JPH0339496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing trifluoromethylbenzal chloride or a derivative thereof, in particular, a method for producing trifluoromethylbenzal chloride or a derivative thereof, by reacting trichloromethylbenzal chloride or a derivative thereof with hydrogen fluoride to produce the corresponding trifluoromethylbenzal chloride or The present invention relates to a method for producing the derivative.

Trifluoromethylbenzal chloride or its derivatives are useful as intermediates for medicines, agricultural chemicals, and dyes. Among these, it has been reported that orthotrifluoromethylbenzal chloride can be produced by reacting the corresponding trichloromethylbenzal chloride and hydrogen fluoride in a heterogeneous system in a liquid phase (Anal.Chim. Acta.10, P34, 1954; J.Chem.
Soc.4003, 1960). In this case, the temperature is 90-150℃
The pressure is high, ranging from 70 to 140 atm. However, in this method, the reaction rate is not sufficient, it is necessary to carry out the reaction for a long time using a large excess of hydrogen fluoride to improve the yield, the yield of the target product is low, and the reaction is difficult to achieve under high pressure. It was unsuitable as an industrial production method because it required stirring and had problems with the equipment. On the other hand, regarding meta, para-trifluoromethylbenzal chloride or their derivatives, the corresponding meta-, para-trichloromethylbenzal chloride or their derivatives are heated at about 1 to 3 atm in the presence of a halogen transfer catalyst such as antimony pentachloride. A method has been proposed in which fluorination is performed using hydrogen fluoride under a pressure of However, even with this production method, the yield is quite low and is not industrially satisfactory.

In order to improve the various drawbacks associated with conventional methods, the present inventors conducted studies on the gas phase catalytic reaction of trichloromethylbenzal chloride or its derivatives with hydrogen fluoride at around normal pressure, and found that aluminum fluoride and hydrogen fluoride We have discovered that by using a catalyst in combination with a specified metal fluoride, the target trifluoromethylbenzal chloride or its derivatives can be selectively obtained in extremely high yields, and the reaction rate is also sufficiently high. This has led to the completion of the present invention. That is, in the present invention, the raw material trichloromethylbenzal chloride or its derivative has two trichloromethyl groups and a dichloromethyl group.
Among the active groups that can be fluorinated, only the former trichloromethyl group can be selectively fluorinated with a high yield. According to the present invention, in the presence of aluminum fluoride and a fluoride of one or more metals selected from the group consisting of zinc, chromium, manganese, iron, and nickel,
Production of trifluoromethylbenzal chloride or a derivative thereof, which is characterized by reacting trichloromethylbenzal chloride or a derivative thereof with hydrogen fluoride in a gas phase to obtain the corresponding trifluoromethylbenzal chloride or a derivative thereof. law is provided.

Conventionally, for example, in JP-A-54-130524, trichloromethylbenzene or its derivatives were reacted with hydrogen fluoride in the presence of aluminum fluoride to produce the corresponding trifluoromethylbenzene or its derivatives. A method is disclosed. However, when using trichloromethylbenzal chloride or its derivatives, which are the raw materials of the present invention, with known catalysts such as the above-mentioned aluminum fluoride, the fluorination reaction generally proceeds as a sequential reaction, resulting in by-products. It is difficult to selectively obtain trifluoromethylbenzal chloride or its derivatives in high yield.

