MXPA97000447A - Processes to prepare 4-ter-butilciclohexanol and 4-ter-butilciclohex acetate - Google Patents

Abstract

The 4-tert-butylcyclohexanol having a higher content of its cis isomer is described, which is prepared by the hydrogenation of 4-tert-butylphenol in a solvent in the presence of a rhodium catalyst and a compound selected from the group consisting of of hydrogen, perchloric acid and sulfuric acid (anhydrous). In addition, the obtained 4-tert-butylcyclohexanol is acetylated to give 4-tert-butylcyclohexy acetate

Description

PROCESSES FOR PREPARING 4-TER-BUTILYCLOHEXANOL AND 4-TER-BUTYLOCYLOXHEXYL ACETATE Background of the invention Field of the invention The present invention relates to a process for preparing 4-tert-butylcyclohexanol containing a greater amount of a cis isomer by hydrogenation of 4-tert-butylphenol. The present invention also relates to a process for preparing 4-tert-butylcyclohexyl acetate by acetylation of 4-tert-butylcyclohexanol obtained by the process described above.

Description of the Related Art 4-tert-butylcyclohexyl acetate is widely used as a perfume for cosmetics in which soaps are included and the fragrance of its cis isomer is more favorable than that of its trans isomer. To prepare 4-tert-butylcyclohexyl acetate having a high content of cis isomer, it is desired to provide a process for preparing 4-tert-butylcyclohexanol containing its cis isomer in a larger amount as a raw material of 4-teracetate. -butyl-cyclohexyl. In general, 4-tert-butylcyclohexanol is prepared by hydrogenation of 4-tert-butylphenol.

REF: 23877 Patent JP-B-42 13938 describes a process for preparing 4-tert-butylcyclohexanol which comprises catalytically reducing 4-tert-butylphenol in the presence of a rhodium base catalyst. MARUZEN OIL TECHNICAL REVIEW (MARUZEN SEKIYU GIHO) (1991) page 77 describes a process for preparing 4-tert-butylcyclohexanol which comprises hydrogenating 4-tert-butylphenol in the presence of various transition metals of groups 8 to 10 of the periodic table . JP-A-54122253 describes a process for preparing a cis-alkylcyclohexanol comprising hydrogenating an alkylphenol in the presence of a ruthenium-alumina catalyst. US Patent 2927127 describes a process for preparing 4-tert-butylcyclohexanol which has a high content of the cis isomer, which comprises hydrogenating 4-tert-butylphenol. JP-A-3-173842 discloses a process for preparing 4-tert-butylcyclohexanol which comprises hydrogenating 4-tert-butylphenol in the presence of a combined Rh catalyst supported on a carrier and a boron fluoride type acid such as HBF4 . However, the cis isomer content in 4-tert-butylcyclohexanol which is prepared by the processes described in JP-B-42-13938, MARUZEN OIL TECHNICAL REVIEW and JP-A-122253 is still insufficient. The process of US Patent 2927127 achieves a high content of cis isomer in ethanol in the presence of the rhodium catalyst, but the reaction must be carried out under a high hydrogen pressure. Thus, an improvement has been sought as a process for the preparation of 4-tert-butylcyclohexanol. In addition, since the process of JP-A-3-173842 uses boron fluoride acid, a workload is required to recover the fluorine and boron and the acids generated such as HF corrode the production equipment .

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for preparing 4-tert-butylcyclohexanol which can be carried out under a moderate condition and producing 4-tert-butylcyclohexanol having a high content of cis isomer. Another object of the present invention is to provide a process for preparing 4-tert-butylhexyl acetate having a high content of cis isomer. According to a first aspect, the present invention provides a process for preparing 4-tert-butylcyclohexanol, which comprises hydrogenating 4-tert-butylphenol in a solvent in the presence of a rhodium catalyst and a compound selected from the group consisting of of hydrogen and sulfuric acid (anhydrous). According to the second aspect, the present invention provides a process for preparing 4-tert-butylcyclohexyl acetate, which comprises acetylating the 4-tert-butylcyclohexanol which has been prepared by hydrogenation of 4-tert-butylphenol in a solvent in the presence of a rhodium catalyst and a compound selected from the group consisting of hydrogen chloride, perchloric acid and sulfuric acid (anhydrous).

