンケタールの選択率が上昇する。シクロヘキサノンは追酸化を受け、シクロヘキセノン等に酸化されるおそれがあるため、シクロヘキサノンケタール選択率が高いのが好ましい。
【００４６】
【発明の効果】
本発明によれば、Pd成分の析出を抑制しつつ、高転化率且つ高選択率で、オレフィン類からケタール及び／又はアセタールを製造することが可能となり、工業的な利用価値が高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing ketals and / or acetals by oxidizing olefins with molecular oxygen.
[0002]
[Prior art]
Corresponding aldehydes or ketones obtained by oxidizing olefins with molecular oxygen are industrially useful compounds and have been synthesized for a long time by catalytic reactions. Among them, a useful method is a reaction generally known as a Wacker reaction. That is, a method of producing acetaldehyde from ethylene and acetone from propylene by molecular oxygen using an aqueous solution containing PdCl2 and CuCl2 as a catalyst has also been adopted industrially. However, in this conventional Wacker reaction, the aqueous solution is under strong acidic conditions and highly corrosive hydrochloric acid is present, so that a high-grade material is required for the reactor and peripheral devices, and a reactive substrate. However, it is not always an industrially advantageous process in that it is limited to lower hydrocarbons such as ethylene and propylene.
[0003]
As a reaction similar to the conventional Wacker reaction, an ketonation reaction of an olefin with a hydroperoxide complex of Pd (Pd—OOH species) has been studied (Japanese Patent Laid-Open No. 57-156428 (corresponding to US Pat. No. 4,444,544)). 60-92236, JP 61-60621). In this reaction, a monovalent alcohol such as methanol or ethanol is used as a reaction medium instead of water used in the conventional Wacker reaction, and a metal salt of Pd and Cu and / or Fe is used as a catalyst. .
[0004]
In addition, J. Org. Chem. Vol. 34, 3949 (1969) uses 1,4,4 from cyclohexene by using PdCl2 and CuCl2 as catalysts and using a polyhydric alcohol such as ethylene glycol or glycerol as a reaction solvent. Although it is disclosed that dioxospiro [4,5] decane can be obtained in high yield, there is no description of details such as specific yield.
[0005]
[Problems to be solved by the invention]
As described above, various industrially effective methods for synthesizing the corresponding aldehydes or ketones from olefins have been studied. In the conventional method, however, the sequential reaction of ketals and / or acetals in an oxidation reaction system. The present inventors have found that there is a problem in that the selectivity of ketal and / or acetal tends to be lowered due to water generated by oxidation and the catalyst component tends to precipitate. In particular, when the catalyst-containing liquid after the reaction is reused again in the oxidation reaction system, it is expected that water will generally accumulate in the reaction system by about 30 wt% or more, and the selectivity and catalyst component precipitation are remarkable. The inventors focused on a certain point.
[0006]
In particular, cyclohexanone useful as a precursor of caprolactam is obtained by oxidizing cyclohexane in the presence of a catalyst, if necessary, and dehydrogenating the resulting cyclohexanone-cyclohexanol mixture, or cyclohexanol obtained by hydrating cyclohexene. It is manufactured by the method of dehydrogenation reaction. However, the former method requires that the conversion rate be kept at a very low level during the oxidation of cyclohexane because the reaction product is susceptible to sequential oxidation, and it is necessary to circulate a large excess of unreacted cyclohexane. As a result, the process is not energy efficient. In the latter method, the yield of the hydration reaction is not sufficient, or when cyclohexene is extracted and separated from a mixture of benzene and cyclohexane with extremely close boiling points, or when the mixture has an equimolar mixture of cyclohexanone and cyclohexanol having a high boiling point. There was a problem that a large amount of energy was consumed when only cyclohexanone was separated from the mixture.
[0007]
Therefore, if a technique for efficiently synthesizing the corresponding aldehyde or ketone, particularly cyclohexanone, from cycloolefin or other olefins while suppressing the decrease in selectivity while suppressing the precipitation of catalyst components is of great significance. .
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve such problems in the oxidation reaction of olefins, the present inventors have made an oxidation reaction when producing ketals and / or acetals by reacting olefins with oxygen and alcohol. By carrying out the oxidation reaction while maintaining the amount of water in the liquid below a specific amount, the ketal and / or acetal can be reduced in a high yield while suppressing the precipitation of the catalyst component while suppressing the decrease in selectivity. It has been found that it can be produced, and has reached the present invention.
