JP2647757B2 - Method for producing aromatic halide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a method for selectively producing an aromatic halide having a halogen atom substituted at the para position.

[0002]

2. Description of the Related Art Aromatic halides are industrially important compounds as solvents, raw materials for pharmaceutical and agricultural chemical intermediates, and raw materials for engineering plastics. In particular, paradichlorobenzene (hereinafter abbreviated as PDCB) is one of engineering plastics, polyphenyl sulfone (hereinafter referred to as PP).
S) (abbreviated as S), and its importance is increasing with the rapid growth of PPS demand.

It is known that PDCB can be obtained by liquid-phase chlorination of benzene using L-type zeolite as a catalyst (Japanese Patent Application Laid-Open No. 59-163329). According to this method, paradichlorobenzene can be obtained with a high selectivity.

However, in general, the activity of a solid catalyst such as zeolite is low, and the activity of the L-type zeolite is not sufficiently high. For this reason, PDCB using L-type zeolite
In order to industrially efficiently produce, it is necessary to raise the reaction temperature and increase the amount of PDCB produced per unit time and per unit amount of catalyst. However, when the L-type zeolite is used as a catalyst, there is a problem that the selectivity of PDCB is temperature-dependent, and the selectivity of PDCB is reduced in a reaction at a high temperature.

[0005]

As described above, L-type zeolite is used as a catalyst for halogenating an aromatic compound.
Despite the excellent feature of selectively producing para-substituted products with relatively high activity, the disadvantage that when the reaction temperature is increased to improve the catalytic activity, the selectivity of para-substituted products decreases. Had. Therefore, a method that does not decrease the selectivity of the para-substituted product even by a reaction at a high temperature is desired.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, they have found that when the L-type zeolite is brought into contact with alkoxysilane, the selectivity of the para-substituted product can be maintained even by the reaction at a high temperature, and the present invention has been proposed.

That is, the present invention provides the following formula:

[0008]

Embedded image

(Wherein R ¹ is a hydrogen atom, a halogen atom or an alkyl group), characterized in that the compound is chlorinated or brominated in the presence of L-type zeolite which has been brought into contact with alkoxysilane. The following equation

[0010]

Embedded image

(Where R ² is a halogen atom or an alkyl group, and R ³ is a chlorine atom or a bromine atom). here,
In the above formula (I), when R ¹ is a hydrogen atom, R ² is a chlorine atom or a bromine atom, and when R ¹ is a halogen atom or an alkyl group other than a chlorine atom and a bromine atom, R ² Is the same as R ¹ .

The raw material used in the present invention is a compound represented by the above formula (I). The alkyl group in the formula (I) is not particularly limited. However, when the alkyl group is bulky, the raw material does not enter the pores of the L-type zeolite used as a catalyst, and the activity and the selectivity of the para-substituted product are reduced. So
Alkyl groups having 1 to 3 carbon atoms are preferred.

Specific examples of the raw materials used in the present invention include benzene, monofluorobenzene, monochlorobenzene, monobromobenzene, monoiodobenzene, and toluene.

In the present invention, known L-type zeolites are used without any limitation. L-type zeolite is generally following formula _{aM 2 / n O · Al 2} O 3 · bSiO 2 ( where, M is an alkali metal or alkaline earth metal, n is the valence of M, a is 0.7 ~ 1.7, b is 4
８8. ) And 11.8 °, 14.8 °, 22.7 ° and 28.0 ° at 2θ in X-ray diffraction.
It is a compound having a peak in the vicinity. M in the above formula is usually potassium, but can be replaced by ion exchange with another metal, for example, an alkali metal such as sodium, rubidium and cesium; and an alkaline earth metal such as magnesium, calcium, strontium and barium. . The L-type zeolite in the present invention may be ion-exchanged with an alkali metal or alkaline earth metal other than potassium, or may be ion-exchanged with two or more metals.

The L-type zeolite in the present invention must be in contact with an alkoxysilane. As the alkoxysilane, a known alkoxysilane having one or more alkoxy groups can be used without any limitation. In particular, in the present invention, the following formula R _m SiY _4-m (where R is an alkyl group or a phenyl group,
Is an alkoxy group, and m is an integer of 0 to 3. It is preferable to use the compound represented by the formula (1). In particular, by using an alkoxysilane in which m in the above formula is 0 to 2, the effects of the present invention can be more sufficiently exerted. The types of the alkyl group, phenyl group and alkoxy group contained in one molecule may be the same or different.

