JPH0796516B2 - Method for producing cycloalkanone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved process for producing cycloalkanones. More specifically, the present invention relates to polymer compounds such as nylon and polyester, plasticizers,
Cycloalkanone, which is extremely useful as an intermediate raw material for synthetic lubricants and other organic chemicals, or as a solvent,
The present invention relates to a method for efficiently producing a corresponding cycloalkene by liquid phase oxidation.

[Conventional technology]

Conventionally, cycloalkanones having 5 to 12 ring carbon atoms are known to be important compounds as intermediate raw materials and solvents for various applications.

For example, ε-caprolactam and lauryllactam derived from cyclohexanone and cyclododecanone, respectively, are important as raw material monomers for nylon 6 and nylon 12, respectively, and various dicarboxylic acids obtained by oxidizing cycloalkanone, for example, cycloalkane. Glutaric acid obtained from pentanone, adipic acid obtained from cyclohexanone, azelaic acid obtained from cyclononanone, oxidative dimerization of cyclopentanone or sebacic acid obtained from cyclodecanone, oxidative dimerization of cyclohexanone or dodecane obtained from cyclododecanone Diacids include various nylons, polyesters, plasticizers,
It is important as a raw material for synthetic lubricants and other organic chemicals. Furthermore, cyclohexanone is used in large amounts as a general-purpose solvent, and high-purity cyclopentanone has recently been highlighted as a special solvent in the electronics field.

By the way, various attempts have been made so far to produce a corresponding cyclic ketone by oxidizing a cycloalkene.

For example, as a method for producing a cycloalkanone by liquid-phase oxidation of cycloalkene, a method of liquid-phase oxidation with molecular oxygen using a palladium compound and a copper compound or an iron compound as a catalyst in alcohol has been proposed (Japanese Patent Publication No. 60
-330 gazette, Japanese Patent Publication No. 60-332 gazette). Further, a method of oxidizing with a peroxide in the presence of a noble metal catalyst has also been proposed (JP-A-60-81139).

However, in these methods, since the reaction system is a homogeneous system,
A so-called palladium mirror is formed in the reaction step or the product separation step, and it is difficult to separate and recover the palladium used as a catalyst, and the catalyst cannot be reused.

In order to overcome the above drawbacks, we previously proposed a method of using a catalyst in which a palladium compound and a copper compound or an iron compound are supported on activated carbon (Japanese Patent Laid-Open No. 60-60621). However, the recovery rate of palladium was not high enough.

[Problems to be solved by the invention]

The present invention improves the drawbacks of such a conventional method for producing a corresponding cycloalkanone by oxidizing a cycloalkene, improves the recovery rate of palladium, and also improves the catalytic activity, resulting in high conversion. With rate and selectivity,
It is intended to provide a practical method for producing cycloalkanone from cycloalkene.

[Means for solving problems]

The present inventors have conducted extensive studies to achieve the above-mentioned object, and as a result, after the oxidation reaction was stopped, hydrogen was introduced into the reaction system to reduce the palladium catalyst, and then the product was separated to obtain the palladium catalyst. It has been found that the recovery rate of the can be improved, and the present invention has been completed based on this finding.

That is, in the present invention, when the cycloalkene is liquid-phase oxidized to produce cycloalkanone, the catalyst (A) is used as a catalyst.
Using a palladium compound and (B) at least one compound selected from a copper compound and an iron compound, liquid phase oxidation of cycloalkene was performed in the presence of activated carbon and alcohol, and then hydrogen was introduced after stopping the reaction. The present invention provides a method for producing a cycloalkanone, which comprises reducing a palladium catalyst and then separating the product.

In the method of the present invention, the cycloalkene used as a raw material is an unsubstituted or substituted one having at least one unsaturated bond, and preferably one unsaturated bond having 5 to 12 ring carbon atoms. And cycloalkene having a substituent inert to the reaction such as an alkyl group, an alkoxy group and an aryl group on the ring. Examples of such substances include cyclopentene,
Methylcyclopentene isomers, cyclohexene, methylcyclohexene isomers, ethylcyclohexene isomers, cyclooctene, cyclododecene, etc. are particularly preferably mentioned from the viewpoint of availability of raw materials and usefulness of the obtained cycloalkanone. it can.

The cyclopentene is 4 to 5% by weight of ethylene production amount.
By partial hydrogenation of by-produced cyclopentadiene, and cyclohexene can be easily obtained by partial dehydrogenation of cyclohexane or dehydrochlorination of chlorocyclohexane.Methylcyclohexene isomers and ethylcyclohexene isomers are It can be easily obtained by partially dehydrogenating methylcyclohexane and ethylcyclohexane obtained by hydrogenation of toluene and ethylbenzene. Also, cyclooctene is obtained by partially hydrogenating cyclooctatetraene obtained by tetramerization of acetylene, while cyclododecene is easily obtained by partially hydrogenating cyclododecatriene obtained by trimerization of butadiene. .

