JP3188173B2 - Method for producing aromatic sulfone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic sulfone.

[0002]

2. Description of the Related Art Aromatic sulfones such as dichlorodiphenyl sulfone are important compounds as synthetic resin raw materials, pharmaceutical intermediates and the like.

[0003] Conventionally, it is known that such aromatic sulfones can be obtained by reacting dialkyl sulfate, sulfur trioxide and an aromatic compound. For example, U.S. Pat. No. 2,971,1985 discloses that a commercially available mixture of stabilized sulfur trioxide and dimethyl sulfate is reacted to obtain a mixture of dimethyl pyrosulfate and sulfur trioxide, and the mixture is reacted with chlorobenzene to obtain dichlorodiphenyl sulfone. Are disclosed.

[0004]

Conventional methods for obtaining stabilized sulfur trioxide include, for example, Japanese Patent Publication No. Sho 38
No. -16852 discloses that 0.005 to 0.1% by weight of diboron trioxide and 0.05 to 1.0% by weight of dimethyl sulfate based on sulfur trioxide to be stabilized are mixed with liquid trioxide. A method of adding to sulfur oxide is known.

Further, when the present inventors analyzed commercially available stabilized sulfur trioxide, it was found that it contained about 0.05% by weight of diboron trioxide and about 0.5% by weight of dimethyl sulfate. I understood.

[0006] The inventors of the present invention have repeated the prior art using the above-mentioned commercially available stabilized sulfur trioxide, and as a result, despite the fact that 98.2% of chlorobenzene has reacted,
The selectivity of aromatic sulfone was 85.6%, and chlorobenzenesulfonic acid was by-produced in a large amount of 11.0%.

In the method for producing an aromatic sulfone by reacting a dialkyl sulfate, sulfur trioxide and an aromatic compound as described above, even if the stabilized sulfur trioxide as described above is used, chlorobenzenesulfonic acid can be used. However, there is a problem that a large amount of aromatic sulfonic acid is produced as a by-product. As described above, when a large amount of by-product is generated, not only the yield of the target substance with respect to the used raw material is reduced, but also when water is poured to isolate the target substance from the reaction solution, the by-product is generated as a by-product. Since the aromatic sulfonic acid is water-soluble, there arises a problem of treating an acid waste liquid in which the aromatic sulfonic acid is dissolved in a large amount, which is not industrially satisfactory.

Against this background, an object of the present invention is to suppress the by-product of aromatic sulfonic acid and obtain aromatic sulfone with high selectivity.

[0009]

Means for Solving the Problems The present inventors have intensively studied in view of the above problems. As a result, by adding a small amount of diboron trioxide to the dialkyl sulfate used in producing the aromatic sulfone, and then reacting with sulfur trioxide and an aromatic compound, the above-mentioned stabilized triazole is surprisingly obtained. The inventors have found that aromatic sulfone can be obtained with a higher selectivity by suppressing the by-product of aromatic sulfonic acid than the conventional technique using sulfur oxide, and the present invention has been completed.

That is, the present invention is a process for producing an aromatic sulfone, which comprises reacting a dialkyl sulfate containing a boron oxo compound, sulfur trioxide and an aromatic compound.

As the dialkyl sulfate in the present invention, known dialkyl sulfates can be used without any limitation. As the alkyl group,
C1 such as methyl, ethyl, propyl, isopropyl, etc.
5 are preferable. Suitable dialkyl sulfates include dimethyl sulfate and diethyl sulfate in terms of availability, and dimethyl sulfate is particularly preferred.

The properties of the sulfur trioxide used in the present invention are not particularly limited, and any of a gas, a liquid and a solid can be used, but a gas and a liquid which are easy to handle are preferable. Furthermore, when gas is used, not only is the selectivity of aromatic sulfone further improved, but also an energy-unfavorable step such as liquefaction of sulfur trioxide gas produced by oxidizing sulfur is not required, and storage and storage can be performed. It is particularly preferable because there is no possibility of clogging of pipes and the like due to coagulation during transportation and transportation to a reactor for producing aromatic sulfone. In order to prevent coagulation, there is no problem even if a material stabilized with diboron trioxide, dimethyl sulfate, a siloxane polymer, phthalic anhydride or the like is used.

