JPH08198806A - Production of alkylbenzoylchloride - Google Patents

Abstract

PURPOSE: To obtain the subject compound useful as a raw material for an agrochemical, a chemical, in a single step reaction in high yield at a low cost by reacting an alkylbenzaldehyde with chlorine under the coexistence of a substituted benzene. CONSTITUTION: This compound is obtained by reacting (A) alkylbenzaldehyde, e.g. a compound expressed by formula [R is an alkyl; m, n are each 1-5, m+n<=6], concretely o-, m- or p-tolualdehyde, etc., with (B) chlorine under the coexistence of (C) a substituted benzene having at least one functional group selected from methyl, (di)chloromethyl and trichloromethyl, e.g. a compound expressed by formula II [X is methyl, (di)chloromethyl or trichloromethyl; Y is F, Cl, Br, etc.; (i)=1-6; (j)=0-5; (i)+(j)$6], concretely toluene, etc. Further for instance, the component C is preferably used in an amount of 0.005-50 pts.wt. based on 1 pts.wt. of the component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an alkylbenzoyl chloride by chlorinating an alkylbenzaldehyde. Alkylbenzoyl chloride is widely used as a raw material and an intermediate for agricultural chemicals, chemical products and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for producing benzoyl chlorides, a method obtained by hydrolysis of corresponding benzotrichloride has been considered economical. Further, a method of obtaining a corresponding acid chloride by chlorinating an alkylbenzenecarboxylic acid as a raw material with a chlorinating agent such as thionyl chloride or phosphorus pentachloride, or a method of reacting benzaldehyde having no alkyl side chain with chlorine and benzoyl chloride Is known (US Pat. No. 3,894,923) and the like.

[0003]

Of these, when the corresponding alkylbenzoyl chloride is produced by a method by hydrolysis of benzotrichlorides, the alkylbenzotrichloride must be used as a raw material. In order to obtain alkylbenzotrichloride, only one methyl group on the alkylbenzene having at least two alkyl substituents must be selectively chlorinated, and it is extremely difficult to selectively carry out such a reaction. Is. Although the method of chlorinating alkylbenzene carboxylic acid with thionyl chloride has a high yield of acid chloride, the use of these chlorinating agents is more expensive than the case of using chlorine as a raw material, and the point of purification and post-treatment is required. There are many problems.

On the other hand, benzaldehyde reacts with chlorine to obtain benzoyl chloride in a high yield, and is therefore an excellent method for producing benzoyl chloride having no alkyl substituent. However, when an alkylbenzaldehyde having an alkyl side chain as a raw material is reacted with chlorine, it is difficult to obtain a corresponding alkylbenzoyl chloride in a high yield, and an industrial production method of such an alkylbenzoyl chloride has never been known so far. Not not.
This is because the side chain alkyl group of the alkylbenzaldehyde easily reacts with chlorine. For example, when the side chain alkyl group of the raw material alkylbenzaldehyde is reacted with chlorine by the method described in the above-mentioned US Pat. No. 3,894,923. Also, a large amount of a side chain chlorinated product of the desired product, alkyl benzoyl chloride, is produced as a by-product, and the yield of the desired product, alkyl benzoyl chloride, is significantly impaired. Further, since the boiling points of these by-products and the target substance are close to each other, separation by distillation is difficult, which causes a problem of purification. In view of these facts, an object of the present invention is to provide a method for producing an alkylbenzoyl chloride from an alkylbenzaldehyde and chlorine at a high yield and at a low cost.

[0005]

Means for Solving the Problems The present inventors have conducted extensive studies to obtain an excellent method for producing an alkylbenzoyl chloride from alkylbenzaldehyde and chlorine, and as a result, a methyl group, a chloromethyl group, By coexisting a substituted benzene having at least one functional group selected from dichloromethyl group and trichloromethyl group, side reactions such as nuclear chlorination and side chain chlorination are significantly suppressed, and the desired acid chloride is obtained. The present invention has been achieved by finding that it can be obtained in an extremely high yield. That is, the present invention
Alkylbenzaldehyde and chlorine are reacted in the presence of a substituted benzene having at least one functional group selected from a methyl group, a chloromethyl group, a dichloromethyl group, and a trichloromethyl group. It is a manufacturing method.