These cycloalkenes may contain saturated cycloalkanes as long as they do not inhibit the oxidation reaction.

In the method of the present invention, as the catalyst, a composite catalyst composed of (A) a palladium compound and (B) at least one compound selected from a copper compound and an iron compound is used.

Examples of the palladium compound used as the component (A) of the catalyst include halides, inorganic acid salts, organic acid salts, and organic complex salts. Of these, palladium chloride, particularly palladium dichloride, is preferable. . The addition amount of this component (A) is usually relative to cycloalkenes.
It is selected in the range of 0.001 to 10% by weight, preferably 0.01 to 4% by weight.

Examples of the copper compound and iron compound used as the component (B) include halides, inorganic acid salts, organic acid salts,
Examples thereof include organic complex salts, and among these, chlorides such as cupric chloride and ferric chloride are preferable. These compounds may be used alone or in combination of two or more, and the addition amount thereof is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, based on the cycloalkene. To be elected.

In the present invention, activated carbon needs to coexist. Activated carbon may be present as a carrier for the catalyst or may be present separately from the catalyst. The presence of activated carbon improves conversion and selectivity, facilitating separation and regeneration of the catalyst.

The method for supporting the palladium compound or the copper or iron compound on the activated carbon is not particularly limited, and a conventionally used method can be used. For example, a predetermined amount of activated carbon is added to an acidic aqueous hydrochloric acid solution containing palladium dichloride and a chloride of copper or iron at a predetermined concentration, and the mixture is preferably heated to a temperature of 60 to 100 ° C to evaporate to dryness, and then this By calcination under a flow of air at a temperature preferably in the range of 50 to 300 ° C. for usually 2 to 8 hours, a catalyst in which a palladium compound and a copper or iron compound are supported on activated carbon can be obtained. The supported amount of the metal element in the catalyst thus obtained is usually 0.01 to 10% by weight, preferably 0.
It is preferably in the range of 1 to 3% by weight.

There are various types of activated carbon used here. For example, wood, coconut husk, lignin, beef bones, lignite, coal, etc. which are carbonized as a raw material, activated, and further granulated as necessary are used. Particularly preferably, those activated carbons treated with hydrogen peroxide are used. The treatment method of hydrogen peroxide may be any method as long as hydrogen peroxide is brought into contact with activated carbon, and is carried out by bringing the hydrogen peroxide into contact with the activated carbon in a liquid phase or a gas phase. The amount of activated carbon to be added is not particularly limited, but is usually 2 to 50 g, preferably 5 to 25 g per 1 mmol of the palladium compound.

The alcohol is preferably an aliphatic alcohol having 2 to 20 carbon atoms, an alicyclic alcohol and an aromatic ring-substituted alcohol thereof, which may be linear or branched, primary, It may be of the second class or the third class. Examples of such alcohols include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, n-octyl alcohol. Two
Examples thereof include aliphatic alcohols such as ethylhexyl alcohol and nonyl alcohol, alicyclic alcohols such as cyclopentyl alcohol and cyclohexyl alcohol, and aromatic ring-substituted alcohols such as benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol.

Each of these alcohols may be used alone,
Two or more kinds may be used in combination, and as long as the object of the present invention is not impaired, a solvent compatible with the alcohol, for example, dioxane, ethers such as tetrahydrofuran, acetone, ketones such as methyl ethyl ketone, methyl acetate, It may contain esters such as ethyl acetate, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene and toluene.

Water may be present in the reaction system in order to enhance the catalytic activity. Water is 10 ~ per 1 mmol of palladium compound
1000 mmol, preferably 30-600, particularly preferably 40
~ 400 mmol added to reaction system. If the amount of water is less than 10 mmol, the activity of the catalyst will not improve, and if it exceeds 1000 mmol, the activity of the catalyst will decrease.

In the method of the present invention, hydrogen peroxide, a third
Peroxides such as butyl butyl hydroperoxide and oxygen can be used, but it is preferable to use molecular oxygen, for example, pure oxygen gas or a diluent inert to the reaction of oxygen gas, such as nitrogen or helium. A mixed gas diluted with argon or the like, or air or the like is used.

Next, a preferred example of the embodiment of the present invention will be described. First, alcohol is added in an amount of preferably 10 to 1000 parts by weight to 100 parts by weight of cycloalkene, and activated carbon (A ) Component and / or (B) component-supported one is added in a predetermined amount, respectively, and then,
Cycloalkenes are usually liquid phase oxidized at temperatures in the range of 20 to 200 ° C, preferably 30 to 100 ° C, using an oxidizing agent such as molecular oxygen. The reaction pressure is not particularly limited as long as it is equal to or higher than the pressure required for maintaining the liquid phase in the reaction system,
Oxidation is usually accompanied within the range of atmospheric pressure to 20 kg / cm ² · G. If the reaction temperature is too low, the reaction rate is too slow to be practical, while if it exceeds 200 ° C., side reactions and solvent loss increase, and the equipment becomes expensive.

