JPS6034526B2 - Method for producing cis-4-tert-butylcyclohexanol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cis-enriched 4-rt-butylcyclohexanol, more specifically a method for producing cis-rich 4-rt-butylcyclohexanol, and more specifically, a method for producing cis-rich 4-rt-butylcyclohexanol.
The present invention relates to an economical method for producing rt-butylcyclohexanol.

4-te-91-butylcyclohexanol is used as an ester of acetic acid, propionic acid, butyric acid, cyanobic acid, etc. in perfumery products, but its cis isomer has a strong y-methylionone-like aroma. There is a strong demand for industrial production of 4-rt-butylcyclohexanol with a high content of cis isomers.

As a method for obtaining 4-ten-butylcyclohexanol rich in cis-isomers, NIPPON TOKYO has developed a method in which 4-tert-butylphenol is catalytically reduced in acetic acid in the presence of a rhodium-carbon catalyst to obtain 70-80% of the cis-isomer. Kosho 42-139
It is disclosed in No. 38.

However, a method using a relatively inexpensive ruthenium catalyst involves the catalytic reduction of 4- to rt-butylphenol in the presence of a ruthenium carbon catalyst in ethanol to convert up to 55% of 4- to rt-butylcyclohexanol into cis-4-. The only thing known is what can be obtained. Rhodium catalysts are expensive;
Moreover, in both of the above two examples, it is necessary to use a large amount of catalyst, and furthermore, the durability of the catalyst is poor, so that it cannot be used as a practical catalyst, and it is difficult to implement it on an industrial scale. However, since ruthenium metal is relatively inexpensive, if a method for producing a catalyst that has low-temperature activity, high selectivity, and durability can be found, it would be possible to find a method for producing a catalyst that is rich in cis-type. Industrial production of rt-butylcyclohexanol becomes possible.

In view of these circumstances, the present inventor aimed to selectively obtain cis-41-ten-butylcyclohexanol using a ruthenium catalyst, and as a result of research focusing on catalyst preparation methods, the present invention was developed. It was completed.

The gist of the present invention is to adsorb ruthenium salt onto alumina in a strong alkaline aqueous solution, and then adsorb sodium borohydride (
Using a ruthenium catalyst obtained by reducing with SBH (hereinafter abbreviated as SBH) and further treatment with hydrochloric acid, 4-rt-butylphenol was reduced under hydrogen pressure to produce 4-te containing a large amount of cis isomer. 9-butylcyclohexyl is obtained.

The catalyst used in the method of the present invention is obtained by further subjecting the ruthenium catalyst obtained according to the invention filed at the same time as the present application (Samurai Iso Sho 53-141 P, JP 54-194491) to hydrochloric acid treatment as a final finish. It will be done.

The effect of this hydrochloric acid treatment is to make the catalyst surface acidic and at the same time dissolve a part of the carrier surface to form catalyst active sites. Therefore, the adsorption posture of 4-rt-butylphenol on the catalyst surface is controlled, and in particular, the approach of the hydroxyl group of the substrate to the catalyst is skillfully prevented. As a result, the direction of the catalyst active site and the substrate is always constant, and hydrogen activated on the catalyst is always introduced only from a constant direction. Therefore, it is thought that the proportion of cis isomers produced increases during the course of the experiment. As an embodiment of the present invention, the method for preparing the catalyst used is as follows: An alumina carrier is suspended in an aqueous sodium hydroxide solution, the temperature is raised to 40-600°C, and an aqueous ruthenium chloride solution is poured into the suspension.

After about 10 minutes, the glaze becomes transparent, and the ruthenium chloride is completely adsorbed to the alumina as ruthenium hydroxide, giving it a black color. Next, add an aqueous solution of SBH to a liquid temperature of 40 to 80 oo
and drip in about 1 hour. At this time, hydrogen gas is violently generated and the ruthenium hydroxide is reduced to a completely metallic state. After completion of reduction, cool to room temperature. This product is washed as it is, or after washing with water until the pH of the catalyst washing solution becomes 8 to 9, hydrochloric acid is added to bring the pH of the solution to 2 or less, and the solution is left to stand for a while. Then, after washing thoroughly with water, 110~120oo
to obtain a dried ruthenium-supported alumina catalyst. 4-t
In the hydrogenation process of en-butylphenol, this catalyst and 400ml rt-butylphenol were charged into an autoclave together with a solvent, and the initial hydrogen pressure was 80 kg/c and the reaction temperature was 55.
Hydrogenation is carried out at ~15,000 ℃.

