JPH0393768A - Production of bis(4-allyloxy-3,5-dibromophenyl)sulfone - Google Patents

Abstract

PURPOSE:To carry out the reaction for the production of the subject compound in high efficiency by converting bis(4-hydroxy-3,5-dibromophenyl) sulfone to allyl ether with allyl chloride, recovering the crystal of the subject compound, adding an acid to the filtrate and reusing the recovered reaction intermediate. CONSTITUTION:Bis(4-hydroxy-3,5-dibromophenyl) sulfone is converted to allyl ether with allyl chloride in the presence of an alkali. The obtained slurry solution is filtered to separate and recover bis(4-allyloxy-3,5-dibromophenyl)sulfone in the form of crystal. An acid is added to the filtrate and the crystallized 4-allyloxy-4'-hydroxy-3,3',5,5'-tetrabromodiphenylsulfone is separated and recovered as a reaction intermediate. The recovered intermediate is recycled to the reaction system. The present process achieves high yield and purity without using a catalyst.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to bis(4-allyloxy-3,5-dibromophenyl)sulfone (hereinafter abbreviated as TBS-BA).
The present invention relates to a manufacturing method for obtaining the compound in high yield and purity.

TBS-BA is useful as a flame retardant for polyolefin resins and as an intermediate for flame retardants, especially bis(3,5-dibromo-4-dibromobropoxyphenyl) sulfone obtained by brominating an allyl group. (Hereinafter, TBS-B
It is stated in Japanese Patent Publication No. 35103/1983 and Japanese Patent Publication No. 23693/1983 that P (abbreviated as P) is extremely useful as a flame retardant for polypropylene and the like.

[Conventional technology]

Conventionally, allyl chloride was used as an allylating agent to produce TBS-
When BA is produced, the etherification rate is very slow unless a catalyst such as bromide or iodide is added, and TBS-B
It is known that A has almost no survival (Special Public Interest Publication in 1983-
No. 39585). This production method uses bis(4-hydroxy-3.5-dibromophenyl)sulfone (hereinafter referred to as TBS).
) is dissolved in a solvent such as alcohol or water together with an alkali, then a catalyst such as bromide or iodide is added, allyl chloride is added all at once, and TBS-BA is heated under reflux. This is a method of generating.

However, since this method uses a relatively large amount of an expensive catalyst such as bromide or iodide, it has not always been economically satisfactory as an industrial-scale production process.

Therefore, in order to solve the problem that the etherification rate is very slow in the conventional technology without adding a catalyst, the present inventors investigated ways to improve the reaction rate, and found that water was used as the reaction solvent. When a homogeneous aqueous solution containing a specific soluble organic solvent in a certain concentration range is used, a remarkable reaction acceleration is observed, side reactions are suppressed, and TBS-BA
They discovered that the yield of the new method was improved and filed a patent application earlier.

However, the yield of TBS-BA obtained by this method is 24
Even after reacting for more than 3 hours, it is still a little low at about 85%, and 4-allyloxy-4''-hydroxy-3,3, which is a reaction intermediate dissolved in the filtrate obtained by filtering and separating TBS-BA after the reaction. Since the treatment of '5,5'-tetrabumodiphenyl sulfone (hereinafter abbreviated as TBS-MA) also poses a problem, this method has not yet been satisfactory as an industrial production method.

[Problem to be solved by the invention]

An object of the present invention is to provide an industrial method for producing TBS-BA in high yield and purity without requiring the addition of a catalyst.

[Means to solve the problem]

The inventors of the present invention have conducted extensive studies in order to resolve the problems that the conventional techniques have not yet been industrially satisfied with. As a result, (1) In the reaction between TBS and allyl chloride, after the reaction is completed, the precipitated crystals are almost only TBS-BA, and unreacted TBS and reaction intermediate TBS-MA are dissolved in the filtrate. (2) add acid to the filtrate;
When crystallized, the precipitated crystals are T with extremely few impurities.
(3) Furthermore, when TBS-MA is added to TBS and the allylation reaction is performed, a significant reaction acceleration is observed, and a high yield is achieved in a short time. I found out what I can do.

