JPH0441460A - Production of cyclohexyl acetate - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a raw material of cyclohexanol, etc., which is an intermediate of nylon, etc., in a high yield by carrying out an addition reaction between cyclohexene and acetic acid using a sulfuric acid-supported zirconium oxide and sulfuric acid as a catalyst. CONSTITUTION:An addition reaction between cyclohexene and acetic acid is carried out using a sulfuric acid-supported zirconium oxide and sulfuric acid as a catalyst to obtain the objective compound. The ratio of acetic acid used to cyclohexene is >=1 in which acetic acid is excessive, preferably within a range of 2-15 on molar ratio base. The reaction temperature is 0-500 deg.C, preferably within a range of 30-300 deg.C. The above-mentioned catalyst is a mixture composed of the sulfuric acid-supported zirconium oxide prepared by reacting zirconium hydroxide with dilute sulfuric acid and calcining the resultant product at >=500 deg.C and sulfuric acid. The amount of the catalyst used is 0.1-50 wt.%, preferably 1-30 wt.% based on cyclohexene.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for producing cyclohexyl acetate. Specifically, the present invention relates to a method for producing raw materials such as cyclohexanol, which are useful as intermediate raw materials for phenol, adipic acid, and nylon, and cycloalkanol aliphatic carboxylic acid esters, which are useful as special solvents. This invention relates to a method for producing cyclohexyl acetate, which is the acetate ester of cyclohexanol, in high yield and high selectivity by adding acetic acid to cyclohexene using zirconia oxide supporting sulfuric acid and sulfuric acid as a catalyst.

2. Description of the Related Art Conventionally, as a method for producing cyclohexanol, a method of obtaining a mixture of cyclohexanone and cyclohexanol by air oxidation of cyclohexane is common and has been widely industrialized. In addition, a method of producing by direct hydration reaction from cyclohexene has recently been widely used. For example, methods for producing zeolite as a catalyst include JP-A-63-250334 and JP-A-63-156736.
or Japanese Patent Application Laid-open No. 1-190644. Furthermore, JP-A-63-253040, JP-A-62-123140
In this paper, the reaction is carried out using an organic acid as a catalyst. Further, in JP-A-62-120333, a strongly acidic cation exchange resin is used as a catalyst. However, in these methods, for example, with a zeolite catalyst, the conversion rate of cyclohexene is as low as about 10%, and in the reaction using an organic acid catalyst, an organic acid several times the weight of the raw material cyclohexene is used. Furthermore, even when using a strongly acidic cation exchange resin catalyst, the amount of catalyst used is approximately 1.5 times that of cyclohexene, and in addition, the amount of catalyst added is the same as that of cyclohexene! The amount of phenols used is
It is difficult to say that either method is an economical method.

On the other hand, it has been known for a long time that cyclohexanol acetate is produced by an esterification reaction between cyclohexanol and acetic acid and a reaction between cyclohexanol and acetic anhydride. However, both of these methods use cyclohexanol as a raw material, and as mentioned above, the use of cyclohexanol has various drawbacks, such as the production method having problems as described above. have. In addition, since the esterification reaction is an equilibrium reaction, it is difficult to achieve a high reaction yield of the ester, and it is also necessary to take some means to remove by-produced water. In addition, although the yield of the ester is high in the method using acetic anhydride, the acetic anhydride used is expensive, and in addition, acetic acid molecules are liberated and it is impossible to convert this acetic acid into an anhydride. It has various drawbacks.

Here, as a way to solve these problems,
Recently, a method has been proposed for producing cyclohexyl acetate, which is the acetate ester of cyclohexanol, by an addition reaction between cyclohexene and acetic acid. For example, in JP-A-1-254634, cyclohexyl acetate is produced by the reaction of cyclohexene and acetic acid using a strongly acidic cation exchange resin as a catalyst. However, in the patent application, in order to obtain cyclohexyl acetate in high yield, it is necessary to conduct the reaction at 130'C for 5 hours, which is an extremely high temperature and reaction time for a cation exchange resin catalyst. long. In addition, these strongly acidic cation exchange resins have the following characteristics: - The heat resistance temperature for boat fishing is around 100°C, and even those with high heat resistance do not substantially exceed 160°C.

In addition, these exchange resins also have drawbacks such as low mechanical strength and susceptibility to destruction, and therefore pose an extremely high risk to the stability of the catalyst.