[0009]
That is, the gist of the present invention is a method for producing a ketal and / or acetal by oxidizing an olefin having at least one ethylenic double bond, oxygen and an alcohol in the presence of a catalyst containing palladium. The alcohol solution containing the catalyst after recovering the target reaction product from the reaction product solution after the oxidation reaction is reused in the oxidation reaction system, and the water content in the oxidation reaction solution is maintained at 20 wt% or less to oxidize. The present invention resides in a method for producing a ketal and / or acetal characterized in that a reaction is carried out.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
The present invention recycles an alcohol solution containing a catalyst obtained from a reaction product solution after an oxidation reaction to an oxidation reaction system when producing a ketal and / or an acetal by an oxidation reaction of olefins. By maintaining the water content within 20 wt% or less, ketal and / or acetal is produced with high selectivity while suppressing precipitation of catalyst components.
(amount of water)
In the present invention, the reaction is carried out while constantly maintaining the water content in the oxidation reaction system at 20 wt% or less. However, in order to further improve the selectivity of the target product and suppress the precipitation of the catalyst component, it is preferably 18 wt%. % Or less, more preferably 15 wt% or less, further 12 wt% or less, further preferably 10 wt% or less, particularly 8 wt% or less, and most preferably 5 wt% or less. As a method for specifying the amount of water, in the case of batch reaction, the amount of water at the end of the reaction is usually maximized, so the amount of water at the end of the reaction can be used as a reference. In the case of a continuous reaction, it is necessary to set the amount of water in the reaction solution in a steady state to the above specific range amount. The moisture content can be determined by the Karl Fischer method
As a method of maintaining the water content at the specific amount of the present invention, there are the following methods.
1) A method of previously removing the water content in the reaction raw material and catalyst
2) A method of sequentially removing water accumulated in the reaction system by azeotropic distillation.
3) A method of adsorbing and removing anhydrous metal salts such as anhydrous magnesium sulfate and molecular sieves such as zeolite in the reaction solution and recycle catalyst solution as water adsorbates.
4) A method in which an organic silicon compound such as ethyl silicate is added to a reaction solution or a recycle catalyst solution, and water is removed by hydrolysis.
5) Method of distilling off water from recycled catalyst solution
6) A method in which a gas containing or not containing oxygen is blown into the recycle catalyst solution, and water is accompanied and distilled off along with the gas.
7) A part of the recycled catalyst solution containing water accumulated in the reaction system is purged to the outside of the system to reduce the water content in the reaction system. To replenish the solvent and catalyst
Among the methods described above, the method 6) is particularly preferable from the viewpoint that unnecessary components are not added to the system as much as possible.
[0011]
Specific examples of the above method 4) are described in Examples.
(catalyst)
The catalyst of the present invention is not particularly limited as long as it is a catalyst containing palladium, but preferably (a) palladium, (b) other than at least one kind of palladium in groups 8, 9, 10, and 14 of the periodic table. A catalyst composed of a metal and (c) a component containing halogen is preferably used. Here, the components (a) to (c) may exist in any form such as dissociated ions, salts or molecules in the reaction system.
[0012]
(A) Palladium should just be a bivalent-tetravalent form, and can be arbitrarily selected from a well-known thing, a commercially available thing, etc. For example, palladium halides such as palladium chloride and palladium bromide, palladium salts of inorganic or organic acids such as palladium nitrate, palladium sulfate, palladium acetate, palladium trifluoroacetate, palladium acetylacetonate, palladium oxide, palladium hydroxide, etc. Inorganic palladium is mentioned. Also, a base coordinated compound derived from these metal salts, for example, [Pd (en) 2] Cl2, Pd (phen) 2] Cl2, [Pd (CH3CN) 2] Cl2, [Pd (C6H5CN) 2] Cl2, [Pd (C2O4) 2] 2, [PdCl2 (NH3) 2], [Pd (NO2) 2 (NH3) 2], etc., but are not limited to these (en: Ethylenediamine, phen: represents 1,10-phenanthroline). Among these paradium sources, a divalent palladium source is preferably used for the reaction, and is preferably used for the reaction as a compound coordinated with a chloride or a nitrile compound.