Therefore, an acid is added to the reaction filtrate obtained in the TBS-BA manufacturing process to crystallize and separate and recover the component mainly composed of TBS-MA, and the recovered component mainly composed of TBS-MA is used in the next reaction. If the reaction is repeated and this operation is repeated, TBS-
They discovered that not only the yield of BA was greatly improved, but also that the obtained crystals were of high purity, leading to the completion of the present invention.

That is, the gist of the present invention is a method for producing TBS-BA by allyl etherifying TBS using allyl chloride, including (A) allyl etherifying TBS using allyl chloride in the presence of an alkali. Step; (B) Step of filtering the slurry solution obtained in step (A) and separating and recovering TBS-BA as crystals; (C) Adding acid to the filtrate obtained in step (B) and TBS-BA.
- A step of crystallizing and separating and recovering a component mainly composed of MA; and (D) recycling the component mainly composed of TBS-MA obtained in step (C) to step (A) for re-reaction. A method for manufacturing TBS-BA is characterized by comprising steps.

When allyl chloride is used as an allylating agent, there is no need to add a catalyst as described above, and if a homogeneous aqueous solution containing a specific water-soluble organic solvent in a certain concentration range is used as the reaction solvent, The rate of etherification is accelerated,
Although the yield of TBS-BA is improved, the method is still unsatisfactory from an industrial perspective.

However, in the method of the present invention in which the recovered fraction mainly consisting of TBS-MA is recycled to the next reaction,
Furthermore, the etherification reaction is promoted, and as a result, the yield of TBS-BA can be greatly improved in a shorter reaction time than in conventional methods.

Although it is not necessarily clear why the yield increases in the method of the present invention, the reaction intermediate T
Due to the presence of B S-MA in the reaction system, TBS
The solubility of alkali salts in organic solvents is improved, and TBS and 7
This is thought to be because the reactivity of lyl chloride is further accelerated.

In addition, since the method of the present invention recovers TBS-MA, which is the main component in the filtrate, from the reaction filtrate, the product cost can be reduced and the filtrate can be easily processed, making it an extremely advantageous method from an industrial perspective. You can say that.

On the other hand, when the filtrate itself containing TBS-MA is circulated in the circulation of TBS-MA, the reaction by-product Na
As salts such as Cl accumulate in the reaction system each time they are circulated, the reaction solvent, which is a mixture of organic solvent and water, is salted out and causes two-phase separation, resulting in a significant decrease in reactivity. have.

[Effect]

Hereinafter, each step of the present invention will be explained in detail.

(A) Step TBS is allyl etherified using allyl chloride in the presence of an alkali.

This process can be explained using the following reaction formula.

Br BrBr
Br The amount of allyl chloride used in the method of the present invention is 2 mol or more, preferably 2.0 to 3.0 mol, per 1 mol of TBS.

Even if 3.0 mol or more is added, no improvement in yield is observed.

The reaction solvent used in the method of the present invention is a homogeneous aqueous solution prepared by mixing a water-soluble organic solvent in a concentration range of 25 to 60% by volume. Water-soluble organic solvents include monovalent lower alcohols having 1 to 3 carbon atoms and ethers having 2 to 5 carbon atoms, and specifically include methanol, ethanol, n-probanol, isopropanol, and dioxane. , THF. These include methyl cellosolve and ethyl cellosolve. Among these, water-isopropanol and water-dioxane mixed solvent systems are particularly preferred due to their high reactivity.

There is no particular limitation on the substrate concentration of TBS in these reaction solvents, but it is usually about 15 to 35% by weight.

The alkali used in the method of the present invention includes alkali metal hydroxides, carbonates, and hydrogen carbonates, such as sodium hydroxide. Potassium hydroxide. Examples include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate.

The amount of this alkali to be used is 2 mol or more, preferably 2.0 mol or more per 1 mol of TBS. The amount is preferably 0 to 3.0 mol, and even if 3.0 mol or more is added, no particular improvement in yield will be observed.

