JPS6327054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for nuclear chlorination having excellent selectivity for the p-position of alkylbenzene.

Nuclear chlorides 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-
-Chlorotoluene is in high demand.

However, in the conventional nuclear chlorination reaction, in which chlorine is chlorinated with chlorine gas using a Lewis acid such as antimony chloride, ferric chloride, or aluminum chloride as a catalyst, o-chloroalkylbenzene is mainly produced. Furthermore, m-chloro derivatives, polychlorinated derivatives, etc. were also produced as by-products, making it impossible to produce p-chloroalkylbenzene with a selectivity of 40% or more.

Therefore, various catalysts have been developed to produce p-chloroalkylbenzene in good yield.

For example, in a method using Lewis acid and sulfur or selenium as a catalyst, p-chloro form accounts for 45 to 52%.
(for example, Japanese Patent Publication No. 50-34009, U.S. Patent No. 403144, etc.), and p-chloroalkylbenzene can be obtained with a selectivity of 55 to 60% in a method using a Lewis acid and a thianthrene compound as a catalyst. (e.g., JP-A No. 52-19630, U.S. Pat. No. 4,031,147, etc.), p-chloroalkylbenzene can be obtained with a selectivity of 50 to 64% in a method using a Lewis acid and a phenoxatine compound as a catalyst. (For example, Japanese Patent Application Laid-Open No. 56-5139
(Japanese Patent Application Laid-open No. 110630/1983, etc.).

However, these catalysts are still not fully satisfactory as catalysts for the selective production of p-chloroalkylbenzene, and there has been a desire for a catalyst that exhibits even higher selectivity.

In view of the current situation, the present inventors have conducted intensive research to provide a catalyst for nuclear chlorination of alkylbenzene with excellent selectivity toward the p-position. We have discovered that p-chloroalkylbenzene can be produced with superior selectivity compared to conventional catalysts by using a catalyst chemically modified with a derivative or a benzyl derivative, and based on this knowledge, we have completed the present invention.

That is, the present invention provides the general formula (In the formula, A represents silica gel, R represents a hydrogen atom or an alkyl group, and X represents a sulfonyl group or a methylene group. Also, m represents an integer of 0 or 1, and n represents an integer of 1 or 2. This is a catalyst for nuclear chlorination of alkylbenzene made of chemically modified silica gel represented by:

The chemically modified silica gel of the present invention represented by the general formula () can be obtained by reacting silica gel for column chromatography with 3-(N-alkyl)aminopropyltriethoxysilane in an inert solvent such as benzene, and has the general formula A≡SiCH ₂ A chemically modified silica gel represented by CH ₂ CH ₂ NHR () (in the formula, A and R represent the same meanings as above) is obtained, and then in the presence of a dehydrochlorination agent in an inert solvent such as benzene,
general formula (In the formula, Y represents a halogen atom, and x, m and n represent the same meanings as above.) Obtained by reacting nitrohalogenated benzene, nitrobenzenesulfonyl halide or nitrobenzyl halide shown by .

In order to carry out nuclear chlorination of alkylbenzene using the catalyst of the present invention, chemically modified silica gel represented by the above general formula () is added per mole of alkylbenzene.
The chlorine gas is present in a proportion of 20 to 200 g, preferably 100 to 500 g, and is introduced at a temperature below the boiling point of the reaction mixture. If the temperature is too high, the amount of polychlorinated products produced increases and the yield of p-chloro compound 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 for the p-chloro compound 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. The pressure of the chlorine gas may be normal pressure, increased pressure, or reduced pressure, but the reaction is usually carried out under normal pressure.

Examples of alkylbenzenes to be nuclear chlorinated using the catalyst of the present invention include benzenes monosubstituted with various straight-chain and branched-chain alkyl groups, and those in which the alkyl group has 1 to 4 carbon atoms are particularly preferred. preferable.

By using the catalyst of the present invention, it is possible to suppress the chlorination of the o-position of alkylbenzene and efficiently chlorinate the p-position, and the production of m-chloro and polychlorinated products is extremely small. In addition, the catalyst of the present invention does not lose its activity even after repeated use, and has excellent durability.
It is suitable for industrially producing chloroforms and has high industrial value.

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

[Example 1] 0.6 g of cumene was placed in a 30 ml reaction flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel.
(5m mol) and catalyst (1) [the above general formula ()
0.5 _g of R=H,
Add 0.35 g of chlorine to 15 ml of carbon tetrachloride at 30°C (5 m
mol) was added dropwise, and the mixture was reacted at 30°C for 1 hour. After the reaction was completed, the catalyst was removed, washed with sodium hydrogen carbonate, dried, and analyzed by gas chromatography. As a result, the production ratio of monochlorocumene was 4-chlorocumene/2-chlorocumene ratio (p/o) = 2.09. .

[Comparative Example 1] (Method described in JP-A No. 56-5139) 480 g of cumene and 2 g of antimony trichloride were placed in a 1-4 neck flask equipped with a stirrer, a thermometer, a gas blowing tube, and a reflux condenser. Take 2 g of phenoxatin and heat it in a water bath to about 50°C 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 replaced with catalyst 2 [the general formula ()
Example 1 except that R=H, X=SO ₂ , m=1, n=2, substitution position 2,4-]
The reaction was carried out under the same conditions. As a result of analysis by gas chromatography, the composition of the reaction solution was 4-chlorocumene/2-chlorocumene ratio (p/o) = 2.00.

[Example 3] Catalyst 1 of Example 1 was replaced with catalyst 3 [the general formula ()
In R=H, m=0, n=2, substitution position 2,
The reaction was carried out under the same conditions as in Example 1, except that the reaction mixture was replaced with [4-]. As a result of gas chromatograph analysis, the reaction solution composition was 4-chlorocumene/2-
The chlorocumene ratio (p/o) was 1.56.

[Brief explanation of the drawing]

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. General formula (In the formula, A represents silica gel, R represents a hydrogen atom or an alkyl group, X represents a sulfonyl group or a methylene group, m represents an integer of 0 or 1, and n represents an integer of 1 or 2. ) Catalyst for nuclear chlorination of alkylbenzene consisting of chemically modified silica gel.