[0013]
The role of palladium in the catalyst system is manifested by interaction with iron ions and polyhydric alcohols, and the state of action is not always clear. It is essential that palladium exhibits its activity by constituting an active species with other catalyst components, and it is sufficient if a palladium source sufficient to induce the essence is present in the system.
(B) At least one metal other than palladium in groups 8, 9, 10, and 14 of the periodic table (IUPAC inorganic chemical nomenclature, 1990 rules) includes iron, cobalt, nickel, ruthenium, and tin. Preferably, it is iron.
[0014]
The catalyst compound serving as the iron source may be in a divalent or trivalent form. For example, chlorides such as iron (II) chloride, iron (III) chloride, bromides such as iron (II) bromide, iron (III) bromide, iron (II) sulfate, iron (III) sulfate, iron nitrate ( II), inorganic acid salts such as iron (III) nitrate, various salts such as iron (II) acetate, iron (III) acetate, iron (II) oxalate, iron (III) oxalate, iron formate, iron acetylacetone Or it can use for reaction in the form of a coordination compound. Like palladium, it is essential that iron exhibits its activity by constituting an active species with other components, and it is sufficient that an iron source sufficient to induce the essence is present in the system.
[0015]
The catalyst compound used as a source of cobalt, nickel, ruthenium, and tin may be in a divalent, trivalent, or tetravalent form. Specifically, these halides such as chlorides and bromides, inorganic acid salts such as sulfates and nitrates, various salts such as acetates, oxalates, formates and acetylacetonato salts, and coordination compounds are used. In particular, chloride. When the component (b) is cobalt, nickel, ruthenium or tin, it is preferable to further combine with copper.
[0016]
It is possible to remarkably suppress the precipitation of Pd by adding such a component (b). However, if a copper compound such as CuCl or CuCl2 is further added to this, the reaction rate is improved and by-products such as halides are added. Further advantageous results can be obtained as an industrial process of reducing
(C) Halogen is chloro (Cl) and / or bromine (Br), with chloro (Cl) being particularly preferred. Halogen may be present in the reaction system as a counter anion of Pd and / or Fe. Also, a method of supplying the reaction system as a halide of other catalyst components or a method of supplying it to the reaction system in the form of HCl, HBr, etc. is possible, but in either case, in the form of ions in the reaction system It is necessary to exist. Among them, (c) chloro as a halogen is preferably used as the chloride of (a) or (b).
[0017]
In the present invention, ketals and / or acetals are produced by reacting olefins with oxygen and polyhydric alcohols in a liquid phase in which the above-described catalyst is dissolved.
(Olefins)
The olefins subject to the present invention are aliphatic or alicyclic organic compounds containing at least one ethylenic double bond. Examples of chain olefins include olefins having usually 2 or more carbon atoms, preferably 2 to 25 carbon atoms, more preferably 3 to 10 carbon atoms, such as ethylene, propylene, butene, pentene, hexene and octene. In this case, the position of the double bond may be either terminal or internal, and in the case of a terminal olefin, an acetal or methyl ketone ketal is mainly produced, and if it is an internal olefin, the corresponding ketal Is mainly obtained.
[0018]
Cyclic olefins are compounds having one or more ethylenic double bonds having 4 to 10 carbon atoms, preferably 5 to 8 carbon atoms, and include cyclopentene, cyclohexene, cyclohexadiene, cycloheptene, cyclooctene, etc. Cyclopentene and cyclohexene are industrially useful compounds. When cyclohexene is used as the olefin, 1,4-dioxospiro [4,5] decane (hereinafter referred to as cyclohexanone ketal) is generated as a product.
[0019]
One or more substituents such as an alkyl group, an alkoxy group, an aryl group, a phenyl group, a carboxyl group, a halogen group, and a nitro group may be present at any position on the main chain of these olefins. For example, olefins having a functional group at the 2-position, such as acrylonitrile, acrolein, acrylic acid, and vinyl chloride, or styrene and methylstyrenes react well. Furthermore, even a compound having a condensed ring such as 3,4-dihydronaphthalene can be used as long as it has an ethylenic double bond.
