JPS6136239A - Production of dihydro-beta-ionone - Google Patents

Abstract

PURPOSE:In producing dihydro-beta-ionone useful as perfume, etc. by reducing catalytically beta-ionone, to obtain the aimed compound advantageously, by reducing selectively the double bond of a side chain by the use of a specifically treated Raney nickel catalyst. CONSTITUTION:A Raney alloy (alloy of nickel and aluminum) is added to an aqueous solution of sodium hydroxide, heated at about 70-110 deg.C, aluminum is eluted from the alloy, the supernatant liquid is removed, the precipitate is heated in water or an organic solvent (preferably ethanol) at about 50-80 deg.C to give Raney nickel catalyst. beta-Ionone is catalytically reduced by the use of the Raney nickel catalyst, to give selectively dihydro-beta-ionone useful as an intermediate for ionone derivatives useful as perfume existing in yellow passion fruit, osmanthus, etc., further to be expected as theaspirane, theaspirone, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved method for producing dihydro-β-ionone.

More specifically, the present invention selectively reduces double bonds in side chains by using a specially treated Raney nickel catalyst in a method for producing dihydro-β-ionone by catalytic reduction of β-ionone. Improved dihydro, -
This invention relates to a method for producing β-ionone.

Dihydro-β-ionone is present in strawberry, yellow fruit, osmanthus, etc., and is useful as a flavoring agent in itself.It is also useful for the synthesis of numerous ionone derivatives that are expected to be used as flavoring agents in the future, such as theaspiran and theaspiran. It is also useful as an intermediate.

2 of the side chain of unsaturated carbonyl compounds having a double bond in the side chain such as α-ionone, β-ionone, vanylidene acetone, etc.
As a method for selectively reducing only heavy bonds, a method using a Raney catalyst prepared by developing Raney nickel under specific conditions is known (Japanese Patent Publication No. 58-19656).

In this conventional method, Raney alloy (Ni:AA=1:1) is added to an aqueous sodium hydroxide solution, the system is heated at 90 to 95°C for about 3 hours, allowed to cool for about 24 hours, and then hydroxylated.
A Raney catalyst obtained by adding a Jium aqueous solution and further heating at about 90 to 95° C. for about 2 hours is used.

(Problems to be Solved by the Invention) According to the above conventional method, α-ionone is selectively dihydro-
Although it is reduced to α-ionone, β-ionone is not selectively reduced to dihydro-β-ionone, and considerable amounts of tetrahydrofuran are formed.

Therefore, an object of the present invention is to provide a method for producing dihydro-β-ionone by selectively reducing only the double bond in the side chain of β-ionone.

(Means for Solving the Problem) The above object of the present invention is achieved by the method of the present invention which uses the Raney nickel catalyst described below in a method for producing dihydro-β-ionone by catalytic reduction of β-ionone. : (Raney nickel catalyst) Raney alloy (nickel and aluminum alloy) is added to an aqueous sodium hydroxide solution and heated to approximately 70 to 110°C to elute aluminum from the alloy. The supernatant is removed and the precipitate is dissolved in water or Raney nickel catalyst obtained by heating to about 50-80°C in an organic solvent.

In preparing the Raney nickel catalyst used in the method of the present invention, first, a Raney alloy consisting of nickel and aluminum is heated to about 70 to 110 DEG C. in an aqueous sodium hydroxide solution according to a conventional method. There is no particular limit to the ratio (weight) of nickel to aluminum in Raney alloys, but it is usually 1
:1. The heating temperature is preferably within the above range; at temperatures higher than this, the catalytic activity becomes too weak and the yield decreases, and at lower temperatures, the catalytic activity becomes too strong and the selectivity of reduction becomes poor. Heating time is approximately 3 to 10 hours. After heating, let it cool, remove the supernatant, and preferably adjust the pH.
7, add water or an organic solvent to the precipitate, and heat at about 50 to 80°C. As an organic solvent, methanol, ethanol, ProA? Alcohols such as alcohol and butanol, esters such as ethyl acetate, ethers such as dioxane and tetrahydrofuran, or aromatic hydrocarbons such as toluene are used. Particularly preferred solvents are ethyl acetate or ethanol.

Although the lower limit of the heating temperature is not critical, it is preferably about 50° C. or higher from the operational standpoint such as heating time. The upper limit of the heating temperature is about 80° C., and heating at a temperature higher than this lowers the yield. Heating time depends on heating temperature. Heating temperature is 5
In the case of 0°C, it is 2 hours or more, preferably 5 to 6 hours,
In the case of the reflux temperature of ethanol (79°C), 1 to 2 hours is appropriate.

In the method of the present invention, the reduction step of β-ionone is carried out in the same manner as conventionally known methods. That is, β-ionone is dissolved in a suitable inert organic solvent such as ethyl acetate, the Raney nickel catalyst of the present invention is added, and the reaction system is replaced with hydrogen gas. Normal hydrogen pressure is sufficient.

The reaction temperature is preferably 40 to 60°C. At temperatures below 40°C, the reaction is slow, and at temperatures above 60°C, the amount of by-product tetrahydrofuran increases.

