JPH066554B2 - Method for producing trans dairy chrysanthemate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing trans primary chrysanthemate. More specifically, the general formula (I) (In the formula, R represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group or an aralkyl group.) The cis primary chrysanthemic acid ester represented by the formula (1) contains boron in the presence or absence of organic hydroperoxide. The present invention relates to a method for producing a corresponding trans primary chrysanthemic acid ester by reacting bromide with trans.

Primary chrysanthemic acid constitutes the acid component of a low-toxic, fast-acting insecticidal ester called so-called pyrethroid such as pyrethrin, allethrin and phthalthrin, and is useful as a raw material for these pyrethroid insecticides.

By the way, primary chrysanthemic acid has cis and trans geometrical isomers, and it is known that the insecticidal effect of trans-form ester is stronger than that of cis-form ester. Therefore, trans-transformation of the cis form into a trans form is far more advantageous from the viewpoint of insecticidal efficacy than using a cis form or an ester containing a large amount of cis form.

Conventionally, the primary chrysanthemate is 2,5- as shown in the following formula.
It is widely industrially produced by the method of reacting dimethyl-hexa-2,4-diene and diazoacetic acid ester.

However, the primary chrysanthemate obtained by the method is
It is obtained by mixing the desired product, the trans form and the cis form.

Therefore, a technique for converting a cis or cis / trans mixed primary chrysanthemate to a trans form is important.

Conventionally, as a method for converting cis-primary chrysanthemate to trans-primary chrysanthemate, a cis-primary chrysanthemate is combined with an alkali metal lower alkyl primary alcoholate in the presence of a lower alcohol to give about 150 ℃ ~ 200
A method of operating at ℃ (Japanese Patent Publication No. 40-6457),
Alternatively, a method of treating with a special basic catalyst (Japanese Patent Publication Sho 53)
No. 18495, Japanese Patent Publication No. 53-18496, etc.), and a method of reacting cis-primary chrysanthemate with boron trifluoride etherate, iron chloride, aluminum chloride, etc. (JP-A-57-176930). )It has been known.

As a result of various studies on the method for producing an ester primary chrysanthemate, the present inventors have found that the cis primary chrysanthemate or the cis / trans mixed primary chrysanthemate shown by the general formula (I) contains boron. Surprisingly, it has been found that by reacting bromide, it can be converted into a corresponding trans form extremely smoothly and efficiently as compared with the known method.
By carrying out this in the presence of an organic peroxide, it was found that trans-formation can be carried out more easily, and various studies were conducted to arrive at the present invention.

That is, the present invention, the cis primary chrysanthemic acid ester represented by the general formula (I), the corresponding ester by reacting boron bromide in the presence or absence of organic hydroperoxide to trans-form A method for producing a primary chrysanthemic acid ester is provided.

According to the method of the present invention, a catalytic amount of bromide of boron is allowed to act on a cis primary chrysanthemate or a mixed cis / trans primary chrysanthemate to convert it into a trans form at room temperature in a short time. And a trans isomer or a primary chrysanthemate rich in it is obtained as a product.
Further, the amount of boron bromide used can be further reduced by carrying out the method of the present invention in the presence of organic hydroperoxide.

The trans-primary chrysanthemate obtained by the method of the present invention or the primary chrysanthemate rich in it is hydrolyzed as an ester or by adding an alkaline aqueous solution according to a conventional method to lead to a carboxylic acid. Can be used for the above-mentioned purpose, and a highly effective insecticidal compound can be obtained by reacting with a group of alcohols called pyrethroid alcohol.

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

In the cis primary chrysanthemate represented by the general formula (I) used as a raw material in the present invention, the substituent R is a carbon such as a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group or a benzyl group. Examples thereof include an alkyl group, a cycloalkyl group and an aralkyl group having a number of 1 to 20.

Further, the cis-primary chrysanthemate may be a cis isomer alone or a mixture with a trans isomer in an arbitrary ratio.

A typical example of the boron bromide used in the method of the present invention is boron tribromide, which may form a complex with a small amount of water, acid, alcohol, ether or the like. The amount used is 1/2000 to 1/10 mol, preferably 1 per mol of the primary chrysanthemate.
It is in the range of / 1000 to 1/20 mol.

Examples of the organic hydroperoxide 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 hydroperoxide, etc. (2) Aromatic hydroperoxide Kyumen hydroperoxide Diisopropylbenzene hydroperoxide, etc.

The amount used is usually 1/10 to 5 mol, preferably 1/4 to 2 mol, based on 1 mol of the boron bromide used. When carrying out the method of the present invention, it is preferable to use an inert solvent, and examples of such a solvent include saturated hydrocarbons, aromatic hydrocarbons and their halides, ethers and the like.

Further, the reaction temperature is not particularly limited, but usually, the object can be sufficiently achieved within the range of -20 ° C to 40 ° 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 several minutes to 10 hours.

When the method of the present invention is carried out, it is usually carried out by dissolving the primary chrysanthemic acid ester to be treated in a solvent and adding the bromide of boron to this, and when carried out in the presence of organic hydroperoxide. Is usually dissolved in a solvent to be treated primary chrysanthemic acid ester and hydroperoxide, and then added to the bromide of boron, or the treated primary primary chrysanthemic acid ester is dissolved in a solvent, then to this It is performed by an operation of pouring hydroperoxide and boron bromide together.

