JPS60188333A - Production of halogenated benzene - Google Patents

Abstract

PURPOSE:In the liquid-phase halogenation of substituted benzenes, a specific zeolite treated with a lower acylating agent is used as a catalyst to enable high-selectivity production of p-halogenated substituted benzenes which are used as a starting material for medicines and agricultural chemicals. CONSTITUTION:In the production of the compound of formula II (X is halogen) by the liquid-phase halogenation of the compound of formula I (R is lower alkyl, lower alkoxy, halogen), a zeolite which has been treated with a lower acylating agent, preferably acetic anhydride, acetyl chloride, chloracetyl chloride, dichloroacetyl chloride, trifluoroacetic anhydride or methyl orthoformate, has a formulation of SiO2/Al2O3 at a molar ratio of 3-8 and pore sizes of 6-10Angstrom , such as L-type zeolite or Y-type zeolite is used as a catalyst to inhibit the halogenation in the o-position and the polyhalogenation on the benzene nucleus, thus with high selectivity of p-halogenated compound of formula II which has high demand in industry.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing halogenated benzenes, and more specifically, halogenates nuclear-substituted benzenes using a novel catalyst to produce p −/·rodanized nuclear substitution with good selectivity. This invention relates to a method for producing benzenes.

The nuclear halides of benzenes are used as raw materials for the production of medicines, agricultural chemicals, etc. Among them, the ones in particular demand are nuclear-substituted benzenes in which the p-position of the substituent is halogenated. Therefore, various studies are being conducted to increase the selectivity of p-halogenation.

Conventionally, methods for halogenating alkylbenzenes include:
Generally, halogenation is carried out using a halogen such as chlorine gas in the presence of a Lewis acid catalyst such as antimony chloride, ferric chloride, or aluminum chloride. According to this method, O-chloroalkylbenzene is mainly is produced, and m-chloride, polychloride, etc. are also produced as by-products, so the yield of p~dichlorolkylbenzene is reduced to 40%.
It was impossible to do more than that. Therefore, in order to increase the selectivity of p-chloroalkylbenzene, various catalyst development studies have been conducted, and several proposals have been made so far.

For example, a method of obtaining p-chloride with a yield of 45-52% using a catalyst consisting of a Lewis acid and sulfur or selenium, and a method of obtaining a p-chloride with a yield of 55-60% using a catalyst consisting of a Lewis acid and thianthrene.
A method for obtaining p-chloride with a yield of (%)
630 (Japanese Patent Laid-Open Publication No. 175133/1982), and a method for obtaining a p-ri-free compound with a yield of 52 to 60% using a catalyst system consisting of a Lewis acid and a phenoxatine compound (Japanese Patent Application Laid-Open No. 175133/1982). .

On the other hand, regarding the chlorination of chlorobenzene, p-
Method for obtaining dichlorobenzene (JP-A-50-64231
Japanese Patent Publication No. 50-34010), Hikodo (Japanese Patent Publication No. 50-34010), is known as a method for obtaining p-dichlorobenzene at a yield of 72 by reacting selenium or a selenium compound with a catalyst and chlorine.

However, all of these methods have low selectivity to p-halides, and are not necessarily satisfactory as methods for producing p-halogenated benzenes.

The present inventors have conducted extensive research in order to overcome the drawbacks of such conventional methods and to develop a method capable of producing p-halogenated nucleus-substituted benzenes with high selectivity. It was discovered that the object could be achieved by using a certain type of zeolite treated with a lower acylating agent as a catalyst, and based on this knowledge, the present invention was accomplished.

That is, in the present invention, in the presence of a catalyst, the general formula (R in the formula
is a lower alkyl group, a lower alkoxy group, or a halogen atom) Nuclearly substituted benzenes represented by ) In order to produce halogenated benzenes represented by
Eij, 02 treated with lower acylating agent as catalyst
The present invention provides a method for producing a halogenated nucleus-substituted benzene, which is characterized by using a zeolite having a pore size of 203 to 8 on At203 and a pore diameter of 6 to 10.