After hydrogenation, the catalyst was separated from the furnace and subjected to gas chromatography.
Confirm the conversion rate and selectivity of the cis isomer. The selectivity to the cis isomer is 65-70%. The carrier of the catalyst used in the present invention is alumina, and its shape is preferably a y-type or a polymer type.

Other forms of alumina, such as 0-form and Q-form, can also be used, but the selectivity to the cis-form is somewhat reduced. The alkali used in preparing the catalyst of the present invention is a strong base selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide, and the amount used is 10% based on the alumina.
It is preferable to use a weight percent of 1 to 4. If the ruthenium salt is less than 1 weight percent, the ruthenium salt will not be completely adsorbed on the alumina and will become colloidal when the catalyst is washed with water, resulting in loss of metal and deterioration of catalyst performance. Although there is no problem in using more than 4% by weight, it is uneconomical and increases the number of washings, which is not preferable.

Sodium bicarbonate or sodium carbonate, which has a weak basicity, may be used, but complete adsorption of the ruthenium salt onto alumina cannot be expected. The ruthenium salt used in the preparation of the catalyst of the present invention may be any salt as long as it can be adsorbed as ruthenium hydroxide on the carrier in an aqueous alkali metal hydroxide solution. Ruthenium chloride is particularly suitable.

When preparing the catalyst in the present invention, the temperature at which the ruthenium salt is adsorbed onto the carrier must be 40 °C or higher, preferably in the range of 40 to 6,000 °C. Adsorption temperature is 4000
Below, the adsorption rate of ruthenium salt becomes extremely slow;
During this time, ruthenium hydroxide that is not adsorbed is generated and precipitated, making it difficult to obtain a catalyst with consistent performance. At high temperatures of 60 qo or more, alumina is immersed in the alkaline solution and no longer plays the role of a carrier.

Furthermore, when the adsorption temperature is 6,000 or higher, the rate of adsorption of ruthenium salts onto alumina is high, and some hydroxides may settle without being adsorbed to the carrier, resulting in a constant quality of ruthenium salts as at low temperatures. Catalyst is difficult to obtain. The reducing agent used in the preparation of the catalyst of the present invention is SBH, and the amount used is 1.0 to 2.0% by weight relative to ruthenium metal. It is a loud sound.

1. There is a danger that unreduced ruthenium hydroxide will remain if the amount is less than 2.0 times, and although there is no problem in using more than 2.0 times, it is uneconomical and at the same time increases the number of washings.

The ruthenium catalyst obtained by the method of the present invention has 0.01% and 0.01%. It contains Z% by weight of boron, which is one of the factors that improves catalyst performance through interaction with ruthenium metal.

Reduction with SBH is carried out at 40-7020.
At this time, the reduction rate is slow at 40q° or less, and the reduction rate is high at 70oC or higher, resulting in intense hydrogen gas generation, which may escape from the system without being fully utilized. When preparing the catalyst of the present invention, it is treated with hydrochloric acid as a final finishing touch, but the concentration is not limited as long as hydrochloric acid is used, and the purpose can be achieved as long as the pH of the catalyst itself is between 1 and 5.7. .

The pH of the catalyst here refers to the pH of the liquid obtained when one ounce of the catalyst is immersed in 50 liters of water underground. Although this ruthenium catalyst without hydrochloric acid treatment has hydrogenation ability, the selectivity to the cis isomer is 45 to 55%. The ruthenium content in the catalyst of the present invention is preferably 0.1 to 5% by weight, but is not particularly limited. The reaction pressure during hydrogenation of 4-tert-butylphenol is not particularly limited, and hydrogenation can be carried out at normal pressure, but the optimum conditions are 40 to 80 k9/m.

Although hydrogenation can be carried out without a solvent, a solvent such as methanol, ethanol, isopro/gnol, cyclohexane, dioxane, or tetrahydrofuran is used for operational reasons. The hydrogenation reaction temperature is preferably 55 to 1550 qo. By hydrogenating 4-ten-butylphenol according to the method of the present invention, rt-butylcyclohexanol can be obtained in the cis-4-1 with a selectivity of 65 to 70%. It can also be applied to the nuclear hydrogenation of phenolic compounds that can have different structures, such as 21-rt-butylphenol and 1,4-diethanolbenzene.