(alcohol)
As the alcohol used in the present invention, a monohydric or polyhydric alcohol can be used, and among them, a polyhydric alcohol is preferable. Examples of the monovalent alcohol include methanol, ethanol, propanol and the like. The polyhydric alcohol is usually divalent to tetravalent, and diols are particularly preferable. In the case of a diol, it usually has 2 or more carbon atoms, and preferably has 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms, considering the price, stability, and ease of formation of acetals and ketals. Diols, specifically ethylene glycol, 1,3-propanediol, 1,2-dihydroxybutane, 1,2-dihydroxypropane, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1, 2-cyclohexanedimethanol, diethylene glycol, 1,2-transcyclopentanediol, 2,4-pentanediol, styrene glycol, 1,5-dihydroxycyclooctane, 1,4-dihydroxycyclooctane, 2,5-dihydroxynorbornane, 2,6-dihydroxynorbornane, 1,4-dihydroxy-2,3-dimethylbutane, , 5-dihydroxy-2,4-dimethylpentane, cyclobutane-1,2-dimethanol, cyclohexane-1,3-dimethanol, 1,4-dihydroxy-2,3-dichlorobutane, 2,5-dihydroxyhexane preferable. More preferably, ethylene glycol, 1,3-propanediol, 1,2-dihydroxybutane, 1,2-dihydroxypropane, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol Diethylene glycol, 1,2-transcyclopentanediol, 2,4-pentanediol, and styrene glycol. Of course, these may be used in combination.
[0020]
The reason why polyhydric alcohol is preferred among alcohols in the present invention is not necessarily clear, but it is believed that palladium starts from a divalent form such as chloride and forms a divalent peroxy complex as an active component. It is believed that effective active species are derived by involving alcohol in the active ingredients of In addition to this role, by reacting with the produced aldehyde or ketone to produce the corresponding acetal or ketal, extremely high stability against oxygen oxidation is ensured as compared to the free aldehyde or ketone. This makes it possible to maintain the selectivity of the target product at a very high level.
(Reaction conditions)
In the present invention, the reaction is preferably carried out in a liquid phase in which the catalyst is dissolved.
[0021]
In the present invention, it is necessary to use a gas containing oxygen. However, since oxygen and organic compounds may form explosive mixtures at a certain temperature, a certain pressure range, and a composition range, the danger is avoided. It is necessary to. If the partial pressure of oxygen is 0.001 Mpa or more, the reaction proceeds, but if the partial pressure of oxygen is low, the reaction rate becomes slow and the catalyst tends to be deactivated. In the present invention, 0.01 to 10 MPa is preferable, and 0.05 to 5 MPa is more preferable, but more preferable pressure is selected from the viewpoint of safety and economy.
[0022]
If the reaction temperature is 0 ° C. or higher, the reaction proceeds. However, in the present invention, the temperature dependency of the reaction is large, so a higher temperature is preferable. The reaction temperature is selected in consideration of the formation conditions of the explosive mixture and the increase of by-products due to radical auto-oxidation. Generally, the reaction temperature is 20 to 200 degrees, preferably 40 to 180 degrees. A significant reaction rate can be obtained. Although the total pressure of the reaction varies depending on the oxygen concentration, it may be equal to or higher than the liquid phase holding pressure, but is usually 0.1 to 20 MPa, preferably 0.1 to 15 MPa. The reaction time (residence time) is usually 5 seconds to 20 hours, preferably 10 seconds to 10 hours.
[0023]
The concentration of (a) palladium as a catalyst is in the range of 0.001 wt% or more and 10 wt% or less, and preferably 0.01 wt% or more and 5 wt% or less as [Pd2 +] with respect to the total reaction solution weight. Under high concentration conditions, the concentration dependence of the reaction rate behaves differently from that under low concentration conditions, and the catalyst efficiency tends to deteriorate. Therefore, an efficient concentration is selected from an economical viewpoint.
[0024]
(B) The concentration of at least one metal M other than palladium in groups 8, 9, 10, and 14 of the periodic table can be described as (a) a relative concentration with respect to palladium. That is, usually 0.1 <[M] / [Pd] <100 (molar ratio), preferably 0.1 <[M] / [Pd] <10 (molar ratio). At a concentration lower than this, the reaction rate tends to decrease, and (b) the effect of suppressing Pd precipitation, which is the main effect of the metal, tends to be small. Addition of a large amount does not inhibit the reaction itself, but tends to limit the amount dissolved in the reaction system.