Trichloromethylbenzal chloride or its derivative used as a starting material in the present invention is o
-, m-, p-trichloromethylbenzal chloride or hydrogen of their benzene ring to fluorine, chlorine, bromine, alkyl group such as methyl group, nitro group,
Substituted with a cyano group, etc., and specific examples include 2-chloro-3-trichloromethylbenzal chloride, 2-chloro-4-trichloromethylbenzal chloride, 2-chloro-6-trichloromethylbenzal chloride, 2-chloro-5-trichloromethylbenzal chloride, 3-chloro-4-
Trichloromethylbenzal chloride, 3-chloro-6-trichloromethylbenzal chloride, 2-
Trichloromethyl-4-chlorobenzal chloride, 2-trichloromethyl-5-chlorobenzal chloride, 3-trichloromethyl-4-chlorobenzal chloride, 3-chloro-5-trichloromethylbenzal chloride, 2,4-dichloro- 3-trichloromethylbenzal chloride, 2.5-dichloro-3-trichloromethylbenzal chloride,
2.4-dichloro-6-trichloromethylbenzal chloride, 2.6-dichloro-3-trichloromethylbenzal chloride, 2-fluoro-3-trichloromethylbenzal chloride, 2-fluoro-5
-trichloromethylbenzal chloride, 2-fluoro-6-trichloromethylbenzal chloride,
3-Trichloromethyl-4-fluorobenzal chloride, 3-fluoro-5-trichloromethylbenzal chloride, 2.5-difluoro-3-trichloromethylbenzal chloride, 2-bromo-3-
Trichloromethylbenzal chloride, 2-bromo-5-trichloromethylbenzal chloride, 2-
Bromo-6-trichloromethylbenzal chloride, 3-bromo-5-trichloromethylbenzal chloride, 2.5-dichloro-4-trichloromethylbenzal chloride, 2-fluoro-4-trichloromethylbenzal chloride, 2-trichloromethyl -5-fluorobenzal chloride, 3-fluoro-4-trichloromethylbenzal chloride,
2.5-difluoro-3-trichloromethylbenzal chloride, 2-bromo-4-trichloromethylbenzal chloride, 3-bromo-4-trichloromethylbenzal chloride, 2-trichloromethyl-
Examples include 5-nitrobenzal chloride, 3-trichloromethyl-5-methylbenzal chloride, and 2-trichloromethyl-5-cyanobenzal chloride. Among these, when o-trichloromethylbenzal chloride or its derivatives are used as a raw material, the reaction targeted by the present invention can be carried out more selectively. Preferred effects can be obtained when the derivative is substituted with a halogen atom, particularly chlorine.

In the present invention, it is extremely important to use at least one fluoride selected from the group consisting of zinc, chromium, manganese, iron, and nickel, preferably iron fluoride, together with aluminum fluoride as a catalyst. Even if the conditions are in accordance with the present invention, the reaction rate (conversion rate) of trichloromethylbenzal chloride or its derivative as a raw material, the proportion of trifluoromethylbenzal chloride or its derivative as the target substance in the product (selectivity) ) or both may become significantly lower, resulting in a decrease in yield. The reason why the desired trifluoromethylbenzal chloride or its derivatives can be obtained with high conversion rate and selectivity by using the combination catalyst of the above-mentioned aluminum fluoride and the specified metal fluoride of the present invention will be explained in detail. Although it is not known, the reaction to obtain the desired fluorinated product involves several steps of fluorination reaction, intermolecular and This is thought to be due to the fact that the specified metal fluoride catalytically contributes to different types of elementary reactions, which consist of elementary reactions such as intramolecular heterogenization reactions.

The aluminum fluoride used in the present invention is not limited by crystal type etc., and α-, β-, γ-aluminum fluoride or a mixture thereof can be used. Among these, the α type is particularly preferred. The fluorides of zinc, chromium, manganese, iron, and nickel used in the present invention include zinc fluoride (ZnF ₂ ), chromium difluoride (CrF ₂ ), chromium trifluoride (CrF ₃ ), and chromium tetrafluoride ( CrF ₄ ), manganese fluoride (MnF ₂ ), manganese fluoride (MnF ₃ ), manganese tetrafluoride (MnF ₄ ), ferrous fluoride (FeF ₂ ), ferric fluoride (FeF ₃ ), nickel fluoride (NiF ₂ ), nickel fluoride (NiF ₃ ), etc., and hydrates of these compounds are also used.

