JPS60197634A - Preparation of unsaturated alcohol - Google Patents

Abstract

PURPOSE:In hydrogenating an unsaturated aldehyde as a raw material, to obtain the titled compound economically in high yield, by using both easily obtainable Raney nickel and Raney cobalt as a hydrogenating catalyst. CONSTITUTION:An unsaturated aldehyde shown by the formula I (R<1> and R<2> are H, or lower alkyl; n is 1-4) is hydrogenated in the presence of Raney nickel and Raney cobalt as a catalyst, and preferably a tertiary amine as a cocatalyst in a polar solvent such as methanol, methyl Cellosolve, etc. at 20-150 deg.C, especially at about 50-90 deg.C, to give a compound shown by the formula II. Citral(3,7-dimethyl-2,6-octadienal), etc. may be cited as the compound shown by the formula I . A ratio of Raney nickel to Raney cobalt used is 1pt.wt/0.2- 10pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an unsaturated alcohol, and more specifically, a method for producing an unsaturated alcohol, which is characterized by hydrogenating an unsaturated aldehyde represented by the general formula (1') in the presence of Raney nickel and Raney cobalt. The present invention relates to a method for producing an unsaturated alcohol represented by formula (It).

In the above formula, R1 and R2 are each a hydrogen atom or a methyl group,
It represents a lower alkyl group such as an ethyl group, a propyl group, an inbutyl group, a butyl group, an inbutyl group, a 1iee-butyl group, a tert-butyl group, and n represents an integer of 1 to 4.

Conventionally, an unsaturated aldehyde having at least one carbon-carbon double bond in addition to α- and β-position carbon-carbon double bonds, such as citral, is used as a raw material, and its carbonyl group and the As a method for producing an unsaturated alcohol such as citronellol by selectively hydrogenating only the heavy bonds, for example, (1) a method using a multicomponent catalyst containing platinum, nickel and iron as a hydrogenation catalyst <qi open (Refer to Report 1984-460084A)
1)” 9 A method of hydrogenation at a hydrogen pressure of about 20 to 150 bar in the presence of a composite catalyst consisting of Sifl and ruthenium, rhodium, osium, iridium or platinum and a tertiary amine (JP-A-56-34644) ), (I
I) A method using chromium-activated Raney nickel as a hydrogenation catalyst (see vP Publication No. 100405/1983) is known. In order to obtain citronellol from citral and citral in a yield of 9% and 8% using the method (1) above, it is necessary to use expensive platinum as a catalyst component in an amount of about 1% by weight based on the raw material citral, and ( 2
) method uses expensive platinum group metals and requires high hydrogen pressure of 30 bar or more to obtain citronellol from citral in a yield of 9096 or more, which is difficult to adopt industrially. There are some difficulties. In the method of (8), a yield of 94% was obtained from citral in a long reaction time of about 13 hours.
It is said that citronellol was obtained in -.

The present inventors have conducted intensive studies to produce unsaturated alcohols such as citronellol economically and in high yield by hydrogenating unsaturated aldehydes such as citral. It was discovered that the desired product could be obtained in high yield by using a combination of available Raney nickel and Raney nickel (Ruto), and the present invention was completed. Unsaturated aldehydes are specifically citral (3,7-dimethyl-2,6-octagenal), farnesal (3,7,11-)dimethyl-2,6,10-dodecatrienal), 3.7 .11.15-tetramethyl-2
, 6,10,14-hexadecatetraenal, 7-methyl-2,6-octagenal, 3-ethyl-7-methyl-2,6-octagenal%3-propyl-7-
Methyl-2,6-octagenal, 2,3,7-drimethyl-2,6-octagenal, etc. In the method of the present invention, Raney nickel and Raney cobalt are used in combination as hydrogenation catalysts. Although it is possible to use products prepared by known methods such as the method for preparing W-1 to W-7 by J.D. It is preferable to use catalysts prepared by the method described above (see Catalyst Engineering Course 10, “Catalyst Handbook by Element” edited by Catalyst Ugan, pp. 482-489)
.

An example of Raney nickel obtained by an industrial preparation method is NDT manufactured by Kawaken Fine Chemicals Co., Ltd.

Examples include series such as NDHT. Also, for Raney nickel, any one obtained by a known preparation method can be used, but as with the Raney nickel mentioned above, it is preferable to use one prepared by a method usually called an industrial preparation method. Preferred (see pages 528 to 530 of the above-mentioned "Element Side Catalyst Handbook"). Good Raney cobalt obtained by industrial preparation methods includes, for example, the series 0DHT and OFT manufactured by Kawaken Fine Chemicals Co., Ltd. The usage ratio of Raney nickel and Raney cobalt is 1 part by weight of the former to 0.2 to 10 parts by weight of the latter (ToJ), preferably 1 part by weight of the former to 1 to 10 parts by weight of the latter.
It is 3 parts by weight. The preferred amount of catalyst to be used varies depending on various conditions such as the presence or absence of a co-catalyst and solvent, hydrogen pressure, and reaction temperature, which will be described later, but it is usually the case that nickel and cobalt are used for the unsaturated aldehyde represented by the general formula (supervisor). The total amount is about 0.
It is selected from a range of 1 to 10 weight.

