DE2334928A1 - PROCESS FOR THE PRODUCTION OF CIS-PTERT.-BUTYL-CYCLOHEXANOL - Google Patents

Description

BASF Aktiengesellschaft

Our reference: O.Z. 29 988 Rr / IG

6700 Ludwigshafen, July 6, 1973 Process for the preparation of cis-p-tert-butyl-cyclohexanol

The invention relates to a process for the preparation of essentially cis-p-tert-butyl-cyclohexanol (axial hydroxyl; I) in addition to a little trans-p-tert-butyl-cyclohexanol (equatorial hydroxyl; II) by catalytic hydrogenation of p- tert-butyl-cyclohexanone. Subsequent fractionation of the reaction product can increase the cis content in the reaction mixture up to 99 % .

Cis- and trans-p-tert “-butyl-cyclohexanols are direct precursors for the production of the acetates of cis- and trans-p-tert-butyl-cyclohexanol, which are used in large quantities (annual consumption in the world about 200 tons) as fragrances with woody, methyljonon-like odor notes can be used. The cis-p-tert-butyl-cyclohexanol acetate is far superior to the trans isomer in terms of both the fineness of smell and the intensity of the smell. In the production of p-tert-butyl-cyclohexanol by catalytic hydrogenation of p-tert-butyl-phenol over nickel catalysts, which is customary in industry, an isomer mixture is generally obtained which contains only about 30 % of the cis compound. Although the cis isomer can be enriched from this isomer mixture by fractional distillation, it cannot be obtained in pure form.

Also in the reduction of p-tert-butyl-cyclohexanone with Reducing agents such as lithium aluminum hydride, alkali metals in liquid ammonia, organomagnesium halides, tributyltin hydride, Iridium trichloride sulfoxide, n-butyl lithium in Pyridine, lithium tri-tert-butoxyaluminum hydride, alkali isopropylate and sodium dihydrido-bis-2-methoxy-ethoxy-aluminate is the main product, which is always the thermodynamically more stable one trans-p-tert-butyl-cyclohexanol.

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In order to obtain a mixture containing essentially cis-p-tert-butyl-cyclohexanol from the trans-rich isomer mixtures obtained, the mixture according to Dutch patent 6 6o4 974 could be heated in the presence of strongly alkaline isomerization catalysts and the cis- isomer rich mixture at l60 to 17O ⁰ C and distilling off l40 to 170 mm Hg continuously. As the relatively high temperatures show, such an isomerization is associated with high energy costs and preparative effort.

According to American patents 2,840,599 and 2,927,127, isomer mixtures of p-tert-butyl-cyclohexanol with a proportion of the cis compound of 56 to about 88 % are used directly in the catalytic reduction of p-tert-butylphenol to rhodium -, platinum or ruthenium catalysts obtained. However, the disadvantage of this process is the use of the very expensive noble metal catalysts.

Furthermore, the cis-p-tert-butyl-cyclohexanol is obtained as the main product in the reduction of p-tert-butyl-cyclohexanone with boiling propan-2-ol in the presence of HJrCl ₂ ^ CH ₅ ) ₂ S07-x (cf. . Chem. Comm. 1967 , p. 544); with phosphorous acid in aqueous propanol in the presence of a catalyst prepared in situ from iridium tetrachloride and phosphorous acid (cf. J. Chem. Soc. (London) 1910 , page 785) or with lithium hydrido-tri-sec-butyl borate (cf. J Am. Chem. Soc. £ 4 (1972), page 7159) · In the processes mentioned, however, extremely complicated and / or expensive complexes or catalysts which are not economical or technical are used to reduce the p-teit-butyl cyclohexanone Allow easy-to-carry manufacturing processes.

It was therefore the object of the invention to develop a process by which one essentially cis-p-tert-butylcyclohexanol can produce in an economical and technically easy-to-implement manner.

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It has now been found that the catalytic hydrogenation of p-tert-butyl-cyclohexanone gives a p-tert-butyl-cyclohexanol which essentially contains cis-p-tert-butyl-cyclohexanol if the p- tert-butyl-cyclohexanone on Raney nickel or Raney cobalt as a catalyst in an aliphatic alcohol having 1 to 5 carbon atoms as solvent at temperatures below 50 ° C, preferably at temperatures from -10 ⁰ C to 3O ⁰ C. hydrogenated under pressure.

Particularly good yields of cis-p-tert-butyl-cyclohexanol are obtained if the p-tert-butyl-cyclohexanone is used additionally hydrogenated in the presence of an alkali hydroxide or an alkali alcoholate.

The p-te * t-butyl-cyclohexanone used as the starting compound can be obtained, for example, by partial hydrogenation of p-tert-butylphenol.

Raney nickel and Raney cobalt are suitable as catalysts, preferably Raney nickel. The catalyst is used in an amount of 0.1 to 100 g, preferably 10 to 70 g per mole of ketone.

Aliphatic alcohols with 1 to 5 carbon atoms, in particular methanol, ethanol and isobutanol, are used as solvents used. The amount of solvent is not critical. It can be used in a wide range, namely between that by the Reaction temperature set saturation point of the solution and the 20-fold excess fluctuate.

