JPH0822835B2 - Process for producing trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention has the general formula (I) (In the formula, X represents a halogen atom, and R represents an alkyl group, a cycloalkyl group or an aralkyl group.), Cis 2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester To a corresponding trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester by translating.

<Conventional technology. Problems to be Solved by the Invention> 2,2-Dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid (hereinafter, abbreviated as dihaloacid) is not only for household and epidemic prevention but also for agricultural pests or It constitutes an acid component such as the insecticides permethrin and cypermethrin, which also show 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 the ester derived from the trans form is less toxic to warm-blooded animals than the ester derived from the cis form. It has been known. (Nature, 24
4, 456 (1973)).

The dichlorate ester is usually produced by reacting 1,1-dichloro-4-methyl-1,3-pentadiene with a diazoacetate ester. It is produced as a mixture of cis isomers. Therefore, conversion of the cis form to the trans form has industrial significance.

For the primary chrysanthemum acid ester in which X in the general formula (I) corresponds to a methyl group, a method of converting a cis form into a trans form using an alkali metal alkoxide has been proposed (Japanese Patent Publication No. 56-12625). Issue).

However, when this method using an alkali metal alkoxide is applied to a dihaloacid ester, the transhalogenation reaction hardly proceeds, or even if it proceeds, the dehalogenation reaction of the dihalovinyl group occurs simultaneously (Tetrahedro).
n Letters, 23 , 5003 (1982)), the problem was that the yield of dihaloacid ester was extremely low.

<Means for Solving the Problems> As a result of intensive investigations by the present inventors to find out a better method for producing a trans isomer by trans-transforming the cis isomer of dihaloacid ester, the presence of titanium alkoxide If you act alkali metal alkoxide below,
Surprisingly and conveniently, it was found that the trans-reaction can be efficiently and selectively proceeded, and further various studies were conducted to complete the present invention.

That is, the invention has the general formula (I) (In the formula, X represents a halogen atom and R represents an alkyl group, a cycloalkyl group or an aralkyl group.) Cis 2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester The present invention provides an industrially excellent method for producing a corresponding trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester by converting the compound into trans.

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

Examples of the dihalo acid ester (I) which is a raw material of the present invention include methyl, ethyl, propyl, butyl, cyclohexyl, cyclohexylmethyl, benzyl and other esters of dichloric acid, dibromic acid and the like. Preferably it is an ethyl ester.

Further, the dihaloester may be a cis isomer alone or a mixture with a trans isomer at an arbitrary ratio, but when the cis isomer alone or a cis isomer-rich dihaloacid halide is used in view of the purpose of the present invention, its significance is exerted. Needless to say.

Examples of the alkali metal of the alkali metal alkoxide used in the present invention include lithium, sodium, potassium and the like. As for alkoxide,
Examples thereof include methoxide, ethoxide, n-propoxide, isopropoxide, t-butoxide, Sec-butoxide, isobutoxide, pentanoxide and hexanoxide.

Of these, alkoxides of lithium and sodium are preferable, and lithium ethoxide, lithium propoxide, sodium ethoxide, sodium propoxide and the like are more preferable.

The amount used is usually relative to the dihaloester to be treated.
The amount is 1/20 to 1 mol times, preferably 1/10 to 1/3 mol times.

Examples of titanium alkoxides include tetramethoxy titanium, tetraethoxy titanium, tetra-n-propoxy titanium, tetraisopropoxy titanium and tetra-
Examples thereof include n-butoxy titanium, tetraisobutoxy titanium, tetra-Sec-butoxy titanium and tetra-t-butoxy titanium.

The amount used is generally 1/1 with respect to the dihalic acid halide to be treated.
It is 50 to 1/2 molar times, preferably 1/20 to 1/5 molar times.

The method of the present invention is usually carried out by mixing the dihaloacid ester and titanium alkoxide in the absence of a solvent, and then mixing the alkali metal alkoxide.

The reaction temperature varies depending on the amount and type of titanium alkoxide, alkali metal alkoxide, etc.,
It is usually 50 to 200 ° C, preferably 100 to 150 ° C. The reaction time also varies depending on the amount and type of titanium alkoxide, alkali metal alkoxide, etc. used, but usually 1 to
It takes about 15 hours.

The progress of the reaction can be determined by sampling a part of the reaction solution and analyzing it 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 dihaloacid ester can be used as it is as a raw material for biochemical optical resolution, or can be converted to a free acid by adding an alkaline aqueous solution or the like and hydrolyzing it according to a conventional method.