The reaction time is approximately 10 to 40 hours, and the reaction time is greatly shortened by stirring. After the reaction is complete, the desired product is recovered from the reaction mixture according to conventional methods. For example, the reaction mixture is filtered to remove the catalyst and the lachrymal fluid is concentrated under reduced pressure. Distillation of the residue under reduced pressure yields the desired dihydro-β-ionone.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 Sodium hydroxide 12.6L? 100m7 of water! and cooled to an internal temperature of 10°C or less in an ice water bath. Raney alloy (Ni:, AA=1:1, 50%) 2o1 is added little by little to this while stirring well. Meanwhile, keep the liquid temperature at 25℃.
Keep below. After the addition is complete, the mixture is heated to an oil bath temperature of 90-90.
Heat and stir at 5°C, internal temperature 70-75°C for 7 hours. After cooling, the precipitate was washed with running water, and when the pH reached 7, it was washed twice with 95% ethanol, and then 99.5% ethanol was added and heated at 50°C for 6 hours.

Dissolve 72 g of β-ionone (98% purity) in 108 g of ethyl acetate. Ethanol is removed from the ethanol solution of Raney nickel catalyst prepared above by decanting, and 11 g of Raney nickel catalyst in mud form is added to the solution. The inside of the reaction system was replaced with hydrogen gas, and the mixture was vigorously stirred at an internal temperature of 50° C. for 29 hours. The reaction solution is filtered, the catalyst is thoroughly washed with ethyl acetate, and the solvent is removed by concentration under reduced pressure. When the crude oil was distilled under reduced pressure, dihydro-β-ionone 64.91 (purity 93%, bp 105℃/
:llmmI(g + yield 89.3 w/w%, 83
1 mole) is obtained.

For comparison, in Example 1, β-ionone was reduced in the same manner as above using a catalyst that was not heated in ethanol after development of Raney nickel, and the yield of sohydro β-ionone was 42.3 w/w%. The yield of the by-product (tetrahydro ion) is 54.4. It was w/w chi.

Furthermore, when β-ionone was reduced in the same manner as above using the Raney nickel catalyst described in Japanese Patent Publication No. 58-19656, the yield of dihydro-β-ionone was 32.2%.
Met.

Example 2 Preparation of Raney Nickel Catalyst 101 parts of sodium hydroxide was dissolved in 40 parts of water and cooled to an internal temperature of 2° C. or less in an ice water bath. This is combined with Raney alloy (Ni:
AA=1:1.50ch) Add 10t little by little while stirring well. During this time, keep the liquid temperature below 25°C. After the addition was completed, the mixture was heated to an oil bath temperature of 130°C and an internal temperature of 110°C.
Heat and stir for an hour.

Next, 19 hydroxide) IJium aqueous solution (NaOH2
, 7g, ) I20137 was added, and the mixture was heated and stirred at an internal temperature of 110°C for 3 hours (oil bath temperature: 130°C). After cooling, the precipitate was washed with running water until the pH reached 7, then washed twice with 95% ethanol, added with 99.5% ethanol, and heated under reflux for 2 hours.

25 ft' of β-ionone (98% purity) in 50 ml of ethyl acetate
Dissolve in fI. Ethanol is decanted from the ethanol solution of Raney nickel catalyst prepared above, and 3.5 liters of Raney nickel catalyst in slurry form is added to the solution. The reaction system was purged with hydrogen gas and stirred vigorously for 4 hours at an internal temperature of 50°C. The reaction solution is filtered, the catalyst is thoroughly washed with ethyl acetate, and the solvent is removed by concentration under reduced pressure. Dihydro-β-ionone 21.7 f (purity 86%, bp 96°C) was distilled under reduced pressure from the crude oil.
72 mmEg, yield 86.6 w/w%, 74.5
1 mol %) is obtained.

Example 3 Preparation of Raney nickel catalyst In preparing the Raney nickel catalyst of Example 2, the same procedure as in Example 1 was performed except that instead of heating the Raney developed catalyst in ethanol, the catalyst was heated at 50° C. for 6 hours in an aqueous medium. A silane nickel catalyst was prepared.

β-ionone (98% purity) 2Of ethanol 40'?
dissolve in Water is removed from the Raney nickel aqueous solution prepared above by decanting, and muddy Raney nickel catalyst 31 is added to the solution. The reaction system was replaced with hydrogen gas, and the internal temperature was 50℃.
Stir vigorously for 4 hours. The reaction solution is filtered, the catalyst is thoroughly washed with ethanol, and the solvent is removed by concentration under reduced pressure. Dihydro-β-ionone 17f (purity 88
%.

bp 96℃/2 mmHg + Yield 85 w/w
%, 75.5 mol 1 ruti) is obtained.

Claims (2)

[Claims] (1) A method for producing dihydro-β-ionone, which comprises using the following Raney nickel catalyst in the method for producing dihydro-β-ionone by catalytic reduction of β-ionone. (Raney nickel catalyst) Raney alloy (nickel and aluminum alloy) is added to an aqueous sodium hydroxide solution, heated to approximately 70 to 110°C to elute aluminum from the alloy, the supernatant liquid is removed, and the precipitate is washed with water or organic Raney nickel catalyst obtained by heating to about 50-80°C in a solvent. (2) Claim 1 in which the organic solvent is ethanol
Method for producing dihydro-β-ionone as described in Section 1.