Further, the present invention will be explained in detail with reference to Examples.

Example: 1 particle size: 60 mm Y-alumina: 980 mm, water: 50 mm
00, and then add 20% sodium hydroxide aqueous solution 1
500 ml of secretion was added and incubated at room temperature for 30 minutes.

The liquid temperature was raised to 4,000 °C, and 3,000 °C of a ruthenium chloride aqueous solution containing 20 °C as ruthenium metal was introduced. 40 to 60 qo to complete the adsorption for 1 hour, and then add a dilute alkali aqueous solution containing 40 qo of SBH 10
00M was continuously added over a period of 1 hour at a liquid temperature of 55 to 70 oo to complete the reduction.

Furthermore, 100% of 36% hydrochloric acid solution was added, and after stirring at room temperature for 30 minutes, 5000
Washed with water. After that, it was dried in a hot air dryer at 1100C for 10 hours, and the 2% supported ruthenium-y
- An alumina catalyst was obtained. Analysis of this catalyst revealed that it contained 1.9% by weight of ruthenium and 0.0% by weight of boron. Further, when one ounce of this catalyst was added to 50 liters of water and allowed to stand for 1 minute, the pH of the solution was 3.2. Take 1 hour of this catalyst, 4 hours of butylphenol, 15 hours of butylphenol and 30 minutes of
Put it in an autoclave with isopropanol,
Hydrogenation was carried out at a hydrogen pressure of 80 k9/kg and a reaction temperature of 60 to 80 °C. After the hydrogenation was completed, the catalyst was suctioned off and the isopropanol was removed under reduced pressure to obtain 15.0 g of white 4-ten-butylcyclohexanol. As a result of gas chromatography analysis, the isomer ratio in 4-tert-butylcyclohexanol was 68% cis isomer and 32% trans isomer. Next, the recovered catalyst was directly used for the next hydrogenation and used repeatedly under the same conditions. As a result of repeating the process a total of seven times, the results shown in Table 1 were obtained. Table 1 Comparative Example 1 4-te-butylphenol was hydrogenated in the same manner as in Example 1 using a commercially available 5% ruthenium-alumina catalyst.

Hydrogen absorption started at 118 qo. 118-140q
Hydrogenation was completed in 80 minutes at 0.

After the hydrogenation was completed, the ratio of the cis isomer to the trans isomer was measured by gas chromatography, and the ratio was 50.3% for the cis isomer and 49.7% for the trans isomer. Note that the pH of the commercially available catalyst used was 6.3. Comparative Example 2 4-ten-butylphenol was hydrogenated according to Example 1 using a commercially available 5% supported rhodium-y-alumina catalyst.

Hydrogen absorption started at 120:00. 120-13 is C
Hydrogenation was completed in 28 minutes.

As a result of gas chromatography analysis, the ratio of the cis isomer to the trans isomer was measured, and it was found that the cis isomer was 70.3% and the trans isomer was 29.3%. Comparative Example 3 A commercially available 5% supported ruthenium-carbon catalyst was used for 4 hours according to Example 1.
When 91-butylphenol was hydrogenated, hydrogen absorption started from 14 to 0.

Claims (1)

[Claims] 1. When producing cis-4-tert-butylcyclohexanol by catalytic reduction of 4-tert-butylphenol in the presence of a ruthenium catalyst, (1) alumina is used as a carrier; Step (2) of suspending ruthenium in an aqueous alkali metal hydroxide solution; Step (3) of adding a ruthenium salt aqueous solution to the suspension and adsorbing the ruthenium hydroxide on alumina as ruthenium hydroxide; (3) suspending the ruthenium hydroxide with sodium borohydride; Step (4) of reducing cis-4-te, which is characterized by hydrogenating 4-tert-butylphenol using a ruthenium catalyst obtained by a method comprising a step of further treating the obtained product with hydrochloric acid.
Method for producing rt-butylcyclohexanol. 2. The method according to claim 1, wherein the alumina used in preparing the catalyst is γ-alumina. 3. The method according to claim 1, wherein the alkali metal hydroxide used in preparing the catalyst is a hydroxide of at least one alkali metal selected from the group consisting of sodium, potassium, and lithium. 4. The method according to claim 1, wherein the ruthenium salt for preparing the catalyst is ruthenium chloride. 5 The boron content in the catalyst is 0.01 to 0.2
% by weight.