JP2629863B2 - Trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the general formula (1) (In the formula, X represents a halogen atom, and R represents an alkyl group, a cycloalkyl group or an aralkyl group.) A cis 2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester represented by the following formula: To produce the corresponding trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester.

<Conventional technology. Problems to be Solved by the Invention> 2,2-Dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid (hereinafter abbreviated as dihalic acid) is used not only for household and epidemic control but also for agricultural pests or It constitutes an acid component such as the insecticides permethrin and cypermethrin, which exhibit excellent efficacy against forest pests. Dihaloesters are useful as intermediates for these pesticides.

Dihalo acids have cis and trans geometric isomers based on a three-membered ring, but esters derived from trans are less toxic to warm-blooded animals than esters derived from cis. It has been known. (Nature, 24
4 , 456 (1973)).

Dihaloesters are usually produced by reacting 1,1-dihalo-4-methyl-1,3-pentadiene with diazoacetate, and the dihaloesters obtained by the process are trans-forms. It is produced as a mixture of cis isomers. Therefore, conversion of the cis form to the trans form has industrial significance.

Heretofore, as a method of converting a cis-dihalo acid ester into a corresponding trans form, a method of irradiating light in the presence of a photosensitizer has been proposed (Japanese Patent Application Laid-Open No. 52-5738).
However, this method is not industrially satisfactory because it consumes a large amount of energy and has a photo-steady state at a cis / trans ratio of 4/6 of the product.

<Means for Solving the Problems> The present inventors have conducted intensive studies to find a better method for producing a trans form by trans-transforming a cis form of a dihalo acid ester. ,
Surprisingly, it has been found that the trans-form is efficiently produced, and it is found that the trans-formation proceeds more smoothly if this is carried out in the presence of iodine halide. Completed the invention.

That is, the present invention relates to (1) a compound represented by the general formula (I): (Wherein X represents a halogen atom, and R represents an alkyl group, a cycloalkyl group or an aralkyl group.) 2,2-Dimethyl-3- (2,2-dihalovinyl) -mixed cis or cis / trans A process for producing trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester, which comprises reacting silicon iodide with cyclopropanecarboxylic acid ester; It is intended to provide a production method which is carried out in the coexistence of iodine iodide.

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

Examples of the dihalic acid ester (I) which is a raw material of the present invention include methyl, ethyl, dichloroic acid, dibromoic acid and the like.
Esters such as propyl, butyl, cyclohexyl, cyclohexylmethyl, benzyl and the like can be mentioned. Preferably it is an ethyl ester.

The dihaloester may be a cis-form alone or a mixture with a trans-form in an arbitrary ratio. However, in view of the object of the present invention, the dihaloester exhibits its significance when using a cis-form alone or a cis-form-rich dihaloester. Needless to say.

The silicon iodide used in the present invention typically includes silicon tetraiodide. The amount used is usually 1/50 to 1 mol times, preferably 1/25 to 1/2 mol times, relative to the dihalic acid ester to be treated.

Further, in the present invention, trans-formation can be made to proceed more smoothly by coexisting with iodine halide. In that case, the amount of the iodine halide to be used is usually 1/200 to 1 mol, preferably 1/100 to 1/5 mol, relative to the dihalic acid ester to be treated.

Examples of such halogenated iodine include iodine, bromoiodide, chloroiodide and the like.

In carrying out the method of the present invention, it is usually carried out in the presence of a solvent. Any solvent may be used as long as it does not inhibit the reaction, and examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, cumene, trimethylbenzene, and nitrobenzene, chloroform, carbon tetrachloride, dichloroethane, chlorobenzene, and 0-. Examples thereof include halogenated hydrocarbons such as dichlorobenzene and bromobenzene, and nitriles such as acetonitrile, propionitrile, and butyl nitrile. Preferably, halogenated hydrocarbons and nitriles are used.

The reaction is usually carried out by dissolving the dihalo ester to be treated in a solvent and adding iodide of silicon, and when using iodine halide, further adding it.

The reaction temperature varies depending on the amount of silicon iodide, the amount of iodine halide, etc. used, the type of solvent, and the like.
The temperature is 150 ° C, preferably 15 to 150 ° C. The reaction time also varies depending on the amount of silicon iodide, iodine halide, etc. used, the type of solvent and the like, but is usually about 0.5 to 15 hours.

