JPH0613455B2 - Method for producing tetrabromobisphenol A - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing tetrabromobisphenol A with high purity and high yield.

"Prior Art" Tetrabromobisphenol A is widely used as a flame retardant for synthetic resins and synthetic fibers. This tetrabromobisphenol A is produced by substituting bromine for bisphenol A (hereinafter referred to as BPA). A known method for bromination of BPA is to suspend BPA in water and add bromine to it to react, or to disperse or dissolve BPA in a halogenated hydrocarbon and then add bromine to the reaction. is there.

Tetrabromobisphenol A obtained by these methods
Contains a large amount of impurities consisting of di-, tri-substituted and 5- to 8-substituted compounds in addition to the desired tetrabromine-substituted compound, and a more complicated purification step for obtaining high-purity tetrabromobisphenol A. Was needed. Further, as an improved method of these, as shown in JP-A-51-54538,
It has been proposed that the temperature be raised after the addition of bromine and the aging is carried out under the reflux of the solvent. According to this method, it is effective to reduce the production amount of di- and tri-substituted products, but on the contrary, a large amount of 5- to 8-substituted products is produced.

As an improved method, it has been proposed to dissolve BPA in a lower alcohol such as methanol and water and add bromine to this. In this case, although it is effective in reducing the amount of impurities produced, lower alcohols react with bromine or byproduct hydrogen bromide to produce various alkyl bromides. Further, since tetrabromobisphenol A dissolves in alcohols, a complicated separation operation is required when tetrabromobisphenol A is taken out as crystals from an alcohol solution of tetrabromobisphenol A.

The tetrabromobisphenol A produced by the above method was not satisfactory in the amount of impurities produced, and was insufficient in terms of quality and yield.

"Problems to be Solved by the Present Invention" The present invention is intended to reduce the amount of impurities produced, which was not satisfied by the above-mentioned conventional method, and to produce high-purity tetrabromobisphenol A in a high yield.

"Means for Solving Problems" The inventors of the present invention have highly pure tetrabromobisphenol A.
As a result of earnest efforts to produce (hereinafter referred to as TBA) in high yield, the amount of carbon tetrachloride in the amount of 2 to 5 times the weight of bisphenol A or the weight of perchlorethylene and bisphenol A is 2 to 3 times. After adding bromine to bisphenol A dispersed in a mixed solvent with a certain amount of water and reacting at a temperature of 15 to 20 ° C. and adding all bromine to finish, 15
The present invention has found a method for producing TBA, which comprises performing low temperature aging at -20 ° C for 1 hour or more and further performing high temperature aging by heating to the evaporation temperature of a solvent for 1 to 1.5 hours.

In the present invention, the temperature during bromine addition is 15 to 20 ° C.
Is. In addition, it is important to ripen at a low temperature after the addition of bromine, and the presence or absence of this step greatly affects the quality and yield of TBA.

Usually, at the end of the addition of bromine, the bromination reaction is not completed, and in addition to TBA, di- and tri-substituted compounds and unreacted bromine are present in relatively large amounts. When the temperature is raised in this state, TBA is further reacted with bromine along with the reaction of converting the di- or tri-substituted product to TBA, thereby producing a high-bromine adduct composed of the 5- to 8-substituted product. These high bromine adducts act as impurities, lowering the quality of TBA and significantly deteriorating the yield.

Further, if the temperature at the time of bromine addition is 25 ° C. or higher, a large amount of high bromine adduct is already formed at the end of bromine addition, which is not preferable.

Furthermore, at a temperature of 10 ° C. or lower, the reaction rate is slow and the reaction takes a long time, which is not realistic.

The low temperature aging time after the completion of bromine addition in the present invention is at least 1 hour, preferably 1.5 to 2 hours.

The solvent used in the present invention may be any substance as long as it is a halogenated hydrocarbon, but carbon tetrachloride and perchlorethylene are preferable from the viewpoint of stability in the presence of bromine and suitable boiling point.

In addition, the amount used is preferably 2 to 5 times the weight of BPA.