The reaction time varies depending on the reaction temperature, the type of catalyst and the amount added, but is usually in the range of 10 minutes to 24 hours.

In the method of the present invention, after stopping the reaction, if necessary, the reaction system is replaced with nitrogen gas to remove oxygen, then hydrogen is introduced into the reaction system to reduce the palladium catalyst, and then the product is separated. To do. The obtained residue can be subjected to the reaction again.

The hydrogen reduction condition is that the temperature is usually 20 to 150 ° C., preferably 2
At 0 to 100 ° C, the reaction pressure is usually atmospheric pressure to 10 kg / cm ² · G
The reaction time is usually 0.1 to 3 hours, preferably 0.1 to 1
It's time.

The reaction product is separated into a solid content and a liquid content by means such as filtration, centrifugation, sedimentation, etc., and the solid content catalyst can be pre-oxidized as necessary and recycled to the reaction system for use. The liquid reaction mixture is separated into unreacted substances and cycloalkanones by means such as distillation, and the unreacted substances can be recycled to the reaction system for use.

By such hydrogen reduction, the palladium catalyst is recovered in the solid content at a high recovery rate and can be reused.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 1 mmol of palladium dichloride (PdCl ₂ ) was dissolved in 10 ml of concentrated hydrochloric acid, and 10 ml of pure water was added and diluted. 8 g of granular activated carbon was added to this solution, and the mixture was evaporated to dryness at 80 ° C in a hot water bath and then calcined at 250 ° C for 4 hours in an air stream to obtain an activated carbon-supported catalyst carrying 1.3% by weight of palladium. Obtained.

The above-mentioned activated carbon-supported catalyst was placed in a stainless steel autoclave.
3.5 g, 40 ml of ethanol, 6.8 g of cyclopentene and 0.8 mmol of cupric chloride (CuCl ₂ .2H ₂ O) were added. Oxygen was injected into this autoclave at a pressure of 9 kg / cm ² · G and at 50 ° C for 6 hours.
The reaction was carried out with stirring. After the reaction, nitrogen gas was introduced into the reaction system to remove oxygen. Next, cool the autoclave to room temperature, and under normal pressure hydrogen gas at a rate of 40 ml / min.
Minutes introduced. Then, nitrogen gas was introduced again to remove hydrogen, and then the reaction solution was filtered to separate into a solid content and a liquid content. As a result of analyzing the content of Pd dissolved in the liquid component, 3.1 ppm of Pd was dissolved, and the recovery rate based on the amount of Pd charged in the solid component containing activated carbon was 99.7%. In this reaction, 65 mmol of cyclopentanone was produced.

Example 2 A stainless steel autoclave was charged with palladium dichloride (Pd
Cl ₂ ) 0.4 mmol, ethanol 60 ml, cyclopentene 6.8 g,
Cupric chloride (CuCl ₂ · 2H ₂ O) 0.8 mmol and granular activated carbon 6 g
I put it in. Oxygen 9kg / cm ² · G in this autoclave
It was pressed in and reacted at 50 ° C. for 6 hours while stirring. After the reaction, the same operation as in Example 1 was carried out to separate into a solid content and a liquid content. As a result, 2% of Pd was dissolved and the recovery rate based on the amount of charged Pd in the solid content containing activated carbon was 99.8%. It was In addition, 67 mmol of cyclopentanone was produced in this reaction.

Comparative Example 1 After carrying out the reaction by the same operation as in Example 1, the autoclave was cooled to room temperature and filtered without introducing hydrogen into the reaction solution to separate into a solid content and a liquid content. As a result of analyzing the content of Pd dissolved in the liquid, Pd 10ppm
Was dissolved, and the recovery rate based on the amount of charged Pd in the solid content containing activated carbon was 99%.

〔The invention's effect〕

According to the method for producing a cycloalkanone of the present invention, cycloalkene gives a corresponding cycloalkanone with high conversion and selectivity, and expensive palladium used as a catalyst is obtained by coexisting activated carbon. ,
It can be separated and collected easily. Further, the catalyst used in the present invention has a small decrease in catalytic activity even if it is recovered and reused, and can be repeatedly used. Therefore, the method of the present invention has high practical value.

Claims (2)

[Claims] 1. When a liquid phase oxidation of cycloalkene is carried out to produce a cycloalkanone, (A) a palladium compound and (B) at least one compound selected from a copper compound and an iron compound are used as catalysts. A method for producing a cycloalkanone, characterized in that the cycloalkene is subjected to liquid-phase oxidation in the coexistence of activated carbon and an alcohol, and then the reaction is terminated to introduce hydrogen to reduce the palladium catalyst, followed by separation of the product. Method. 2. The method for producing cycloalkanone according to claim 1, wherein the activated carbon is treated with hydrogen peroxide.