As the aromatic compound used in the present invention, known compounds can be used without any limitation.
Specifically, arenes such as benzene, toluene and t-butylbenzene; fluorobenzene, chlorobenzene,
Aryl halides such as bromobenzene, iodobenzene and benzyl chloride; and benzaldehydes; and arenes such as benzene, toluene and t-butylbenzene; fluorobenzene, chlorobenzene, bromobenzene, iodobenzene, and chloride. Aryl halides such as benzyl are preferred, and aryl halides such as fluorobenzene, chlorobenzene, bromobenzene, iodobenzene and benzyl chloride are more preferred.

[0014] The greatest feature of the present invention is that the reaction was contained oxo compound of advance boron sulfate di alkyl, which sulfur trioxide and aromatics. By doing so, the by-product of aromatic sulfonic acid is reduced and the selectivity of aromatic sulfone is increased. On the other hand, when a dialkyl sulfate, sulfur trioxide, or an aromatic compound is reacted without containing an oxo compound of boron, the selectivity of aromatic sulfone is remarkably lowered, and a large amount of aromatic sulfonic acid is by-produced.

Known oxo compounds of boron used in the present invention can be used without any limitation. Specifically, carbon atoms of 3 such as trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, etc.
~ 12 boric esters; trimethoxyboroxine;
C3 to C12 alkoxyboroxines such as triethoxyboroxine; boric acids such as orthoboric acid, metaboric acid and tetraboric acid; diboronic trioxide, diboronic dioxide, tetraboric trioxide, tetrapentoxide Examples thereof include boron oxides such as boron, and in particular, boric esters having 3 to 12 carbon atoms such as trimethyl borate, triethyl borate, tripropyl borate, and triisopropyl borate; trimethoxyboroxine, triethoxy 3 to 1 carbon atoms such as boroxine
2 alkoxyboroxins; orthoboric acid; diboron trioxide are preferred.

In the present invention, the amount of the boron oxo compound contained in the dialkyl sulfate is not particularly limited.
0.01% by weight based on the weight of sulfur trioxide used in the reaction
The above amount may be added to dialkyl sulfate. Moreover,
If the oxo compound of boron is used in an excessively large amount, it is not economically advantageous. Therefore, the range of 0.02 to 1% by weight, particularly 0.02 to 0.6% by weight, is particularly preferable.

In the present invention, the dialkyl sulfate, sulfur trioxide and aromatic compound containing these boron oxo compounds may be reacted by any method. For example, these three raw materials may be simultaneously mixed to carry out a reaction for generating aromatic sulfone. However, in the present invention, a dialkyl sulfate containing a boron oxo compound and a trialkyl sulfate are preliminarily prepared. The reactant containing the dialkyl pyrosulfate may be obtained by blending with sulfur oxide, and then the reaction may be performed in a blending sequence such that the reactant reacts with the aromatic compound. The amount of each raw material used may be any molar ratio, but usually, the molar ratio of dialkyl sulfate, sulfur trioxide and aromatic compound is 0.02: 0.0
A range of 1: 2 to 2: 1: 2 is preferred.

In the present invention, the reaction can be carried out in any of a batch system, a semi-continuous system, and a continuous system.
Any of reduced pressure can be performed.

The reaction temperature is not particularly limited, but a method of simultaneously adding dialkyl sulfate, sulfur trioxide and an aromatic compound containing these oxo compounds of boron, or containing an oxo compound of boron in advance. Any method of blending dialkyl sulfate and sulfur trioxide to obtain a reactant containing dialkyl pyrosulfate, and then reacting the reactant with an aromatic compound is usually 30 to 130.
° C, preferably in the range of 50 to 100 ° C. The reaction time varies depending on the reaction temperature, but each and every step is usually in the range of 0.1 to 20 hours, preferably 0.5 to 10 hours. It is preferable to stir during the reaction.

In the present invention, the method for isolating the aromatic sulfone from the reaction solution obtained as described above may be any known method without any limitation. For example, a method in which the reaction solution is poured into water, and a dialkyl sulfate, a monoalkyl sulfate by-produced in the reaction of the sulfur trioxide and the aromatic compound from the reaction solution are reduced under reduced pressure based on an equilibrium reaction of the following formula 1. A method of distilling off dialkyl sulfate by distillation and pouring the remaining liquid into water can be exemplified.

[0021]

(Equation 1)

When the method for isolating the aromatic sulfone is the latter method, the dialkyl sulfate distilled off can be recycled and used as a reaction raw material.

