JPS625421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a nitrobenzonitrile derivative represented by the general formula () is reacted with a fluoride of an element in Group 1 of the periodic table in an aprotic polar solvent. The present invention relates to a method for producing a fluoropenzonitrile derivative represented by ().

General formula () General formula () (In the formula, X represents a halogen atom of Cl, Br, I, or F, and n represents 0 to 4.) Fluorobenzonitrile derivatives are useful substances as agricultural chemicals and agricultural chemical intermediates, but until now they have not been used industrially. There is no way to manufacture it cheaply.

The present inventor developed a nitrobenzonitrile derivative, which can be easily obtained by substituting a cyano group for the halogen group of a halogenonitrobenzene derivative, which can be obtained at low cost as a raw material, in an aprotic polar solvent. It has been found that fluorobenzonitrile derivatives can be obtained in good yield by substituting nitro groups with fluoro groups under mild conditions by reacting with a fluorinating agent consisting of a fluoride. Conventionally, a common method for converting an aromatic nitro group into a fluoro group is to reduce the nitro group to an amino group, and then introduce a fluoro group by a Siemann reaction. However, this method has drawbacks such as long reaction steps, low total yield, and large amounts of waste water and waste. The method of the present invention also includes a halogen exchange reaction (for example, converting 2,6-dichlorobenzonitrile to 2-chlorobenzonitrile using potassium fluoride).
6-Fluorobenzonitrile (method for synthesizing 6-fluorobenzonitrile), the product can be obtained under mild conditions compared to the method for producing fluorobenzonitrile derivatives;
Since the physical properties of the raw materials and the products are significantly different, the inventors discovered that this is an industrially advantageous production method because it facilitates the separation and purification of the products after the reaction, leading to the completion of the present invention. .

The nitrobenzonitrile derivatives used in the present invention include 2-nitrobenzonitrile, 3-nitrobenzonitrile, 4-nitrobenzonitrile, 2-chloro-6-nitrobenzonitrile, 2-nitrobenzonitrile,
-Chlor-4-nitrobenzonitrile, 3-chloro-6-nitrobenzonitrile, 4-chloro-6
-Nitrobenzonitrile, 2,3-dichloro-6
-Nitrobenzonitrile, 2,4-dichloro-6
-Nitrobenzonitrile, 2-bromo-6-nitrobenzonitrile, 2-bromo-4-nitrobenzonitrile, 3-bromo-6-nitrobenzonitrile, 4-bromo-6-nitrobenzonitrile,
3-Bromo-4-nitrobenzonitrile, 2,3
-dibromo-6-nitrobenzonitrile, 2,4
-dibromo-6-nitrobenzonitrile, 2-iodo-6-nitrobenzonitrile, 2-iodo-
4-nitrobenzonitrile, 2-fluoro-6-
Compounds having a cyano group and a nitro group on the benzene ring, such as nitrobenzonitrile and 2-fluoro-4-nitrobenzonitrile, preferably have a nitro group at the ortho or para position of the cyano group.

Fluorides used as fluorinating agents include:
Fluorides of elements in group of the periodic table, such as cesium fluoride, rubidium fluoride, potassium fluoride,
Sodium fluoride, lithium fluoride, silver fluoride, silver fluoride, cuprous fluoride, and cupric fluoride are used. Although the reaction of cesium fluoride and rubidium fluoride proceeds satisfactorily, they are expensive. In addition, the reaction progresses slower with sodium fluoride and lithium fluoride than with others. Practically speaking, potassium fluoride, which is industrially available at low cost, is particularly preferred.
Although expensive, silver fluoride, which has a good selectivity for the main reaction in this reaction and can be easily recovered by conventional methods after the reaction, is also used as a useful fluorinating agent. The amount of the fluorinating agent to be used is preferably 0.5 to 5.0 times, more preferably 1.0 to 3.0 times, by mole, relative to the nitrobenzonitrile derivative used.

Examples of the aprotic polar solvent include N,N-dimethylformamide, N,N-diethylformamide, dimethylsulfoxide, dimethylsulfone,
Tetramethylene sulfone, acetamide, hexamethylphosphoramide, N-methylpyrrolidone,
N,N'-dimethylimidazolidone and the like are used. The amount used is 0.5 to 10.0 parts by weight of the nitrobenzonitrile derivative used as a raw material.
Parts by weight are preferred, particularly 1.0 to 5.0 parts by weight.

The reaction temperature and reaction time vary depending on the type and amount of solvent used, but the reaction temperature is generally 50°C.
The temperature range is preferably from 100°C to 200°C, preferably from 100°C to 140°C. A suitable reaction time is 0.5 to 20.0 hours.

After the reaction is completed, the inorganic substances are separated and the liquid is distilled under reduced pressure, whereby the desired fluorobenzonitrile derivative can be easily separated from the unreacted nitrobenzonitrile derivative.