In addition, when the amount of alkali used is 2.2 mol or less per 1 mol of TBS, TBS and TBS-M are added during the reaction.
A becomes easier to precipitate, and as a result, they become TBS-B
Since it is easily incorporated into the crystals of A and causes a decrease in purity, it is necessary to add a small amount of alkali during the reaction.

The reaction is usually carried out at a temperature ranging from room temperature to 150° C. under normal pressure or increased pressure. In the reaction under normal pressure, it is desirable to carry out the reaction at the reflux temperature of the reaction solution in order to increase the reaction rate. Although the reaction time depends on the reaction temperature and cannot be determined unconditionally, it is usually about 1 hour to 30 hours.

(B) Step The slurry solution obtained in the above step (A) is filtered, and TB
S-BA is separated and recovered as crystals.

The separated crystals are washed with water and then dried to form a product. The obtained TBS-BA crystals are of high purity and can be used as a raw material for TBS-BP, which is extremely useful as a flame retardant for polyolefin resins and polypropylene, without any special purification process.

(C) Step Add an acid to the filtrate obtained in the above step (B) and
Components mainly composed of S-MA are crystallized and separated and recovered.

The acid used in the method of the present invention is not particularly limited, but industrially inexpensive mineral acids such as hydrochloric acid, sulfuric acid, or nitric acid can be used. The amount of these acids used for quality analysis of TBS-MA is usually such that the pH of the solution is 2 to 3.

The temperature during crystallization of TBS-MA is not particularly limited, but usually room temperature may be used.

The method of crystallization of TBS-MA is carried out by dropping the above-mentioned acid into a filtrate mainly consisting of TBS-MA, and it is preferable that stirring is performed at that time.

Note that the component mainly consisting of crystallized TBS-MA does not require any process such as drying, only by washing with water after separation by filtration.

(D) Step TBS-M obtained in the above step (C)
It is circulated to the step (A) in order to re-react the components mainly composed of A. Specifically, when charging TBS, components mainly consisting of TBS-MA obtained in step (C) are charged in a wet crystalline state, and after further addition of alkali, reaction solvent, and allyl chloride, the reaction is performed again. .

The amounts of allyl chloride, reaction solvent, and alkali to be charged must be slightly adjusted by taking into account the amount of wet crystals of the circulated TBS'-MA.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, by circulating the reaction intermediate TBS-MA, the yield of TBS-BA can be greatly increased in a shorter reaction time than in the conventional method. It is possible to do so.

In addition, since TBS-MA in the reaction filtrate is efficiently recovered and separated, treatment of TBS-MA is not required, reducing product costs and making it extremely useful for industrially advantageous production of TBS-BA. It shows a new technology.

[Large example]

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

(Example 1) (A) In a 300-capacity four-eye flask equipped with a process thermometer, stirring blade, and cooling tube, 87 m of isopropyl alcohol and 13 m of water were added.
8.4 g (210 gaol) of 0 mL NaOH was charged, and further 56.6 g (100 mol) of TBS was added and dissolved.

The isobrobyl alcohol concentration in the water medium corresponds to 40% by volume.

Next, 19.1g of allyl chloride (250ma+o
1) was added all at once, heated to reflux temperature, and 1
The reaction took place for 5 hours.

In addition, 1.6 g of NaOH (
40 wmol) was added.

(B) Step (A) The slurry solution obtained in step (A) was suction-filtered and separated into crystals and filtrate. The obtained crystals were washed with water and then dried to obtain 49.5 g of TBS-BA as white needle-like crystals.

This isolated TBS-BA crystal and . As a result of liquid chromatography analysis of the jIfi liquid, the TBS conversion rate was 100%, the yield of isolated crystals of TBS-BA was 76.7%, and the purity of isolated crystals was 100%.

Incidentally, the filtrate contains TBS-MA9., which is a reaction intermediate.
7 g was melted, and the target product, TBS-BA, was not dissolved at all.

