JPS6330292B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides p-
The present invention relates to a method for producing a nuclear chloride. Nuclear chlorinated products of alkylbenzenes are useful as raw materials for various organic synthetic chemicals including medicines and agricultural chemicals, and in particular p-chloroalkylbenzenes, such as p-
-There is a high demand for chlorotoluene. BACKGROUND ART Conventionally, as a general method for producing an alkylbenzene nuclear chloride, a method is known in which alkylbenzene is chlorinated with chlorine gas using a Lewis acid such as antimony chloride, ferric chloride, or aluminum chloride as a catalyst. However, in this method, o-chloroalkylbenzene is mainly produced, and m-chloro derivatives, polychlorinated products, etc. are also produced as by-products, and p-chloroalkylbenzene cannot be produced with a selectivity of 40% or more. Therefore, various methods have been developed to produce p-chloroalkylbenzene with good selectivity. For example, in a method using a Lewis acid and a sulfur compound or a selenium compound as a catalyst, p-chloroalkylbenzene can be obtained with a selectivity of 45 to 52% (Japanese Patent Publication No. 50-34009, U.S. Pat. No. 4,031,144, etc.); In the method using a Lewis acid and a thianthrene compound as a catalyst, p-chloroalkylbenzene can be obtained with a selectivity of 55 to 60% (Japanese Patent Application Laid-Open No. 1989-1999).
-19630 publication, U.S. Patent No. 4031147 publication, etc.),
In a method using a Lewis acid and a phenoxatine compound as a catalyst, p-chloroalkylbenzene can be obtained with a selectivity of 50 to 64% (Japanese Patent Application Laid-open No. 1983-1999).
5139, JP-A-56-110630). However, these methods are not fully satisfactory as methods for selectively producing p-chloroalkylbenzene, and even higher selectivity p-
It is desired to provide a method for producing chloroalkylbenzene. In view of the current situation, the present inventors focused on the fact that organic synthesis reactions using the surface of an inorganic carrier such as silica gel as a reaction site proceed with good selectivity under mild conditions, and the p- As a result of extensive research to provide a method for producing p-nuclear chlorides, it was unexpectedly possible to use silica gel chemically modified with nitrobenzamide as a catalyst to achieve superior selectivity compared to conventional methods. It was discovered that chloroalkylbenzene can be produced, and the present invention was completed based on this knowledge. That is, the present invention provides a method for producing an alkylbenzene nuclear chloride by chlorinating alkylbenzene in the presence of a catalyst. (In the formula, A represents silica gel, R represents an alkyl group, and n represents an integer of 1 or 2.) A method for producing an alkylbenzene nuclear chloride characterized by using a chemically modified silica gel represented by the following as a catalyst: It is. The chemically modified silica gel represented by the general formula () used in the method of the present invention can be obtained by reacting silica gel for column chromatography with 3-(N-alkyl)aminopropyltriethoxysilane in an inert solvent such as benzene. A chemically modified silica gel represented by ≡SiCH ₂ CH ₂ CH ₂ NHR () (in the formula, A and R represent the same meanings as above) is obtained, and then a dehydrochlorination agent is added to this in an inert solvent such as benzene. In the presence of
general formula (In the formula, X represents a halogen atom, and n represents the same meaning as above.) It can be obtained by reacting a nitrobenzoic acid halide represented by the following. The general formula () used in the method of the present invention
Examples of the chemically modified silica gel represented by R include those in which R is an alkyl group such as a methyl group, ethyl group, or propyl group, and n is 1 or 2, that is, mononitro or dinitro, but in particular, R is a methyl group, and n 2,4-dinitro with 2 is preferred. Furthermore, as the alkylbenzene to be chlorinated by the method of the present invention, benzene monosubstituted with various straight-chain and branched-chain alkyl groups can be mentioned, but those in which the alkyl group has 1 to 5 carbon atoms are particularly preferred. . In order to chlorinate alkylbenzene by the method of the present invention, 20 to 20 to
The chlorinating agent is introduced at a temperature below the boiling point of the reaction mixture in a proportion of 2000 g, preferably from 100 to 500 g. If the temperature is too high, the amount of polychlorinated products produced increases and the yield of p-chlorinated products decreases, which is not preferable. On the other hand, the reaction can be carried out at a low temperature of minus several tens of degrees Celsius or lower, and the selectivity of p-chlorinated products is high, but the reaction rate is slow and uneconomical, so it is usually carried out at a temperature of 0 to 80 degrees Celsius, and is not suitable for industrial use. It is suitable to carry out at a temperature of 20-70 °C. As the chlorinating agent in this case, commonly used chlorinating agents such as thionyl chloride and hypochlorite can be used, but chlorine gas is particularly preferred. When using this chlorine gas, either reduced pressure or increased pressure may be used, but it is usually carried out at normal pressure. In addition, in the method of the present invention, it is not necessary to use a solvent during the chlorination reaction, but inert solvents such as carbon tetrachloride, methylene chloride, chloroform, benzene, etc. may be used to facilitate the reaction. good. According to the method of the present invention, alkylbenzene o
It is possible to selectively and efficiently chlorinate the p-position by suppressing the chlorination at the - position, and the production of m-chloro and polychlorinated products is extremely small, so p-chloroalkylbenzenes such as p-chlorotoluene can be produced. It is suitable for this purpose and its effectiveness is extremely high. Hereinafter, the method of the present invention will be specifically explained with reference to Examples. Example 1 0.6 g of cumene in a 30 ml reaction flask equipped with a stirrer, thermometer, reflux condenser and addition funnel.
(5 mmol) and catalyst (1) [in the above general formula (), R=CH ₃ , n=2, substitution position 2,4-position] were charged, and carbon tetrachloride was added at 30°C with stirring.
A solution of 0.35 g (5 mmol) of chlorine dissolved in 15 ml was added dropwise, and the mixture was reacted at 30° C. for 1 hour. After the reaction is complete, remove the catalyst and wash with sodium hydrogen carbonate.
After drying, gas chromatography analysis revealed that the production ratio of monochlorocumene was 4-chlorocumene/
The 2-chlorocumene ratio (p/o) was 4.82. Comparative Example 1 (method described in JP-A No. 56-5139) 480 g of cumene, 2 g of antimony trichloride, and phenoxatin were placed in a four-necked flask equipped with a stirrer, a thermometer, a gas blowing tube, and a reflux condenser. Take 2g and heat it in a water bath to about 50℃ while stirring. After the temperature becomes constant,
Chlorine gas is introduced at a rate of 300 ml/min, and the reaction temperature is maintained at 50-55°C with a water bath. The reaction was stopped by introducing chlorine gas for 5 hours, and the reaction solution was analyzed by gas chromatography. As a result, the composition of the monochlorocumene produced was 4-chlorocumene/2-chlorocumene ratio (p/o) = 1.76. Example 2 Catalyst (1) of Example 1 was converted to catalyst (2) [the general formula ()
The reaction was carried out under the same conditions as in Example 1, except that R=CH ₃ , n=2, and the substitution position was 3,5-position]. As a result of analysis by gas chromatography, the composition of the reaction solution was 4-chlorocumene/2-chlorocumene ratio (p/o) = 4.38. Examples 3 to 6 Reactions were carried out under the same conditions as in Example 1, except that various alkylbenzenes were used in place of cumene. Table 1 shows the 4-chloroalkylbenzene/2-chloroalkylbenzene ratio (p/o) of the various chloroalkylbenzenes thus obtained.

