CS233142B1 - Process for preparing 1-cyclohexylethanol - Google Patents

Abstract

According to the invention, acetophenone is hydrogenated in the first stage to 1-phenylethanol in the presence of a mixed oxide catalyst of the Adkins type, which is hydrogenated in the following stage in the presence of a ruthenium supported catalyst at a temperature of 100 to 200 °C and a pressure of 1 to 25 MPa. Hydrogenation can be carried out in an environment of aliphatic alcohols or aromatic hydrocarbons. It is preferable to fix the catalyst, containing 0.5 to 5 wt. % ruthenium, on ^-alumina or activated carbon. It is preferable to return the ruthenium catalyst to the reaction 1 to 5 times.

Description

The present invention relates to a process for the preparation of 1-cyclohexylethanol which serves as one of the components for the preparation of perfume products based on its esters. The disadvantage of Grignard synthesis lies in the unpleasant work with the flammable reaction solvent (diethyl ether, tetrahydrofuran) and in the large amount of magnesium waste. In addition, this synthesis is difficult to carry out on a larger scale.

It is difficult to carry out catalytic hydrogenation in that, in the presence of conventional hydrogenation catalysts (e.g., nickel and platinum catalysts), side reactions - hydrogenolysis or hydrogenolysis - occur. by hydrogenation of the starting substrate to ethylbenzene, respectively. ethylcyclohexane, which greatly reduce the yield of 1-cyclohexylethanol.

The increase in the yield of the preparation of 1-cyclohexylethanol and the aforementioned drawbacks removes the process for the preparation of 1-cyclohexylethanol according to the invention, which consists in the fact that the starting acetophenone is hydrogenated in two steps. First, acetophenone is hydrogenated to 1-phenylethanol in the presence of a mixed oxide catalyst (e.g., copper-chromium, copper-zinc, etc.) that selectively hydrogenates the carbonyl group in the starting substrate. In the second step, the 1-phenylethanol is then hydrogenated to 1-cyclohexylethanol in the presence of a ruthenium supported catalyst under a hydrogen pressure of 1 to 25 MPa, preferably 5 to 15 MPa and at a temperature in the range 100 to 200 ° C, preferably 130 to 160 ° C. . Hydrogenation can be carried out both in and without the presence of a suitable solvent, for example aliphatic alcohols or aromatic hydrocarbons. The hydrogenation in the first stage proceeds in a yield of 99-100%, the yield achieved in the second stage being 90-95%.

233 142

The following examples illustrate the invention.

Example 1

1 of acetophenone was hydrogenated to 1-phenylethanol using 10 g of a copper-chromium catalyst of 47.5% CuO, 47.5% O 2 * 2θ3, 5% MnOg at 120 ° C and 5 MPa in a 2.5 L autoclave. After 2 hours, the catalyst was removed from the reaction mixture and the resulting 1-phenylethanol in 99.6% yield was hydrogenated in the second step using 10 g of 1% w / w ruthenium catalyst. Ru-N-alumina at a temperature of 150 ° C and a pressure of 12 MPa.

After 6 hours, the reaction mixture contained 92.5 wt. % Of 1-cyclohexylethanol and 7.5 wt. ethylcyclohexane by-product.

Example 2

1-Phenylethanol was hydrogenated using 10 g of the ruthenium catalyst used in Example 1 at 140 ° C and 15 MPa. After 8 hours, the reaction mixture contained 85 wt. % Of 1-cyclohexylethanol, 5 wt. % methylcyclohexyl ketone, wt. % ethylcyclohexane and 2 wt. ethylbenzene.

Example 3 ml of a 1-phenylethanol / ethanol (1: 1) mixture was hydrogenated with 0.5 g ruthenium (3.2 wt% Ru / activated carbon catalyst at 150 ° C and 10 MPa in a 150 ml autoclave) After 7 hours the conversion to 1-cyclohexyl ether was 94%.

Claims (5)

. SUBJECT OF THE INVENTION First ^r ^ method of preparing 1-cyclohexylethanol of acetophenone wherein acetophenone is hydrogenated in the first step, to 1-phenyl ethanol in the presence of a mixed oxide catalyst Adkins type, which in the following step, is hydrogenated in the presence of a ruthenium supported catalyst at temperatures from 100 to 200 ° C and a pressure of 1 to 25 MPa. 2. A process according to claim 1, wherein the hydrogenation is carried out in an environment of aliphatic alcohols. 3. The process of claim 1 wherein the hydrogenation is carried out in an aromatic hydrocarbon environment. 4. A process according to claim 1, wherein the ruthenium catalyst comprises 0.5 to 5 wt. ruthenium and is fixed on γ-alumina or activated carbon, 5. A process according to claim 1, wherein the hydrogenation is carried out with a ruthenium catalyst which is returned to the reaction 1 to 5 times.