[0025]
When copper is used as the catalyst component, (b) in an amount of 0.1 to 100 molar ratio to at least one metal other than palladium in groups 8, 9, 10, and 14 of periodic table It is preferable to do this.
(C) The relative concentration of halogen to Pd is usually in the range of 1 <[Cl and / or Br] / [Pd] <100 (molar ratio), preferably 0.3 <[Cl and / or Br] / [Pd ] <50. In situations where the halogen concentration is high, water in the reactor may cause corrosion of the reactor material, so the halogen concentration should be selected so that the catalyst system functions in as low a region as possible. In addition, a component containing halogen derived from the catalyst system may be generated in a part of the by-product. In this case, the halogen that is consumed continuously or periodically is replenished, for example, in the form of a metal salt. Better.
[0026]
The amount of alcohols present in the reaction system may be a theoretical amount (1 mol) relative to the olefin, but in the present invention, it is preferable to use the reaction solvent as well. Usually, it is 1 vol% or more and 99 vol% or less, preferably 5 vol% or more and 99 vol% or less with respect to the entire reaction volume. Moreover, alcohol is 1-100 mol normally with respect to an olefin, Preferably it is 2-50 mol. The abundance of olefins in the reaction system can be selected in the range of 1 vol% to 99 vol%, preferably 1 vol% to 50 vol%.
[0027]
When the concentration of alcohols is relatively low, that is, when the relative concentration of olefins is too high, part of the catalyst component tends to be distributed to the olefin phase, and palladium tends to be deposited. On the other hand, when the alcohol concentration is high, the olefin concentration to be supplied becomes relatively low, and the productivity and the phase separation after the reaction tend to be difficult. It is also possible to add a third component inert to the oxidation reaction to the reaction system to adjust the relative concentrations of alcohols and olefins, and to further improve the phase separation characteristics.
[0028]
In the present invention, further components can be added to increase the activity and reactivity. For example, an additive having an effect of promoting an oxidation reaction, such as a copper compound, an alkali, an alkaline earth, and a rare earth, may be added. Moreover, you may employ | adopt the method of adding a radical trap agent and suppressing a side reaction.
Among the reactions of the present invention, in particular, in industrial processes that are produced in large quantities, such as a method for producing cyclohexanone from cyclohexene, even if a small amount of impurities is taken into consideration, efficient separation can be achieved by considering the mass balance of the entire process. Some are required. For example, impurities that are particularly difficult to separate and may adversely affect the product, such as cyclohexenone, cyclohexenol, chlorocyclohexanone, and cyclohexenone ketal should be suppressed as much as possible.
[0029]
The reaction mode of the present invention can be carried out according to a general oxidation reaction. When each component of the catalyst is present in a solution state, the oxidation reaction can proceed by contacting the olefin with a gas containing oxygen for a specific reaction time by a batch reactor, and oxygen can be promoted by a continuous phase reactor. The gas and olefins to be contained can be continuously supplied to advance the oxidation reaction. On the other hand, when the catalyst component of the present invention is immobilized, the liquid phase reaction described above can be used, or the catalyst is packed in a fixed bed and the corresponding olefins and oxygen are added as a liquid phase state. A so-called trickle bed system can be employed. In the present invention, it is particularly preferable to carry out the reaction by a continuous flow system in that the effect of the invention is remarkable.
[0030]
For oxygen supply, a method of making gas containing oxygen fine bubbles with a stirring blade, a method of providing a baffle plate inside the reactor to make oxygen gas fine bubbles, and spraying into the system at a higher linear velocity than the nozzle Thus, a technique effective for dissolving oxygen in the reaction solution system can be employed.
(Processing after oxidation reaction)
In the reaction product solution after the oxidation reaction, raw material olefin, product ketal and / or acetal, catalyst component and alcohol are contained. When the reaction product liquid is in a pressurized state, the pressure may be released to some extent to reduce the pressure. In the present invention, the alcohol solution containing the catalyst component obtained from the reaction product after the oxidation reaction is recycled to the oxidation reaction system.