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

Thus, the desired trans dihalo acid ester is produced. The desired product can be isolated by, for example, distillation after removing the catalyst from the reaction mass.

The obtained trans dihalo acid ester can be used as it is as a raw material for biochemical optical resolution, or can be derived into a free acid by adding an alkaline aqueous solution or the like and hydrolyzing it according to a conventional method.

<Effect of the Invention> Although the intended trans dihaloester is thus produced, the method of the present invention has an advantage that the trans-ester can be produced very efficiently.

<Examples> Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited only to these.

Example 1 After dissolving 2.5 g of dichloroethyl ethyl ester composed of 57.6% of cis form and 42.4% of trans form in 10 g of chlorobenzene, 1.01 g of silicon tetraiodide was added thereto under a nitrogen atmosphere, and the mixture was heated at 100 ° C.
For 4 hours.

After the reaction, the mixture was cooled to room temperature, washed with water, and distilled to obtain 1.89 g of a fraction having a boiling point of 88 to 90 ° C / 1 mmHg. The product was confirmed to be ethyl dichlorate from the infrared absorption spectrum.

As a result of analysis by gas chromatography,
It was 24.1% and trans form was 75.9%.

Example 2 The same ethyl dichlorate used in Example 1 2.
After dissolving 5 g in 22.5 g of acetonitrile, 571 mg of silicon tetraiodide and 278 mg of iodine were added thereto under a nitrogen atmosphere.
Stirred at 80 ° C. for 4 hours.

After the reaction, the mixture was cooled to room temperature, washed with 9 g of a 2% aqueous solution of sodium thiosulfate, and then washed with water. By distilling the obtained organic layer, 2.25 g of ethyl dichlorate was obtained. The analysis results were 15.5% for the cis form and 84.5% for the trans form.

Example 3 In Example 2, instead of stirring at 80 ° C. for 4 hours, 25
The procedure was carried out in the same manner as in Example 2 except for stirring at 4 ° C. for 4 hours to obtain ethyl dichlorate. The analysis results were 34.1% for the cis form and 65.9% for the trans form.

Example 4 The procedure of Example 2 was repeated, except that 15.4 g of acetonitrile, 503 mg of silicon tetraiodide, and 209 mg of bromine iodide were used instead of iodine and stirred at 80 ° C. for 5 hours.
94 g of ethyl dichlorate were obtained.

The analysis results were cis form 23.9% and trans form 76.1%.

Example 5 The procedure of Example 2 was repeated except that 13.5 g of acetonitrile, 582 mg of silicon tetraiodide, and 183 mg of chlorine iodide were used instead of iodine and stirred at 80 ° C. for 4 hours.
86 g of ethyl dichlorate were obtained.

The analysis results were 21.2% for the cis form and 78.8% for the trans form.

Example 6 In Example 2, 9.2 g of chlorobenzene was used in place of acetonitrile, 2.5 g of dichloroethyl ethyl ester composed of 96.3% of cis-form and 3.7% of trans-form, silicon tetraiodide
The same operation as in Example 2 was carried out except that the mixture was stirred at 50 ° C. for 6 hours using 579 mg of iodine and 259 mg of iodine to obtain 1.97 g of ethyl dichlorate.

The analysis results were 17.8% for the cis form and 82.2% for the trans form.

Example 7 In Example 2, 22.5 g of dichloroethane was used instead of acetonitrile, 573 mg of silicon tetraiodide and 246 m of iodine were used.
In the same manner as in Example 2 except that g was used, 2.01 g of ethyl dichlorate was obtained.

The analysis results were 18.6% for the cis form and 81.4% for the trans form.

Claims (2)

(57) [Claims] (1) General formula (Wherein X represents a halogen atom, and R represents an alkyl group, a cycloalkyl group or an aralkyl group.) 2,2-Dimethyl-3- (2,2-dihalovinyl) -mixed cis or cis / trans A process for producing trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester, comprising reacting iodine substitute of silicon with cyclopropanecarboxylic acid ester. 2. The process according to claim 1, which is carried out in the presence of iodine halide.