JPS6241490B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing decabrom diphenyl ether, and particularly to a method for producing decabrom diphenyl ether with good hue.

Decabrom diphenyl ether is well known as an additive flame retardant for synthetic resins and others. This decabrom diphenyl ether is usually produced by brominating diphenyl ether. Bromine is usually used as the brominating agent, and metal halides such as iron halides and aluminum halides are used as catalysts to promote the reaction.
The bromination reaction can be carried out using an inert solvent or using bromine itself as a solvent without using any other solvent. As for the latter method, for example,
There is one described in Publication No. 37735. The characteristics of this method, compared to methods using inert solvents, are that no side reactions occur due to the presence of an inert solvent, and operations such as solvent recovery are unnecessary. The disadvantage of the method for brominating diphenyl ether described above is that the obtained decabrom diphenyl ether has an inferior hue and that treatments such as recrystallization are required for its purification. Therefore, as a method for producing decabrom diphenyl ether with good hue, for example, JP-A-52-139033 and JP-A-53-
A method using post-processing for hue improvement has been proposed, as described in Publication No. 21129 and the like. However, these methods are not only complicated, but also require a long time for post-processing. Therefore, the present inventors have investigated a method for producing decabrom diphenyl ether that simplifies the post-processing for improving hue, and further eliminates the need for this post-processing. As a result, it was found that decabrom diphenyl ether with improved hue could be obtained by carrying out the bromination reaction in two stages.

The present invention provides a method for producing polybrominated diphenyl ether containing decabrom diphenyl ether as a main component by reacting diphenyl ether and bromine in the presence of a catalyst. to produce a polybrominated diphenyl ether with an average of less than 9.5 bromine bonds, and then add at least the polybrominated diphenyl ether to the reaction system as decabrom diphenyl ether. The reaction was further carried out in the presence of a sufficient amount of bromine and a chlorinated hydrocarbon solvent to obtain an average of 9.5
This is a method for producing a polybrominated diphenyl ether, which is characterized by producing the polybrominated diphenyl ether to which bromine is bonded.

The first bromination in the method of the present invention is the bromination of diphenyl ether using bromine as a solvent. The amount of bromine used in this bromination is the amount necessary to produce a polybrominated diphenyl ether with an average of less than 9.5 bromine bonds, that is, an amount of 9.5 moles or less of bromine per 1 mole of diphenyl ether. . More than this amount of bromine may be used, but the reaction must not be carried out until a large amount of decabrom diphenyl ether is produced. The reaction is usually carried out by slowly adding bromine dropwise to diphenyl ether. Preferred polybrominated diphenyl ethers have 5 to 8 polybrominated diphenyl ethers per molecule.
It is a polybrominated diphenyl ether in which bromines are bonded, and the amount of bromine used in the first step is also the theoretical reaction amount (10 moles of bromine per 1 mole of diphenyl ether).
The preferred amount is 5 to 8 mol per mol of diphenyl ether. If a large amount of decabrom diphenyl ether is produced in the first stage, a large amount of decabrom diphenyl ether precipitate will be formed in the reaction system, making it difficult to remove colored impurities.

The subsequent bromination is carried out in the presence of a chlorinated hydrocarbon solvent. In a later stage, additional bromine and chlorinated hydrocarbons are added to the reaction system. The amount of bromine is at least the amount necessary to convert the polybrominated diphenyl ether produced in the previous step to decabrom diphenyl ether, which has an average of 9.5 or less, preferably 6 to 8 bromines, and is preferably in a certain amount of excess. In particular, bromine is added from 1.0 to 1 mole of diphenyl ether.
1.15 mol is added. If bromine remains in the reactions before and after, the total amount of the remaining bromine and the added bromine may be the required amount of bromine. Although additional bromine may not be necessary in some cases, it is preferable to carry out the subsequent reaction with almost no bromine remaining in the initial reaction. The amount of chlorinated hydrocarbon added is not particularly limited, but is 28 to 94% by weight based on the amount of raw material diphenyl ether in the previous stage,
Preferably, 37 to 47% by weight is appropriate.

Bromination catalysts used in the first and second stages include halogenated groups, aluminum halides,
Other metal halide catalysts may be used, and metals or metal compounds capable of producing these metal halides may also be used. For example, metal powders such as iron and aluminum can be used. As the chlorinated hydrocarbon solvent, a chlorinated hydrocarbon having 1 to 2 carbon atoms is preferred, and carbon tetrachloride and perchlorethylene are particularly suitable.

A feature of the latter reaction is that colored impurities are not included in the precipitate of decabrom diphenyl ether produced. The colored impurities dissolve in the solvent and are no longer included in the precipitate of decabrom diphenyl ether as it forms. Further, even if colored impurities adhere to the surface of the precipitate once formed, they are easier to remove than the colored impurities contained in the precipitate when the precipitate is formed.