Further, the used solvent and unreacted nitrobenzonitrile derivative can be recovered and reused.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of dimethyl sulfoxide was added to 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. After the completion of the reaction, the inorganic substances were separated, and the product in the liquid was quantified by gas chromatography to obtain 2-chloro-6-fluorobenzonitrile in a yield of 70.3%.

Example 2 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of dimethyl sulfoxide was added to 18.2 g of cesium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 2 hours. Post-treatment was performed in the same manner as in Example 1 to obtain 2-chloro-fluorobenzonitrile in a yield of 89.7%.

Example 3 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of dimethyl sulfoxide was added to 30.8 g of silver fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. Post-treatment was performed in the same manner as in Example 1 to obtain 2-chloro-6-fluorobenzonitrile in a yield of 85.2%.

Example 4 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of dimethyl sulfoxide was added to 5.0 g of sodium fluoride, and the mixture was reacted at a reaction temperature of 160° C. for 6 hours. Post-processing was performed in the same manner as in Example 1,
2-chloro-6-fluorobenzonitrile was obtained with a yield of 37.4%.

Example 5 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of N,N-dimethylformamide was added to 7.0 g of potassium fluoride and reacted at a reaction temperature of 120° C. for 6 hours. Post-treatment was performed in the same manner as in Example 1 to obtain 2-chloro-6-fluorobenzonitrile in a yield of 63.6%.

Example 6 2-chloro-6-nitrobenzonitrile 18.2
60.0 g of N-methylpyrrolidone was added to 7.0 g of potassium fluoride and reacted at a reaction temperature of 120° C. for 12 hours. Post-treatment was performed in the same manner as in Example 1 to obtain 2-chloro-6-fluorobenzonitrile in a yield of 52.5%.

Example 7 60.0 g of dimethyl sulfoxide was added to 14.8 g of 2-nitrobenzonitrile and 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. Post-treatment was carried out in the same manner as in Example 1, and 2 was obtained with a yield of 66.2%.
-Fluorobenzonitrile was obtained.

Example 8 60.0 g of dimethyl sulfoxide was added to 14.8 g of 4-nitrobenzonitrile and 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 140° C. for 6 hours. Post-treatment was carried out in the same manner as in Example 1, and 4 was obtained with a yield of 45.2%.
-Fluorobenzonitrile was obtained.

Example 9 4-chloro-6-nitrobenzonitrile 18.2
60.0 g of dimethyl sulfoxide was added to 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. Post-treatment was performed in the same manner as in Example 1 to obtain 4-chloro-6-fluorobenzonitrile in a yield of 69.2%.

Example 10 2,3-dichloro-6-nitrobenzonitrile
60.0 g of dimethyl sulfoxide was added to 21.7 g of potassium fluoride and 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. Post-processing was performed in the same manner as in Example 1,
2,3-dichloro-6-fluorobenzonitrile was obtained with a yield of 72.0%.

Example 11 2-bromo-6-nitrobenzonitrile 22.7
60.0 g of dimethyl sulfoxide was added to 7.0 g of potassium fluoride, and the mixture was reacted at a reaction temperature of 120° C. for 6 hours. Post-treatment was performed in the same manner as in Example 1, and the yield was
2-bromo-6-fluorobenzonitrile was obtained at 68.7%.

Example 12 The reaction and post-treatment were carried out in the same manner as in Example 2 except that 12.6 g of rubidium fluoride was used instead of 18.2 g of cesium fluoride, and 2-chloro-
6-fluorobenzonitrile was obtained.

Example 13 2, instead of 14.8 g of 2-nitrobenzonitrile
3,4-trichloro-6-nitrobenzonitrile
The reaction and post-treatment were carried out in the same manner as in Example 7, except that 25.2 g was used, and 2,3,4-trichloro-6-fluorobenzonitrile was obtained in a yield of 73.5%.

Example 14 Instead of 14.8 g of 2-nitrobenzonitrile, 2-
The reaction and post-treatment were carried out in the same manner as in Example 7, except that 27.4 g of iodo-6-nitrobenzonitrile was used, and 2-iodo-6-fluorobenzonitrile was obtained in a yield of 68.3%.

Example 15 Instead of 14.8 g of 2-nitrobenzonitrile, 2-
The reaction and post-treatment were carried out in the same manner as in Example 7, except that 16.6 g of fluoro-6-nitrobenzonitrile was used, and 2,6-difluorobenzonitrile was obtained with a yield of 65.4%.

Claims (1)

[Scope of Claims] 1. A nitrobenzonitrile derivative represented by the general formula () is reacted with a fluoride of an element in Group 1 of the periodic table in an aprotic polar solvent. ) A method for producing a fluorobenzonitrile derivative represented by General formula () General formula () (In the formula, X represents a halogen atom of Cl, Br, I, F, and n represents 0 to 4)