[0031]
If the boiling points of olefin and ketal and / or acetal in the reaction product are significantly different from those of alcohol solvents and have a low boiling point, the low boiling components (olefin and ketal and / or acetal) are separated directly from the reaction product by distillation. can do. In this case, the alcohol solution containing the catalyst component obtained as the bottoms of distillation is recycled to the oxidation reaction step.
Further, when the boiling point of the olefin and the ketal and / or acetal is higher than that of the alcohol solvent, it can be phase separated as it is into an alcohol phase containing a catalyst and an organic phase containing a reaction product and an unreacted olefin. . Alternatively, an extraction solvent such as an organic solvent that forms a two-phase with alcohol is added, and two-phase separation is performed by extraction, and an extraction solvent phase containing an olefin and a ketal and / or an acetal and a polyhydric alcohol phase containing a catalyst component Can be separated.
[0032]
As the extraction solvent, a compound that cannot form a hydrogen bond or a compound that has an active hydrogen atom but does not have an electron donor can be used. Specifically, hydrocarbons such as benzene, n-hexane, cyclohexane, toluene, 1-hexene, 1,3-butadiene, styrene, halogenated hydrocarbons such as chloroform, methylene chloride, and 1,2-dichloroethane, sulfides And mercaptans, and hydrocarbon compounds are preferred. When the oxidation reaction process of the present invention is combined with a partial hydrogenation reaction process of benzene, unreacted benzene and by-produced cyclohexane function as an extraction solvent, which is advantageous for the present invention.
[0033]
The amount of the extraction solvent varies depending on the type of olefin and alcohol, but is usually 0 to 100 times, preferably 0 to 50 times, and more preferably in volume ratio with respect to the total amount of the mixture after the oxidation reaction including alcohol. Is from 0 to 10 times. Extraction is easy to perform by batch operation, but in some cases, it may be performed by co-current or countercurrent multistage extraction. Moreover, you may extract continuously. In the present invention, it is preferable to perform extraction continuously.
[0034]
In the present invention, the catalyst component-containing alcohol phase after phase separation or distillation separation is recycled to the oxidation reaction system, but in some cases, an oxygen-containing gas (for example, air) is present to prevent reduction of Pd ions. Preferably it is recycled below. Alternatively, the catalyst that has been partially reduced by the reaction may be returned to the oxidized state with an oxygen-containing gas (for example, air) and then circulated to the reaction system. The conditions in this case are 0 to 150 ° C. and oxygen partial pressure of 0.01 to 10 MPa. The amount of cyclohexene in the recycle liquid is preferably as small as possible to promote the reduction of Pd. The concentration of cyclohexene is 3 wt% or less, preferably 2 wt% or less, more preferably 1 wt% or less.
[0035]
When a small amount of catalyst components are mixed in the extraction solvent containing olefin and ketal and / or acetal during the two-phase separation, the extraction solvent phase is further extracted twice or more with an alcohol solvent. The residual amount of the catalyst component in the solvent phase can also be reduced to a negligible level. In addition, after the first two-phase separation, the olefin and the ketal and / or acetal are separated from the extraction solvent phase by distillation, the residual catalyst concentration in the extraction solvent phase is increased to some extent, and then the extraction operation is performed again. Is possible.
[0036]
From the extraction solvent phase or organic phase containing the product, the olefin and ketal and / or acetal are usually separated and recovered from the extractant, and then the ketal and / or acetals can be removed by distillation separation.
As described above, in the reactor, water is generated by the sequential oxidation that occurs in a small amount during the production of ketals. Although it is preferable to maintain the produced water below the specific amount of the present invention, if there is a halogen component such as Cl in the system together with a very small amount of water, there is a great concern about the reactor corrosion. Therefore, it is necessary to use a material having high resistance to a corrosive acid such as hydrogen chloride at a necessary place.
[0037]
In regions where the reaction pressure is not too high, materials such as glass, ceramic, and Teflon can be used, and when the reaction pressure is high, those that are generally regarded as corrosion-resistant reaction vessels, that is, various stainless steels. It is preferable to use a container such as an alloy, particularly a so-called hastelloy, an alloy containing titanium, an alloy containing zirconium, or a container in which these alloys are coated and pressure-bonded on the surface. In particular, the reactor is highly likely to be corroded, but when a stationary tank and a separation tank are further provided, this part has a high possibility of corrosion. Furthermore, in the distillation of the oil phase containing the product, when the catalyst component remains, the halogen component may be concentrated and the possibility of corrosion is high. These main containers and the pipes attached to them are preferably made of a corrosion-resistant material in an economically acceptable range depending on the possibility of corrosion.
