JPH1053573A - Production of 2,3-dihalogeno-6-trifluoromethyl benzamidoxime - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound useful as an agrochemical/medicine, esp. agricultural/horticultural germicide, in short process by oximating a benzaldehyde compound followed by amidoximating the reaction product. SOLUTION: First, a 2,3-dihalogeno-6-trifluoromethylbenzaldehyde of formula I (X1 and X2 are each F, Cl or Br) is oximated to form a compound of formula II, which, in turn, is amidoximated to obtain the objective compound of formula III, e.g. 2,3-dichloro-6-trifluoromethylbenzamidoxime. For the oximation, the compound of formula I is reacted with hydroxylamine in an inert solvent. For the amidoximation, a halogenating agent such as N-chlorosuccinimide is made to act on the compound of formula II to effect conversion to the corresponding imidoyl halide, which, in turn, is subjected to ammonia. Thus, the objective 2,3-dihalogeno-6-trifluoromethylbenzamidoxime can be obtained easily in high yield and in short process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing 2,3-dihalogeno-6-trifluoromethylbenzamide oxime, which is useful as a fungicide intermediate for agricultural and horticultural use.

[0002]

2. Description of the Related Art Hitherto, 2,3-dihalogeno-6-trifluoromethylbenzamide oximes have been produced via 2,3-dihalogeno-6-trifluoromethylbenzonitrile (WO / 19442). reference).
However, this method has problems such as a low yield and a long reaction step.

[0003]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for preparing 2,3-dihalogeno-6-trifluoromethylbenzaldehyde as a starting material.
An object of the present invention is to provide an industrially excellent method for producing dihalogeno-6-trifluoromethylbenzamide oxime.

[0004]

That is, the present invention provides a compound represented by the general formula (I):

[0005]

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(Wherein X ¹ and X ² are the same or different and each represents a fluorine atom, a chlorine atom or a bromine atom), and the compound represented by the general formula (II)

[0007]

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(Wherein X ¹ and X ² have the same meanings as described above), and then are converted to amide oximes.

[0009]

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(Wherein, X ¹ and X ² have the same meanings as described above), which is a process for producing 2,3-dihalogeno-6-trifluoromethylbenzamide oxime.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The benzaldehyde represented by the general formula (I), which is a raw material of the compound of the present invention, can be produced as follows.

[0012]

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(Wherein X ¹ and X ² are the same or different and each represents a fluorine atom, a chlorine atom or a bromine atom).

In the first step of the present invention, the oximation reaction from the compound of the general formula (I) to the compound of the general formula (II) is carried out by reacting hydroxylamine in an inert solvent. The hydroxyamine may be in the form of a hydrochloride or a sulfate. The solvent used for the reaction is not particularly limited as long as it is an inert solvent. For example, alcohols such as methanol, ethanol, propanol and isopropanol, water, acetonitrile and the like can be exemplified. The reaction proceeds smoothly within the range from room temperature to the boiling point of the solvent used.

In the second step, the amide oximation reaction from the compound of the general formula (II) to the compound of the general formula (III) comprises
In an inert solvent, a halogenating agent is allowed to act to give imidoyl halide (IV), and then ammonia is caused to act. The reaction solvent is not particularly limited as long as it is inert. For example, in the halogenation step, halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, and 1,2-dichloroethane may be mentioned. In the amidoximation step, alcohols such as methanol, ethanol, propanol and isopropanol may be used. Water, acetonitrile and the like can be mentioned.

Examples of the halogenating agent include N-chlorosuccinimide, N-bromosuccinimide, chlorine, bromine, sulfuryl chloride, hypochlorite and the like. Ammonia can be used in the form of ammonia water, in addition to ammonia gas or an alcohol solution of ammonia such as methanol or ethanol. The reaction is -1
It proceeds smoothly in the temperature range from 0 ° C. to the boiling point of the solvent used. The following shows the manufacturing process of the present invention.

[0017]

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The compound of the formula (II) is reacted with acetic anhydride to give the compound of the formula (V)

[0019]

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(Wherein X ¹ and X ² have the same meanings as described above). The reaction is usually performed by heating and refluxing the compound represented by the general formula (II) in acetic anhydride. The present compounds are also useful as pesticide intermediates.

In any case, after completion of the reaction, the desired product can be obtained by performing ordinary post-treatment. The structure of the compound of the present invention was determined from IR, NMR, MASS and the like.

[0022]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention thereto.

