KR20070063429A - Process for preparing ethylcyclohexane by selectively hydrogenating 4-vinylcyclohexene - Google Patents

Abstract

Provided is a method for preparing ethylcyclohexane by selectively hydrogenating 4-vinylcyclohexene, whereby an easily reproducible and inexpensive catalyst is used, a spatial and temporal yield and selectivity are high, and the reaction condition is mild. The method for preparing ethylcyclohexane by selectively hydrogenating 4-vinylcyclohexene consists of using a metallic ruthenium as a catalyst, wherein solvent is not used. The hydrogenation is carried out at 0-200 deg.C under a hydrogen pressure of 1-300bar using 0.001-10mol%, based on 4-vinylcyclohexene to be used, of a metallic ruthenium. The catalyst is a metallic ruthenium on a supporter selected from activated carbon, alumina, silica, titania, carbon black, and graphite.

Description

Process for preparing ethylcyclohexane by selective hydrogenation of 4-vinylcyclohexene {Process for preparing ethylcyclohexane by selectively hydrogenating 4-vinylcyclohexene}

The present invention relates to a process for selectively preparing ethylcyclohexane by hydrogenating 4-vinylcyclohexene.

Ethylcyclohexane is prepared by hydrogenating 4-vinylcyclohexene using a catalyst.

Catalysts are commonly used for such reactions, which are complicated to manufacture because they are generally prepared from metal salts and ligands, and are subsequently further modified if necessary. See Tetrahedron Lett. 1987, 28, 2507; Chemistry Letters 1985, 6, 793. See Dupont et al., J. Am. Chem. Soc. 2002, 124, 4228-4229, describes catalysts containing iridium nanoparticles in ionic liquids for the hydrogenation, which catalysts are 1-n-butyl-3-methylimidazolium hexafluorophosphate. It is prepared by hydrogenation of [IrCl (1,5-cyclooctadiene)] ₂ in water.

Disadvantages of this process are that the expensive solvents immiscible with vinylcyclohexane must be used in part for the regeneration of the catalyst, or the immiscible solvents are used in very large amounts, resulting in reduced space-time yields.

In addition, ethylcyclohexane is used for the selective hydrogenation of 4-vinylcyclohexene endocyclic (see EP 0 599 728) or exocyclic (US Pat. No. 4,716,256). Obtained as an unwanted byproduct.

However, EP 0 599 728 uses a catalyst containing at least one Group VIII transition metal and Group IV metal. EP 0 599 728 also uses an organic solvent, such as n-heptane, in the hydrogenation.

The catalyst used in US Pat. No. 4,716,256 is, for example, elemental nickel on an inorganic support material in the presence of a nitrogen compound, for the hydrogenation of 4-vinylcyclohexene to 4-ethylcyclohexane. In this hydrogenation, an organic solvent such as cyclohexane is used. Similar processes using Raney nickel as solvent and catalyst are described in US Pat. No. 2,576,743.

It is also known that 4-vinylcyclohexene is in contact with various noble metals, especially at elevated temperatures, for disproportionation as shown in the following scheme [Compt. Rend. Acad. Sci. URSS, 1940, 26, 73].

The aromatic ring hydrogenation of the resulting ethylbenzene can also produce the desired ethylcyclohexane, but more intense conditions are imposed.

Preferably, ethylcyclohexane is in liquid form over a wide temperature range and is used as a special solvent with special solvent properties.

It is therefore an object of the present invention to provide a process for the preparation of ethylcyclohexane, characterized by the use of commercially available catalysts which increase in space-time yield, have high selectivity and are not expensive. In addition, the catalyst used must be readily regenerated and used repeatedly without complex aftertreatment in the process. In particular, the present invention should be characterized by mild reaction conditions.

Surprisingly, in catalysts based on metallic ruthenium, it has been found that under mild reaction conditions, 4-vinylcyclohexene can be selectively hydrogenated to ethylcyclohexane as a liquid (ie, without the use of a solvent).

Since the process according to the invention has a high selectivity of generally 99.9%, ethylcyclohexane is prepared without the formation of ethylbenzene by-products or no ethylbenzene is formed as an intermediate.

Since prior art in the art generally uses solvents, the space-time yield in the process according to the invention without solvents is increased compared to the prior art.

The catalysts based on metallic ruthenium and used in the process according to the invention are characterized in that they can be used in a further process according to the invention without post-treatment, in which the selectivity and reaction conversion are lowered.

In addition, the process according to the invention is characterized in that it can be carried out at mild temperatures and hydrogen pressure.

The present invention provides a process for producing ethylcyclohexane by hydrogenation of 4-vinylcyclohexene, characterized by the use of metallic ruthenium as a catalyst.

The process according to the invention for producing ethylcyclohexane by hydrogenation of 4-vinylcyclohexene is characterized by the use of metallic ruthenium as catalyst.

The catalyst used for hydrogenation in the process according to the invention is preferably metallic ruthenium (hereinafter referred to as 'ruthenium catalyst'). In the process according to the invention, preference is given to using a ruthenium catalyst wherein the metallic ruthenium is provided on a support material selected from activated carbon, alumina, silica, titania, carbon black and graphite. However, it is also possible to use metallic ruthenium without a support material as catalyst in the process according to the invention. Ruthenium catalysts with a support material are characterized by an increased activation surface area compared to ruthenium catalysts without a support material. In the hydrogenation of the process according to the invention, the concentration of metallic ruthenium is preferably from 0.001 to 10 mol%, more preferably from 0.01 to 5 mol%, very preferably from 0.02 to based on the 4-vinylcyclohexene used. 0.1 mol%. The ruthenium catalyst used in the process according to the invention preferably has a ruthenium content of 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. The ruthenium catalyst has ruthenium, preferably 50 to 100% by weight, more preferably 90 to 100% by weight, very preferably 98 to 100% by weight, based on the active metal of the ruthenium catalyst. In addition to metallic ruthenium as the activating metal, the ruthenium catalyst may contain further metals such as iron, vanadium, manganese, rhenium, chromium and / or cerium. These additional activated metals preferably have zero oxidation number.

In certain embodiments, the ruthenium catalyst may contain ruthenium as an oxide, for example RuO ₂ , which oxide is reduced to the activated state by the catalyst [Ru (O)] under the conditions of the process according to the invention.

Preferably, the ruthenium catalyst with the support material is prepared by adding a ruthenium salt solution to the support material and subsequently treating the precursor of the ruthenium catalyst with heat or hydrogen. However, ruthenium catalysts based on support materials may be prepared by any of the prior art.

In the process according to the invention, 4-vinylcyclohexene is first charged to the hydrogenation equipment, preferably together with the ruthenium catalyst. Solvents used in the process according to the invention may be alkanes, in particular n-hexane or heptane, cycloalkanes, in particular cyclohexane, and alcohols. However, it is preferred that no solvent be used in the process according to the invention.

In the process according to the invention, the hydrogenation is carried out with a suitable hydrogenation equipment, for example a lift-stirrer autoclave, a rotary-stirrer autoclave, a loop reactor or a gas burette. It can be carried out in conventional laboratory glass equipment.

In the process according to the invention, if an inert gas atmosphere is present in the hydrogenation equipment, the hydrogenation equipment is charged with hydrogen and the hydrogen pressure is preferably 1 to 300 bar, more preferably 5 to 100 bar, very preferably 5 to 50 bar. to be.

In the process according to the invention, the hydrogenation is carried out at temperatures of 0 to 200 ° C, preferably 20 to 150 ° C, very preferably 50 to 100 ° C. In the process according to the invention, the hydrogenation is preferably carried out at a pressure of 1 to 300 bar, more preferably 5 to 100 bar and very preferably 5 to 50 bar.

Since hydrogenation is an exothermic reaction, temperature and hydrogen pressure may increase in stages and may increase continuously. It is desirable to increase the temperature and hydrogen pressure step by step. In particular, the hydrogenation is carried out at a hydrogen pressure of 10 to 25 bar and at a temperature of 60 to 80 ° C. in a first stage, at a further stage of hydrogen pressure of 10 to 25 bar and at a temperature of 70 to 85 ° C., and at a final stage of hydrogen pressure of 30 to 50 bar. And at a temperature of 85 to 110 ° C.

The process according to the invention can be carried out batchwise or continuously.

In a batchwise process, the reaction time is preferably 10 minutes to 8 hours, more preferably 20 minutes to 5 hours, very preferably 30 minutes to 3 hours. During the hydrogenation and prior to the hydrogenation, the ruthenium catalyst can be suspended in 4-vinylcyclohexene using suitable stirring techniques, which is particularly advantageous for the batch process of the process according to the invention.

In a particular embodiment of the process according to the invention, the hydrogenation is carried out continuously, in which case the ruthenium catalyst is in the form of a fixed catalyst bed. In the continuous process of the process according to the invention, the residence time of the 4-vinylcyclohexene is preferably 3 minutes to 20 hours, more preferably 15 minutes to 3 hours, or Liquid Hourly Space Velocity (LHSV). Speed) is preferably 0.05 to 20 / h.

After cooling the reaction mixture and reducing the hydrogenation equipment to atmospheric pressure, the catalyst is removed from the ethylcyclohexane by filtration and sedimented or further separated by methods known to those skilled in the art. The catalyst can be used in the process according to the invention without further workup for further hydrogenation in the process according to the invention.

The following examples will illustrate in detail the method according to the invention without limiting the invention to this aspect.

Example  1 (of the present invention Example ):

50 g (0.46 mol) of 4-vinylcyclohexene and metallic ruthenium on carbon [ H 105 R / AW 5% Ru from Degussa: Ruthenium 5% by weight, Support material: activated carbon, water content of 55.8% by weight 1.0 g of a catalyst, 0.22 mmol of ruthenium] is placed in an autoclave. The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 15 bar of hydrogen within 1 hour and heated to 70 ° C. Subsequently, the pressure is raised to 25 bar and the temperature is raised to 80 ° C. within 1 hour. The reaction mixture is stirred at 40 bar, 90 ° C. for an additional 1 hour.

After cooling to room temperature, the mixture is reduced to atmospheric pressure, filtered to remove the catalyst, and ethylcyclohexane is obtained in quantitative yield exceeding 99.5% of GC area. Ethylbenzene cannot be detected as a by-product by gas chromatography. The yield based on 4-vinylcyclohexene used is 99.93% and the selectivity is 99.94%.

Example  2 (of the present invention Example ):

1000 g (9.24 mol) of 4-vinylcyclohexene and 10 g of metallic ruthenium on alumina ( H 214 B / D 5% Ru made by Degussa: 5 wt% ruthenium, support material: alumina, 4.95 mmol) of ruthenium are placed in an autoclave. . The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 25 bar of hydrogen within 1 to 20 minutes and carefully heated to 65 ° C., resulting in a rapid exothermic reaction. The temperature is maintained at about 75 ° C., for which it is necessary to cool the autoclave. After about 1.5 hours the exothermic reaction has eased, then the pressure is raised to 40 bar and the mixture is stirred at 100 ° C. for about 1 hour.

After cooling to room temperature, the mixture is reduced to atmospheric pressure, filtered to remove the catalyst, and ethylcyclohexane is obtained in quantitative yield exceeding 99.5% of GC area. Ethylbenzene cannot be detected as a by-product by gas chromatography. The conversion based on 4-vinylcyclohexene used is 99.98% and the selectivity is 99.99%.

The removed catalyst can be used for further hydrogenation without loss of selectivity and activity, the results depending on the number of regenerations of the catalyst are listed in Table 1.

Number of regenerations of catalyst Conversion rate [%] Selectivity [%] 0 99.98 99.99 One 99.98 99.99 2 99.96 99.99 3 99.98 99.99 4 99.98 99.99

Example  3 (of the present invention Example ):

Autoclave 1000g (9.24mol) of 4-vinylcyclohexene and 10g of metallic ruthenium on silicon dioxide ( H 3317 B / D 5% Ru made by Degussa, 5% by weight ruthenium, support material: silicon dioxide, 4.95mmol of ruthenium) Put it inside. The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 10 bar of hydrogen and carefully heated to 70 ° C., resulting in a rapid exothermic reaction. The temperature is maintained at about 75 ° C., for which it is necessary to cool the autoclave. After about 2 hours the exothermic reaction is alleviated, then the pressure is raised to 40 bar and the mixture is stirred at 100 ° C. for about 1 hour.

After cooling to room temperature, the mixture is reduced to atmospheric pressure, filtered to remove the catalyst, and ethylcyclohexane is obtained in quantitative yield exceeding 99.5% of GC area. Ethylbenzene cannot be detected as a by-product by gas chromatography. The conversion based on 4-vinylcyclohexene used is 99.97% and the selectivity is 99.99%.

The removed catalyst can be used for further hydrogenation without loss of selectivity and activity, the results depending on the number of regenerations of the catalyst are shown in Table 2.

Number of regenerations of catalyst Conversion rate [%] Selectivity [%] 0 99.97 99.99 One 99.97 99.99

Example  4 (compare Example ):

50 g (0.46 mol) of 4-vinylcyclohexene and metallic palladium on carbon [ E 101 NN / W manufactured by Degussa 5% Pd : palladium 5% by weight, support material: activated carbon, water-containing catalyst of 54% by weight of water, palladium 0.22 mmol] 1.02 g are placed in an autoclave. The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 15 bar of hydrogen within 1 hour and heated to 55 ° C. Subsequently, the pressure is raised to 25 bar and the temperature is raised to 80 ° C. within 1 hour. The reaction mixture is stirred at 40 bar, 80 ° C. for an additional 1 hour.

After cooling to room temperature, the pressure is reduced to atmospheric pressure and the catalyst is removed by filtration to obtain a mixture containing the following components.

