JPH07110827B2 - Method for producing tetrabromobisphenol A - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a method for producing tetrabromobisphenol A with high purity and high yield.

"Conventional technology" Tetrabrom bisphenol A (hereinafter referred to as TBA)
It is widely used as a flame retardant for synthetic resins such as epoxies and polycarbonates, synthetic rubbers, and synthetic fibers.

This TBA is produced by brominating benzene ring hydrogen of bisphenol A (hereinafter referred to as BPA) with bromine, but in the conventional method, it contains an acid or a halogenated impurity by-produced during the production process. However, it was colored or had a low purity of the desired tetrabromide substitution product. Also, TB
A Most of the equipment in the manufacturing process was made of corrosion-resistant material, and the equipment cost of the plant was enormous.

Known TBA production methods are: 1) A method in which BPA is suspended in water and bromine is added to the suspension to react.

2) A method in which BPA is dispersed or dissolved in a halogenated hydrocarbon, and bromine is added to this to react.

3) A method in which BPA is dissolved in a lower alcohol such as methanol and water, and bromine is added to this to react.

4) As a reaction solvent, there is a reaction using a mixed solvent of a halogenated hydrocarbon and a lower alcohol such as methanol.

However, TBA obtained by the methods 1) and 2) is
In addition to the target tetrabromide substitution product, it contains a large amount of by-products consisting of di-, tri-bromine substitution products and 5-8 bromine substitution products,
Further, in order to obtain high-purity TBA, a complicated purification step such as using a purification solvent different from the reaction solvent was required.

Although the methods 3) and 4) are effective in reducing the amount of by-products produced, a large amount of alkyl bromide, which is a bromide of a lower alcohol, is by-produced during TBA synthesis, and the treatment is Have difficulty. On the other hand, since the produced TBA dissolves in alcohols, a complicated separation operation is required when taking out TBA as crystals from the alcohol solution of TBA. or,
Product purity is also unsatisfactory.

The TBA produced by the above method is not satisfactory in terms of the amount of impurities produced, is insufficient in terms of quality and yield, requires complicated purification methods, and uses corrosion-resistant materials. Was unsatisfactory, such as being expensive.

[Problems to be Solved by the Invention] The present invention reduces the amount of impurities that could not be satisfied by the above-mentioned conventional methods, and eliminates the need for complicated purification steps to obtain highly pure TBA.
In a high yield and further in a significant reduction in the use of corrosion resistant materials.

"Means for Solving the Problem" The present inventors have made diligent efforts to produce high-purity TBA in high yield, and as a result, a method for producing TBA in which BPA is reacted with a predetermined amount of bromine in a heterogeneous solvent. The solvent is chlorobenzene in an amount of 1 to 10 times that of BPA, and water and BPA in an amount of 1 to 4 times that of BPA.
Bromine was added to the system in which 10 to 25 ° C. was added to the reaction, and after all the bromine had been added, the temperature was kept at the same temperature for 1 hour or longer, and then the mixture was heated to 70 to 90 ° C. and aged. Unreacted bromine is decomposed at the same temperature, the aqueous layer is separated at the same temperature, the organic layer is washed at the same temperature, some chlorobenzene is recovered if necessary, the organic layer is cooled, and TBA is removed. The inventors have found a method for producing high-purity TBA, which is characterized by crystallization.

The solvent used in the present invention is chlorobenzene which is a good solvent for by-products and completely dissolves TBA at high temperature.

It was found that when chlorobenzene was used as a solvent, the TBA production rate at the low temperature reaction was high, the impurity production rate was suppressed, and the high temperature aging time was shortened. Moreover, when the temperature was raised to a high temperature after the decomposition of bromine, TBA was completely dissolved, and the HBr water produced by the reaction could be separated and removed, and further washing and purification with water or the like could be performed at the same temperature. As a result, it is possible to significantly reduce the plant construction cost without requiring a corrosion resistant material for the equipment in the subsequent steps.