Problems to be Solved by the Invention The purpose of the present invention is to add acetic acid to cyclohexene using a super strong acid in which sulfuric acid is supported on zirconium oxide and sulfuric acid as a catalyst to obtain acetic acid, which is an acetate ester of cyclohexanol. The object of the present invention is to produce cyclohexyl with high selectivity and yield and to provide a catalyst that is stable even in the high temperature range of the reaction. In addition, since the acetate ester is easily hydrolyzed to produce cyclohexanol, another object of the present invention is to provide a highly economical method for producing cyclohexyl acetate, which is a precursor of cyclohexanol.

Means for Solving the Problems The present inventors investigated an efficient method for producing cyclohexyl acetate, which is a precursor of cyclohexanol, and noticed that the addition reaction of cyclohexene and acetic acid is an excellent production method. After intensive study to solve the conventional drawbacks such as low catalytic activity, durability problems including mechanical strength and heat resistance of the catalyst, and restrictions on the temperature range of catalyst use, we found that By carrying out this reaction using a mixture of super strong acid and sulfuric acid obtained by reacting zirconium oxide and sulfuric acid as a catalyst, surprisingly high yield and high selectivity can be achieved even at the extremely mild temperature of 70°C. Cyclohexyl acetate was obtained, and the present invention was completed by making it possible to carry out the process stably and effectively even under high temperature conditions.

The catalyst used in the present invention is essentially a mixture of a super strong acid obtained by the action of sulfuric acid on zirconium oxide and a mineral acid, and their synergistic action improves the catalytic action.

Furthermore, when the present invention is carried out using this catalyst, the reaction is substantially carried out as a solid-liquid heterogeneous reaction, and the essential catalyst can be easily recovered. Furthermore, since this catalyst system is extremely stable both thermally and mechanically, it is possible to carry out the method of the present invention with sufficient stability even at high temperatures.
The present invention has now been completed.

That is, the present invention is a method for producing cyclohexyl acetate by adding acetic acid to cyclohexene, which is characterized in that the reaction is carried out in the presence of sulfuric acid supported zirconium oxide and sulfuric acid.

The present invention will be explained in detail below.

Acetic acid and cyclohexene, which are raw materials in the production method of the present invention, do not need to be particularly purified, and acetic acid and cyclohexene with a reagent purity that can be used as is can be used as they are. Further, in the present invention, the amount of acetic acid used relative to the cyclohexene charged when carrying out the reaction is not particularly limited, but in order to carry out the reaction efficiently, the molar ratio of acetic acid to cyclohexene charged should be 1 or more. It is recommended to carry out the test with excess acetic acid. This means that this molar ratio is 1
If the reaction is below, the conversion rate of cyclohexene is substantially 1
This is because it is impossible to achieve 00%. Furthermore, use of acetic acid in too large a quantity will result in an excessive load on subsequent product separation, etc., and therefore, extremely large quantities should be avoided. Therefore, in order to carry out the present invention efficiently, the molar ratio of acetic acid to cyclohexene is preferably 1 or more and 30 or less, more preferably 2 or more and 15 or less.

In the present invention, the reaction temperature is not particularly limited, but it is recommended that the reaction temperature is preferably 0°C or higher and 500°C or lower, more preferably 30°C or higher and 300°C or lower. If carried out at too low a temperature, the reaction rate will decrease and it will be difficult to achieve the desired reaction conversion rate, and if carried out at too high a temperature, the thermal stability of the reaction reagent such as cyclohexene will decrease, making it uneconomical. things are predicted. In carrying out the present invention, if the reaction is carried out at a temperature above the boiling point of acetic acid or cyclohexene at atmospheric pressure, it is also theoretically possible to carry out the reaction as a liquid phase reaction under pressure. Furthermore, it is also possible to carry out the reaction using acetic acid and/or cyclohexene in a gaseous state. At this time, there is no problem in using the sulfuric acid as a catalyst component in the form of a gas. The present invention is a method for producing cyclohexyl acetate, which is an acetate ester of cyclohexanol, by an addition reaction of acetic acid and cyclohexene using a catalyst. The catalyst used for this is a mixture of zirconium hydroxide and dilute sulfuric acid reacted and calcined at 500°C or higher, ie, zirconium oxide supported on sulfuric acid and sulfuric acid.