To carry out the process, the p-tert-butyl-cyclohexanone or an alkali metal, alkali metal alcoholate or alkali hydroxide and the p-tert-butyl-cyclohexanone are generally dissolved in the aliphatic alcohol, the catalyst is added and hydrogenated at temperatures below 50 ⁰ C with vigorous stirring and increased pressure.

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The reaction temperature must be below 50 ° C. The most favorable range is -10 to ⁰

The hydrogen pressure can be 10 to 300 atm, especially 150 up to 250 atm.

The reaction time is a maximum of 30 hours, preferably 3 to 20 hours.

As Examples 1, 4 and 5 show, the addition of an alkali hydroxide or alcoholate increases the cis content of the reaction product considerably. Lithium, sodium and potassium hydroxide, especially potassium hydroxide, as well as the alcoholates of these metals corresponding to the solvent, in particular potassium alcoholates. The amount of alkali can vary widely Limits vary. We achieved good results with 0.01 to 0.5 moles of alkali metal or alkali hydroxide per mole of ketone.

To work up the reaction mixture, the contents of the autoclave are generally filtered off from the catalyst and fractionated or, in the presence of an alkali hydroxide or alkali alcoholate, the alcohol is removed by distillation, the remaining product is absorbed in inert solvents such as ether, petroleum ether, or benzene, the precipitating The alkali compound is separated either by filtration or by washing and then the organic phase distilled.

With the aid of the process according to the invention, the cis-ptert-butyl-cyclohexanol economically and in a technically simple manner in over 90 percent yield and in over 90 percent purity.

Esters of cis-p-tert-butyl-cyclohexanol with lower Carboxylic acids, such as acetic acid, are important as fragrances with woody, methyljonon-like odor notes attained.

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The following examples are intended to illustrate the process according to the invention explain.

example 1

First, 1 g of potassium is dissolved in 100 ml of isobutanol, then 50 g of p-tert-butyl-cyclohexanone are added and the resulting solution is placed together with 15 g of Raney nickel in a 1 l autoclave which, for thorough mixing of the gas Liquid-solid phase is equipped with a lifting stirrer. It is then hydrogenated at 0 to +10 ⁰ C and a hydrogen pressure of 200 atm. The hydrogen uptake has ended after about 20 hours. The contents of the autoclave are filtered and the isobutanol is removed by distillation. The product that remains is taken up in ether or benzene, washed neutral with water and, after the solvent has been distilled off, purified by vacuum distillation. This gives 48 g of a fraction having the boiling point Kp, g = 112 ° C and a melting point m.p. = 78-79 ⁰ C. The yield is 94.8 # of theory.

According to gas chromatographic analysis, the product contains 94 % ice and approx. 6 % trans-p-tert-butyl-cyclohexanol. Fractional distillation can increase the cis content to 99 % .

Example 2

The solution of 77 g of p-tert-butyl-cyclohexanone in 300 ml Methanol is placed in the 1 l autoclave described in Example 1 together with 10 g of Raney nickel

It is then ^{hydrogenated at 20 °} C. and a hydrogen pressure of 200 atm. The hydrogen uptake has ended after 20 hours. The contents of the autoclave are filtered and fractionated. The yield is 93 %, the cis-trans ratio 75:25.

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Example J5

If you work as described in Example 2, but used

instead of 10 g of Raney nickel, 10 g of Raney cobalt is obtained

a p-tert-butyl-cyclohexanol is obtained with approximately the same yield

with an eis: trans ratio of 78 to 22.

Example 4

The solution of 200 g of p-tert-butyl-cyclohexanone in 600 ml of methanol, 20 ml of a 30 percent strength by weight solution of sodium methylate in methanol and 30 g of Raney nickel are placed in a 2 l autoclave with a lifting stirrer. The mixture is then hydrogenated for 18 hours at 20 ° C. and 200 atm. Hydrogen pressure. The work-up is carried out as in Example 1. The yield of p-tert-butyl-cyclohexanol is 97 %, the cis-trans ratio is 87 to Γ5.

Example 5

The solution of 100 g of p-tert-butyl-cyclohexanone in 300 ml of methanol, 10 ml of a 10 percent strength by weight solution of NaOH in methanol and 15 g of Raney nickel are placed in a thin 11 autoclave with a lifting stirrer. The mixture is then hydrogenated for 18 hours at 20 ° C. and 200 atm. Hydrogen pressure. The reaction mixture is worked up as in Example 1. The yield of p-tert-butyl-cyclohexanol is 95 % and the cis-trans ratio is 90:10.

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Claims (2)

- 7 - .0.Z.29 988 Claims Process for the preparation of p-tert-butyl-cyclohexanol which essentially contains cis-p-tert-butyl-cyclohexanol by catalytic hydrogenation of p-tert-butyl-cyclohexanone, characterized in that the p-tert. -Butyl-cyclohexanone hydrogenated over Raney nickel or Raney cobalt as a catalyst in an alcohol with 1 to 3 carbon atoms as a solvent at temperatures below 50 ° C. under pressure. 2. The method according to claim 1, characterized in that the p-tert-buty1-cyclohexanone is hydrogenated in the presence of an alkali metal hydroxide or alkali metal alcoholate. 3. Process according to Claim 1 or 2, characterized in that the p-tert-butyl-cyclohexanone is hydrogenated at temperatures from -10 to + 30 ° C. BASF Aktiengesellschaft 409885/1346