The proportion of one or more metals selected from the group consisting of iron, chromium, nickel, zinc, and manganese used for aluminum fluoride is usually 0.2 to 20% by weight based on the amount of aluminum fluoride.
It is preferably 0.5 to 10% by weight and needs to be finely dispersed. If the proportion of the metal fluoride is out of the above range, the effect of the combination of two or more metal fluorides, which is a feature of the present invention, cannot be expected in terms of conversion rate and selectivity of the reaction. The best way to prepare such a catalyst in the present invention is to place the metal salt specified above inside porous aluminum fluoride particles in the form of an aqueous solution, or by using a solvent other than water that can be dispersed by heating. The form of the solution, e.g.
After absorbing the nitrate or chloride in the form of an aqueous solution and heating, the aluminum fluoride particles carrying the obtained metal salt are injected into a hydrogen fluoride gas stream diluted with nitrogen or other inert gas or air as necessary. In this method, metal salts are converted into metal fluorides by heating at a temperature range of usually up to 500°C. In this case, it is not necessarily necessary to convert all metal salts such as chlorides other than the above-mentioned fluorides into fluorides, and it is also possible to subject aluminum fluoride carrying the metal salts to the reaction. The metal salt is converted into a fluoride in order to achieve the desired purpose. In this case, the aluminum fluoride particles preferably have a porosity of 25 to 80% and a surface area of 15 m ² /g or more as measured by the BET method.
Those having a particle size of 30 m ² /g or more and a pore size of 20 to 2000 Å are preferably used, and from the viewpoint of handling during reaction, etc., the average particle size is preferably 20 to 1000 μm, preferably 50 to 500 μm. The method for producing such aluminum fluoride particles is not particularly limited, and any known method may be used. Another method for preparing catalysts is to support salts of other metals on activated alumina having appropriate porosity, surface area, and particle size in the same manner as described above without converting it into aluminum fluoride in advance, and then A method in which both the activated alumina and the metal salt supported thereon are simultaneously fluorinated with hydrogen fluoride is also used.

It is necessary to control the feed ratio of trichloromethylbenzal chloride or its derivative, which is the starting material of the present invention, and hydrogen fluoride to 3 to 6 moles, preferably 3.2 to 4.8 moles, of the latter to 1 mole of the former. If the amount of hydrogen fluoride supplied is less than the lower limit of the above range, the conversion rate will be low, and if it is more than the upper limit, the selectivity will drop sharply. In the present invention, there is no problem in adding a gas such as nitrogen or argon or a low-boiling organic compound that does not participate in the reaction to the reaction system as a diluent. Furthermore, the reaction temperature in the present invention is 180 to 400°C.
Preferably, the temperature is 200 to 350°C; if the reaction temperature is lower than this range, the reaction rate will be low, which is industrially disadvantageous; if the reaction temperature is too high, the reaction selectivity will decrease or the catalyst will deteriorate rapidly. do. The reaction pressure is not particularly limited and can be carried out under increased pressure or reduced pressure, but it is usually carried out around normal pressure.

The space velocity when carrying out the present invention varies depending on the reaction temperature, activity of the catalyst, etc., but is 200 to 5000 hr ^-1 , preferably 400 to 4000 hr ^-1 .If it is smaller than the lower limit of this range, the selectivity will decrease, and the upper limit When it is made larger, the conversion rate decreases. Note that when the activity of the catalyst decreases due to long-term use, the activity can be restored using oxygen or air diluted with nitrogen or the like as necessary at a temperature of 350 to 500°C.

In carrying out the method of the present invention, trichloromethylbenzal chloride or a derivative thereof and hydrogen fluoride are introduced into a heated contact reaction tube together with a diluent if necessary, and a predetermined reaction is carried out. In addition to a fixed catalyst bed, a fluidized bed or the like can be used for the reaction. Usually, these raw materials are heated and vaporized by passing them through a preheater before being supplied to the reaction tube. After the reaction, hydrogen fluoride and hydrogen chloride, which come out of the reaction tube along with the reaction products, are easily separated using the difference in boiling point from the target compound. The resulting crude product is purified using distillation, extraction, or other means.

