JPS6130666B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for directly producing chloro-β-trifluoromethylpyridines from β-picoline or chloro-β-picolines, and more specifically, in the presence of a catalyst and an inert diluent.
- A method for producing chloroβ-trifluoromethylpyridines (hereinafter abbreviated as β-TFPs) by reacting picolines with chlorine and anhydrous hydrogen fluoride in the gas phase. β-TFPs are compounds useful as raw materials for agricultural chemicals such as herbicides and insecticides, dyes, and medicines, and their industrial value has recently attracted attention. The method for producing β-TFPs involves blowing chlorine gas into a carbon tetrachloride solution under ultraviolet irradiation to produce chloroβ-trichloromethylpyridines, and then adding chloroβ-trichloromethylpyridines to the liquid phase. A method of producing it by reacting it with anhydrous hydrogen fluoride or antimony trifluoride is known, but
It is not suitable for industrial use because the reaction takes a long time, a large amount of by-products are generated, and the yield is low. In the present invention, β-
This method is based on the knowledge that when picoline or chloro β-picolines are brought into contact with chlorine and anhydrous hydrogen fluoride to react in a gas phase, β-TFPs are produced in a single step and in a short time. That is, in the present invention, in the presence of a catalyst consisting of a fluoride of at least one metal element selected from the group consisting of aluminum, chromium, iron, and nickel, and an inert diluent,

A general formula characterized by reacting a pyridine compound represented by [Formula] (wherein X ¹ and Y ¹ are hydrogen atoms or chlorine atoms) with chlorine and anhydrous hydrogen fluoride in a gas phase.