DETAILED DESCRIPTION OF THE INVENTION The rhodium catalyst to be used in the hydrogenation reaction according to the present invention includes rhodium metal (zero valence) or a rhodium compound having a valence of up to 6, such as rhodium chloride, rhodium oxide and so on. The rhodium metal or rhodium compound is preferably used in the form of a supported type catalyst, that is, the metal rhodium or rhodium compound supported on a carrier such as activated carbon, SiO ?, AI2O3, etc. Among the supported type catalyst, metallic rhodium supported on the carrier is more preferable. In the case of the supported type catalyst, a supported amount of metallic rhodium is usually 1 and 10% by weight, preferably between 3 and 5% by weight, based on the weight of the carrier. After the reaction, the rhodium catalyst can be recovered from a reaction mixture by a conventional method such as filtration, decantation, centrifugation and recycling. The amount of the rhodium catalyst used in the reaction is between about 0.01 and 1% by weight (in terms of the metal rhodium) based on the weight of the starting material, 4-tert-butylphenol. In the case of the supported type catalyst, while the amount of the catalyst (including the carrier) depends on the supported amount of the rhodium metal or compound, it is between about 0.1 and 50% by weight (in a dry form) based on to the weight of 4-tert-butylphenol. As the amount of catalyst increases, the selectivity of the cis isomer increases. The amount of the catalyst is preferably between 0.5 and 10% by weight, in view of the cost and workability in the filtration step to recover the catalyst. Any solvent can be used as long as it has no adverse effect on the reaction. A solvent which is liquid at room temperature (25 ° C) is preferable due to easy handling. Examples of the solvent are alkanes having from 5 to 10 carbon atoms, ethers having from 4 to 10 carbon atoms, alcohols having from 1 to 6 carbon atoms and so on. Specific examples of the solvent are acyclic alkanes (for example pentane, hexane, heptane, etc.), cyclic alkanes (for example cyclohexane, etc.), acyclic ethers (for example diethyl ether, etc.), cyclic ethers ( for example tetrahydrofuran, dioxane, etc.) and alcohols (for example methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, 4-methyl-2-pentanol, cyclohexanol, etc.). Among them, cyclohexane and isopropanol are preferable. In particular, isopropanol is preferable. The amount of the solvent is usually between about 0.2 and up to 20 times, preferably 0.4 and 5 times the weight of 4-tert-butylphenol. In the process of the present invention, the reaction is carried out in the solvent in the presence of the rhodium catalyst and also hydrogen chloride, perchloric acid or sulfuric acid (anhydrous).

The hydrogen chloride can be supplied to the reaction system in any form, for example, by bubbling the hydrogen chloride gas through the reaction system or adding the hydrochloride acid to the reaction system. Alternatively, hydrochloric acid can be formed in the reaction system, for example, by charging water and AICI3 or TiCl4 to the reaction system. In addition, a catalyst which generates hydrogen chloride in the reaction system, such as rhodium chloride, can be used. Also, sulfuric acid (anhydrous) can be supplied in the reaction system in any form, for example, by bubbling SO3 gas through the reaction system or adding an aqueous solution of sulfuric acid to the reaction system. The perchloric acid is added to the reaction system in general in the form of an aqueous solution. The order of the addition of raw materials, the rhodium catalyst, the solvent and the hydrogen chloride, perchloric acid or sulfuric acid (anhydrous) is arbitrary. The amount of hydrogen chloride, perchloric acid or sulfuric acid (anhydrous) is usually between about 0.01 and 100 moles, preferably between about 0.05 and 10 moles, more preferably between 0.1 and 10 moles per one mole of the rhodium atom in the rhodium catalyst. The process of the present invention can be carried out in a stream of hydrogen gas or in a pressurized hydrogen atmosphere. The other reaction conditions may not be critical. In view of the reaction rate, the reaction is preferably carried out in the atmosphere of pressurized hydrogen. In this case, a pressure reactor is used. When the reaction is carried out under the atmosphere of pressurized hydrogen, the partial pressure of hydrogen is at least about 1.5 x 10 5 Pa. In view of the reaction rate, the selectivity of the cis isomer and the pressure resistance of the equipment, the partial pressure of the hydrogen is preferably between 3 x 105 and 2 x 106 Pa, more preferably between 5 x 105 and 1.5 x 106 Pa. The reaction temperature is at least about 20 ° C in view of the reaction rate and the selectivity of the cis isomer and preferably 100 ° C or lower in view of the selectivity of the cis isomer. More preferably, the reaction temperature is between 40 and 80 ° C in view of the speed of the reaction and the selectivity of the cis isomer. The process of the present invention can be carried out continuously or in batches. The completion of the reaction can be confirmed by a conventional method. For example, the reaction mixture is analyzed and the time when the conversion of 4-tert-butylphenol is 100% is used as the termination of the reaction, or the time when no further decrease in hydrogen pressure is observed is used as the termination of the reaction. In addition, the 4-tert-butylcyclohexanol obtained by the above reaction can be acetylated to obtain 4-tert-butylcyclohexyl acetate.