Specific examples of alkoxysilanes that can be suitably used in the present invention include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,
Methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyl Dibutoxysilane,
Diphenyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, trimethylbutoxysilane, triphenylmethoxysilane and the like.

The method of contacting the L-type zeolite with the alkoxysilane is not particularly limited, but a method in which the L-type zeolite is brought into contact with the vapor of alkoxysilane, a method in which the L-type zeolite is brought into contact with the alkoxysilane in a solvent and the like are preferred. It is. In the present invention, the former method is preferable because the pores of the L-type zeolite are not blocked. When the L-type zeolite is brought into contact with the alkoxysilane, it is preferable that the L-type zeolite contains a small amount of water in order to sufficiently exert the effects of the present invention. As a method of slightly adding moisture to the L-type zeolite, a method of passing an inert gas containing water vapor through the fixed L-type zeolite layer can be suitably adopted.

The contact between the L-type zeolite and the alkoxysilane in the present invention can be performed by passing an inert gas containing water vapor through an immobilized L-type zeolite layer and then passing an inert gas containing vapor of alkoxysilane. It can be suitably adopted. In this case, an inert gas containing water vapor and an inert gas containing vapor of alkoxysilane can be obtained by passing an inert gas through a layer of water and an alkoxysilane, respectively.

The contact temperature between the L-type zeolite and the alkoxysilane is not particularly limited, but is generally preferably in the range of 20 to 100 ° C. The contact time is not particularly limited, but may be from 10 minutes to 1 minute in terms of the unit amount of L-type zeolite.
A range of 0 hours / g-zeolite is preferred. further,
The flow rate of the inert gas containing water vapor and the inert gas containing the vapor of alkoxysilane with respect to the L-type zeolite is not particularly limited, but is 10 cc to 1000 cc / min · g-.
A range of zeolites is preferred.

The L-type zeolite thus brought into contact with the alkoxysilane can be used alone or as a mixture with different types of zeolites. Further, the L-type zeolite that has been brought into contact with the above-mentioned alkoxysilane may be further subjected to the following treatment unless the method destroys the basic structure of the L-type zeolite. Examples of the treatment method include ion exchange, modification with a salt of an alkali metal, an alkaline earth metal, a rare earth metal or another metal, an alkali treatment or a heat treatment. In addition, as long as it does not significantly lower the catalytic activity or the selectivity of the para-substituted product, it can be used together with an additive. Those usable as additives include organic phosphorus compounds such as trialkylphosphines; aromatic amines such as quinoline and pyridine; quaternary ammonium halides such as benzyltrimethylammonium chloride and sulfur-containing compounds such as sulfur halides. It is.

The shape of the L-type zeolite that has been brought into contact with the alkoxysilane is not particularly limited, and any shape such as a powder or a pellet can be used. Also, molding can be performed using a binder such as alumina, silica, and silica-alumina. In general, it is preferable to use a binder by molding it into a pellet form from the viewpoint of ease of handling. At this time, the order of the contact of the L-type zeolite with the alkoxysilane and the order of molding are not particularly limited, and the L-type zeolite molded with a binder or the like can be used in contact with the alkoxysilane.

In the present invention, a chlorinating agent or a brominating agent is used for chlorination or bromination of the raw material. The chlorinating agent or brominating agent used in the present invention (hereinafter, the term “halogenating agent” used in this specification means a chlorinating agent or a brominating agent) is known. Can be used without any limitation, but generally, a chlorine molecule or a bromine molecule is usually used. The chlorination or bromination reaction can be performed without distinction between a liquid phase and a gas phase. However, in the gas phase method, the reaction temperature is generally high, and a high halide is easily generated. Therefore, it is preferable to use the liquid phase method. .
When chlorination or bromination is performed by a liquid phase method, the raw materials can be used as they are, or can be used after being diluted with a solvent. The solvent that can be used at this time is not particularly limited, but examples of those that can be preferably used include:
Examples thereof include halogenated hydrocarbons such as carbon tetrachloride, chloroform, and Freon 113. Generally, it is preferable to perform the reaction without a solvent in consideration of the separation of the product after the completion of the reaction.