Example 1 (Synthesis of 2,3-dichloro-6-trifluoromethylbenzaldehyde oxime)

[0024]

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4.86 g (0.02 mol) of 2,3-dichloro-6-trifluoromethylbenzaldehyde was dissolved in 30 ml of ethanol, and 2.78 g of hydroxylamine hydrochloride was dissolved.
g (0.04 mol) was added and the mixture was heated under reflux for 1 hour. After cooling, the reaction solution was poured into ice water, extracted with ethyl acetate, and the organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 5.0 g of the desired product. 97% yield. m
p. 102-104 ° C.

Example 2 (Synthesis of 2,3-difluoro-6-trifluoromethylbenzaldehyde oxime)

[0027]

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9.0 g (42.8 mmol) of 2,3-difluoro-6-trifluoromethylbenzaldehyde was dissolved in 50 ml of ethanol, and 3.
39 g (85.6 mmol) was added, and the mixture was heated under reflux for 1 hour. After cooling, the reaction solution was poured into ice water, extracted with ethyl acetate, and the organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 9.4 g of the desired product. Yield 9
7.6%. mp. 111-112 ° C.

Example 3 (Synthesis of 2,3-difluoro-6-trifluoromethylbenzamide oxime)

[0030]

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2.25 g (10 mmol) of 2,3-difluoro-6-trifluoromethylbenzaldehyde oxime
l) was dissolved in 20 ml of chloroform, and 1.59 g (12 mmol) of N-chlorosuccinimide was dissolved while cooling with ice water.
1) was added, and the reaction solution was returned to room temperature and stirred for 2 hours.
Then, low-boiling substances were distilled off under reduced pressure, and ether was added to the residue. The precipitated crystals are filtered off, and the filtrate is treated with 0.5 g of ammonia.
(30 mmol) was dropped into a solution of 10 ml of ethanol, and the mixture was stirred as it was for 30 minutes. The solvent was distilled off under reduced pressure, the residue was extracted with ethyl acetate, and the organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain the desired product 1.9.
g was obtained. Yield 79.2%. mp. 105-107 ° C.

Example 4 (Synthesis of 2,3-difluoro-6-trifluoromethylbenzamide oxime)

3.5 g (15 mmol) of 2,3-difluoro-6-trifluoromethylbenzaldehyde oxime
l) was dissolved in 20 ml of chloroform, and 2 g (30 mmol) of chlorine was blown in over 30 minutes while cooling with ice water. The reaction solution was returned to room temperature and stirred for another 2 hours. Next, the residue obtained by evaporating low-boiling substances from the reaction solution under reduced pressure was dropped into a mixture of 4.6 g of 28% aqueous ammonia and 20 ml of ethanol, and the mixture was stirred for 30 minutes. The reaction solution was concentrated under reduced pressure, the residue was extracted with ethyl acetate, and the organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 2.72 g of the desired product. Yield 72.9%.

Reference Example 1 (Synthesis of 2,3-dichloro-6-trifluoromethylbenzonitrile)

[0035]

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2,3-dichloro-6-trifluoromethylbenzaldehyde oxime 5.0 g (19.3 mmol)
1) was dissolved in acetic anhydride (20 ml) and heated under reflux for 4 hours. Excess acetic anhydride was distilled off from the reaction solution under reduced pressure, the residue was dissolved in ethyl acetate, and the ethyl acetate solution was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by distillation to obtain 4.2 g of the desired product. 90.3% yield. m
p. 53-54 ° C.

Reference Example 2 (Synthesis of 2,3-difluoro-6-trifluoromethylbenzonitrile)

[0038]

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3.0 g (13.3 mm) of 2,3-difluoro-6-trifluoromethylbenzaldehyde oxime
ol) was dissolved in 12 ml of acetic anhydride and heated under reflux for 4 hours. Excess acetic anhydride was distilled off from the reaction solution under reduced pressure, the residue was dissolved in ethyl acetate, and the solution was washed with water and dried over anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the residue was purified by distillation to obtain 2.33 g of the desired product. Yield 84.4%. 9
8-100 ° C / 25mmHg.

[0040]

As described above, according to the production method of the present invention, 2,3-dihalogeno-6-trifluoromethylbenzamide oxime can be obtained in a simple, high yield, and short process. This is an industrially superior method. The compound of the present invention is useful as an intermediate for the synthesis of agrochemicals, in particular, agricultural and horticultural fungicides.

Claims (1)

[Claims] 1. A compound of the general formula (I) (Wherein X ¹ and X ² are the same or different and each represents a fluorine atom, a chlorine atom or a bromine atom), and the compound represented by the general formula (II) is converted to an oxime. (Wherein X ¹ and X ² have the same meanings as described above), and then are converted to an amide oxime. (Wherein X ¹ and X ² have the same meanings as described above.) A method for producing 2,3-dihalogeno-6-trifluoromethylbenzamide oxime represented by the formula: