JPS5840933B2 - Method for producing 2,4,2',4'-tetrabromidiphenyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2,4,2,4'-tetrafluoromdiphenyl ether.

The method for producing tetrabromidiphenyl ether involves reacting bromine and diphenyl ether in an organic solvent such as dibromoethane, tetrachloroethane, or carbon tetrachloride with a molar ratio of 4, or in fuming sulfuric acid with a molar ratio of bromine and diphenyl ether of 2. There are known ways to do this.

However, these methods require recovery and purification of the brominated organic solvent, treatment of waste sulfuric acid, etc., and also have industrial disadvantages such as the need for large production equipment for the same scale of production. In addition, isomers of tetrabromidiphenyl ether, trifluoromdiphenyl ether, pentabromidiphenyl ether, etc. are produced as by-products, and only 2,4/4'-tetrabromidiphenyl ether can be selectively produced. I couldn't do it.

On the other hand, the method of producing tetrabrominated diphenyl ether by brominating diphenyl ether in bromine has hitherto been more difficult to control the reaction than the above-mentioned production method, resulting in the production of a wide range of brominated diphenyl ethers with different bromination rates. It was thought that

The present inventors conducted intensive studies on a method for producing tetrabromidiphenyl ether in bromine, and surprisingly found that it can be produced without a catalyst in excess bromine at a temperature of 35°C to the boiling point of bromine under normal pressure. By brominating diphenyl ether, 2,4,2,4'-tetrabromidiphenyl ether is selectively produced, and in the presence of certain catalysts as described below, at temperatures below 35°C, excess The present invention was achieved by discovering that 2,4,g,4'-tetrabromidiphenyl ether is selectively produced by brominating diphenyl ether in bromine.

The tetrabromidiphenyl ether obtained by the present invention includes 98 to 100% of 2,4/4'-tetrabromidiphenyl ether, its isomers, tribromidiphenyl ether, yohypentafrom diphenyl ether O to
It is extremely pure 2,4./.4'-tetrabromphenyl ether consisting of 2%.

The present invention makes it possible to produce 2,4./.4'-tetrafluorodiphenyl ether in bromine with extremely high selectivity, which has many industrial advantages.

The present invention is carried out by using excess bromine as a reaction solvent and adding diphenyl ether to the bromine without a catalyst or in the presence of a certain type of catalyst as described below.

The amount of bromine used in the present invention is 1.5 to 5 times the reaction equivalent, preferably 2 to 4 times the reaction equivalent.

If the amount of bromine is less than 1.5 times the reaction equivalent, the solvent effect of bromine will weaken as the bromine is consumed by the reaction, and homogeneous mixing will no longer be maintained, resulting in a decrease in the selectivity of tetrabrom diphenyl ether. If the amount is more than double the amount, it is not preferable because it causes economic disadvantages such as recovery of bromine after the reaction.

Although the reaction in the present invention does not require the use of a catalyst, in the case of not using a catalyst, it is necessary to carry out the reaction at a higher temperature and for a longer time than in the case of using a catalyst. It is preferable to use

The reaction is carried out at temperatures above 35°C, preferably at 4°C when no catalyst is used.
At a temperature of 0°C or higher and lower than the boiling point of bromine under normal pressure for 3 hours or more,
When a catalyst is used, the reaction is carried out at 35°C or lower, preferably 30°C or lower for 1 hour or more.

The catalysts used in the invention are chlorides and sulfates of zinc and tin; chlorides, sulfates and phosphates of iron with water of crystallization; and sulfates and phosphates of aluminum.

The amount of catalyst is between 0.01% and 5% by weight based on the bromine used.
% by weight, preferably from 0.1% to 2% by weight.

If it is less than 0.01% by weight, the catalytic effect is weak, and if it is more than 5% by weight, the catalyst may be mixed into the product, which is not preferable.

Diphenyl ether can be added to bromine at once or in parts, but compared to adding in parts, it is difficult to control the temperature due to the reaction heat when adding it all at once, and the selectivity of tetrabrom diphenyl ether decreases. It is preferable to add the mixture in portions, as there is a risk of this.

After the reaction is completed, if a catalyst is used, water or an acid aqueous solution such as hydrochloric acid or sulfuric acid is added to the reaction solution to extract the catalyst into the aqueous layer, and excess bromine is removed by distillation. - Occasionally, water is added to the reaction solution, and then excess bromine is removed by distillation to precipitate the reaction product in water.

The reaction product is separated, washed and dried by any method.

The reaction product obtained in the present invention is 2.4.2/.4'-
Tetrabromodiphenyl needle content 98-100
%, and can be used as is.

If necessary, recrystallization is performed using a solvent such as dichloroethane, dichlorobenzene, toluene, or xylene.

The 2,4,2',4'-tetrabromidiphenyl ether obtained by the present invention is extremely useful as a flame retardant with excellent light resistance for polyolefins such as polystyrene and polyethylene, and also for fibers such as polyester and nylon. As a result of studies conducted by the present inventors, it has become clear that the present invention is effective as a flame retardant for polyurethanes, polyurethanes, and paints.

The method of the present invention will be explained in detail with reference to examples below.

Note that all parts and % in the examples indicate parts by weight and % by weight.

Examples 1 to 6 Bromine and a catalyst shown in Table 1 were placed in a four-way flask equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel, and diphenyl ether was added dropwise at a predetermined temperature.

After dropwise addition of diphenyl ether, a ripening reaction was performed as necessary.

Thereafter, water or an aqueous hydrochloric acid solution was added and the mixture was stirred for 30 minutes to extract the catalyst, and then the reflux condenser was replaced with a distillation device to remove excess bromine by distillation.

(However, in Example 1, excess bromine was removed by distillation immediately after adding water.

) After cooling, the obtained reaction product was filtered once, washed with water, and dried.

Gas chromatography analysis was performed on the dried reaction product to determine its composition.

The reaction conditions and results are shown in Table-1.

The abbreviations in the composition column of Table 1 are as follows.

2.4-TBDPE: 2.4./.4'-tetrabromidiphenyl ether TBDPE: isomer of tetrafromdiphenyl ether

Claims (1)

[Claims] 1. Diphenyl ether in excess bromine (a) at 35°C
or (b) chlorides and sulfates of zinc and tin; chlorides, sulfates and phosphates of iron with water of crystallization; and sulfates of aluminum; A method for producing 2,4./.4'-tetrabromidiphenyl ether, characterized in that the reaction is carried out at a temperature of 35° C. or lower in the presence of one or more kinds of phosphates.