JP2000044500A - Aromatic mono-nuclear chlorination of alkyl aromatic hydrocarbon and its aromatic nuclear chlorination catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mono-nuclear chlorination process for an alkylaromatic hydrocarbon with reduced formation of poly-nuclear chlorinated by-products, as a high O/P ratio and high chlorine utilization are retained and a catalyst for mono-nuclear chlorination to be used in this process. SOLUTION: When an alkylaromatic hydrocarbon is mono-nuclear chlorinated with a chlorine gas, a chloride of an element in the group Va in the periodic table is used as a nuclear chlorination catalyst. The catalyst is used in this mono-nuclear chlorination of an alkylaromatic hydrocarbon and mainly comprises a chloride of an element in the group Va in the periodic table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mononuclear chlorination of alkylaromatic hydrocarbons and a nuclear chlorination catalyst for alkylnuclear chlorination of alkylaromatic hydrocarbons with chlorine gas. Moreover, the present invention relates to a method for mononuclear chlorination of alkyl aromatic hydrocarbons having excellent ortho-selectivity and a nuclear chlorination catalyst thereof.

[0002]

2. Description of the Related Art As a method for nuclear chlorination of an aromatic hydrocarbon, a method of reacting an aromatic hydrocarbon with chlorine gas in a liquid phase is known (Ullmanns; Encyclopaedie der Te Tel).
chnischen Chemie, 4th edition, Volume 9, pp. 499 et seq.) In addition, a Lewis acid catalyst is generally used for the nuclear chlorination reaction.

[0003] In this nuclear chlorination reaction, an isomer mixture of a monochloride and a polychloride is obtained as a nuclear chlorination product. For example, when toluene is subjected to nuclear chlorination with chlorine gas, it is used as a Lewis acid catalyst. When ferrous chloride (FeCl ₃ ) is used, a mixture of monochlorotoluene and cyclotoluene is obtained. As monochlorotoluene, o-chlorotoluene and p-chlorotoluene are main products, and a small amount of
m-chlorotoluene is formed.

However, since all of the isomers of monochlorotoluene are valuable substances, it has been conventionally required to enhance the selectivity of the desired isomer according to its purpose. Attempts have been reported for many types of catalysts that significantly affect the composition of chlorination products (Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, A5
Volume, p. 343). For example, in the above example using ferrous chloride, the ratio of o-chlorotoluene to p-chlorotoluene (O / P ratio) is 2.2, whereas this ferrous chloride is used as a co-catalyst. When sulfur is used, the O / P ratio is reduced to 1.0, and the production ratio of p-chlorotoluene is improved.

[0005] By the way, studies on nuclear chlorination catalysts so far have shown that p-chlorotoluene has a wide utility value as a raw material for industrial chemicals, agricultural chemicals, pharmaceuticals and the like.
Spent on exploring catalyst systems to improve the production of p-chlorotoluene, especially Lewis acid catalysts,
The search for a catalyst system that improves the o-chlorotoluene production ratio has been enthusiastically conducted because the industrial value of o-chlorotoluene was considered to be relatively lower than that of p-chlorotoluene. The fact was not.

[0006] However, in recent years, for example, 2,6-dichlorotoluene, 2,5-dichlorotoluene, and 2,4-dichlorotoluene, which are isomers of dichlorotoluene, for use as intermediates for pesticides, pharmaceuticals, and the like. The use of toluene is increasing, and in order to efficiently produce these dichlorotoluene isomers, it is necessary to increase the production ratio of monochlorotoluene to o-chlorotoluene.

Attention is now directed to a nuclear chlorination catalyst having a high production ratio of o-chlorotoluene. For example, US Pat. No. 3,000,975 discloses titanium tetrachloride, tin tetrachloride, It has been reported that a nuclear chlorination reaction of toluene was performed using tungsten hexachloride or zirconium tetrachloride to obtain monochlorotoluene with an O / P ratio of 1.60 to 3.26. 33,6
No. 96, using a mixture of an antimony compound and an iron compound as a Lewis acid catalyst, performing a nuclear chlorination reaction of toluene using a predetermined polyether compound as a cocatalyst,
It has been reported that monochlorotoluene was obtained with an O / P ratio of 2.19 to 3.28.