After completion of the second-stage reaction, the reaction system, which was aged if necessary, contained polybrominated diphenyl ether containing decabrom diphenyl ether as the main component, hydrogen bromide,
Contains unreacted bromine, solvent, catalyst, etc. Water is added to the reaction system to inactivate the catalyst and dissolve hydrogen bromide, and then heated to distill off the bromine and solvent.
After most of the bromine is removed, the remaining bromine is preferably removed by reduction with sodium sulfite or the like. next,
The polybrominated diphenyl ether is filtered off and dried. Although this post-treatment can be carried out by any other method, an almost pure white polybrominated diphenyl ether can be obtained only by this post-treatment. Therefore, a polybrominated diphenyl ether containing decabrom diphenyl ether as a main component and having a good hue can be produced without any need for the above-mentioned known post-treatments. Moreover, this decabrom diphenyl ether has a high purity and can be used as a product as it is.

EXAMPLES The present invention will be specifically explained below using Examples, but the present invention is not limited only to these Examples.

Example 1 17 g (0.1 mol) of diphenyl ether and 1 g of aluminum chloride as a catalyst are added to a 0.5 mm flask equipped with a stirrer, and the mixture is stirred while maintaining the temperature at 30°C. Next, 96 g (0.6 mol) of dehydrated bromine is added over about 30 minutes while gradually raising the reaction temperature to 70°C. Next, 60 g of perchlorethylene was added and 72 g (0.45 mol) of bromine dehydrated at 70 to 100°C was gradually added. When the amount of bromine added was around 40 g (0.25 mol), a part of decabrom diphenyl ether was precipitated and a high It becomes a viscous slurry. Addition of bromine is completed in about 50 minutes,
After further stirring and aging for about 1 hour while maintaining the temperature at 120-130℃, add a small amount of sodium sulfite and about 100g
Add water and cool to room temperature.

After filtering the reaction solution and washing with water and perchlorethylene, the solid content was dried at 120°C for 10 hours to form a crystalline powder.
Killed 94g. The bromine content of the product is over 82% by weight, and the melting point measured by DTA is 305°C.
APHA (hereinafter the same) was 15.

Example 2 17 g (0.1 mol) of diphenyl ether and 1 g of aluminum chloride are added to a 0.5 mm flask equipped with a stirrer, and 80 g (0.5 mol) of bromine dehydrated at a temperature of 30 to 40° C. is added over 30 minutes. Then carbon tetrachloride 32
g and 160 g (1.0 mol) of bromine are added over 20 minutes at 40°C. Subsequently, the temperature was raised to reflux temperature (60-62℃), and after aging for 2.5 hours, 200ml of water was added to evaporate the bromine, then a small amount of sodium sulfite aqueous solution and about 100g of carbon tetrachloride were added, and the mixture was heated at room temperature. Cool until cool. Next, the slurry was filtered, the solid content was washed with water and carbon tetrachloride, and 90 g of crystalline powder was obtained by drying at 120° C. for 10 hours. The bromine content of this product is 82% by weight, the melting point is 305℃, and the APHA is
It was 50.

Comparative Example 1 17 g (0.1 mol) of diphenyl ether and 1 g of aluminum chloride are placed in a 0.5 flask with a stirrer, and 170 g (1.063 mol) of bromine is gradually added at a temperature of 30 to 50°C.The amount of bromine added is approx. 120g
The viscosity increased from around (0.75 mol), and after that, some lumps were observed to form as bromine was added, making uniform stirring impossible, but the entire amount of bromine was added in about 1 hour. Then under reflux (approximately 57
℃) for 1 hour, about 200 g of water was added to drive out unreacted bromine, and a small amount of aqueous sodium sulfite solution was added and the mixture was cooled to room temperature. After taking out the lumps and pulverizing them, wash them thoroughly and reduce the solid content to 120℃.
By drying for 10 hours, 85 g of crystalline powder with a yellowish color was obtained. The melting point was 295°C and the APHA was 150.

Comparative Example 2 When the reaction was carried out under the same conditions as in Comparative Example 1 except that the amount of bromine added was 240 g (1.5 mol), lumps were similarly produced. The same treatment as in Comparative Example 1 was carried out to obtain 90 g of crystalline powder with a stale yellow color. The melting point was 300°C and the APHA was 200.

Claims (1)

[Scope of Claims] 1. A method for producing polybrominated diphenyl ether containing decabrom diphenyl ether as a main component by reacting diphenyl ether and bromine in the presence of a catalyst, in which diphenyl ether and bromine are reacted. A polybrominated diphenyl ether having an average of less than 9.5 bromines is produced by reacting without the presence of a solvent other than the bromine, and then a polybrominated diphenyl ether having an average of less than 9.5 bromines bound to the reaction system. Diphenyl ether is further reacted in the presence of an amount of bromine and a chlorinated hydrocarbon solvent to convert diphenyl ether into decabrom diphenyl ether, resulting in a polybrominated diphenyl ether containing decabrom diphenyl ether as the main component and an average of 9.5 or more bromine atoms. A method for producing polybrominated diphenyl ether, the method comprising producing enyl ether. 2. The method of claim 1, wherein the polybrominated diphenyl ether with an average of less than 9.5 bromines is a polybrominated diphenyl ether with an average of 5 to 8 bromines. 3. The method according to claim 1, characterized in that the reaction between diphenyl ether and bromine is carried out in a ratio of 5 to 8 moles of bromine per mole of diphenyl ether, and the bromine is gradually added dropwise to the diphenyl ether. . 4. The method of claim 1, wherein the total reaction molar ratio of bromine to diphenyl ether is 1.0 to 1.15.