The acetylation can be carried out in a continuous manner from the previous hydrogenation of 4-tert-butylphenol. Alternatively, the 4-tert-butylcyclohexanol obtained by the above reaction can be once isolated from the reaction mixture and then acetylated in a separate step. For acetylation, any conventional acetylating agent, such as acetic anhydride, acetic acid, acetyl chloride and the like can be used. The amount of the acetylating agent is usually between 1 mol and 5 mol, preferably between 1 mol and 1.5 mol per one mol of 4-tert-butylcyclohexanol. The reaction temperature in acetylation is usually between room temperature (about 25 ° C) and 150 ° C, preferably between room temperature (about 25 ° C) and 130 ° C. The acetylation can be terminated when the conversion of 4-tert-butylcyclohexanol is found to be 100%, by means of the analysis of the reaction mixture. The presence of a solvent is not essential in the acetylation process, whereas a solvent which is less acetylated can be used. Solvents which are in the liquid state at room temperature are preferable in view of the easy handling. Examples of such solvents are acyclic alkanes (for example pentane, hexane, heptane, etc.), cyclic alkanes (for example cyclohexane, etc.), unsaturated hydrocarbons (for example toluene, etc.), acyclic ethers ( example diethyl ether, etc.), cyclic ethers (for example tetrahydrofuran, etc.) and the like. Among them, toluene and cyclohexane are preferable. In addition to the acetylating agent, a catalyst can be used in the acetylation reaction. The class of the catalyst depends on the acetylation agent to be used. For example, sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, zinc chloride, sodium acetate, pyridine and the like can be used when acetic anhydride is used as the acetylating agent. Alternatively, sulfuric acid or BF3 can be used, when the acetic acid is used as the acetylating agent. Among these catalysts, sulfuric acid is preferable in view of cost. The amount of the catalyst is usually between 0.01 and 5 mol%, preferably between 0.1 and 2 mol% of the amount of 4-tert-butylcyclohexanol.

When the amount of the catalyst is too small, the reaction rate is too slow, whereas when it is too high 4-tert-butylhexanol tends to dehydrate. When acetic acid is used as the acetylating agent, the acetylation is preferably carried out while the water produced as a by-product is removed in view of the speed of the reaction. The water can be removed by evaporating the water azeotropically with a solvent which can be azeotropically evaporated with water under reflux conditions or by adding a drying agent such as silica gel to the reaction system. When acetyl chloride is used as the acetylating agent, the acetylation is preferably carried out while the hydrogen chloride produced as a by-product is separated in view of safety. The hydrogen chloride can be separated with a base such as inorganic bases (for example potassium carbonate, 10% sodium hydroxide, etc.) or organic bases (for example pyridine, etc.), potassium carbonate. Among the acetylating agents, acetic anhydride is preferable in view of the conversion of the starting material into the acetylation reaction. It is difficult to separate 4-tert-butylcyclohexyl acetate from 4-tert-butyl-cyclohexanol by distillation, since they have very close boiling points. Accordingly, the conversion of 4-tert-butylhexanol is preferably equal to or close to 100%. For this purpose, for example, acetic acid or acetyl chloride is used as the acetylating agent and the acetylation reaction is carried out until the conversion reaches 90% or a higher percentage and then the acetylation is completed with acetic anhydride in the same molar quantity as the residual raw material, in such a way that the raw material is consumed completely.

