JPS6130664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for directly producing β-trifluoromethylpyridine from β-picoline, in which β-picoline is combined with chlorine and anhydrous hydrogen fluoride in the presence of a catalyst and a diluent. β-Trifluoromethylpyridine (hereinafter abbreviated as TF) is produced by reacting in the gas phase.
Relating to a method of manufacturing.

TF is a compound useful as a raw material for agricultural chemicals such as herbicides and insecticides, dyes, and medicines.

Conventionally, a known method for producing TF is to react nicotinic acid and sulfur tetrafluoride in a liquid phase at 150° C. for 3 hours in an autoclave in the presence of hydrogen fluoride. However, this method uses sulfur tetrafluoride, which is dangerous to handle.
It cannot be said to be an industrially suitable manufacturing method because it requires the use of an autoclave.

The present invention is based on the knowledge that TF is produced in a short time when β-picoline is brought into contact with chlorine and anhydrous hydrogen fluoride in the gas phase to react in the presence of a catalyst and a diluent.

That is, the present invention provides aluminum, chromium, iron,
Reacting β-picoline with chlorine and anhydrous hydrogen fluoride in the gas phase in the presence of a diluent and a catalyst consisting of a fluoride of at least one metal element selected from the group consisting of nickel, cobalt and manganese. A method for producing β-trifluoromethylpyridine, characterized by the following.

β-picoline used in the present invention is easily available as a raw material for various organic synthetic chemical industries,
The method of the invention is advantageous because TF can be produced directly from it.

Aluminum used as a catalyst in the present invention,
Fluorides of chromium, iron, nickel, cobalt and manganese include aluminum trifluoride (AlF ₃ ),
Chromium difluoride (CrF ₂ ), chromium trifluoride (CrF ₃ ),
Ferrous fluoride (FeF ₂ ), ferric fluoride (FeF ₃ ), nickel fluoride (NiF ₂ ), nickel fluoride (NiF ₃ ), cobalt fluoride (CoF ₂ ), Cobalt fluoride (CoF ₃ ), manganese fluoride (MnF ₂ ), manganese fluoride (MnF ₃ ), manganese tetrafluoride (MnF ₄ ), and the like can be mentioned. Although the amount of the catalyst to be used cannot be absolutely defined depending on the reaction conditions, it is usually 0.001 to 3 moles per mole of β-picoline as a raw material. This catalyst is usually activated carbon, activated alumina,
It is mixed with a carrier such as aluminum trifluoride, formed into particles or pellets of an appropriate size, and then placed in a fixed bed or a fluidized bed. There is also a method in which the catalyst is present in the form of a fluoride of the metal element directly into the reaction tube, but industrially it is present in the form of an oxide, chloride, carbonate of the metal element, or Advantageously, they are present in the form of hydrates in a reaction tube and converted into fluorides by reaction with anhydrous hydrogen fluoride. For example, oxides and chlorides of the metal elements such as chromium trioxide, nickel oxide, and ferric chloride are supported on an alumina carrier, and this is placed in a reaction tube and anhydrous hydrogen fluoride is introduced in advance.
The reaction according to the present invention is carried out after the reaction is carried out at 200 to 600°C to convert the metal element into a fluoride.

Diluents include carbon tetrachloride, chloroform, methylene chloride, F-112 (CFCl ₂ / CFCl ₂ ), F-
Organic solvents for halogenated hydrocarbons such as 113 (CF ₂ Cl, CFCl ₂ ) and inert gases such as nitrogen, helium, and argon can be used; these diluents inhibit combustion, carbonization, and the formation of tar-like byproducts. It has the function of

In carrying out the present invention, the raw materials and diluent can be supplied to the reactor separately, or they can be supplied in a mixed state. For example, the raw material β-picoline is supplied after being vaporized as it is, or once dissolved in an organic solvent and then vaporized, and anhydrous hydrogen fluoride is supplied after being vaporized as is. When these substances are supplied, they are appropriately mixed with chlorine or a diluent before being subjected to the reaction.

The amounts of chlorine and anhydrous hydrogen fluoride to be used cannot be absolutely specified due to differences in other reaction conditions, reaction equipment, etc., but are generally 2.5 to 6 mol and 2.5 to 10 mol, respectively, per 1 mol of β-picoline as a raw material. The amount of diluent used is usually 2 to 70 moles per mole of β-picoline starting material. The reaction temperature is generally between 300 and 600℃ and the residence time of the reaction mixture in the reaction zone is usually between 0.5 and 30 seconds.

Normally, gaseous substances containing fluorinated products mainly composed of TF, unreacted hydrogen fluoride and chlorine, intermediate products, by-product hydrogen chloride, and diluents are discharged from the reactor. After passing through appropriate cooling and condensation equipment, TF is collected as a liquid mixture. TF can be obtained, for example, at a production rate of 60% or more. When the collected liquid mixture contains intermediate products that have not reached the level of TF production, these intermediate products can be separated and recovered together with unreacted raw materials or diluent, and recycled to the reaction zone. can. In addition, β- containing one or more chlorine atoms in the pyridine nucleus
When perchlorofluoromethylpyridines or β-trifluoromethylpyridines are contained, they can be appropriately reduced and, if necessary, recycled to the reaction zone again to be induced into TF.

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: As a reactor, the reaction part has an inner diameter of 151 mm and a height of 1440 mm.
An Inconel vertical reaction tube with a catalyst fluidized bed of 1.0 mm in diameter was installed, and two Inconel preheating tubes with an inner diameter of 40 mm and a length of 1500 mm were connected for the raw material and diluent. It was covered with an electric heater and insulation material to control the temperature. The catalyst filling section was filled with a mixture of 970 g of hydrated chromium trifluoride and 12 kg of activated alumina with a particle size of 0.18 to 0.4 mm, and the reaction tube was heated to 430°C and 20 kg of anhydrous hydrogen fluoride was added.
/min for 3 hours.

The reactor was heated to 380°C and β-picoline was
Mix at approximately 200°C through a preheating tube to mix nitrogen gas at a rate of 41 g/min and nitrogen gas at a rate of 41/min, and chlorine gas at a rate of 14.9/min and anhydrous hydrogen fluoride at a rate of 21/min, respectively. It was introduced as a gas into the reaction tube and reacted for about 6 hours. During this time, the above-mentioned activated catalyst was continuously supplied and discharged at a rate of 3 kg/hour. The residence time of the reaction mixture in the tube was about 3.9 seconds.

The gas discharged from the reactor was condensed through a water washing tower and an alkali washing tower. The oily substance was separated and collected, washed with water to obtain 8.2 kg of oily substance, and this oily substance was rectified to obtain the desired β-trifluoromethylpyridine.
5.8Kg was collected.

In this example, the procedure was the same except that the mixture of hydrated chromium trifluoride and activated alumina was replaced with a prescribed amount of an anhydrous ferric chloride and aluminum trifluoride mixture and a prescribed amount of alumina. When carried out, almost the same results as those described above were obtained.

Claims (1)

[Claims] 1 β-picoline, chlorine and anhydrous hydrogen fluoride in the presence of a catalyst and diluent consisting of a fluoride of at least one metal element selected from the group consisting of aluminum, chromium, iron, nickel, cobalt and manganese. 1. A method for producing β-trifluoromethylpyridine, which comprises reacting in a gas phase to produce β-trifluoromethylpyridine.