Examples of the nuclear substituent R in the raw material compound represented by general formula (1) in the method of the present invention include linear and branched alkyl groups, and alkoxy groups containing this alkyl group. However, an alkyl group having 1 to 4 carbon atoms or a lower alkoxy group containing the same is particularly preferred. Also R
Examples of halogen atoms include fluorine atom, chlorine atom,
Mention may be made of the bromine atom.

Next, in the method of the present invention, 5102/
The molar ratio of At203 is in the range of 3 to 8, and the pore diameter is 6.
It is necessary to use a zeolite in the range of 10 to 10 that has been treated with a lower acylating agent. S i O2
/A7205 molar ratio or pore diameter outside the above range, the selectivity of p-halides will be significantly reduced.

A typical zeolite that meets these conditions is L-type zeolite, which is made of silicon oxide (S
iO2) It is a crystalline alumina silicate having a composition with a molar ratio of aluminum dioxide (A1203) of 4°1 to 8°1 and a pore size of about 7 to 10. Other examples of zeolites that meet the above conditions include 5j02: At
Mention may be made of Y-type zeolite having a composition in which the molar ratio of 203 to 203 is from 3°1 to 7°1 and the pore size is approximately 6 to 9'A.

As the catalyst in the present invention, synthetic zeonites and natural zeolites having the same X-ray diffraction spectra as these can also be used. The ion-exchangeable cations contained in these zeolites are usually thorium or potassium, but they may also contain other cations. Such cations include, for example, periodic table I
Examples include ions or protons of metals of Group A, ■A, IIIA, ■A, and VA. One type of these cations may be included, or two or more types may be included.

In the method of the present invention, the zeolite treated with a lower acylating agent is used, but this treatment may be carried out in advance prior to use in halogenation, or the lower acylating agent may be added to the reaction system during the halogenation reaction. The acylating agent and zeolite may be added simultaneously.

In the case of pre-treatment, for example, the zeolite powder is suspended in a solvent, a lower acylating agent is added thereto, the solvent and excess lower acylating agent are distilled off, and the suspension is dried under reduced pressure. At this time, the zeolite powder may be directly added to the lower acylating agent without using a solvent, and the excess amount may be distilled off.

On the other hand, when processing during the reaction, zeolite powder is suspended in nuclear-substituted benzenes as a raw material charged into a halogenation apparatus, a lower acylating agent is added thereto, and the mixture is heated at a temperature below the boiling point, preferably at room temperature. ], after stirring at a temperature of 0°C, the! , or perform subsequent halogenation.

It is sufficient to perform either one of these treatments with the lower acylating agent, but if desired, both can be performed.

Examples of lower acylating agents used in this case include acetic anhydride and its halides such as trifluoroacetic anhydride, acetic acid halides such as acetyl chloride, acetyl bromide, halogenated acetic halides such as chloroacetyl chloride, dichloroacetyl chloride, trichloroacetyl Mention may be made of formic acid derivatives such as methyl orthoformate, such as chlorides and the corresponding bromides. If a large molecule such as benzoyl chloride is used as the acylating agent, no improvement in the selectivity of p-halides can be obtained. It is sufficient that the acylating agent be used in an amount of 1% by weight or more based on the zeolite.

To halogenate nuclear-substituted benzene according to the method of the present invention, for example, zeolite treated with a lower acylating agent is added per mole of the raw material compound! 70.0l-10F preferably 0
．． The halogenating agent is mixed at a ratio of 1 to 7 tons, and the halogenating agent is introduced in the liquid phase while stirring at a temperature below the boiling point. At this time, a reaction solvent may be used if desired. As the halogenating agent, those commonly used for halogenating aromatic rings are used, but chlorine, bromine, sulfuryl chloride and the like are preferred. These can also be used after being diluted with an inert gas such as nitrogen, if desired. Further, the temperature is higher than the practical reaction temperature of halogenation Ho° C. and lower than the boiling point of the reaction mixture. The reaction with may be carried out either under reduced pressure or increased pressure, but is usually carried out under normal pressure.

