JPS5826730B2 - Separation method of citronellol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently separating citronellol from a mixture of geraniol and/or nerol and citronellol.

Citronellol is usually obtained by selectively subjecting geraniol and/or nerol to a partial hydrogenation reaction using Raney cobalt, Raney nickel, or the like as a catalyst, and many natural essential oils contain a large amount of these as a mixture.

Generally, when separating citronellol from the reaction solution or mixture, the boiling point of citronellol (222°C/760°Hg, 143°C/150°Hg) is the boiling point of nerol (222°C/760°Hg).
25℃/760 mmHg (1142℃/150 mmHg) and the boiling point of geraniol (230℃/760 mmHg,
147°C and 150 mmHg), it is extremely difficult to separate citronellol from the reaction solution or mixture.

Conventionally, citronellol has not been industrially separated from a mixture of geraniol and/or nerol and citronellol, and citronellol is produced from geraniol and/or nerol by one of the following methods. It is.

That is, (1) hydrogenation is performed until geraniol and/or nerol disappear.

In this case, the yield decreases due to the formation of tetrahydrogeraniol.

(2) A citronellol product containing geraniol and/or nerol.

The present inventors found that geraniol and nerol have a three-way, isomer equilibrium relationship with linalool in the presence of a vanadium compound or tungsten compound catalyst, and the boiling point of linalool (198°C/760mmHg, 115°C/50 m
mHg ) is the lowest, and while a vanadium compound or a tungsten compound is present as a catalyst in the reaction solution or mixture to isomerize geraniol and/or nerol to linalool, or after the isomerization reaction, the catalyst is By conducting distillation in the presence of citronellol, we successfully recovered low-boiling point naol, which is easy to separate after isomerization, and then distilled highly pure citronellol.

When citronellol is obtained by a selective partial hydrogenation reaction using geraniol and/or nerol as a raw material, Raney cobalt, Raney copper, Raney nickel, or a catalyst mixed with other metals during the production of these Raney catalysts is used as a catalyst. However, the selectivity of these catalysts is not perfect, and as the reaction progresses, the target citronellol is further hydrogenated to form tetrahydrogeraniol (boiling point: 2
15℃/760mmHg, 137℃/50mm
Hg) is partially produced as a by-product.

Therefore, in order to obtain citronellol in good yield, it is desirable to avoid raising the conversion rate extremely high, and to separate and recover unreacted geraniol and/or nerol from citronellol and subject it to the hydrogenation reaction again.

Separation of tetrahydrogeraniol and citronellol, which are by-produced in the above hydrogenation reaction, is easier than separation of geraniol and/or nerol, which are raw materials, from citronellol. Therefore, when obtaining high-yield, high-purity citronellol, The problem is the separation of geraniol and/or nerol from citronellol.

When performing a selective partial hydrogenation reaction using geraniol and/or nerol as a raw material, a solvent such as methanol, furopanol, phthanol, hexane, benzene, etc. can be used, and the hydrogen pressure is from normal pressure to several 100 kg/c.
The appropriate range of rA and reaction temperature is room temperature to 200°C.

Further, the amount of the catalyst added for the selective partial hydrogenation reaction is preferably in the range of 0.1% by weight to several 10% by weight based on the raw material.

When isomerizing geraniol and/or nerol to nalol, a vanadium compound or a tungsten compound is used as a catalyst. Specifically, inorganic salts of vanadium and tungsten such as chlorides, sulfates, and phosphates, Organic acid salts such as stearate and naphthenate, metal alkoxides (metal acid esters) such as ethoxide, infropoxide, n-propoxide and n-butoxide, β-diketone complexes such as acetylacetonate and benzoylacetonate, ethylenediamine , derivatives such as glyoxime, metal carbonyls, metal alkyls, metal oxides, metal salts, etc. are used.

Among these, preferred catalysts are metal alkoxides,
Examples include β-diketone complexes, metal oxides, and metal salts, and particularly preferred catalysts include vanadium alkoxides such as orthovanadate esters (vanadyl trialkoxides), vanadium tetraalkoxides, and vanadium β-diketones such as vanadyl acetylacetonate. complex,
Examples include tungsten alkoxides such as tungstate ester (tungsten oxytetraalkoxide).

The amount of the above isomerization catalyst added is usually 0.0 to the target stock solution.
The range is from 0.01 to 10% by weight, preferably from 0.01 to 10% by weight.
3% by weight is suitable.

Further, the reaction temperature for isomerization is preferably in the range of 50 to 300°C, particularly preferably in the range of 150 to 250°C.