This zirconium hydroxide (Zr (OH) 4) (!
: Products calcined by the action of N sulfuric acid exhibit the properties of a super strong acid, as described, for example, in Journal of Chemical Society Chemical Communication, 1980, page 851. In the present invention, by adding sulfuric acid to this super strong acid, a synergistic effect between them is observed, and it becomes an effective catalyst for the production of cyclohexyl acetate through the addition reaction of acetic acid to cyclohexene. Here, in the method of the present invention, the method for producing this super strong acid is not particularly limited, and it is possible to use those produced by various methods.

For example, as the acid described in the above journal, 1N sulfuric acid is added to commercially available zirconium hydroxide, and after filtration, 575%
zirconyl oxide (ZrOCl z) was hydrolyzed into zirconium hydroxide, which was then treated with sulfuric acid and fired in the same manner, and zirconyl nitrate (ZrO(N( h) Examples include those obtained by hydrolyzing 2) to produce zirconium hydroxide and then subjecting it to sulfuric acid and calcination treatment in the same manner.

Next, a method for converting cyclohexene to cyclohexyl acetate by addition reaction of cyclohexene and acetic acid will be described.

The conversion process basically proceeds as an addition reaction of acetic acid to cyclohexene. In the present invention, the reaction is preferably carried out as a solid (catalyst)-liquid heterogeneous phase reaction, but it is also a heterogeneous reaction in which the isomer-liquid (catalyst)-gas and/or g-acid, which is a part of the catalyst, is also used as a gas. It is also possible to do this as Furthermore, in order to effectively carry out the present invention, if necessary, an inert medium (gas and/or liquid) to the catalyst and reaction reagent may be used as a solvent or diluent. The present invention can be carried out under normal pressure, reduced pressure, or increased pressure. Particularly when carried out at high temperatures, it is preferable to carry out the reaction as a liquid phase reaction under pressure. In some cases, it is also possible to carry out the reaction system of the present invention by previously pressurizing a medium inert to the reaction reagents and catalysts, such as nitrogen and argon.

In carrying out the present invention, the amount of the catalyst to be added is not intentionally limited, but the amount of super strong acid obtained by treating zirconium oxide with sulfuric acid is 0.1 to 50% by weight, preferably 1% by weight, based on the cyclohexene used. It is recommended to use it at ~30% by weight. Regarding the amount of sulfuric acid added, it is similarly recommended to use it in an amount of 0.1 to 50% by weight, preferably 1 to 30% by weight based on cyclohexene. If the amount is less than this, the progress of the reaction will be slow, and if the amount is more than this, the reaction will proceed sufficiently, but 1. This is because it is difficult to say that this is a desirable situation from an economic point of view and because it is predicted that the amount of solids in the reaction system will increase, the viscosity of the reaction liquid will increase, etc.

On the contrary, in view of the high activity of the catalyst, a larger amount is unnecessary. However, it is of course possible to implement the present invention outside this range, and the present invention is not limited to this range.

Next, specific embodiments for carrying out the present invention will be described. As mentioned above, the reaction in the present invention is preferably performed using O
The reaction may be carried out at a temperature of ``C0 or higher, preferably 30°C or higher, but it can be carried out by either a flow reaction method or a batch reaction method.

The method of carrying out the present invention is not particularly limited, but the following method may be mentioned as a method that is easy to carry out. Of course, the present invention is not limited to these methods.

(1) Place a predetermined amount of catalyst, acetic acid, and cyclohexene in a glass flask equipped with a stirring device, along with a diluent such as a solvent if necessary, and after installing a reflux device if necessary, perform a heating stirring reaction. Method.

(2) A method in which a predetermined amount of catalyst, acetic acid, and cyclohexene are placed in an autoclave together with a diluent such as a solvent and a pressurizing medium such as nitrogen or argon if necessary, and then the reaction is carried out with stirring and heating.

(3) A method in which a reaction is carried out by continuously introducing a predetermined amount of catalyst, cyclohexene, and acetic acid into a reaction group previously maintained at a predetermined temperature and pressure, together with a diluent such as a solvent if necessary.

(4) Pour a specified amount of super strong acid obtained by treating zirconium oxide with sulfuric acid into a reactor maintained at a specified temperature and pressure.
A method in which the reaction is carried out by continuously introducing acid, cyclohexene, and acetic acid together with a diluent such as a solvent if necessary.

Example EXAMPLES The present invention will be specifically explained below using examples.