According to the present invention, the reaction can be carried out with extremely high conversion and selectivity, resulting in a yield of 85% or more for orthotrifluoromethylbenzal chloride or its derivatives, and 90% or more under preferable conditions ( Note: The molar ratio of the desired product to the feedstock) and in the case of meta- or para-trifluoromethylbenzachloride or its derivatives, it can be produced with a yield of 80% or more, and under favorable conditions 85% or more. .

Example 1 50 g of α-type aluminum fluoride particles having an average particle size of 200 μm, a surface area of 50 m ² /g measured by the BET method, a porosity of 45%, and an average pore size of 250 Å measured by a mercury porosimeter were taken, and each
After placing in 300 ml flasks and evacuating, 150 ml of the following solution was poured into each flask.

20% (by weight) aqueous solution of FeCl ₃ 12% (by weight) aqueous solution of CrCl ₂ 23% (by weight) aqueous solution of NiCl ₂ 12% (by weight) aqueous solution of ZnCl ₂ 23% (by weight) aqueous solution of MnCl ₂ After stirring each solution for 2 h under vacuum,
The aluminum fluoride particles impregnated with the above metal chloride were separated by filtration. After heating and drying this at 130°C for 5 hours under reduced pressure, it was filled into a Monel tube with a diameter of 3/4 inch, and heated to 330°C for those carrying ZnCl ₂ and MnCl ₂ and 200°C for others. Both contain hydrogen fluoride and nitrogen, respectively.
The chloride supported on aluminum fluoride was converted into fluoride by introducing the solution at a flow rate of 200 ml/min for 4 hours. The weight ratio of each supported metal fluoride to aluminum fluoride was calculated from the weight change as follows.

(1) FeF ₃ 5.3% by weight (2) CrF ₂ 2.9% by weight (3) NiF ₂ 5.9% by weight (4) ZnF ₂ 2.7% by weight (5) MnF ₂ 5.8% by weight At this point, aluminum fluoride is α It was confirmed by X-ray diffraction that the mold remained intact.

Using aluminum fluoride supporting the metal fluoride of (1) to (5) obtained above as a catalyst,
A 4-inch Monel reaction tube was filled. Then,
While maintaining the temperature of the reaction tube at 250°C, o-trichloromethylbenzal chloride was added at a rate of 50 g/hr.
Further, hydrogen fluoride and nitrogen were introduced into the reaction tube at a molar ratio of 4 times and 7 times that of o-trichloromethylbenzal chloride, respectively (space velocity: about 900 hr ^-1 ). After the reaction reached a steady state, the exhaust gas was introduced into a condenser at 0° C. for 5 hours, and nitrogen, hydrogen chloride, and excess hydrogen fluoride in the gas were separated to obtain a liquid component. This was purified by vacuum distillation to obtain o-trifluoromethylbenzal chloride. Confirmation of the product is done by elemental analysis, gas chromatography analysis, IR spectrum,
This was carried out by measuring ¹³ C-NMR spectra and GC-mass spectra. The products O- obtained with the metal fluoride-supported catalysts of (1) to (5) above
The yield (g) and yield (%) of trifluoromethylbenzal chloride are shown below.

(1) 189g (92%) (2) 175g (85%) (3) 179g (87%) (4) 177g (86%) (5) 174g (85%) Example 2 o-Trichloromethylbenzal chloride The procedure was carried out in exactly the same manner as in Example 1, except that p-trichloromethylbenzal chloride was used instead of p.
-trifluoromethylbenzal chloride was obtained.
The yield (g) and yield (%) using each catalyst are shown below for each of the metal fluoride types (1) to (5) supported as in Example 1.

(1) 183g (89%) (2) 166g (81%) (3) 171g (83%) (4) 164g (80%) (5) 169g (82%)

Claims (1)

[Claims] 1. Trichloromethylbenzal chloride or a derivative thereof and hydrogen fluoride are heated in the presence of aluminum fluoride and a fluoride of at least one metal selected from the group consisting of zinc, chromium, manganese, iron, and nickel. A method for producing trifluoromethylbenzal chloride or a derivative thereof, which comprises reacting in a phase state.