JPH0533692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing trans-synthetic acid. More specifically, the present invention relates to a method for producing trans-based chrysanthemum acid, which comprises reacting cis or cis/trans mixed stochastic acid with boron bromide in the presence or absence of an organic hydroperoxide.

Chrysanthemum acid constitutes the acid component of low-toxicity, fast-acting insecticidal esters called pyrethroids, such as pyrethrin, allethrin, and phthalthrin, and is useful as a raw material for these pyrethroid insecticides.

Incidentally, daichusic acid has cis and trans geometric isomers, and it is known that the insecticidal effect of the trans ester is stronger than that of the cis ester. Therefore, converting the cis isomer into a trans isomer is far more advantageous in terms of insecticidal efficacy than using the cis isomer or an ester containing a large amount of the cis isomer.

Conventionally, primary chrysanthemum acid has been widely used industrially by a method of hydrolyzing primary chrysanthemum acid ester obtained by the reaction of 2,5-dimethyl-hexa-2,4-diene and diazoacetic acid ester as shown in the following formula. Manufactured by

However, the primary chrysanthemum acid obtained by this method is
Obtained as a mixture of trans and cis forms.

Therefore, a technique for converting cis-dairy chrysanthemum acid or mixed cis/trans chrysanthemum acid into trans-dairy chrysanthemum acid is of important significance.

Conventionally, the method for directly converting cis-based chrysanthemum acid into trans-based chrysanthemum acid was to convert cis-based chrysanthemum acid itself into trans-based chrysanthemum acid.
Method of heating at a temperature of 180℃ or higher
126650), or a method in which cis-dairy chrysanthemum acid itself is reacted with a nitrile complex catalyst of palladium dichloride (Tetrahedron Letters, 22 385 (1981)); the former requires heating to high temperatures. Furthermore, the yield is low, and the latter requires relatively large amounts of expensive reagents.

As a result of intensive research into the production method of trans-based chrysanthemum acid, the present inventors found that by reacting boron bromide with cis-based chrysanthemum acid or mixed cis/trans-based chrysanthemum acid, the substrate was unexpectedly damaged. They found that the trans-form can be converted to the trans form in a high yield without any oxidation, and that the trans-conversion can be carried out even more easily by carrying out the conversion in the presence of an organic hydroperoxide. I've reached it.

That is, the present invention provides a method for producing trans-based chrysanthemum acid by reacting boron bromide with cis-based chrysanthemum acid or mixed cis/trans-based chrysanthemum acid in the presence or absence of an organic hydroperoxide. This is what we provide.

According to the method of the present invention, by allowing a catalytic amount of boron bromide to act on cis-synthetic chrysanthemum acid or mixed cis/trans-synthetic acid, trans-synthetic chrysanthemum acid or trans-synthetic acid can be directly produced in a short period of time at room temperature. Furthermore, by carrying out the method of the present invention in the presence of an organic hydroperoxide, the amount of boron bromide used can be further reduced, which is particularly advantageous in industrial implementation. be.

Next, the method of the present invention will be explained in detail.

The cis primary chrysanthemum acid used as a raw material in the present invention may be either the cis form alone or a mixture with the trans form.

The boron bromide used in the method of the present invention is typically boron tribromide, which may form a complex with a small amount of water, acid, alcohol, ether, etc. The amount used is in the range of 1/2000 to 1/10 mol, preferably 1/1000 to 1/20 mol, per 1 mol of chrysanthemum acid to be treated.

Examples of organic hydroperoxides include the following.

(1) Aliphatic hydroperoxide Hydroperoxide produced by oxidation of ethers such as tetrahydrofuran and dioxane t-Butyl hydroperoxide 1,1,3,3-tetramethylbutyl hydroperoxide p-menthane hydroper such as oxide.

(2) Aromatic hydroperoxides such as ayumene hydroperoxide, diisopropylbenzene hydroperoxide, etc.

The amount used is usually 1/10 to 5 mol, preferably 1/4 to 5 mol, per 1 mol of boron bromide used.
The range is 2 moles.

Further, when carrying out the method of the present invention, it is preferable to use an inert solvent, and examples of such solvents include aromatic hydrocarbons, saturated hydrocarbons, their halides, and ethers.

Further, the reaction temperature is not particularly limited, but the objective can usually be sufficiently achieved within the range of about -20°C to 50°C.