[0023]

According to the present invention, aromatic sulfone can be produced with high selectivity by suppressing the by-product of aromatic sulfonic acid. Specifically, the selectivity of the aromatic sulfone is as good as 94% or more with respect to the aromatic compound used in the reaction. Therefore, the present invention is industrially extremely useful as a method for producing an aromatic sulfone.

In the present invention, when gaseous sulfur trioxide is used as sulfur trioxide, not only the yield of aromatic sulfone is further improved, but also sulfur trioxide gas produced by oxidizing sulfur is liquefied. This is extremely industrially very useful because there is no need for an energy-unfavorable process, such as storage and transportation, and there is no risk of clogging of piping and the like due to coagulation during transportation to the reactor for producing aromatic sulfone.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

EXAMPLE 1 126.13 g of dimethyl sulfate was placed in a reactor equipped with a reflux unit, a stirrer and a thermometer in which a refrigerant having a temperature of 20 ° C. was circulated, and 80.0 mg of diboronic trioxide (30.0 mg of triborane) was used. After adding 0.05% by weight to sulfur oxide), absorb 160.12 g of sulfur trioxide gas at a temperature of 70 to 75 ° C. over 30 minutes, and stir at the same temperature for 30 minutes to contain dimethyl pyrosulfate. A reaction solution was obtained.

This reaction solution was added dropwise to 225.12 g of chlorobenzene maintained at a reaction temperature of 50 to 55 ° C. over 30 minutes, and after completion of the addition, the mixture was stirred at the same temperature for 1 hour. When this reaction solution was analyzed, chlorobenzene was found to be 9%.
The conversion was 9.5%, and chlorobenzenesulfonic acid was formed at a selectivity of 4.3% and dichlorodiphenylsulfone at a selectivity of 95.5%.

Next, the above reaction solution was batch-processed at a reflux ratio of 0.5 to 140 to 150 ° C. and a degree of vacuum of 20 to 2 mmHg using a distillation column having three actual plates, until almost no distillate was formed. Distillation was carried out under reduced pressure to give dimethyl sulfate at 115.17
g (purity; 99.0%, recovery rate: 90.4).
%).

Further, the residual liquid after the recovery of dimethyl sulfate was poured into 600 mL of water with vigorous stirring, and the precipitated crystals were collected by filtration, washed with water until the washing liquid reached pH 5, dried and weighed. 272.80 g of dichlorodiphenylsulfone (yield after isolation based on chlorobenzene used; 95.0%) were obtained (Table 1).

Example 2 Example 1 was repeated except that liquid sulfur trioxide was added dropwise to dimethyl sulfate to which diboron trioxide had been added over 30 minutes.
The same operation was performed. The results are shown in Table 1.

Example 3 The same operation as in Example 1 was carried out except that commercially available stabilized sulfur trioxide was added dropwise to dimethyl sulfate containing diboron trioxide over 30 minutes. The results are shown in Table 1.

Examples 4 to 6 The procedure of Example 1 was repeated except that the amount of diboron trioxide shown in Table 1 was used. The results are shown in Table 1.

Examples 7 and 8 The same procedures as in Example 1 were carried out except that the boron oxo compounds shown in Table 1 were used. The results are shown in Table 1.

Comparative Example 1 Dimethyl sulfate containing no oxo compound of boron was added to
The same operation as in Example 1 was carried out except that the same stabilized sulfur trioxide used in Example 3 was added dropwise to obtain a reaction solution containing dimethyl pyrosulfate. The results are shown in Table 1.

Comparative Examples 2 to 4 As sulfur trioxide, prepared by adding diboron trioxide and dimethyl sulfate as stabilizers to liquid sulfur trioxide obtained by cooling sulfur trioxide gas, as shown in Table 1. The same operation as in Comparative Example 1 was carried out except that the stabilized sulfur trioxide thus obtained was used. The results are shown in Table 1.

Comparative Example 5 The same operation as in Comparative Example 1 was carried out except that a liquid sulfur trioxide obtained by cooling sulfur trioxide gas was used without adding a stabilizer. The results are shown in Table 1.

Comparative Example 6 Dimethyl sulfate containing no oxo compound of boron was added to
The operation was performed in the same manner as in Example 1 except that a reaction solution containing dimethyl pyrosulfate was obtained by absorbing sulfur trioxide gas. The results are shown in Table 1.

[0038]

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 317/14 C07C 315/00

Claims (1)

(57) [Claims] 1. A process for producing an aromatic sulfone, which comprises reacting a dialkyl sulfate containing an oxo compound of boron, sulfur trioxide and an aromatic compound.