However, in the method described in US Pat. No. 3,000,975, although the O / P ratio is high,
There is a problem that the chlorine utilization rate is low and the amount of higher-order nuclear chlorination by-products is relatively large.
In the method described in Japanese Patent No. 3,696, there is a problem that raw material costs and separation costs increase because a cocatalyst such as a polyether compound is used.

[0009]

Accordingly, the present inventors have developed not only a high O / P ratio but also a high chlorine utilization rate and a highly nuclear chlorinated by-product (higher nuclear chlorination). As a result of intensive studies on the mononuclear chlorination reaction of alkyl aromatic hydrocarbons, which produces as little by-products as possible and reduces the burden on exhaust gas treatment and waste liquid treatment as much as possible, as a nuclear chlorination catalyst, a Group Va element of the periodic table It has been found that the object can be achieved by using chloride of the present invention, and the present invention has been completed.

Accordingly, it is an object of the present invention to provide a mononuclear chlorination of an alkyl aromatic hydrocarbon which not only has a high O / P ratio, but also has a high chlorine utilization rate and a low generation of higher nuclear chlorination by-products. It is to provide a method. Another object of the present invention is to provide a novel nuclear chlorination catalyst suitable for obtaining a mononuclear chlorination reaction product having a high O / P ratio in a mononuclear chlorination reaction of an alkyl aromatic hydrocarbon. It is in.

[0011]

That is, the present invention relates to a method for mononuclear chlorination of an alkyl aromatic hydrocarbon with chlorine gas, wherein the alkyl aromatic hydrocarbon is a chloride of a Group Va element of the periodic table as a nuclear chlorination catalyst. This is a method for mononuclear chlorination of hydrocarbons.

The present invention also relates to a catalyst for use in a mononuclear chlorination reaction for mononuclear chlorination of an alkyl aromatic hydrocarbon with chlorine gas, wherein the nucleus is mainly composed of a chloride of an element of group Va in the periodic table. It is a chlorination catalyst.

In the present invention, typical examples of the alkyl aromatic hydrocarbon used as a raw material include monoalkyl aromatic hydrocarbons such as toluene, ethylbenzene, propylbenzene, cumene and t-butylbenzene. Preferably it is toluene. The alkyl aromatic hydrocarbon used here has a water content of 200 pp.
m or less, preferably 100 ppm or less.
If the water content exceeds 200 ppm, the activity of the nuclear chlorination catalyst may decrease.

The chlorine gas introduced into the reaction system in the present invention may be 100% chlorine gas as it is.
If necessary, it may be diluted with an inert gas such as nitrogen gas to a concentration of 1 to 50%, preferably 5 to 20%.

Further, the nuclear chlorination catalyst used in the present invention is:
It is necessary to include at least a chloride of a Va group element in the periodic table as its main component, and the chloride of a Va group element in the periodic table is preferably a niobium or tantalum chloride. Specifically, there may be mentioned NbCl ₅ and TaCl ₅ as being preferred, particularly preferably NbCl _5.
As the chloride of Group Va element of the periodic table used as a nuclear chlorination catalyst, only one kind thereof can be used alone.
It can also be used as a mixture of more than one species.

The mononuclear chlorination reaction of the present invention must be carried out in a liquid phase. However, if the alkyl aromatic hydrocarbon used as a raw material is liquid at the reaction temperature, it can be carried out without a solvent. Thus, a suitable solvent that dissolves the alkyl aromatic hydrocarbon as the raw material but is not attacked by chlorine, such as methylene chloride, carbon tetrachloride, chloroform, etc., may be used as the solvent.

In the mononuclear chlorination reaction of the present invention, the amount of the chlorine gas introduced into the reaction system is 0.8 to 1.0 mol, preferably 0.9 to 1.0 mol per mol of the alkyl aromatic hydrocarbon. 1.0 mole. If the introduction amount of chlorine gas is less than 0.8 mol per 1 mol of the alkyl aromatic hydrocarbon, there arises a problem that the amount of unreacted substances increases, and
If it is more than 1.0 mol, there arises a problem that the production of higher nuclear chlorination by-products increases.

