JPH0335303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing decabromodiphenyl ether. More specifically, the present invention relates to a method for producing decabromodiphenyl ether (hereinafter abbreviated as DBDE) which is free from coloration and has high commercial value. DBDE is used as an additive flame retardant for synthetic resins and other materials, and is usually produced by brominating diphenyl ether. Bromine is generally used as a brominating agent for diphenyl ether, and metal halides such as aluminum halides and iron halides are used as catalysts for promoting the reaction. Up until now, DBDE has been produced by brominating diphenyl ether using excess bromine without using a solvent (for example, in Japanese Patent Application Laid-Open No.
-37735) or using a halogenated hydrocarbon as a solvent and stirring it into diphenyl ether,
A method is known in which DBDE is obtained by adding excess bromine (eg, JP-A-53-116332). In these DBDE production methods, excess bromine is separated and recovered from the DBDE produced by various methods, but an economical method has been proposed to convert it into useful bromide. There is. That is, after the bromination reaction of diphenyl ether, olefin, especially ethylene, is blown in to convert excess bromine into ethylene dibromide, which facilitates the recovery of DBDE and produces useful ethylene dibromide. It is a co-production method. Although this co-production method has made it possible to significantly improve economic efficiency, both DBDE and ethylene dibromide obtained by this method are colored and are not satisfactory as products. The present invention was completed as a result of intensive research to eliminate these drawbacks. That is, in the present invention, diphenyl ether is brominated using a halogenation catalyst in the presence of an excess amount of bromine,
In the method for producing decabromodiphenyl ether, after the bromination reaction is completed, water is added to deactivate the halogenation catalyst in the reaction system, and residual excess bromine is reacted with olefin to produce olefin bromide. The purpose of the present invention is to provide a method for producing decabromodiphenyl ether which is free from coloration and is highly economical. The present invention will be explained in more detail below. As the method for brominating diphenyl ether in the present invention, any known method may be employed. That is,
When a halogenated hydrocarbon is used, commonly used solvents such as ethylene dichloride and/or ethylene chlorobromide may be used alone or in combination with ethylene dichloride. Further, the halogenation catalyst is not particularly limited, and any commonly used halogenation catalyst can be used, among which halogenation catalysts such as aluminum chloride and aluminum bromide are preferably effective. The amount used is usually selected from the range of 1 to 30 parts by weight per 100 parts by weight of diphenyl ether. The bromination reaction is carried out at a temperature of 0 to 80°C, preferably 10 to 80°C.
It is carried out at a temperature of 60 ° C. After the bromination reaction is completed, the reaction time can be shortened by increasing the reaction temperature to 50 to 80°C. The amount of bromine added may be at least the theoretical amount, and is usually used in excess of 1 to 50%. In the conventional method, after the bromination reaction is completed, residual excess bromine in the reaction system is reacted with olefin to form olefin bromide, and then DBDE is obtained.
DBDE is not available in colored products. Furthermore, even if this DBDE is purified using a commonly used halogenated hydrocarbon solvent, this coloring problem cannot be completely resolved, and it is highly valuable as a non-colored product.
Obtaining DBDE is difficult. DBDE like this
It is recognized that removing coloration is extremely difficult. The present invention has developed a method for producing DBDE which is extremely simple and completely color-free, without employing any of these purification methods. In the method of the present invention, the temperature is 50°C after the completion of the bromination reaction.
The halogenation catalyst is deactivated by adding water at a temperature below, preferably below 30°C. At temperatures exceeding 50°C, bromine evaporates and scatters, which is undesirable. The amount of water added is not particularly limited as long as it deactivates the catalyst, but in the case of aluminum halide, which is usually advantageously used, it is necessary to add 3 moles or more per mole of the catalyst. If it is less than 3 moles, the catalyst will not be deactivated. Even if the amount is 3 mol or more, if it is 30 mol or less, a solid hydrate will precipitate, so the amount is preferably 30 mol or more. After adding water, stirring will deactivate the catalyst. After deactivating the catalyst, the reaction solution volume is 1 m ³ at a temperature of 10 to 50°C, preferably 20 to 40°C. On the other hand, olefin is 1 to 30Nm ³ /h.
Preferably, the excess bromine in the reaction system is injected at a flow rate of 1 to 20 Nm ³ /h to react with the olefin to form an olefin bromide.
Dry to obtain DBDE. If the temperature is less than 10°C, the reaction rate of the olefin is slow, and if it exceeds 50°C, the olefin bromide becomes colored, which is not preferable. On the other hand, regarding the injection flow rate of olefin, if the flow rate exceeds 30 Nm ³ /h per 1 m ³ of reaction solution volume, the reaction rate of olefin will deteriorate, which is not desirable. The obtained DBDE has an extremely good hue and is of high commercial value. More preferably, the halogenated hydrocarbon solvent and ethylene dibromide are removed by distillation, such as steam distillation, and the average particle size is
It is desirable to remove impurities in the crystal by crushing it to 10μ or less. As described above, the present invention provides an extremely effective method for producing color-free and highly economical DBDE without employing any special purification means. Examples will be shown below, but the present invention is not limited thereto. Example 1 141 g of diphenyl ether was brominated with 1576 g of bromine in 580 ml of a mixed solvent of ethylene dichloride, ethylene chlorobromide and ethylene dibromide in the presence of 10 g of aluminum chloride at a temperature of 20°C. After the bromination reaction is complete, add pure water at a temperature of 25℃.
After adding 35 ml and stirring for 30 minutes, excess bromine was converted to ethylene dibromide by injecting ethylene at a flow rate of 5/h at a temperature of 35°C. The reaction solution was separated into a solvent and DBDE. obtained
After drying the DBDE crystals, they were ground to an average particle size of about 5μ. The analysis results of the obtained DBDE are shown in Table 1. Example 2 A bromination reaction was carried out in the same manner as in Example 1, and an aqueous sodium hydroxide solution was added to the reaction solution containing DBDE, in which ethylene was injected to convert residual excess bromine into ethylene dibromide, and the halogen was then neutralized. The hydrocarbon solvent and ethylene dibromide were removed by steam distillation, and the product was ground to an average particle size of about 5 μm. obtained
The DBDE crystals were filtered and dried. The analysis results of the obtained DBDE are shown in Table 1. Comparative Example 1 After carrying out the bromination reaction in the same manner as in Example 1,
The process was carried out in the same manner as in Example 1, without adding water, by injecting ethylene at a flow rate of 5/h at a temperature of 35° C. to remove excess bromine. The analysis results of the obtained DBDE are shown in Table 1. Comparative Example 2 100 ml of chloroform was added to 100 g of DBDE crystals obtained in Comparative Example 1, heated under reflux for 2 hours, cooled, and filtered and dried. The analysis results of the obtained DBDE are shown in Table 1. 【table】

Claims (1)

[Claims] 1 In a method for producing decabromodiphenyl ether by brominating diphenyl ether using a halogenation catalyst in the presence of an excess amount of bromine, after the bromination reaction is completed, residual excess bromine is reacted with olefin to form olefin. A method for producing decabromodiphenyl ether without coloration, which comprises adding water to the step of recovering bromide to deactivate the halogenation catalyst in the reaction system.