The isomerization equilibrium composition of geraniol, nerol, and linalool is approximately 25:15:60 by weight, and when distilling while performing an isomerization reaction, geraniol and/or nerol are converted to linalool as low-boiling point nerol is distilled out. Once it is isomerized and the linalool fraction disappears,
Geraniol and/or nerol are substantially eliminated from the bottom liquid, and finally, the target citronellol with high purity can be obtained by distillation.

In addition, naol, which is produced by an isomerization reaction and separated from citronellol, can be found in Japanese Patent Publication No. 48-2, for example.
By converting it into geraniol and nerol using the method described in No. 3407, it can be used as a raw material for citronellol again.

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

In addition, all % in an example represents weight %.

Example l 1oo raw material consisting of 92% nerol and 8% geraniol
oy is dissolved in 1oooy of n-propertool, 81% of Raney cobalt is added, and the content is reduced to 5. Pour into an autoclave, maintain hydrogen pressure at 50 kg/c4, and heat at 30 to 50°C.
The reaction was carried out under stirring for 2.5 hours at a temperature of .

The composition of the tear fluid obtained by removing the catalyst from the reaction solution other than n-propanol was 90% citronellol, 4% tetrahydrogeraniol, 6% nerol, and 0% geraniol. After removing the propatool, 1.02 ml of n-butyl orthovanadate was added to the concentrated solution, and the mixture was heated for 20 min under a nitrogen stream.
The reaction mixture was heated to 0° C. and stirred for 1.2 hours.

The composition of the obtained reaction solution was 89% citronellol, 4% tetrahydrogeraniol, 3.6% linalool, 0.9% nerol, 1.5% geraniol, and other
A quantity of by-products such as myrcene, dipentene, alloocimene, purinol, and terpineol were detected.

The fractions shown in Table 1 were obtained by distilling this reaction solution in an all-guusho precision fractionator (HO-7000 type manufactured by Shibata Kagaku Kikai Kogyo Co., Ltd.) in the presence of the n-phthyl orthovanadate catalyst.

(Reflux ratio, 20) As described above, highly pure citronellol could be obtained.

Example 2 2 g of a pyridine complex of tungsten oxytetrapropoxide was added to 1.5 kg of a mixed solution consisting of 75% citronellol, 12% geraniol, and 13% nerol, and the mixture was reacted in the same manner as in Example 1. Distillation was carried out in the presence of the above catalyst, and fractions having the compositions shown in Table 2 were obtained.

Example 1.5 kg of a raw material consisting of 60% geraniol and 40% nerol was dissolved in 1 kg of ethanol, and Raney nickel 25'? Add to the autoclave with a content of 51.
Hydrogen pressure 10kg/crA 160-70°C
The hydrogenation reaction was carried out at a temperature of 3 hours.

After removing Raney nickel from the resulting reaction solution, the composition of the tear fluid other than ethanol was 51% citronellol, 2% tetrahydrogeraniol, 23% nerol, and 24% geraniol.

Next, after distilling away ethanol from this tear fluid, 3ff of inbutyl orthovanadate was added, and using a packed column (packed helipasoku) with a column length of 1.5 m and an inner diameter of 4 CrrL,
Reactive distillation was carried out at a column top pressure of 100100 i and a reflux ratio of 30.

The weight and analytical values of each fraction were as shown in Table 3.

Comparative Example (Comparison with Example 3) 1.5 kg of a liquid with the same composition as the liquid after ethanol distillation in Example 3 (51% citronellol, 2% tetrahydrogeraniol, 23% nerol, 24% geraniol) was used without adding a catalyst. Using the same distillation column as in Example 3,
Distillation was performed under the same conditions.

The analytical values of each fraction are shown in Table 4, and it was not possible to obtain highly pure citronellol.

Claims (1)

[Scope of Claims] 1. A method for separating citronellol from a mixture of geraniol and/or nerol and citronellol, in which a vanadium compound or a tungsten compound is added as a catalyst to the mixture to convert geraniol and/or nerol in the mixture into linalool. A method for separating citronellol, which comprises separating citronellol by distilling it in the presence of the catalyst while or after the isomerization reaction. 2. A method for separating citronellol from a reaction mixture of geraniol and/or nerol and citronellol obtained by partially hydrogenating geraniol and/or nerol, including adding a vanadium compound or a tungsten compound as a catalyst to the reaction mixture, While isomerizing geraniol and/or nerol in the reaction mixture to linalool, or after the isomerization reaction,
A method for separating citronellol, which comprises separating citronellol by distillation in the presence of the catalyst.