The alkylbenzaldehyde used as a raw material in the present invention is represented by the following chemical formula.

Embedded image In the formula, R is an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group, and m and n are integers of 1 to 5 representing the number of substituents and m + n. ≦ 6. Specific examples of the alkylbenzaldehyde are o-, m-, p- tolualdehyde, ethylbenzaldehyde, isopropylbenzaldehyde, isobutylbenzaldehyde, 2,4-dimethylbenzaldehyde, 2,
6-Dimethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde and the like can be mentioned to obtain the corresponding alkylbenzoyl chloride.

The chlorine used in the reaction of the present invention is not particularly limited as long as it is industrially available, but dried chlorine is preferable. Chlorine is usually bubbled into the reaction solution for reaction, but the supply amount and supply rate are not particularly limited. The reaction pressure is 5 kg / cm ² or less, and the reaction is usually performed at normal pressure.

In the present invention, the coexistence of a substituted benzene having at least one functional group selected from a methyl group, a chloromethyl group, a dichloromethyl group and a trichloromethyl group in the reaction system is the objective alkylbenzoyl chloride. It is very effective to increase the yield of These substituted benzenes may have a substituent such as a halogen group or a nitrile group and are represented by the following general formula.

Embedded image In the formula, X represents a methyl group, chloromethyl group, dichloromethyl group or trichloromethyl group, and Y represents-.
F, -Cl, -Br, -I, -CN, -COCl, -N
O _2, -C ₆ H _5, represents a functional group such as -C ₆ H ₅ CH _3, i is an integer representing the number of substituents 1 to 6 X, j is the substituents of 0-5 of Y An integer representing a number, i + j ≦
It is 6.

As the substituted benzene corresponding to the above, toluene, o-, m-, p-xylene, pseudocumene, mesitylene, benzyl chloride, benzal chloride, benzotrichloride, o-, m-, p-tolunitrile, 4 -Methylbiphenyl, 4,4'-dimethylbiphenyl, o-, m-, p-α,
Examples thereof include α, α, α ′, α ′, α′-hexachloroxylene. The amount of the substituted benzene used is preferably 0.001 to 100 parts by weight, more preferably 0.0 to 100 parts by weight, based on 1 part by weight of the alkylbenzaldehyde as a raw material.
It is in the range of 05 to 50 parts by weight. If the amount used exceeds this range, it will not affect the reaction results, but excessive use is not economical. On the other hand, if the amount is less than this range, byproducts such as nuclear chlorinated compounds and side-chain chlorinated compounds as well as high-boiling products are generated, and the yield of the desired acid chloride is reduced, which is not preferable.

In carrying out the present invention, a solvent is not always necessary if the starting material alkylbenzaldehyde is a liquid under the reaction conditions. However, the use of a solvent is effective in suppressing side reactions such as side chain chlorination and increasing the yield of the intended alkylbenzoyl chloride. For this purpose, a solvent inert to chlorination is used, and examples thereof include o-dichlorobenzene, chlorobenzene, carbon tetrachloride, and benzonitrile. Even if the amount of the solvent used is small, it is effective.
It is preferably used in the range of 100 to 100 parts by weight, more preferably 1.0 to 50 parts by weight. If the amount used exceeds this range, it does not affect the reaction results, but it is uneconomical because the amount of solvent circulation increases. By using such a solvent, byproducts such as chlorinated compounds and side chain chlorinated compounds,
The production of high-boiling products is reduced, and the yield of the desired alkylbenzoyl chloride is improved.

