JPH0327334A - Production of 2,5-dihalogenated benzotrichlorides - Google Patents

Abstract

PURPOSE:To obtain the title substance useful as an intermediate for agricultural chemicals, drugs, etc., by reacting a 2-halogenated benzotrichloride with a halogenating agent in the presence of L type zeolite as a catalyst. CONSTITUTION:A 2-halogenated benzotrichloride is reacted with a halogenating agent (preferably chlorine gas or bromine) in the presence of L type zeolite as a catalyst to give the title substance. The reaction temperature is selected from a range from 0 deg.C to the boiling point. Crystalline aluminosilicate having 4-8 molar ratio of SiO2/Al2O3 may be cited as the L type zeolite and generally synthetic zeolite or natural zeolite having the same X-ray diffraction spectrum is used. The catalyst may be calcined or uncalcined and the amount of the catalyst used is preferably 1-50g based on 1mol raw material compound. The catalyst may be recycled for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2,5-dihalogenated benzotrichloride.

2.5-Dihalogenated benzotrichloride can be a useful raw material in the field of organic chemical chemistry, including chemical intermediates for agricultural chemicals and pharmaceuticals.

Among them, 2,5-dihalogenated benzoic acid obtained by hydrolysis is in high demand.

(Prior Art) Conventionally, as a method for producing 2,5-dihalogenated benzotrichloride, a method of side chain chlorination of 2,5-dihalogenated toluene obtained by halogenation of 2-halogenated toluene has been known. ing. However, the 5-position halogenation selectivity due to halogenation of 2-halogenated toluene is low, and complicated separation or purification is required to obtain highly pure 2,5-dihalogenated toluene. That is, JP-A-51-143627, JP-A-57-9
No. 1934 proposes a method of chlorinating 2-chlorotoluene using a sulfur compound or iodine as a catalyst. However, the yield of 2,5-dichlorotoluene is 50 to 53%, which is not industrially satisfactory. Further, JP-A-59-206322 proposes a method of chlorinating 2-chlorotoluene using L-type zeolite as a catalyst, but the yield of 2.5-dichlorotoluene is 56-57. It was only a percentage. ·on the other hand,
A method of halogenating 2-halogenated benzotrichloride in the presence of a Lewis acid, which is a usual halogenation catalyst, is also considered, but in that case, the polymerization reaction proceeds at the same time.
- Yield and selectivity of dihalogenated benzotrichloride are also low. Furthermore, when a Lewis acid is used, benzotrichlorides polymerize during distillation, so complicated post-treatment steps such as hydrochloric acid treatment and drying are required before distillation. In this way, in either method, 2,5-dihalogenated benzo}
The yield and selectivity of dichloride were still not sufficient.

(Problems to be Solved by the Invention) A method for obtaining 2,5-dihalogenated benzotrichloride by an industrial method with high yield and high selectivity has been awaited.

(Means for Solving the Problem) As a result of intensive research into a method for industrially producing 2,5-dihalogenated benzotrichloride, the present inventors have found that, in addition to the method, L-type zelite is used as a catalyst. Use, 2-
It was recognized that 2,5-dihalogenated benzotrichloride can be produced with high yield and high selectivity by suppressing polymerization by halogenating halogenated benzotrichloride, and the present invention has been completed.

That is, the present invention is a method for producing 2,5-dihalogenated benzotrichloride, which is characterized by halogenating 2-halogenated benzotrichloride with a halogenating agent in the presence of L-type zeolite.

The 2-halogenated benzotrichloride used as a raw material is one in which the 2-position of the benzene nucleus is substituted with a halogen atom, such as 2-fluorobenzotrichloride in which the 2-position is substituted with fluorine, chlorine, bromine, etc. Examples include 2-chlorobenzotrichloride and 2-promobenzotrichloride.

In addition, as the L-type zeolite used as a catalyst, Si
Oz/Aj! It is a crystalline aluminosilicate with a molar ratio of 4 to 8, and generally synthetic zeolite or natural zeolite having the same X-ray diffraction spectrum may be used. As such an L-type Zesai light, the special public
They can be combined by the method described in 6-3675. In this case, a KL type zeolite is synthesized in which potassium is used as the ion-exchangeable cation, but this potassium ion can be exchanged with other group IA, IIA, mA, rVA, or vA metals, transition metals, ammonium ions, or Ion exchange with protons is also possible.

Further, for the cation exchange, a known method is appropriately employed. Generally, the L-type zeolite described above is treated with an aqueous solution of nitrate, chloride, etc. of the metal to be exchanged. This exchange rate can be adjusted to any value depending on the concentration, amount, number of treatments, etc. of the aqueous solution. The types of L-type zeolite used in the present invention include Group IA, Group IIA, and Group IA.
Any of nA group, rVA group, VA group metals, transition metals, ammonium ions, or protons may be used, and these catalysts may be one type or two or more types, and the catalyst may be burnt or unburned. There is no harm in using it. The amount of catalyst used is L per mole of 2-halogenated benzotrichloride.
Type zeolite can be selected in an amount of 0.1 g or more, preferably in the range of 1 to 50 g.

Further, as the halogenating agent, any halogenating agent that is commonly referred to as such can be used. Examples include chlorine gas, bromine, sulfuryl chloride, N-chlorosuccinimide, phosphorus pentachloride, chlorine monoxide, etc. Among them, it is preferable to use chlorine gas or bromine. Further, an inert gas such as nitrogen or argon gas or a solvent may be used.