This is a method for producing chloroβ-trifluoromethylpyridines represented by the formula: (wherein X ² and Y ² are hydrogen atoms or chlorine atoms, at least one of which is a chlorine atom). The pyridine compound used in the present invention is β
- In addition to picoline, 2-chloro-β-picoline, 6
-chloro-β-picoline or 2,6-dichloro-
Examples include chloroβ-picolines of β-picoline. In particular, β-picoline is easily available as a raw material for various organic synthetic chemical industries, and the method of the present invention is advantageous because chloroβ-trifluoromethylpyridines can be directly produced from it. Aluminum used as a catalyst in the present invention,
Fluorides of chromium, iron, and nickel include hydrated aluminum trifluoride (AlF _{3.3H 2} O), aluminum trifluoride (AlF ₃ ), and hydrated chromium trifluoride (CrF ₃ .
3H ₂ O), chromium trifluoride (CrF ₃ ), hydrated ferrous fluoride (FeF _{2.8H 2} O), ferrous fluoride (FeF ₂ ), ferric fluoride
Iron (FeF ₃ ), hydrated nickel fluoride (NiF ₂
3H ₂ O), nickel fluoride (NiF ₃ ), and the like. Although the amount of the catalyst to be used cannot be absolutely defined depending on the reaction conditions, it is usually 0.01 to 3 moles per mole of the pyridine compound as a raw material. Usually, this catalyst is mixed with a carrier such as activated carbon or activated alumina, formed into particles or pellets of an appropriate size, and then placed in the form of a fixed bed or a fluidized bed. There is also a method in which the catalyst is directly placed in the reaction tube in the form of a fluoride of the metal element, but industrially, it is placed in the reaction tube in the form of an oxide or chloride of the metal element. Preference is given to the method in which it is present by reaction with anhydrous hydrogen fluoride and conversion to the fluoride. For example, chromium trioxide, dichloride, etc. on an alumina carrier
A molded product supporting an oxide or chloride of the metal element such as iron or nickel oxide is placed in a reaction tube, and anhydrous hydrogen fluoride is introduced in advance to react at 200 to 600°C to form a fluoride of the metal element. The reaction according to the present invention is carried out after the conversion to . Inert diluents include carbon tetrachloride, chloroform, methylene chloride, F-112 (CFCl ₂ / CFCl ₂ ),
Organic solvents for halogenated hydrocarbons such as F-113 (CF ₂ Cl/CFCl ₂ ) and inert gases such as nitrogen, helium, and argon can be used; It has the function of suppressing generation. In carrying out the present invention, the raw material and the inert diluent can be supplied to the reactor separately, or they can be supplied in a mixed state, and they can be supplied simultaneously or sequentially, all at once or in parts. . For example, a mixture of a pyridine compound and an inert diluent or a mixture of chlorine and anhydrous hydrogen fluoride are fed separately. The amount of chlorine and anhydrous hydrogen fluoride to be used cannot be absolutely specified depending on the type of raw material pyridine compound, the type of target product, the reaction equipment, etc., but in general, it is 2 to 15 mol and 2 mol, respectively, per 1 mole of raw material pyridine compound. ~60 moles, and the amount of inert diluent used is typically 2 to 70 moles per mole of starting pyridine compound. The reaction temperature is generally 300-600°C, and the residence time of the reaction mixture in the reaction zone is usually 3-600°C.
It is 60 seconds. Usually, gaseous substances containing fluorinated products mainly composed of β-TFPs, unreacted hydrogen fluoride and chlorine, intermediate products, by-product hydrogen chloride, and inert diluents are released from the reactor. is discharged, and β-TFPs are collected as a liquid mixture through appropriate cooling and condensation equipment. The liquid mixture generally contains 2-chloro-5-trifluoromethylpyridine, 2-chloro-3-trifluoromethylpyridine and 2.6-trifluoromethylpyridine.
-dichloro-3-trifluoromethylpyridine is contained, and β-TFPs can be obtained at a production rate of, for example, 85% or more. β in the collected liquid mixture
- When intermediate products that have not reached the stage of producing TFPs are included, these intermediate products can be separated and recovered together with unreacted raw materials or an inert diluent, and recycled to the reaction zone. Furthermore, the above-mentioned β-TFPs are subjected to ordinary purification treatments such as extraction, distillation, and crystallization to obtain, for example, 2-TFPs.
A single compound of β-TFPs such as chloro-5-trifluoromethylpyridine can be obtained with high purity. Next, examples of the method of the present invention will be described, but the scope of the method of the present invention is not limited by these descriptions. Example 1 A stainless steel reaction tube with an inner diameter of 42 mm and a length of 1250 mm was used as the reaction section, and the rear part of the reaction tube was
A catalyst packed bed with a length of 250 mm was installed in a 500 mm section. On the other hand, as a preheating section, a stainless steel preheating tube with an inner diameter of 20 mm and a length of 500 mm was used for anhydrous hydrogen fluoride and chlorine, and a stainless steel preheating tube with an inner diameter of 20 mm was used for β-picoline and carbon tetrachloride.
A stainless steel preheating tube with a length of 500 mm and a length of 500 mm was used. The reaction tube and preheating tube were covered with an electric heater and heat insulating material and installed at an angle so that the temperature could be controlled from the outside. A mixture of 0.03 mol of hydrated chromium trifluoride and 200 g of activated alumina with a particle size of 4 to 6 mm was filled into the catalyst-filled part of the reaction tube, and the reaction tube was heated to 430°C to inject 1 g of anhydrous hydrogen fluoride. /min for 2 hours. β-Picoline 280 was then preheated at 230°C.
g (3 moles) and 2310 g (15 moles) of carbon tetrachloride, as well as 960 g (13.5 moles) of chlorine and 480 g (24 moles) of anhydrous hydrogen fluoride preheated at 300° C., were fed at a substantially constant flow rate over a period of 290 minutes; The reaction was carried out in the gas phase at 430°C. The residence time of the reaction mixture in the tube was about 9 seconds. The gas discharged from the reaction tube was condensed through a water washing tower and an alkali washing tower. The oily substance was separated, collected, washed with water, dried over sodium sulfate, and carbon tetrachloride was distilled off under reduced pressure to obtain 420 g of an oily substance. This oily substance was analyzed by temperature-rising gas chromatography and the results are shown in Table 1 below. Example 2 300 g of γ-alumina was placed in the catalyst packed bed of the reaction tube used in Example 1, and after activation with anhydrous hydrogen fluoride in the same manner as in Example 1,
465 g (5 mol) of β-picoline preheated at 250°C, 3850 g (25 mol) of carbon tetrachloride, 1950 g (27.5 mol) of chlorine and 900 g (45 mol) of anhydrous hydrogen fluoride preheated at 300°C were added in about 8 hours. The gas phase reaction was carried out at a reaction temperature of 430° C. and a residence time of the reaction mixture in the tube of 10.5 seconds. The gas discharged from the reaction tube was treated in the same manner as in Example 1 to obtain 708 g of an oily substance. This oily substance was analyzed by temperature-rising gas chromatography and the results are shown in Table 1 below. Example 3 Instead of 300 g of γ-alumina, 200 g of activated carbon with a particle size of 2 to 4 mm was used to support 0.1 mole of hydrated nickel fluoride, and the catalytic activity of alumina was increased with anhydrous hydrogen fluoride. The reaction was carried out in the same manner as in Example 2, except that
300 g of oil was obtained. The results of analyzing this oily substance by heating gas chromatography are shown in the following table. Other components in the table are the total amounts of chloroβ-perchlorofluoromethylpyridines and the like.