The reaction can be carried out using any of a flow system, a batch system and a semi-batch system, but it is preferably carried out in a flow system in consideration of productivity and operability. When the reaction is carried out in a flow-through manner, the raw material and the halogenating agent are directly used in a reactor in which the catalyst is fixed, or diluted with an inert gas such as nitrogen when the halogenating agent is a gas. When it is a liquid, it is usually diluted with the solvent and supplied continuously.

The material of the reactor is not particularly limited. However, when a material containing a substance such as iron which reacts with a halogenating agent to generate a Lewis acid is used, resin lining, glass lining, plating or the like may be used. It is preferred to use a treatment so that these materials do not come into contact with the halogenating agent. This is because the Lewis acid catalyst generally has higher activity than the zeolite catalyst, and the presence of even a small amount of Lewis acid in the reaction system impairs the para-substituted selectivity characteristic of L-type zeolites. When a light-transmitting substance such as glass is used as the material of the reactor, it is preferable to use a light-shielding treatment in order to avoid the generation of a halogenated product such as benzenehexachloride by a photoreaction.

The reaction temperature may be in the range from the melting point of the raw material under the reaction pressure to the decomposition temperature, but in the case of conducting the reaction in the liquid phase, it is preferable to carry out the reaction at the boiling point of the raw material or lower. In consideration of the above, the range of 30 to 200 ° C. is preferable. The reaction can be performed under increased pressure, normal pressure or reduced pressure, but is preferably performed under normal pressure or slightly increased pressure in view of the simplicity of the apparatus.

The amount of the catalyst used in the reaction varies depending on the size of the reactor, the feed rate of the raw material, the amount of the binder used in molding the catalyst, the molding conditions, and the like. 0.01 in terms of zeolite weight
-2000 g / liter, more preferably 0.1-10
It is in the range of 00 g / liter. Also, the feed rate of the raw materials varies depending on the size of the reactor, but the residence time is 0.1%.
The speed may be selected so as to be in the range of 100 hours.
When the halogenating agent is liquid, the rate is such that the residence time is in the range of 0.1 to 100 hours, and when the halogenating agent is gaseous, Gas supply rate per unit reactor volume is 0.01 ~
The speed may be selected from the range of 1 liter / minute · liter—reactor volume.

The feed ratio between the raw material and the halogenating agent can be selected from the range of raw material: halogenating agent = 1: 0.001 to 1:10 when expressed by the ratio of the number of moles supplied per unit time. However, considering the utilization of the raw material, the range of raw material: halogenating agent = 1: 0.01 to 1: 2 is preferable.

The aromatic halide obtained by chlorination or bromination is obtained as a mixture with unreacted raw materials. Generally, the aromatic halide can be separated from the mixture by an operation such as distillation or crystallization after the reaction.

[0029]

The L-type zeolite which has been contacted with the alkoxysilane used in the present invention acts as a catalyst in chlorination and bromination reactions, and produces an aromatic halide having a para-substituent at a high selectivity. Let it. At this time, as is apparent from the examples described later, the conventional L-type zeolite exhibits high para-substituted selectivity even in a reaction at a high temperature at which the selectivity of the para-substituted product decreases. Therefore,
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve a catalyst activity, without reducing the selectivity of a para substitution product.

[0030]

EXAMPLES In order to explain the present invention more specifically, the following will be described.
The present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 An L-type zeolite (trade name: H) was placed in a glass tube made of Pyrex.
5 g of SZ-500KOA (manufactured by Tosoh Corporation)
The mixture was heated at 400 ° C. for 2 hours in a He stream. After cooling, 200 cc of He passed through the aqueous layer by bubbling at room temperature.
Per minute for 2 hours, and He gas was further purged at the same flow rate for 30 minutes. Subsequently, He passed through the methyltriethoxysilane layer by bubbling at room temperature.
Was flowed at a flow rate of 200 cc / min for 2 hours, followed by purging with He gas for 30 minutes. Furthermore, the steam saturated He is set to 200
After flowing at a flow rate of cc / min for 2 hours, the mixture was heated at 150 ° C. for 2 hours in a He gas flow to obtain L-type zeolite which was brought into contact with methyltriethoxysilane. When the obtained L-type zeolite was analyzed by powder X-ray diffraction, it showed the same diffraction pattern as the L-type zeolite before the treatment. The representative peak positions in the obtained pattern are as follows: 2θ = 5.6 °;
8 °, 14.8 °, 22.7 °, 28.0 °.