[Table] Example 7 Catalyst (1) of Example 1 was converted to catalyst (3) [the above general formula ()
The reaction was carried out under the same conditions as in Example 1 except that R=CH ₃ , n=1, and the substitution position was at the 4-position]. As a result of analysis by gas chromatography, the composition of the reaction solution was 4-chlorocumene/2-chlorocumene ratio (p/o) = 4.0. Example 8 Catalyst (1) of Example 1 was converted to catalyst (4) [the general formula ()
where R=C ₂ H ₅ , n=2, substitution position 3,5-
The reaction was carried out under the same conditions as in Example 1, except that cumene was replaced with toluene. As a result of analysis by gas chromatography, the composition of the reaction solution was 4-chlorotoluene/2-chlorotoluene ratio (p/o) = 1.60.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the structure of the chemically modified silica gel claimed in the claims. FIG. 2 is a schematic diagram of the reaction between cumene and chlorine using a chemically modified silica gel catalyst in Example 1.

Claims (1)

[Claims] 1. In a method for producing an alkylbenzene nuclear chloride by chlorinating alkylbenzene in the presence of a catalyst, the general formula (In the formula, A represents silica gel, R represents an alkyl group, and n represents an integer of 1 or 2.) A method for producing an alkylbenzene nuclear chloride characterized by using a chemically modified silica gel represented by the following as a catalyst: .