In the mononuclear chlorination reaction, the degree of chlorination of the reaction mixture is preferably not more than 1, based on the alkyl aromatic hydrocarbon to be chlorinated. If the degree of chlorination exceeds 1, the amount of higher-order nuclear chlorine by-products increases and the yield of the target product decreases, which is not preferable.

The amount of the above-mentioned nuclear chlorination catalyst used in the mononuclear chlorination reaction of the present invention is usually 0.01 to 5% by weight, preferably 0.1 to 1% by weight, based on the starting alkyl aromatic hydrocarbon. If the amount used is less than 0.01% by weight, the chlorine utilization decreases, while if it is more than 5% by weight, the production cost becomes high and it is not economical.

The reaction conditions for the mononuclear chlorination reaction of the present invention vary depending on the kind of the alkylaromatic hydrocarbon used as the starting material, the kind of the nuclear chlorination catalyst and the amount used, and the like, from the freezing point to the boiling point of the reaction mixture. The reaction can be carried out in a temperature range of 0 to 100 ° C, preferably 40 to 100 ° C.
The temperature is preferably up to -60 ° C.

The mononuclear chlorination reaction of the present invention can be carried out by either a continuous system or a batch system. After completion of the reaction, the obtained reaction mixture is first filtered to remove the nuclear chlorination catalyst by filtration or distillation, and then purified by a purification method such as distillation or fractional crystallization to produce the desired mononuclear chlorination reaction product. Things.

The mononuclear chlorination reaction product produced according to the present invention is produced via the o-isomer without separation of the o-isomer and the p-isomer due to the high ratio of the o-isomer. Certain dinuclear chlorinated derivatives can be produced in high proportions.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below based on examples.

Examples 1 and 2 and Comparative Examples 1 to 3 In a 200 ml brown three-necked flask, the water content was 5 pp.
and 92.1 g (1.0 mol) of toluene and 0.92 g (1% by weight based on toluene) of the catalyst shown in Table 1 were charged, and heated to 50 ° C. while flowing nitrogen gas (N ₂ ) at 1 g / min. 1.18 chlorine gas while stirring with a mechanical stirrer
g / min (0.17 mol / min), cool with cooling water to maintain the reaction temperature at 50 ° C.
The reaction was continued for 0 minutes, and 70.8 g of chlorine (1.0%) was added to the reaction system.
(Mol), the blowing of chlorine was stopped, and the reaction was terminated.

After completion of the reaction, the reaction system was replaced with nitrogen gas, and the reaction mixture was sampled and its composition was examined by gas chromatography. Table 1 shows the results.

[0026]

[Table 1]

As is clear from the results in Table 1, Example 1
In (2) and (2), not only is the O / P ratio high, but also the chlorine utilization is high, and the yield of o-chlorotoluene, which is the target substance, is high, and the production of dichlorotoluene, a by-product of higher-order nuclear chlorination, is increased. The amount is small.

[0028]

According to the present invention, not only the O / P ratio is high but also the chlorine utilization is high and the generation of higher nuclear chlorination by-products is small, so that It is possible to industrially produce a mononuclear chlorinated product by nuclear chlorination.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G069 AA02 BB08A BB08B BC53A BC55A BC55B BC56A BC56B BD12A BD12B CB01 CB25 CB68 4H006 AA01 AA02 AB84 AC30 BA12 BA37 EA21 4H039 CA50 CD10

Claims (3)

[Claims] 1. In the mononuclear chlorination of an alkyl aromatic hydrocarbon with chlorine gas, a nuclear chlorination catalyst of the periodic table V
A method for mononuclear chlorination of an alkyl aromatic hydrocarbon, comprising using a chloride of a group a element. 2. The method for mononuclear chlorination of an alkyl aromatic hydrocarbon according to claim 1, wherein the group Va element in the periodic table is niobium or tantalum. 3. A catalyst used in a mononuclear chlorination reaction for mononuclear chlorination of an alkyl aromatic hydrocarbon with chlorine gas,
A nuclear chlorination catalyst comprising a chloride of a Va group element in the periodic table as a main component.