The reaction temperature is appropriately selected depending on the halogenating agent, and is usually selected within the range from 0°C to the boiling point. The reaction pressure may be reduced, increased or normal pressure as long as it is sufficient to maintain the liquid phase of the reaction system, but the reaction is usually carried out at normal pressure. Further, this reaction may be carried out either batchwise or continuously.

(Effect of the invention) According to the present invention, 2-
Since halogenated benzotrichloride was halogenated, 5
The position can be selectively halogenated. In addition, this reaction suppresses the production of by-products, so the reaction rate is 90%.
It has become possible to obtain 2,5-dihalogenated benzotrichloride with a very high selectivity of 80% or more. Furthermore, the method of the present invention is valuable as an industrial production method for 2,5-dihalogenated benzotrichloride, as the reaction operation and post-treatment are simple, and the L-type zeolite catalyst used can be recycled for a long period of time. This is the most expensive way to go.

(Example) The present invention will be specifically explained below using Examples.

Example 1 KL type zeolite (trade name
TSZ-5 0 6 ■Made by Tosoh Slo on dry basis
z 64.1wt%, ^f. 0. 18.4%, Na
0 0.202wt% and Ka0 17.4wt%
A group of SiOi/^l, 0, molar ratio 5.9N0.0g
and 92.0 g of 2-chlorobenzotrichloride (0
．． 4 mol) was added thereto, and while stirring at 45 to 150°C, dry chlorine gas was blown in at a rate of 0.05 mol/hour to cause a reaction. 1
The composition of the reaction solution after 4 hours was analyzed by gas chromatography, and the results were as follows.

2-chlorobenzotrichloride 7.8%2.5
-Dichlorobenzotrichloride 82.3% 2.3-dichlorobenzotrichloride 8.4% Trichlorobenzotrichloride 0.7% Other high-boiling substances
The selectivity for 0.6% and 2.5-dichlorobenzotrichloride was 89.3%. The selectivity of 2.5-dichlorobenzotrichloride was determined by the following formula.

Comparative Example 1 126.6 g (1 mol) of 2-chlorotoluene and 5.0 g of L-type zeolite powder were heated in a reactor until the liquid temperature was 9.
When the temperature reached 0°C, it was stirred for about 30 minutes, and then chlorine gas was blown in at a rate of about 0.22 mol/hour.
．． The reaction was allowed to proceed for 5 hours.

Analysis of the reaction mixture by gas chromatography revealed the following.

2-chlorotoluene 4.7%2.3-dichlorotoluene 7.3%2.4-dichlorotoluene 19.0%2.5-dichlorotoluene 55.8
% 2.6-dichlorotoluene 8.3% Trichlorotoluene 4.9% Examples 2 to 3 The same procedure as in Example 1 was carried out except that a catalyst obtained by cation-exchanging the catalyst of Example 1 was used. The results are shown in the table below. (Table 1) The abbreviations listed in Table 1 above represent the following.

OCTC 2-chlorobenzotrichloride2.
5-DCTC 2,5-dichlorobenzotrichloride 2,3-loCTC 2,3-dichlorobenzotrichloride TCTC }Lichlorobenzotrichloride} 1B Other high boiling point substances In addition, Ba-KL used in Example 2 The Ba'' exchange rate of the catalyst was 60%, and the }I-KL used in Example 3
The H+ exchange rate of the catalyst was 61%.

Example 4 (Repetitive experiment on catalyst) The reaction-completed liquid of Example 1 was filtered under a nitrogen atmosphere to recover the catalyst. Using this recovered catalyst, the same procedure as in Example 1 was carried out except for the other conditions. When this operation was repeated 5 times, the reaction solution composition was as follows.

2-chlorobenzotrichloride 8.5%2.5
-Dichlorobenzotrichloride 81.7%2.3-
Dichlorobenzotrichloride 8.3% Trichlorobenzotrichloride 0.7% Other high boiling point substances
The selectivity for 0.6% and 2.5-dichlorobenzotrichloride was 89.3%.

Example 5 The same procedure as in Example 1 was carried out except that 2-chlorobenzotrichloride was changed to 2-7lolobenzotrichloride. The composition of the reaction solution after 11 hours of reaction was as follows.

2-Fluorobenzotrichloride 0.5%5-quaa-'l-7r1-lobenzotrichloride 96.
1% 3-Ku-2-7an-benzotrichloride 2
．． 7% perchloride 0.3% other high boilers 0.0% Comparative Example 2 Anhydrous ferric chloride 0.3% was added to a 200 ml flask equipped with a reflux condenser, thermometer, stirrer and gas injection tube.
65 g (0.004 mol) and 92.0 g (0.4 mol) of 2-chlorobenzotrichloride were added thereto, and while stirring at 80°C, dry chlorine gas was blown in at a rate of 0.05 mol/hour to cause a reaction. The composition of the reaction solution after 4 hours was analyzed by gas chromatography, and the results were as follows.

2-chlorobenzotrichloride 2.5-dichlorobenzotrichloride 2.3-dichlorobenzotrichloride trichlorobenzotrichloride Other high boiling point substances and 2.5-dichlorobenzotrichloride were 11.1%.

48.4% Do 5.7% Do 2.2% 0.4% 31.2% The selectivity of
Atomic absorption spectrometry was used.

Claims (1)

[Claims] A method for producing 2,5-dihalogenated benzotrichloride, which comprises halogenating 2-halogenated benzotrichloride with a halogenating agent in the presence of L-type zeolite.