This chlorobenzene is a good solvent for TBA by-products and is completely dissolved even at low temperatures. On the other hand, it was found that it was a poor solvent for TBA at low temperatures. Therefore,
After the above washing and purification, a part of chlorobenzene was recovered, and the organic layer was cooled and fractionally crystallized, if necessary, to obtain high-purity TBA. Moreover, the reaction solvent and the purification solvent are the same, and the conventional method, in which the reaction solvent and the purification solvent are different and the operation is not complicated.

The amount used is 1 to 10 times, preferably 3 to 6 times the BPA weight.

Although water is also used in the present invention, the amount is 1 to 4 times, preferably 2 to 3 times the BPA weight. BPA
Hydrogen bromide is produced as a by-product of the bromination reaction, 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, it will hinder the bromination reaction of BPA, and an appropriate amount of water will be required.

The amount of bromine used in the present invention may be slightly in excess of the theoretical amount, and a large excess of bromine is not necessary. BP
The molar ratio of A is preferably 4.01 to 4.1 times.

In the present invention, the temperature at the time of adding bromine is 10 to 25 ° C.,
It is preferably 15 to 20 ° C. Also, the bromine addition time is 1-3
Time, preferably 1.5 to 2.5 hours. After adding bromine, aging at the same temperature for 1 to 2 hours, then raising the temperature,
Heat aging is performed at a temperature of 70 to 90 ° C for 0.5 to 1 hour.

Furthermore, after washing the organic layer, the amount of chlorobenzene recovered as necessary is 20 to 50% by weight of the total amount used, preferably 30 to 50% by weight.
It is 40% by weight, and it is better to collect it by distillation under reduced pressure.

Incidentally, the trace amount of unreacted bromine remaining after aging by heating is decomposed by a decomposing agent such as hydrazine hydrate to facilitate the subsequent treatment.

[Operation] In order to produce high-purity TBA in high yield, it is necessary to minimize the amount of impurities, di-, tri-bromine-substituted compounds and 5- to 8-bromine-substituted compounds, which are produced.

In the purification step, a solvent that is a good solvent for TBA byproducts and a poor solvent for TBA is used to
It is better to purify BA by crystallization.

Moreover, in order to eliminate the complexity of the purification step, it is preferable to carry out the purification step with the same solvent as the reaction solvent.

In the bromination of BPA, adjusting the temperature such as bromine addition to 10 to 25 ° C is an effective method for suppressing the formation of a high bromine adduct composed of a 5 to 8 bromine substituent, and is used as a reaction solvent. , Using chlorobenzene and keeping at the same temperature for 1 hour or more after adding bromine are effective for converting di- and tri-bromine substitution products to tetra-bromine substitution products without formation of high bromine adducts. That's the method.

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

In the TBA purification process, chlorobenzene is
It is a good solvent that completely dissolves BA by-products,
It is a poor solvent for TBA. Therefore, in the case of removing water-soluble impurities, by using chlorobenzene as a reaction solvent, the temperature can be raised after the reaction is completed, TBA can be completely dissolved and washed with water or the like, and the aqueous layer can be separated at that temperature. Then, it can be purified. Furthermore, by carrying out this, it is not necessary to use a corrosion-resistant material in the device in the subsequent steps. When removing oily impurities, lower the temperature of the TBA-chlorobenzene solution,
If necessary, a part of chlorobenzene is recovered and cooled to crystallize TBA, and oil impurities are dissolved in chlorobenzene.By passing, oil impurities are removed and TBA is purified. Will be done.

After carrying out the above operation, the diced product is washed and dried to obtain a product.

The TBA produced according to the present invention has a purity of 90% or more by liquid chromatography analysis, and the yield based on BPA is 98% or more.

This is because the purity of TBA produced by a known method is 93 to 98% and the yield is 8%.
Excellent compared to 4 to 97%. 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" Example 1 BPA 50g, chlorobenzene 175g, ion-exchanged water 125g 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. , While stirring and cooling to maintain a temperature of 15 to 20 ° C,
142 g of bromine was added dropwise over 2 hours.