EFFECTS OF THE INVENTION The process of the present invention can easily prepare 4-tert-butylcyclohexanol having the high content of the cis isomer useful as a raw material of a perfume from 4-tert-butylphenol. That is, 4-tert-butylcyclohexanol can be obtained at a yield of about 90% or higher and the content of the cis isomer in the product reaches about 80% or more.

The 4-tert-butylcyclohexyl acetate having the high content of the cis isomer can be obtained by acetylation of 4-tert-butylhexanol which has been prepared by the process of the present invention.

Examples The present invention will be illustrated by the following examples, which do not limit the present invention in any way.

Example 1 4-tert-butylphenol (90 g, 0.60 mole), 5% Rh / C (ie 5% by weight rhodium metal supported on an activated carbon carrier) (1.35 g based on the dried material), isopropanol (180 g) and 36% hydrochloric acid (0.18 g) are charged in an autoclave and then the interior of the autoclave is replaced with nitrogen gas by injecting the nitrogen gas at a pressure of up to 5 x 105 Pa and three is evacuated times. After replacing the inside of the autoclave with hydrogen by injecting hydrogen gas to a pressure of 5 x 105 Pa and evacuating it three times, the nitrogen gas is injected at 1.1 x 106 Pa and the internal temperature rises to 60 ° C, followed by stirring for 1.75 hours. After cooling the autoclave and replacing the interior with the nitrogen gas in the same manner as above, the reaction mixture is analyzed. The yield of 4-tert-butylcyclohexanol was 93.4% and the ratio of the cis isomer to the trans isomer was 89.9: 10.1 Examples 2-10 4-tert-Butylcyclohexanol is prepared in the same manner as in Example 1, except that the Reaction conditions are changed as shown in the table. In Example 10, 98% sulfuric acid was used. The results are shown in the table. In all examples 1-10, the conversion of 4-tert-butylphenol was 100%.

Comparative Examples 1-3 4-tert-Butylcyclohexanol is prepared in the same manner as in Example 1, except that no acid was used (comparative example 1), phosphoric acid (85%) (comparative example 2) or nitric acid was used (61%) (comparative example 3). The results are shown in the table.

Comparative Examples 4 and 5 4-tert-Butylcyclohexanol is prepared in the same manner as in Example 1, except that a Ru catalyst (5% Ru / C) is used (Comparative Examples 4 and 5) and no acid was used hydrochloric (comparative example 5). The results are shown in the table. In comparative example 4, the conversion of 4-tert-butylphenol was 42.2%, whereas in the other comparative examples, the conversion of 4-tert-butylphenol was 100%.

Table > Table (continued) NOTES: IPA: Isopropanol. CHX: Cyclohexane BCHL: 4-tert-butylcyclohexanol.

Example 11 (1) 4-tert-butylphenol (90 g, 0.60 mole), 5% Rh / C (0.9 g based on dry material), isopropanol (180 g) and a 60% aqueous solution of perchloric acid ( 0.10 g) are loaded in an autoclave and then the interior of the autoclave is replaced with nitrogen gas when the nitrogen gas is injected at a pressure of up to 5 x 105 Pa and evacuated three times. The hydrogen gas was injected at a pressure of up to 1.1 x 106 Pa and the internal temperature rises to 60 ° C, followed by stirring for 5 hours. After cooling the autoclave and replacing the interior with the nitrogen gas in the same manner as above, the reaction mixture is analyzed. The yield of 4-tert-butylcyclohexanol was 95.5% and the ratio of the cis isomer to the trans isomer was 82.1: 17.9 The reaction mixture is filtered to remove the catalyst and evaporated to the concentration to obtain 4-tert-butylcyclohexanol crude (91 g, 0.57 mol, a purity of 98.4%, the ratio of the cis isomer to the trans isomer was 82.1: 17.9). (2) Sulfuric acid (0.17 g) is added, 1.8 mmol) to the above concentrated mixture, while maintaining the mixture at 90 ° C and then adding acetic anhydride (76.06 g, 0.75 mol) dropwise to the mixture for 3 hours, followed by maintenance of that mixture. temperature for 1 hour. Analysis of the reaction mixture revealed that the yield of 4-tert-butylcyclohexyl acetate was 99% (based on 4-tert-butylcyclohexanol) and the ratio of the cis isomer to the trans isomer was 82.1: 17.9. 1 The reaction mixture is washed with 5% aqueous sodium bicarbonate (every 120 g) three times and with water subjected to ion exchange (120 g) once. An oil layer is rectified and 4-tert-butylcyclohexyl acetate is obtained which has high purity at a high yield.