Ethylcyclohexane GC Area 88.6%

Ethylbenzene GC Area 9.4%

1-ethylcyclohexene GC area 1.2%

Saturated C ₈ Alkanes and Cycloalkanes GC Area 0.8%

Example  5 (Compare Example ):

50 g (0.46 mol) of 4-vinylcyclohexene and 1.02 g of metallic palladium on alumina ( E 213 R / D 5% Pd from Degussa, 5% by weight of palladium, support material: alumina, 0.23 mmol) of palladium in an autoclave Put it in. The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 15 bar of hydrogen within 1 hour and heated to 45 ° C. Subsequently, the pressure is raised to 25 bar and the temperature is raised to 70 ° C. within 1 hour. The reaction mixture is stirred at 40 bar, 80 ° C. for an additional 1 hour.

After cooling to room temperature, the pressure is reduced to atmospheric pressure and the catalyst is removed by filtration to obtain a mixture containing the following components.

Ethylcyclohexane GC Area 93.7%

Ethylbenzene GC Area 5.2%

1-ethylcyclohexene GC area 0.3%

Saturated C ₈ Alkanes and Cycloalkanes GC Area 0.8%

Example  6 (Compare Example ):

50 g (0.46 mol) of 4-vinylcyclohexene and 0.4 g of Raney Nickel (inclined, water-containing, used catalyst is B 111 W manufactured by Degussa) are placed in an autoclave. The autoclave is purged three times with nitrogen and the reaction mixture is contacted with 15 bar of hydrogen within 1 hour and heated to 45 ° C. Subsequently, the pressure is raised to 25 bar and the temperature is raised to 70 ° C. within 1 hour. The reaction mixture is stirred at 40 bar, 80 ° C. for an additional 1 hour.

After cooling to room temperature, the pressure is reduced to atmospheric pressure and the catalyst is removed by filtration to obtain a mixture containing the following components.

Ethylcyclohexane GC Area 30.0%

Ethylbenzene GC Area 1.4%

1-ethylcyclohexene GC area 3.0%

4-ethylcyclohexene GC area 64.7%

Saturated C ₈ Alkanes and Cycloalkanes GC Area 0.8%

Example  7 (4- by ruthenium Vinylcyclohexene Isomerization )(compare Example ):

In an autoclave, 50 g (0.46 mol) of 4-vinylcyclohexene and metallic ruthenium on alumina [ H 214 B / D 5% Ru : Ruthenium 5 wt% manufactured by Degussa, Support material: Alumina, 0.25mmol of ruthenium] 0.50 The mixture of g is stirred at 102 ° C. for 3 hours under nitrogen.

The 4-vinylcyclohexene used is regenerated without change.

Example  8 (4- by palladium Vinylcyclohexene Isomerization )(compare Example ):

In an autoclave, 50 g (0.46 mol) of 4-vinylcyclohexene and metallic palladium on alumina [ E 213 R / D 5% Pd from Degussa 5% by weight palladium, support material: alumina, palladium 0.23 mmol] 0.50 The mixture of g is stirred at 103 ° C. for 3 hours under nitrogen.

A mixture containing the following ingredients is obtained.

Ethylcyclohexane GC Area 16.5%

4-vinylcyclohexene GC area 3.2%

Ethylbenzene GC Area 19.2%

Isomers C ₈ H ₁₂ and C ₈ H ₁₄ Derivatives GC Area 59.0%

The present invention relates to a method for producing ethylcyclohexane by hydrogenation of 4-vinylcyclohexene, characterized by using metallic ruthenium as a catalyst, and by the present invention, a commercially available catalyst which is easily regenerated and inexpensive is used. Provided is a process for preparing ethylcyclohexane, which has high space-time yield and selectivity and mild reaction conditions.

Claims (7)

A process for producing ethylcyclohexane by hydrogenation of 4-vinylcyclohexene, characterized by using metallic ruthenium as a catalyst. The method of claim 1 wherein no solvent is used. The process according to claim 1 or 2, wherein the hydrogenation is carried out at a temperature of from 0 to 200 ° C. The process according to any one of claims 1 to 3, wherein the hydrogenation is carried out at hydrogen pressure of 1 to 300 bar. 5. The process according to claim 1, wherein the hydrogenation is carried out in metallic ruthenium at a concentration of 0.001 to 10 mol%, based on the 4-vinylcyclohexene used. 6. The process according to claim 1, wherein the catalyst used is a metallic ruthenium added to a support material selected from activated carbon, alumina, silica, titania, carbon black and graphite. 6. The process according to claim 1, wherein the catalyst used is metallic ruthenium free of support material. 7.