Step (C) Add 15% HC to the filtrate obtained in Step (B) while stirring at room temperature.
j? An aqueous solution was added dropwise to crystallize TBS-MA. At this time, the pH in the filtrate was about 2. Next, the obtained slurry solution was suction filtered, washed with water, and then TBS-M
56.8 g of wet crystals of A were obtained.

As a result of analyzing the obtained wet crystals of TBS-MA, it was found that T
BS-MA contains 9.7g, the remainder is water 47.1g.
It was only g.

(D) Step (C) Wet crystals of TBS-MA obtained in Step (C) were added to TBS5.
6.6 g (100 mIIol) was added to a Yotsuro flask, and further added 87 g of isobrobyl alcohol and 8 g of water.
3mj, NaOH9. Ig (2271IIlo1) was charged, stirred and dissolved, and circulated to step (A).

The amount of water to be added is determined by taking into account the water contained in the crystallized Φ, and always keeping the isopropyl alcohol concentration in the water solvent at 40%.
It was adjusted and added to correspond to the volume %.

Next, 22.2 g of allyl chloride (290 gaol
) was added all at once, heated to reflux temperature, and heated to reflux temperature.
Time reacted.

Eight hours after the start of the reaction, 1.6 g of NaOH (40
msol) was added.

Thereafter, steps (B), (C), and (D) were performed in the same manner as the first step, and this series of operations was repeated five times in total.

Table 1 shows the TBS conversion rate and the yield of isolated crystals of TBS-BA in each round.

(Comparative Example 1) In a four-eye flask with a capacity of 300 and equipped with a thermometer, a stirring blade, and a cooling tube, 874 parts of isobrobyl alcohol and 130 parts of water were added.
rIdl, NaOH10. Og( 2 5 0 Ilm
ol) and further added TBS56.6g (10
0a+mol) was added and dissolved.

The isopropyl alcohol concentration in the water medium corresponds to 40% by volume.

Next, 19.1 g of allyl chloride (250 mmo
1) was added all at once, heated to reflux temperature,
The reaction was carried out for 24 hours.

After the reaction is completed, it is cooled to room temperature, the precipitated crystals are filtered off, washed with water, and dried to obtain white needle-shaped crystals of TBS-BA56. Obtained Og.

When this isolated TBS-BA crystal and the above filtrate were analyzed by liquid chromatography, the TBS conversion rate was 100%, the isolated crystal yield of TBS-BA was 86.7%, and the isolated TBS-BA crystal yield was 86.7%. Crystal purity was 100%.

In addition, only TBS-MA, which is a reaction intermediate, was dissolved in liquid a, and TBS-BA, which was the target product, was hardly dissolved.

The reaction conditions and results are shown in Table 2.

(Comparative Examples 2 and 3) According to Comparative Example 1, the composition shown in Table 2 was charged into a 300 rIdl four-tube flask, and the reaction was carried out under the reaction conditions shown in Table 2. The same post-treatment as in Comparative Example 1 was carried out, and TBS-BA
I got it. The results obtained are shown in Table 2.

Claims (1)

[Claims] A method for producing bis(4-allyloxy-3,5-dibromophenyl) sulfone by allyl etherifying bis(4-hydroxy-3,5-dibromophenyl) sulfone using allyl chloride. (A) a step of allyl etherifying bis(4-hydroxy-3,5-dibromophenyl)sulfone using allyl chloride in the presence of an alkali; (B) a slurry obtained in step (A); A step of filtering the solution and separating and recovering bis(4-allyloxy-3,5-dibromophenyl)sulfone as crystals; (C) Adding an acid to the filtrate obtained in step (B) to obtain 4-allyloxy-4' -A step of crystallizing and separating and recovering a component mainly consisting of hydroxy-3,3',5,5'-tetrabromodiphenylsulfone; and (D) 4-allyloxy-4' obtained in step (C) −
In order to re-react the component mainly consisting of hydroxy-3,3',5,5'-tetrabromodiphenyl sulfone (
Bis(4-allyloxy-3
, 5-dibromophenyl) sulfone.