After the bromine addition was completed, the aging reaction was carried out for 1.5 hours while maintaining the temperature at 15 to 20 ° C, then the temperature was raised to 80 ° C, and the temperature was kept at 80 ° C for 30 minutes.

After the above operation, 0.6 g of 60% hydrazine hydrate was added to decompose unreacted bromine, the temperature was further raised to 90 ° C., the aqueous layer was separated and removed, and ion-exchanged water was added to wash the organic layer with stirring. ,
The aqueous layer was separated and removed again. Next, the system was depressurized to recover 62 g of chlorobenzene, then cooled to 25 ° C., TBA was crystallized, and overdried to obtain 117.9 g of purified TBA.

The TBA obtained was weighed and the theoretical yield based on BPA 119.
The value divided by 2 g was expressed as a percentage, which was taken as the yield.

The composition of the produced TBA was determined by liquid chromatographic analysis and is shown in Table 1.

Example 2 The same operation as in Example 1 was performed except that the low temperature aging after the addition of bromine was 2 hours. The results are shown in Table 1.

Example 3 Example 1 except that the charged amount of chlorobenzene was 250 g.
Performed the same operation as. The results are shown in Table 1.

Example 4 The same operation as in Example 1 was carried out except that chlorobenzene was not recovered after washing the organic layer. The results are shown in Table 1.

Comparative Example 1 200 g of perchlorethylene as a reaction solvent, 50 g of BPA, and 125 g of ion-exchanged water were charged, and 142 g of bromine was added over 1.5 hours while stirring and cooling so that the reaction temperature was kept at 15 to 20 ° C. After the bromine addition was completed, the aging reaction was performed for 1.5 hours while maintaining the temperature at 15 to 20 ° C, the temperature was raised to 70 ° C, and the temperature was maintained at 70 ° C for 30 minutes. After that, 0.6 g of 60% hydrazine hydrate was added to decompose unreacted bromine, cooled, dried and dried to obtain a product. The results are shown in Table 1.

Comparative Example 2 The same operation as in Comparative Example 1 was performed except that the reaction solvent was carbon tetrachloride. The results are shown in Table 1.

Comparative Example 3 Using methanol as a reaction solvent, the same reaction as in Comparative Example 1 was carried out. After bromine decomposition, ion-exchanged water was added to crystallize TBA after completion of the reaction, and then dried and dried to obtain a product. The results are shown in Table 1.

Comparative Example 4 The TBA synthesized in Comparative Example 1 was dissolved in 300 g of a toluene solvent, washed with 100 g of water, and then cooled and crystallized. The results are shown in Table 1.

Comparative Example 5 The TBA synthesized in Comparative Example 2 was processed in the same manner as in Comparative Example 4 to obtain a product. The results are shown in Table 1.

"Effects of the Invention" The present invention shows that the solubility of TBA formed at low temperature is low and the solubility of TBA is high at high temperature. In a heterogeneous solvent consisting of chlorobenzene and water, BPA is brominated at low temperature to form a highly substituted product. It is very easy to separate HBr water generated by cleaning the reaction solution and to wash the reaction solution by heating to high temperature after the reaction. It has an excellent effect that TBA of 1) can be obtained in a high yield, and an effect that a device after the cleaning step does not require a corrosion resistant material.

Claims (1)

[Claims] 1. A process for producing tetrabromobisphenol A in which bisphenol A is reacted with a predetermined amount of bromine in a heterogeneous solvent, wherein 1 to 10 times the amount of chlorobenzene as bisphenol A is used as a solvent. 1 to 4 of bisphenol A
In a system in which twice the amount of water and bisphenol A are dispersed,
Bromine was added at 25 ° C to react, and after all bromine had been added, the temperature was kept at the same temperature for 1 hour or longer, and after heating to 70-90 ° C for aging, unreacted bromine was decomposed at the same temperature. After separating the aqueous layer at the same temperature and washing the organic layer at the same temperature, some chlorobenzene is recovered if necessary, and the organic layer is cooled.
A method for producing high-purity tetrabromobisphenol A, which comprises crystallizing tetrabromobisphenol A.