(1) Production of zirconium hydroxide Dissolve 100 g of zirconyl chloride (ZrOClz, 8ToO) in 1 lindre of pure water, and gradually add 28% ammonia water dropwise to it while stirring to obtain a white color at pH 9, qL. A precipitate formed. After filtering and washing this, it was heated to 48°C at 100°C.
After drying for hours, 47 g of zirconium hydroxide was obtained.

(2) Production of zirconium oxide-based sulfuric acid-treated superacid (1)
Add 150 g of 1N sulfuric acid to 10 g of the zirconium hydroxide obtained in
Add m1 and stir at room temperature for 1 hour, then filter and wash.
After heating at 200°C in air for 1 hour, it was fired at 650°C in the presence of air for 3 hours. This was used as a super strong acid catalyst in the following examples.

Comparative Example 1 70ml equipped with magnetic stirrer and reflux condenser
In a Mitsuro flask, 2.0 g of zirconium oxide-sulfuric acid super strong acid obtained by the above preparation method, 20.5 g of commercially available 95% acetic acid (manufactured by Kokusan Kagaku Co., Ltd., special grade), and commercially available 9
Add 4.5 g of 8% cyclohexene (manufactured by Tokyo Kasei Co., Ltd., special), place in a preheated oil bath, and heat to 70"C.
After stirring the reaction for 11.5 hours, stirring was stopped and the flask was taken out from the oil bath.

After cooling to room temperature, the reaction solution was analyzed by gas chromatography. As shown in the table, almost no formation of cyclohexanol acetate was observed.

Comparative Example 2 Concentrated sulfuric acid was used instead of zirconium oxide-sulfuric acid super strong acid.
An addition reaction between cyclohexene and acetic acid was carried out under exactly the same reaction conditions as in Comparative Example 1, except that 56 g was added. As shown in the table, cyclohexyl acetate was produced in low yield.

Example 1 Zirconium oxide-sulfuric acid super strong acid produced by the above preparation method as a catalyst 2. As shown in Table 0, the addition reaction of cyclohexene and acetic acid was carried out under the same reaction conditions as in Comparative Example 1, except that Og and concentrated sulfuric acid were added as 0.56 g.
A synergistic effect between sulfuric acid and super strong acid was clearly evident, and an increase in the amount of cyclohexyl acetate produced was observed.

Example 2 The reaction was carried out under exactly the same reaction conditions as in Example 1 except that the reaction time was 3 hours. As shown in Table 0, acetic acid ester of cyclohexanol was obtained in a high yield.

Example 3 A reaction was carried out under exactly the same reaction conditions as in Example 1, except that the reaction time was 5 hours. As shown in the table, an increase in the amount of cyclohexyl acetate produced was observed as the reaction time increased.

Example 4 A reaction was carried out under exactly the same reaction conditions as in Example 1, except that the amounts of sulfuric acid and zirconium oxide-sulfuric acid super strong acid were twice those of Example 1.The amount of catalyst was changed as shown in Table 1. By increasing the amount, an increase in the amount of cyclohexyl acetate produced was observed.

Example 5 After putting 8.0 g of zirconia oxide-sulfuric acid super strong acid, 2.2 g of sulfuric acid, 61.5 g of acetic acid and 13.5 g of cyclohexene as catalysts into a 200n+ 1 autoclave, 5 kg/cI11! After injecting nitrogen to the gauge pressure, the reaction was carried out at 120° C. for 1.0 hours. As shown in Table 0, acetic acid ester of cyclohexanol was produced in high yield.

Example 6 The addition reaction of cyclohexene and acetic acid was carried out under the same reaction conditions as in Example 5 except that the reaction temperature was 200°C. As shown in Table 0, cyclohexyl acetate was obtained in a very high yield. Ta.

Cy-Hex in Table 1 is cyclohexene, Cy-Hex-
Oac represents cyclohexyl acetate.

Effects of the Invention According to the present invention, it is possible to efficiently carry out the addition reaction between acetic acid and cyclohexene using a catalyst, and to obtain cyclohexyl acetate, which is the acetate ester of cyclohexanol, in high yield and high selectivity.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] (1) A method for producing cyclohexyl acetate by adding acetic acid to cyclohexene, which is characterized in that the reaction is carried out in the presence of sulfuric acid-supported zirconium oxide and sulfuric acid. (2) The method according to claim 1, wherein the zirconium oxide supported on sulfuric acid is obtained by reacting zirconium hydroxide with sulfuric acid and then firing the product. (3) The method according to claim 1, wherein the sulfuric acid is 95% sulfuric acid.