The progress of the reaction can be obtained by sampling a part of the reaction solution and analyzing it by gas chromatography or the like.

The reaction liquid after the reaction as described above is washed with, for example, hydrochloric acid water and then concentrated to obtain the target trans primary chrysanthemic acid ester or the enriched primary chrysanthemic acid ester.

In addition, the primary chrysanthemic acid ester thus obtained can be easily converted to trans-primary chrysanthemic acid or its rich primary chrysanthemic acid by hydrolyzing it with an alkaline aqueous solution according to a conventional method. It can be obtained and further purified by distillation, chromatography or the like, if necessary, to obtain a pure trans form.

As described in detail above, according to the method of the present invention, trans conversion of cis-primary chrysanthemate can be easily carried out in a high yield, which is extremely advantageous particularly for industrial production of trans-primary chrysanthemate. become.

Next, the method of the present invention will be described with reference to examples.

Example 1 In a flask of 50 ml volume, 40.7% of cis isomer in a nitrogen stream,
Trans-form 59.3% composition of the first chrysanthemic acid ethyl ester 2.0
g and 17.0 g of toluene were added, and a mixed solution of 0.041 g of boron tribromide and 1.0 g of toluene was added dropwise thereto while stirring at 20 ° C. After the dropwise addition, stirring was continued for 2 hours, 3.0 g of 10% hydrochloric acid was added, and the mixture was stirred and separated. The organic layer was taken, washed with water, dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to obtain 2.03 g of an oily substance. The oily substance was distilled to obtain 1.88 g of a fraction having a boiling point of 85 to 88 ° C./10 mmHg. The distillate was confirmed to be primary chrysanthemic acid ethyl ester from its infrared absorption spectrum, and when the geometrical isomer ratio was determined by gas chromatography, the cis isomer was 7.0%,
The trans form was 93.0%.

Example 2 A 50 ml flask was charged with 2.0 g of cis-primary chrysanthemic acid ethyl ester and 18.0 g of n-heptane in a nitrogen atmosphere, 0.26 g of boron tribromide was added dropwise thereto, and the mixture was stirred at 15 ° C. for 3 hours. did.

After the reaction, ice water was added to the reaction solution and the mixture was stirred, and after liquid separation, the organic layer was evaporated under reduced pressure to obtain 1.96 g of a residual liquid. This was heated under reflux with 10.2 g of a 10% aqueous sodium hydroxide solution for 3 hours, and then toluene was added for liquid separation to remove a neutral substance as a toluene layer. The aqueous layer was acidified with hydrochloric acid and extracted with toluene. The organic layer was washed with water, dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to obtain 1.6 g of a residual liquid. The residual liquid is distilled to a boiling point of 110-119.
1.53 g of a fraction having a temperature of 2.5 mmHg was obtained. From the infrared absorption spectrum, the distillate was confirmed to be primary chrysanthemic acid. The geometrical isomer ratio was determined by gas chromatography to find that the cis isomer was 7.6% and the trans isomer was 92.4.
%Met.

Example 3 In a flask of 50 ml volume, in a nitrogen stream, 40.7% cis isomer,
Trans-form 59.3% composition of the first chrysanthemic acid ethyl ester 2.0
g, 17.0 g of toluene, and 0.008 g of t-butyl hydroperoxide were added, and a mixed solution of 0.023 g of boron tribromide and 1.0 g of toluene was added dropwise thereto while stirring at 20 ° C. Stirring is continued for 1 hour after dropping, then 10% hydrochloric acid 3.0 g
Was added, and the mixture was stirred and then separated. The organic layer was collected, washed with water, dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to give 2.01 g.
An oily substance was obtained. The oil is distilled to a boiling point of 85 to 88 ° C.
1.93 g of a fraction of / 10 mmHg was obtained. The infrared absorption spectrum of the distillate confirmed that it was ethyl chrysanthemate, and the geometrical isomer ratio was determined by gas chromatography to find that the cis product was 6.5% and the trans product was 93.5%.
Met.

Example 4 In a 30 ml flask, cis-body 35.0% in a nitrogen stream,
Trans-isomer 65.0% composition of primary chrysanthemic acid ethyl ester 2.0
18.0 g of n-heptane and 0.08 g of cumyl hydroperoxide were added to g, and 0.13 g of boron tribromide was added dropwise thereto while stirring at 360 ° C., and the mixture was stirred for 1 hour. Next, after cooling to room temperature, 1.5 g of water was added to wash and separate the liquid, and then the solvent was distilled off under reduced pressure to obtain 1.95 g of a residual liquid.

The residual liquid is distilled to obtain a fraction having a boiling point of 85 to 88 ° C./10 mmHg.
1.84 g was obtained. The infrared absorption spectrum of the distillate confirmed that it was ethyl chrysanthemate and its geometrical isomer ratio was determined by gas chromatography to reveal that it was 5.9% cis and 94.1% trans. there were.

Claims (2)

[Claims] 1. A general formula (In the formula, R represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group or an aralkyl group.) In the cis or cis / trans mixed primary chrysanthemate, in the presence of organic hydroperoxide or A process for producing a trans-chrysanthemic acid ester, which comprises reacting boric acid bromide in the presence thereof to form trans. 2. The method for producing trans primary chrysanthemate according to claim 1, which is carried out in the presence of organic hydroperoxide.