In the hydrogenation reaction of the present invention, it is preferable to use a tertiary amine as a cocatalyst.
It has the effect of suppressing further hydrogenation of the unsaturated alcohol represented by It).

Examples of tertiary amines that can be used include trimethylamine, triethylamine, triethanolamine, pyridine, and quinoline. The appropriate amount of these tertiary amines to be used is approximately 0.05 to 0.5 by weight based on the unsaturated aldehyde represented by general formula (1). The hydrogenation reaction can be carried out in the presence or absence of a solvent, methanol, ethanol, rounding to increase the reaction rate.
Preferably, it is carried out in a polar solvent such as methyl heptatosolve. Although the amount of solvent used is not particularly limited, general formula (1)
Approximately 0.0% per part by weight of unsaturated aldehyde represented by
It is appropriate to use 3 to 2 parts by weight of solvent.

The reaction temperature is carried out within a temperature range of about 20-150°C, preferably about 50-90°C. If the reaction temperature is significantly lower than 20°C, the reaction time will be very long to obtain the unsaturated alcohol represented by general formula (II) in a good yield, and if the reaction temperature is significantly higher than 150°C. Generated general formula (n)
Since the unsaturated alcohol represented by is more likely to produce a hydrogenated saturated alcohol as a by-product, the selectivity to nucleon saturated alcohol is lowered. In addition, the hydrogen partial pressure is approximately 1 to 20 kp/
m, preferably in the range of about 3 to 10 kf/-. If the hydrogen partial pressure is lower than this range, the reaction time will be very long to obtain the desired unsaturated alcohol in good yield.
Furthermore, when the hydrogen partial pressure is higher than the above range, saturated alcohol is likely to be produced as a by-product, and the selectivity to the target unsaturated alcohol becomes low. It may be diluted with an inert gas such as hydrogen, nitrogen, argon, or helium.

The hydrogenation reaction of the present invention can be carried out either batchwise or continuously.

After the completion of the reaction, the unsaturated alcohol represented by the general formula (JI) is easily separated by separating the alcohol catalyst from the reaction mixture by filtration, centrifugation or decantation, and then distilling the residual liquid. I can do that.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 30 g of citral, 30 g of methanol and 0.06 g of triethylamine were placed in a stainless steel autoclave.
Next, Raney nickel (manufactured by Kawaken Fine Chemical Co., Ltd., NDT-65) 0.9.9' and Raney cobalt (
Manufactured by Kawaken Fine Chemical Co., Ltd., 0DHT-66)0
．． 1 was added thereto, and the mixture was stirred vigorously under hydrogen pressure and allowed to react for 7 hours. During the reaction, the temperature was kept at 70° C. and the total pressure at 8 kr/j. After separating the catalyst from the reaction mixture, the residual liquid was quantified by gas chromatography. The conversion rate of citral was 100%, and the yield of the product was as follows.

Tatronellol 97.2 Chinerol 0.6- Geraniol 1.29 and Tetrahydrogeraniol 0.6 Chi Examples 2 to 7 The same procedure as in Example 1 was carried out by variously changing the reaction conditions.
A hydrogenation reaction of citral was carried out. The results are shown in Table 1. Note that the same Raney nickel and Raney cobalt as used in Example 1 were used.

Table 1 Example 8゜77Ai? -30 p.m., methanol 801 p.m., and triethyl acetate <yO.06Ii. (
1 and 0.9 g of Raney cobalt (as described above) were added, and the mixture was stirred vigorously under hydrogen pressure and allowed to react for 7 hours. During the reaction, the temperature was kept at 70°C and the total pressure at 8kF/-. After separating the catalyst from the reaction mixture, the residual liquid was quantitatively determined by gas chromatography. The conversion rate of farnesal was 100%, 3,7.11-trimethyl-6,
10-dodecadien-1-ol was produced in a yield of 94.8-.

Example 9 7-Methyl-2,6-octagenal 3011 30 g of methanol and 0.06,9' of triethylamine were placed in a stainless steel autoclave, and then Raney nickel (JD as mentioned above) 0.9.9 and Raney cobalt (
As mentioned above L) 0.9. Add If and stir vigorously under hydrogen pressure to react for 6 hours. During the reaction, the temperature was kept at 70° C. and the total pressure at 81 w/sl. After separating the catalyst from the reaction mixture, the residual liquid was quantified by gas chromatography. The conversion rate of 7-methyl-2,6-octagenal was 10,096, and 7-methyl-6-octen-1-ol was produced in a yield of 97.2%.

Patent Tanfu RiRashi Co., Ltd. Ken Ken Udo Honda

Claims (1)

[Claims] 1. An unsaturated aldehyde represented by the general formula (wherein 11 and R2 each represent a hydrogen atom or a lower alkyl group, and n represents an integer of 1 to 4) is prepared by combining Raney nickel and Raney cobalt. A method for producing an unsaturated alcohol represented by the general formula (wherein R1, R2 and n are as defined above), characterized by hydrogenation in the presence of 2. The method according to claim 1, wherein the hydrogenation reaction is carried out in the presence of a tertiary amine.