The amount of water used in the present invention is 2 with respect to the weight of BPA.
~ 3 times the amount is good. Hydrogen bromide is by-produced with the bromination reaction of BPA, but most of the hydrogen bromide is dissolved in the aqueous phase in the heterogeneous solvent. If the concentration of this hydrogen bromide water is too high or too low, the bromination reaction of BPA will be hindered, and an appropriate amount of water will be required.

It is preferable that the amount of bromine used in the present invention is slightly in excess of the theoretical amount, and
4.05 to 4.2 times mol is preferable.

The heating and aging in the present invention is preferably carried out under the reflux of the solvent used, and the temperature is preferably 70 to 72 ° C. for carbon tetrachloride and 90 to 92 ° C. for perchlorethylene.
The heating and aging time is preferably 1 to 1.5 hours.

"Operation" In order to produce high-purity TBA in a high yield, it is necessary to minimize the amount of impurities such as di-, tri-substituted products and 5- to 8-substituted products.

In the bromination of BPA, the temperature at the time of bromine addition is 10 to 2
Adjusting to 5 ° C is an effective method for suppressing the formation of high bromine adducts composed of 5 to 8 substituents, and aging at the same temperature after the completion of bromine addition results in the formation of high bromine adducts. This is an effective method for converting a di- or tri-substitution product into a tetra-substitution product.

By performing the above method, the amount of unreacted bromine at the end of the aging is reduced to a level that does not pose a problem, and the formation of a high bromine adduct during the subsequent aging by heating can be suppressed.

The TBA produced according to the present invention has a purity of 97% or more as determined by liquid chromatography, and the yield based on BPA is 98.5.
% Or more.

This is because the purity of TBA produced by a known method is 92 to 95.
%, And the yield is 84 to 97%, which is excellent.

The present invention will be specifically described below with reference to examples of the present invention, but the present invention is not limited to these examples.

"Examples and Comparative Examples" Examples 1 to 5 and Comparative Examples 1 to 4 BPA 50g in a separable flask having a capacity of 1 having a thermometer, a dropping funnel for continuously dropping bromine, a stirring blade, and a cooling tube. Solvents and demineralized water in the types and amounts shown in Table 1 were charged. With stirring, 142 g of bromine was added dropwise over 1.5 hours, during which the temperature shown in Table 1 was adjusted.

After the addition of bromine was completed, in Examples 1 to 5, the temperature and time shown in Table 1 were maintained (low temperature aging). Then, Example 1
5 and Comparative Examples 1 and 2, the temperature was raised and the temperature and time shown in Table 1 were maintained (high temperature aging).

The reaction solution was cooled to 60 ° C, and 60% hydrazine hydrate 0.6
After decomposing unreacted bromine by adding g, further 15 ° C
Cooled to over.

The salt formed was washed with 125 g of demineralized water and dried.

The weight of the obtained TBA was measured, and the value obtained by dividing the theoretical yield based on BPA by 119.2 g was expressed as a percentage. The yield is shown in Table 1.

In addition, the composition of the produced TBA and the composition of the solid content contained in the recovered solvent by liquid chromatography analysis are shown.

"Effect of the invention" When TBA is produced, BPA is added at 15 to 20 ° C in a mixed solvent of carbon tetrachloride or perchlorethylene.
After brominating at 1, the temperature is maintained for 1 hour or more, and then the solvent is evaporated to 70 ° C. or higher for aging to significantly di-, tri-substituted and 5- to 8-substituted compounds. It can be suppressed, and the TBA obtained thereby has a high purity and exhibits an excellent effect of being obtained in a high yield.

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Claims (1)

[Claims] 1. A bisphenol A dispersed in a mixed solvent of carbon tetrachloride or perchlorethylene in an amount of 2 to 5 times the weight of bisphenol A and water in an amount of 2 to 3 times the weight of bisphenol A. Add bromine to 15-20
After reacting at a temperature of ℃, after adding all the bromine,
A method for producing tetrabromobisphenol A, which comprises performing low temperature aging at 15 to 20 ° C. for 1 hour or more, and further performing high temperature aging by heating to a solvent evaporation temperature for 1 to 1.5 hours.