According to the method of the present invention, in the halogenation of nuclear-substituted benzenes, halogenation at the ○-position can be suppressed and halogenation at the p-position can be carried out selectively and efficiently. This method has the advantage that the production of by-products such as polynuclear halides can be suppressed to an extremely small amount, and highly utilized p-halogenated nuclear-substituted benzenes can be obtained in high yield.

Furthermore, according to the method of the present invention, when producing p-dihalogenated benzene using monohalogenated benzene as a raw material, monohalogenated benzene is produced from benzene, and this is further halogenated to produce p-dihalogenated benzene. Advantageously, the steps can be carried out continuously in the same reactor.

Furthermore, the method of the present invention is suitable as an industrial method for producing p-halogenated nucleus-substituted benzenes because the reaction and subsequent post-treatment operations are simple, and the catalyst can be reused.

Next, the present invention will be explained in more detail with reference to Examples.

Example J 20 with cooling pipe, thermometer, stirrer and blowing pipe
0m/! Into a reaction flask with a capacity of 5.0 liters, add L-type zeolite (Toyo Soda KK Rise, trade name TSZ-504). P and toluene92. I S' (1 mol) was introduced, and 0.5 chloroacetyl chloride was introduced! i' and maintained at 50°C;
Stir for 30 minutes while introducing nitrogen gas. continue,
The reaction temperature was maintained at 50° C., and chlorine gas was blown in at a rate of 0.25 mol/hour for 4 hours to cause the reaction.

After the completion of the reaction, the obtained reaction product was analyzed by gas chromatography, and it was found that the reaction rate of toluene was 9 s.
%, o-chloro! - Luene/p-chlorotoluene production ratio (hereinafter abbreviated as o/p ratio) was 0.312.

Example 2 The same experiment as in Example 1 was repeated except that the amount of chloroacetyl chloride added was 0.251, and the reaction rate of toluene was 7d! 'l O, 1%, O/P ratio is 0.3
It was 38.

Example 3 Using various benzenes instead of toluene as raw materials,
Halogenation was carried out at 70°C in the same manner as in Example 1. The results are shown in Table 1.

1st Table 11-Example 4 Sulfuryl chloride 35.2 instead of chlorine gas? (1,
002 mol) was added dropwise over 4 hours and aged for 3 hours to carry out halogenation at 70°C in the same manner as in Example 1. The reaction rate of toluene was 99.4, o/
The p ratio was 0.293.

Example 5 Halogenation was carried out at 70° C. in the same manner as in Example 5, using various different acylating agents in place of chloroacetyl chloride. The results are shown in Table 2.

For comparison, results using untreated zeolite and zeolite treated with benzoyl chloride are also shown.

12- Table 2 Example 6 After the completion of Example 1, the catalyst was recovered from the reaction mixture, and the same experiment as in Example 1 was repeated using it. The reaction was carried out normally, and the reaction rate in this case was 98.2 Section, o/
The p ratio was 0.320.

Claims (1)

[Claims] 1. In the presence of a catalyst, a nuclear-substituted benzene represented by the general formula (R in the formula is a lower alkyl group, a lower alkoxy group, or a halogen atom) is halogenated in a liquid phase to form a compound of the general formula (R in the formula has the same meaning as above, and X is a halogen atom) In producing the halogenated benzene represented by 1-,
S j, 02 treated with a lower acylating agent as a catalyst
/ A method for producing a halogenated nucleus-substituted benzene, characterized by using a zeolite having a molar ratio of 3 to 8 and a pore size of 6 to IOA. 2 The lower unlyzing agent is acetic anhydride, acetyl chloride,
Chloroacetyl chloride, dichloroacetyl chloride,
The method according to claim 1, wherein the trifluoroacetic anhydride or methyl orthoformate is used. 3. The method according to claim 1, wherein the zeolite is an L-type zeolite or a Y-type zeolite.