L-type zeolite 0.11 contacted with alkoxysilane in a 1 liter brown four-necked flask
g, monochlorobenzene (hereinafter abbreviated as MCB) 50
0cc was inserted. After connecting the stirrer, the chlorine blowing nozzle, the reflux device and the thermometer, light was shielded with aluminum foil including the chlorine introduction line and the reflux device in order to avoid the chlorine addition reaction to the aromatic ring by light. Thereafter, the reactor was heated, and when the temperature of the reaction solution reached 110 ° C., 170 N chlorine gas was supplied.
A chlorination reaction was performed by blowing at a flow rate of cc / min. During the reaction, the temperature of the reaction solution was controlled to be 110 ° C. After the start of the reaction, a part of the reaction solution is collected over time and immediately treated with a 0.5N aqueous sodium hydroxide solution.
Organic components were analyzed by gas chromatography. As a result, the conversion of MCB in 3 hours after the start of the reaction was 9.3%,
The ratio of generated paradichlorobenzene to orthodichlorobenzene (hereinafter abbreviated as P / O) was 9.6. The catalyst activity (the number of moles of MCB reacted per unit time per unit catalyst amount) determined from the change over time in the composition of the reaction solution is M
When the CB concentration is 85%, 1.9 × 10 ^-2 MCB mol /
g-cat · min.

Examples 2 to 6 L-type zeolite contacted with each alkoxysilane was prepared in the same manner as in Example 1 except that the alkoxysilane used in Example 1 and the treatment temperature were changed to those shown in Table 1. Obtained. The L-type zeolite was confirmed by X-ray diffraction measurement to show the same diffraction pattern as the L-type zeolite before the treatment.

[0034]

[Table 1]

Further, a chlorination reaction of monochlorobenzene was carried out in the same manner as in Example 1. The results are shown in Table 2.

[0036]

[Table 2]

Comparative Example 1 The reaction and analysis were carried out in the same manner as in Example 1 except that L-type zeolite (trade name: HSZ-500KOA, manufactured by Tosoh Corporation) dried at 400 ° C. without contacting with alkoxysilane was used. Was done. As a result, the MCB conversion rate after 3 hours from the start of the reaction was 9.5%, and the P / O was 7.9. When the MCB concentration was 85%, the catalytic activity was 2.2.
× 10 ^-2 MCB mol / g-cat · min.

Comparative Examples 2 and 3 L-type zeolite (trade name: HSZ-500KOA, manufactured by Tosoh Corporation) dried at 400 ° C. without contact with alkoxysilane was used, and the reaction conditions were changed to the values shown in Table 3. The reaction was carried out in the same manner as in Example 1 except for the above. The results are shown in Table 3.

[0039]

[Table 3]

Example 7 1 g of L-type zeolite and 92.1 g of toluene obtained in the same manner as in Example 1 were placed in a brown four-flask having an internal volume of 200 cc. After connecting a stirrer, a blowing nozzle, a reflux device and a thermometer, the mixture was heated to 110 ° C. while blowing nitrogen gas. Thereafter, the nitrogen gas was switched to chlorine gas, and chlorine gas was blown in at a flow rate of 110 Ncc / min to perform a reaction. After 4 hours, a part of the reaction solution was sampled and analyzed by gas chromatography. The conversion of toluene was 98.4.
%, And the production ratio of 4-chlorotoluene (P-form) and 2-chlorotoluene (O-form) was P / O = 2.1.

Comparative Examples 4 and 5 In Example 7, the reaction was carried out in the same manner as in Example 7 except that the L-type zeolite not contacted with the alkoxysilane was used and the reaction temperature was changed to the value shown in Table 4. ,
Analysis was carried out. The results are shown in Table 4.

[0042]

[Table 4]

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Claims (1)

(57) [Claims] [Claim 1] The following formula: (Wherein R ¹ is a hydrogen atom, a halogen atom or an alkyl group), wherein the compound represented by the following formula is chlorinated or brominated in the presence of L-type zeolite brought into contact with alkoxysilane. Embedded image (Wherein, R ² is a halogen atom or an alkyl group, R ³
Is a chlorine atom or a bromine atom. )).