Example 12 (1) 4-tert-butylphenol (180 g, 1.20 moles), 5% Rh / C (1.8 g based on the dry material), isopropanol (360 g) and 36% hydrochloric acid (0.12 g) are They are loaded in an autoclave and then the interior of the autoclave is replaced with nitrogen gas when the nitrogen gas is injected at a pressure of up to 5 x 105 Pa and evacuated three times. After replacing the inside of the autoclave with hydrogen by injecting the hydrogen gas at a pressure of up to 5 x 105 Pa and evacuating it three times, the hydrogen gas is injected at a pressure of up to 1.1 x 106 Pa and the interior temperature rises to 60 ° C, followed by stirring for 4 hours. After cooling the autoclave and replacing the interior with the nitrogen gas in the same manner as above, the reaction mixture is analyzed. The yield of 4-tert-butylcyclohexanol was 93.2% and the ratio of the cis isomer to the trans isomer was 88.6: 1 1.4 The above reaction is repeated and the two reaction mixtures are combined. The combined reaction mixture is filtered to remove the catalyst and evaporated to the concentration to obtain the crude 4-tert-butylcyclohexanol (350 g, 2.20 moles, a purity of 98.4%, the ratio of the cis isomer to the trans isomer is 88.6. .11.4). (2) Sulfuric acid (0.81 g, 8.1 mmol) is added to the above concentrated mixture while maintaining the mixture at 90 ° C and then acetic anhydride (312.4 g, 2.94 mol) is added dropwise to the mixture during 3 hours, followed by maintenance at that temperature for 1 hour. Analysis of the reaction mixture reveals that the yield of 4-tert-butylcyclohexyl acetate was 99% (based on 4-tert-butylcyclohexanol) and the ratio of the cis isomer to the trans isomer was 88.6: 11.4 The reaction mixture it is washed with aqueous sodium bicarbonate % three times (each with 450 g) and with water (450 g) subjected to ion exchange once. An oil layer is rectified and 4-tert-butylcyclohexyl acetate is obtained which has high purity at a high yield.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property

Claims (9)

1. Claims 1. A process for preparing 4-tert-butylcyclohexanol, characterized in that it comprises hydrogenating 4-tert-butylphenol in a solvent in the presence of a rhodium catalyst and a compound selected from the group consisting of hydrogen chloride, perchloric acid and sulfuric acid (anhydrous).
2. 2. The process according to claim 1, characterized in that an amount of hydrogen chloride, perchloric acid or sulfuric acid (anhydrous) is 0.05 to 10 moles per one mole of the rhodium atom in the rhodium catalyst.
3. 3. The process according to claim 1, characterized in that the rhodium catalyst comprises metallic rhodium supported on a carrier.
4. 4. The process according to claim 3, characterized in that an amount of the rhodium catalyst (in terms of the dry material) is from 0.5 to 10% by weight, based on the weight of the 4-tert-butylphenol.
5. 5. The process according to claim 1, characterized in that the solvent is a solvent selected from the group consisting of alkanes having from 5 to 10 carbon atoms, ethers having 4 to 10 carbon atoms and alcohols having 1 to 6 atoms of carbon.
6. 6. The process according to claim 5, characterized in that the solvent is an alcohol.
7. 7. The process according to claim 6, characterized in that the alcohol is isopropanol.
8. 8. The process according to claim 1, characterized in that the reaction temperature is from 20 to 100 ° C.
9. 9. A process for preparing 4-tert-butylcyclohexyl acetate, characterized in that it comprises acetylating 4-tert-butylcyclohexanol which has been prepared by hydrogenation of 4-tert-butylphenol in a solvent in the presence of a rhodium catalyst and a compound selected from the group It consists of hydrogen chloride, perchloric acid and sulfuric acid (anhydrous).