[0038]
Alcohols present as essential components in the reaction system are not inactive at all to the oxidation reaction. Moreover, although it is a trace amount, there is a product obtained by sequential oxidation of olefins and having a polarity close to that of alcohols. Therefore, when the reaction is repeated batchwise for a long time or in a continuous reaction, components that are not necessarily desirable for the present reaction derived from alcohols or olefins accumulate in the alcohol phase containing the catalyst component. In order to operate the process stably, it is necessary to properly control the entire material balance. Therefore, it is necessary to remove a part of the alcohol phase containing the catalyst from the system and supply a new catalyst raw material liquid in accordance with the production rate of these impurities and the production rate of the sequential oxidation component. At this time, the catalyst component removed out of the system has a high removal rate, and if the economic burden is large, it is necessary to recover the catalyst component. The method is not limited, but techniques such as removal of organic substances, washing, and recovery of metal components are effective.
[0039]
Further, when an extraction solvent such as an organic solvent is recovered from the extraction solvent phase containing the two-phase separated product (ketal and / or acetal) by distillation, impurity accumulation may occur in the same manner. However, a part of the extraction solvent can be removed from the system and a new extraction solvent can be replenished.
The ketal and / or acetals obtained in the present invention are converted into the corresponding ketones and / or aldehydes by hydrolysis reaction in the presence of water and acid. Examples of the acid used in this case include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, polyacids such as heteropolyacid, and solid acids such as ion exchange resins, zeolites and clays. By collecting water and polyhydric alcohols from the resulting reaction product liquid rich in aldehydes and / or ketones, and separating and purifying the target aldehydes and ketones, the desired aldehydes, Ketones can be obtained efficiently.
[0040]
In addition, the ketal and / or acetals obtained in the present invention can be efficiently converted into the corresponding alcohols by hydrogenation reaction in the presence of water, a hydrogen source and a hydrogenation catalyst. Examples of the hydrogen source include hydrogen, formalin, sodium borohydride (NaBH4), etc., and examples of the hydrogenation catalyst include Raney Ni, Raney Co, Cu-Cr oxides, Pd, Pt, Ru and the like. Examples thereof include catalysts in which Group metals are supported on various carriers, complex catalysts having Group 8 metals such as Ru, Pt, and Pd as central metals. From the reaction product liquid rich in alcohols obtained by the hydrogenation reaction, the alcohol that has formed water, acetal and / or ketal is recovered, and the target alcohol is separated and purified to obtain the target alcohol. Can be obtained efficiently.
[0041]
【Example】
Examples The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.
(Example 1)
A cylindrical Teflon beaker with an inner diameter of 40 mm and a height of 15 mm, equipped with a magnetic stirrer, was placed in a 100 kG SUS-316 autoclave where this just fits, and 0.1 mmol of Pd (CH3CN) 2Cl2, 0.1 mmol CuCl2, 0.1 mmol of FeCl3, 10 g of ethylene glycol and 20 mmol of cyclohexene were charged and reacted at a reaction temperature of 80 ° C. and an oxygen pressure of 7 kG for 1 hour. After the reaction, 10 ml of hexane was added to the reaction product solution, and phase separation was completely performed into a hexene phase (organic phase) containing unreacted cyclohexene and products (cyclohexanone ketal and cyclohexanone), and an alcohol phase containing catalyst and ethylene glycol. did. When the hexene phase was analyzed by GC, the conversion of cyclohexene was 30%, the selectivity of cyclohexanone and cyclohexanone ketal was 96%, (cyclohexanone ketal selectivity was 92.3%, and cyclohexanone selectivity was 2.7%). As the product, cyclohexenone was mainly used. The water content at the end of the reaction was 2 wt% or less.