The time required for the reaction may vary depending on the amounts of boron bromide and organic hydroperoxide used and the reaction temperature, but is usually from several minutes to 10 hours.

When carrying out the method of the present invention, the process is usually carried out by dissolving the to-be-treated chrysanthemum acid in a solvent and adding boron bromide to the solution; Usually, the primary chrysanthemum acid to be treated and the hydroperoxide are dissolved in a solvent and then boron bromide is added thereto, or alternatively, the primary chrysanthemum acid to be treated is dissolved in a solvent and then the hydroperoxide is added to the mixture. This is carried out by simultaneously injecting boron bromide and boron bromide.

The degree of progress of the reaction can be determined by sampling a portion of the reaction solution and analyzing it by gas chromatography or the like.

The reaction solution reacted as described above is washed with, for example, hydrochloric acid water, and then concentrated to obtain the target trans-synthetic acid or the intended trans-synthetic acid-rich acid. Further, the product thus obtained can be purified by distillation, chromatography, etc., if necessary.

The method of the invention will now be explained by way of examples.

Example 1 In a 50 ml flask, 70% cis isomer was added in a nitrogen stream.
2.0 g of chrysanthemum acid having a composition of 30% trans isomer and 17.0 g of toluene were added, and a mixed solution of 0.024 g of boron tribromide and 1.0 g of toluene was added dropwise to the mixture while stirring at 20°C. After the dropwise addition, stirring was continued at the same temperature for 2.5 hours, and then 3.0 g of 1% hydrochloric acid was added to the reaction solution, followed by stirring and liquid separation. 10% aqueous sodium hydroxide solution in the organic layer
After adding 7.1 g and stirring while heating to about 40°C, the liquid was separated. The aqueous layer was neutralized with dilute sulfuric acid and extracted with toluene. After washing the toluene layer with water, concentrate and distill to determine the boiling point.
1.8 g of distillate at 110-119°C/2.5 mmHg was obtained. The infrared absorption spectrum of this product matched that of Daiichichrysanthemum acid. In addition, when the geometric isomer ratio of the distillate was measured, it was found that the cis isomer ratio was 7.0% and the trans isomer ratio was 93.0%.
It was hot.

Example 2 In a 30 ml flask under nitrogen atmosphere, cis-dairy chrysanthemum acid
Add 3.0g of boron tribromide and 26.5g of toluene, then add 0.034g of boron tribromide and toluene to this solution at 15-20℃.
A mixture of 0.5 g and 0.5 g was added dropwise and stirred for 1 hour. Next, 1 g of 10% hydrochloric acid was added to the reaction solution, stirred, and then separated. After washing the organic layer with water, it was concentrated under reduced pressure to 3.0
g of a concentrated solution was obtained. As a result of gas chromatography analysis of this product, the content of Daiichichrysanthemum acid was 99.3.
% (yield 99.3%), and the geometric isomer ratio is cis form.
11.5%, and 88.5% trans isomer.

Example 3 Cis isomer 70.0 in a 50 ml flask in a nitrogen stream
%, 2.0 g of Daiichi Chrysanthemum acid with a composition of 30.0% trans isomer,
Add 17.0 g of toluene and 0.005 g of t-butyl hydroperoxide, then add 0.012 g of boron tribromide and 1.0 g of toluene while stirring at 20°C.
A mixed solution of was added dropwise. After dropping, stirring was continued for 1.0 hour at the same temperature, then 3.0 g of 10% hydrochloric acid was added and stirred.
The liquid was separated. 10% aqueous sodium hydroxide solution in the organic layer
7.1 g was added, and the mixture was extracted and separated while heating to about 40°C. The aqueous layer was neutralized with dilute sulfuric acid, extracted with toluene, and the organic layer was washed with water. This toluene solution is concentrated and then distilled to produce a distillate with a boiling point of 110-119℃/2.5mmHg.
1.82g was obtained. The infrared absorption spectrum of this product matched that of Daiichichrysanthemum acid. In addition, when the geometric isomer ratio of the distillate was measured, it was found that the cis isomer ratio was 6.0%;
It was 94.0% trans-isomer.

Claims (1)

[Scope of Claims] 1. A method for producing trans-based chrysanthemum acid, which comprises reacting cis or mixed cis/trans-based chrysanthemum acid with boron bromide in the presence or absence of an organic hydroperoxide. 2. The method for producing trans-synthetic acid according to claim 1, which is carried out in the presence of an organic hydroperoxide.