<Effect of the Invention> Thus, the desired trans dihaloacid ester is produced, but the method of the present invention brings advantages such as the ability to produce a trans-form ester extremely efficiently.

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

Example 1 To 5 g of dichloric acid ethyl ester consisting of 57.6% of cis isomer and 42.4% of trans isomer, 342 mg of tetraethoxy titanium was added under nitrogen atmosphere and stirred for 10 minutes, and then 286 mg of lithium ethoxide was added and the mixture was heated at 140 ° C. for 4 hours. It was stirred.

After the reaction, the mixture was cooled to room temperature, washed with water, and then distilled to obtain 4.81 g of a fraction having a boiling point of 88 to 90 ° C./1 mmHg. This was confirmed to be dichloroic acid ethyl ester by infrared absorption spectrum.

As a result of analysis by gas chromatography,
It was 24.2% and the trans form was 75.8%.

Example 2 To 5 g of cis dichloric acid ethyl ester consisting of 96.4% of cis isomer and 3.6% of trans isomer, 755 mg of tetraethoxy titanium was added under nitrogen atmosphere and stirred for 10 minutes, and then 861 mg of sodium ethoxide was added and the mixture was heated at 100 ° C. for 4 hours. It was stirred.

After the reaction, post-treatment was carried out in the same manner as in Example 1 to obtain 4.2 g of dichloroic acid ethyl ester.

The isomer ratio was 26.0% for cis and 74.0% for trans.

Example 3 The procedure of Example 2 was repeated except that 1.49 g of tetraisopropoxy titanium and 803 mg of sodium ethoxide were used instead of tetraethoxy titanium and the mixture was stirred at 140 ° C. for 4 hours, and 4.05 g of dichloroic acid ethyl ester was used. Got

The isomer ratio was cis 29.7% and trans 70.3%.

Example 4 The procedure of Example 1 was repeated except that 1.36 mg of tetraethoxy titanium and 1.56 g of sodium isopropoxide were used instead of lithium ethoxide, to obtain 4.22 g of ethyl dichlorate and isopropyl dichlorate. A mixture (65.3: 36.5) was obtained.

The isomer ratio was 19.5% for cis and 80.5% for trans.

Example 5 In Example 1, 597 mg of tetraethoxy titanium, and sodium methoxide 33 instead of lithium ethoxide were used.
The same procedure as in Example 1 was carried out except that 5 mg was used to obtain 4.32 g of a mixture of dichloric acid methyl ester and dichloric acid ethyl ester (11.8: 88.2).

The isomer ratio was 38.9% for cis and 61.1% for trans.

Example 6 Example 1 was repeated except that 5 g of dichloromethyl ester consisting of cis isomer 44.1% and trans isomer 55.9%, tetraethoxy titanium 1.27 g, and lithium ethoxide 932 g were used in place of dichloric acid ethyl ester. In the same manner, 4.73 g of a mixture of dichloric acid methyl ester and dichloric acid ethyl ester (16:84) was obtained.

 The isomer ratio was cis 33% and trans 67%.

Example 7 In Example 1, 5 g of isopropyl dichlorate consisting of 96.6% of cis isomer and 3.4% of trans isomer instead of ethyl dichlorate was used, and tetraethoxy titanium 455 m
g, Example 1 except that lithium ethoxide 528 mg was used.
The same procedure was followed to obtain 4.37 g of a mixture of dichloroic acid ethyl ester and dichloroic acid isopropyl ester (27.9: 72.1).

The isomer ratio was 24.6% for cis and 75.4% for trans.

Reference Example 1 The same dichlorochrysanthemic acid ethyl ester used in Example 2
263 mg of lithium ethoxide was added to 5 g, and the mixture was stirred at 140 ° C. for 4 hours.

After the reaction, the same procedure as in Example 2 was carried out to obtain 4.75 g of ethyl dichlorochrysanthemic acid ester.

The isomer ratio was 95.8% for cis and 4.2% for trans.

Reference Example 2 The procedure of Reference Example 1 was repeated except that 1.22 g of sodium ethoxide was used instead of lithium ethoxide to obtain 3.1 g of dichlorochrysanthemic acid ethyl ester.

 The isomer ratio was 25% cis and 75% trans.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masami Fukao 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Kagaku Kogyo Co., Ltd. (56) References Japanese Patent Publication Sho 56-12625 (JP, B2)

Claims (1)

[Claims] 1. A general formula (In the formula, 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)- Of trans-2,2-dimethyl-3- (2,2-dihalovinyl) -cyclopropanecarboxylic acid ester characterized in that an alkali metal alkoxide is allowed to act on cyclopropanecarboxylic acid ester in the presence of titanium alkoxide Production method.