[0042]
To the ethylene glycol phase containing the catalyst recovered by extraction, ethylene glycol equal to the amount consumed as ketal and 20 mmol of cyclohexene were newly added. Subsequently, the second reaction was carried out under the same conditions. As a result, the conversion rate of cyclohexene was 29% and the selectivity of cyclohexanone and cyclohexanone ketal was 95%, and the first reaction results were maintained. It is considered that the water is increased up to 1 wt% by the second reaction.
[0043]
Similarly to the above, a cylindrical Teflon beaker equipped with a magnetic stir bar and having an inner diameter of 40 mm and a height of 15 mm was installed in a SUS-316 autoclave with a pressure resistance of 100 kG, and 0.1 mmol of Pd ( CH3CN) 2Cl2, 0.1 mmol of CuCl2, 0.1 mmol of FeCl3, 10 g of ethylene glycol and 20 mmol of cyclohexene were charged, 10 mmol of ethyl silicate was added thereto, and the reaction was carried out at a reaction temperature of 80 ° C. and an oxygen pressure of 7 kG for 1 hour. As a result, the conversion rate of cyclohexene was 30%, the selectivity of cyclohexanone ketal was 100%, and cyclohexanone ketal was selectively produced.
(Examples 2 and 3 and Comparative Example 1)
In the same manner as in Example 1, an experiment was performed assuming that water was accumulated by repeating the reaction by reusing the alcohol phase containing the catalyst separated after the first oxidation reaction. The second oxidation reaction was performed in the same manner as in Example 1 except that water was added so as to have the water amount shown in Table 1 below (maximum amount in the second oxidation reaction solution). The results are shown in Table-1. The amount of water increased by the reaction is 1 wt% or less.
[0044]
[Table 1]

[0045]
Thus, when the water content in the reaction system is 20 wt% or less, there is no generation of Pd black, and no significant reduction in reaction results is observed. When it is 20 wt% or more, precipitation of Pd is observed and the selectivity is greatly reduced. Moreover, even if the amount of water is 20 wt% or less, the activity and selectivity gradually decrease with an increase in the amount of water. However, as shown in Example 1, for example, by adding ethyl silicate and removing generated water, the selectivity of cyclohexanone ketal increases. Since cyclohexanone is subject to additional oxidation and may be oxidized to cyclohexenone or the like, the cyclohexanone ketal selectivity is preferably high.
[0046]
【The invention's effect】
According to the present invention, it is possible to produce ketals and / or acetals from olefins with high conversion and high selectivity while suppressing precipitation of the Pd component, and the industrial utility value is high.

Claims (9)

  In the method for producing a ketal and / or acetal by oxidizing an olefin having at least one ethylenic double bond, oxygen and an alcohol in the presence of a catalyst containing palladium, a reaction product solution after the oxidation reaction The alcohol solution containing the catalyst after recovering the target reaction product from is reused in the oxidation reaction system, and the oxidation reaction is performed while maintaining the water content in the oxidation reaction solution at 20 wt% or less. A method for producing a ketal and / or acetal.   The method for producing a ketal and / or acetal according to claim 1, wherein the oxidation reaction is carried out while maintaining the water content in the oxidation reaction solution at 15 wt% or less.   After the oxidation reaction, phase separation is performed into an organic phase containing a ketal and / or acetal and unreacted olefins, and an alcohol phase containing a catalyst and an alcohol, and then the separated alcohol phase is recycled to the oxidation reaction system. 2. A method for producing a ketal and / or acetal according to 2.   The reaction is carried out in the presence of (a) palladium, (b) at least one metal other than palladium in groups 8, 9, 10, and 14 of the periodic table, and (c) halogen as a catalyst. The method for producing a ketal and / or acetal according to any one of the above.   The method for producing a ketal and / or acetal according to claim 4, further comprising copper as a catalyst. The method for producing a ketal and / or acetal according to any one of claims 1 to 5 , wherein the olefin is a cyclic olefin having 4 to 10 carbon atoms. The method for producing a ketal and / or acetal according to any one of claims 1 to 5 , wherein the olefin is a terminal olefin having 2 to 25 carbon atoms. The method for producing a ketal and / or acetal according to any one of claims 1 to 5 , wherein the olefin is an internal olefin having 4 to 25 carbon atoms.   The method for producing a ketal and / or acetal according to any one of claims 1 to 8, wherein the polyhydric alcohol is an aliphatic or alicyclic diol.