[Table] Example 4 As a reactor, the reaction section has an inner diameter of 82 mm and a height of 1100 mm.
A vertical Inconel reaction tube with a fluidized bed of catalyst was installed, with an internal diameter of 8.
Two connected Inconel preheating tubes with a length of 2000 mm were used, and the reaction tube and preheating tube were covered with an electric heater and a heat insulator so that the temperature could be controlled. As a catalyst, the activated catalyst used in Example 1 was pulverized to a particle size of 0.18 to 0.4 mm1.7
Kg was filled into the reaction section. The reactor was heated to 430°C and β-picoline was heated to 3.6
Mix at approximately 200°C through a preheating tube to mix nitrogen gas at a rate of 11.3 g/min and nitrogen gas at a rate of 11.3/min, and chlorine gas at a rate of 2.8/min and anhydrous hydrogen fluoride at a rate of 2.5/min. It was introduced as a gas into the reaction tube and reacted for about 5 hours.
The residence time of the reaction mixture in the tube was about 7 seconds. The gas discharged from the reactor was treated in the same manner as in Example 1 to obtain 1,680 g of an oily substance.Table 2 shows the results of analyzing this oily substance by heating gas chromatography. Example 5 In the same manner as in Example 4, β-picoline was supplied at a rate of 2.38 g/min, 3-trifluoromethylpyridine was supplied at a rate of 1.88 g/min, and nitrogen gas was supplied at a rate of 11.3/min. Chlorine gas was supplied at a rate of 2.8/min and anhydrous hydrogen fluoride at a rate of 2.5/min, and the reaction was carried out for about 3 hours. The residence time of the reaction mixture in the tube was about 7 seconds. The gas discharged from the reactor was treated in the same manner as in Example 1 to obtain 1090 g of an oily substance, which was analyzed by temperature-rising gas chromatography and the results are shown in Table 2. Other components in the table are the total amounts of β-trifluoromethylpyridine, β-dichloromethylpyridines having a chlorine atom in the pyridine nucleus, β-fluorodichloromethylpyridines, β-chlorodifluoromethylpyridines, and the like.

[Table] Example 6 As a reactor, the reaction part has an inner diameter of 97.1 mm and a height of 1570 mm.
An Inconel vertical reactor with a catalyst fluidized bed of 30mm internal diameter was installed for feed material and inert diluent.
Two connected Inconel preheating tubes with a length of 1000 mm were used, and the reaction tube and preheating tube were covered with an electric heater and a heat insulator so that the temperature could be controlled. 277g of anhydrous ferric chloride impregnated with 2.2Kg of aluminum trifluoride with a particle size of 105 to 250μ is placed in the catalyst packing section, heated to 200℃, and anhydrous hydrogen fluoride is introduced at a rate of 2.3/min for 1 hour. The catalyst was activated by The reactor was heated to 400℃ and β-picoline was heated to 6.8℃.
g/min and nitrogen gas at a rate of 9.9/min through a preheating tube, and chlorine gas at a rate of 7.4/min and anhydrous hydrogen fluoride through a preheating tube at a rate of 7.4/min, respectively, at approximately 200℃. It was introduced as a gas into the reaction tube and reacted for about 30 hours.
During this period, activated catalyst was continuously supplied and discharged at a rate of 300 g/hour. The residence time of the reaction mixture in the tube was about 3.4 seconds. The gas discharged from the reactor was passed through a water washing tower and an alkali washing tower, and the condensed product was decomposed, neutralized with an aqueous ammonia solution, and subjected to steam distillation to obtain 19.11 kg of oil. This oil is distilled to obtain an initial distillate containing β-trifluoromethylpyridine as the main component.
1.53Kg, main distillate 9.56Kg and tail distillate mainly composed of 2-chloro-5-trifluoromethylpyridine
Obtained 7.62Kg. In addition, 2-chloro-5 is included in the after-distillate.
-trifluoromethylpyridine 3.7%, 2-chloro-3-trifluoromethylpyridine 14.5%,
It contained 47.7% of 2,6-dichloro-3-trifluoromethylpyridine and 34.1% of others.

Claims (1)

[Claims] 1. In the presence of a catalyst consisting of a fluoride of at least one metal element selected from the group consisting of aluminum, chromium, iron and nickel, and an inert diluent,
A pyridine compound represented by the general formula [formula] (wherein X ¹ and Y ¹ are hydrogen atoms or chlorine atoms) is reacted with chlorine and anhydrous hydrogen fluoride in a gas phase. A method for producing chloroβ-trifluoromethylpyridines represented by the formula (wherein X ² and Y ² are hydrogen atoms or chlorine atoms, at least one of which is a chlorine atom).