The reaction of the present invention is usually carried out under exposure. The light source is not particularly limited, but industrially, a mercury lamp, a tungsten lamp, or the like is installed as a light source in the reactor to obtain high reaction activity and selectivity for acid chloride. Further, the use of a radical generator such as benzoyl peroxide or 2,2-azobis (isobutyronitrile) instead of exposing it is also effective to enhance the activity of the reaction. In this case, the radical generator may be used in a small amount, and it is sufficient that the amount is about 0.001 to 0.01 part by weight with respect to 1 part by weight of the raw material alkylbenzaldehyde. Even if the amount of the radical generator used exceeds this range, the yield does not change, and the use of a large amount is economically undesirable.

Control of the reaction temperature is extremely important in carrying out the present invention. The reaction temperature is in the range of -10 to 80 ° C, preferably 0 to 50 ° C. When the reaction is carried out at a temperature higher than this range, side reactions such as chlorination of alkyl side chains and nuclear chlorination, and formation of high-boiling components due to polymerization of raw materials / products are likely to occur, resulting in a target product yield. Markedly reduced. Further, when the reaction is carried out at a temperature lower than this range, not only the activity of the reaction is lowered, but also the raw materials and products may be below the freezing point.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 500 m equipped with a gas blowing pipe, a reflux condenser and an agitator
70 g of p-ethylbenzaldehyde, 20 g of toluene and 210 g of o-dichlorobenzene were charged into a 1-flask, and the temperature in the system was adjusted to 10 ° C. while introducing nitrogen gas from a gas blowing tube. After bubbling nitrogen gas for 1 hour, the reaction was started by stopping the supply of nitrogen and starting the irradiation of light with a mercury lamp at the same time as the supply of chlorine. While maintaining the reaction temperature at 10 ° C., 38 g of chlorine was supplied over 1 hour to carry out the reaction. When this reaction product liquid was analyzed by gas chromatography, the reaction rate of p-ethylbenzaldehyde was 92% and the selectivity of p-ethylbenzoyl chloride was 85%.
%Met.

Example 2 The reaction was carried out in the same manner as in Example 1 except that a 200 ml flask was used and o-dichlorobenzene was not used. As a result, the reaction rate of p-ethylbenzaldehyde was 8
The selectivity was 7% and the selectivity for p-ethylbenzoyl chloride was 78%.

Example 3 The reaction was carried out in the same manner as in Example 1 except that 10 g of benzyl chloride was used instead of toluene. As a result, the conversion of p-ethylbenzaldehyde was 93% and the selectivity of p-ethylbenzoyl chloride was 83%.

Example 4 The reaction was carried out in the same manner as in Example 1 except that 4 g of benzotrichloride was used instead of toluene. As a result, the reaction rate of p-ethylbenzaldehyde was 95%, p-
The selectivity of ethylbenzoyl chloride was 86%.

Example 5 A reaction was carried out in the same manner as in Example 1 except that 70 g of p-isopropylbenzaldehyde was used instead of p-ethylbenzaldehyde and 33 g of chlorine was used. As a result, the reaction rate of p-isopropylbenzaldehyde was 92%,
The selectivity of p-isopropylbenzoyl chloride was 78%.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that toluene was not used. As a result, the conversion of p-ethylbenzaldehyde was 90%, and the selectivity of p-ethylbenzoyl chloride was 75%.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 150 ° C. As a result, the reaction rate of p-ethylbenzaldehyde was 95% and the selectivity of p-ethylbenzoyl chloride was 52%.

Comparative Example 3 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 130 ° C. and o-dichlorobenzene was not added to the reaction system. As a result, the reaction rate of p-ethylbenzaldehyde was 97.
%, The selectivity of p-ethylbenzoyl chloride was 38%.

[0022]

Industrial Applicability According to the method of the present invention, an industrially useful alkylbenzoyl chloride can be produced from an alkylbenzaldehyde and chlorine in a one-step reaction with high reaction results and at low cost.

Claims (1)

[Claims] 1. An alkylbenzaldehyde is reacted with chlorine in the presence of a substituted benzene having at least one functional group selected from a methyl group, a chloromethyl group, a dichloromethyl group and a trichloromethyl group. A method for producing an alkylbenzoyl chloride.