JP3008552B2 - Method for producing high quality tetrabromobisphenol A - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-quality tetrabromobisphenol A (hereinafter abbreviated as TBA) having a reduced content of hydrolyzable bromine and an improved hue. TBA is a compound useful as a flame retardant such as an epoxy resin and an ABS resin.

[0002]

2. Description of the Related Art TBA is usually produced by reacting bisphenol A (hereinafter abbreviated as BPA) with bromine using an organic solvent such as a lower alkyl alcohol or a halogenated hydrocarbon. Particularly, methanol is frequently used as a reaction solvent industrially because of relatively low generation of impurities. However, conventionally produced TBA crystals as described above typically contain about 100-2000 ppm of hydrolysable bromine.

[0003] TBA is used in a large amount in epoxy resin compositions as a reactive flame retardant.
It is compounded in the form of an epoxy resin having a skeleton of BA.
However, in these epoxy resin applications, a problem arises because hydrolyzable bromine contained in TBA adversely affects the curing reaction of the resin and the properties of the resin after curing.

In particular, the presence of an epoxy resin for electric and electronic materials such as a laminate and a sealant is a very important problem. In other words, when TBA having a high content of hydrolyzable bromine is used for an epoxy resin for electric and electronic materials, bromine is liberated as bromine ions due to moisture absorption and the like, which causes metal corrosion and the like, and lowers the reliability of the material. Cause. Furthermore, the hydrolyzable bromine in TBA acts as a catalyst poison in the curing reaction of the epoxy resin, causing a reduction in the curing speed.

Therefore, the TBA used for these applications
Requires purification by recrystallization or the like to reduce the content of hydrolyzable bromine. JP-A-64-3139 proposes a particularly effective purification method in which TBA heated and dissolved in an aromatic hydrocarbon is brought into contact with an alkali metal aqueous solution for treatment.

However, even if this purification method is carried out, the obtained TBA contains about 50 to 100 ppm of hydrolyzable bromine, and is not always satisfactory for use in electric and electronic materials. In addition, this method
Since a special purification step is required, it is industrially complicated and uneconomical.

On the other hand, the present inventors have found that in a method for producing TBA, when methanol containing 5 to 15% by weight of water is used as a reaction solvent, TBA having a reduced hydrolyzable bromine content can be obtained. Heading, filed earlier (Japanese Patent Application No. 1-328168).

Although this method is industrially simple, it is effective as a method for reducing the content of hydrolyzable bromine. However, since the obtained TBA is slightly colored, it is still unsatisfactory as a method for producing high quality TBA. Was not.

That is, when water is contained in the reaction solvent,
Hypobromous acid is generated in the system by the reaction as shown in Reaction formula-1. Therefore, in the reaction system, there is a problem that the oxidation reaction occurs simultaneously with the bromination reaction and the product is slightly colored.

[0010]

Embedded image

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high-quality TBA having a reduced content of hydrolyzable bromine and an improved hue, which has not been satisfied by the conventional methods. In addition, in the manufacturing method which was conventionally complicated and economically problematic in the manufacturing process, economically advantageous,
And to provide an industrial method that simplifies the conventional process.

The hydrolyzable bromine referred to in the present invention is:
The amount of bromine ions desorbed when TBA is dissolved in a potassium hydroxide-methanol solution and then heated and refluxed for 15 minutes is represented by the weight ratio of TBA.

The amount of bromine ions can be determined by a potentiometric titration method using an aqueous silver nitrate solution, ion chromatography, or the like.

[0014]

Means for Solving the Problems In view of the above circumstances, the present inventors have conducted intensive studies to industrially produce high-quality TBA with reduced hydrolyzable bromine content and improved hue. In the method of brominating BPA with bromine in alcohol, the reaction temperature is set to -10 to 20 ° C, and water is added in the aging step to reduce the content of hydrolyzable bromine and improve the hue. It has been found that high quality TBA can be obtained in good yield.

Further, in the method of the present invention, the aging time can be greatly reduced as compared with the conventional method using alcohol alone as the reaction solvent, and in addition, hydrogen bromide generated by the bromination reaction and the solvent can be reduced. It has been found that the reaction with alcohol can be suppressed, and the present invention has been completed.

[0016]

[Action] BPA is brominated with bromine in alcohol,
In the method for producing TBA, the reaction temperature is set to -10 to 2
0 ° C., and by adding water in the aging step,
High quality T with reduced hydrolyzable bromine content and improved hue
BA can be manufactured. Furthermore, in the method of the present invention, compared with the conventional method using alcohol alone as a reaction solvent,
The aging time can be greatly reduced, and additionally, the reaction between hydrogen bromide generated by the bromination reaction and the alcohol as the solvent can be suppressed.

It is believed that hydrolysable bromine is derived from impurities in BPA and / or alkyl bromides having relatively weak carbon-bromine bonds in which the side chain alkyl groups of TBA are brominated. Therefore, it is presumed that bromine radicals are involved in its formation.

It is not clear why the hydrolyzable bromine content was reduced when the reaction temperature was -10 to 20 ° C. and water was added in the aging step.
℃ or lower, and by adding water in the aging step, generation of bromine radicals in the reaction system is suppressed, and as a result, generation of alkyl bromides which cause hydrolyzable bromine is also considered to be suppressed. Can be

On the other hand, in the method of the present invention, the reason why TBA with improved hue can be obtained is that the reaction temperature is 20
It is considered that the oxidation reaction in the reaction system is suppressed by setting the temperature to not more than ° C. and adding water in the aging step, and as a result, product coloring is also suppressed. That is, when the reaction temperature is 2
By keeping the temperature at 0 ° C. or lower and adding water in the aging step, the equilibrium of the above-mentioned reaction formula-1 is biased toward the original system, so that the oxidation reaction in the reaction system is considered to be suppressed.

Further, in the method of the present invention, the reason why the aging time can be greatly reduced is considered to be the effect of water added in the aging step. That is, it is considered that the addition of water promotes the dissociation of the hydroxyl group of the substrate, and increases the reactivity with the bromine cation.

In addition, in the method of the present invention, the reason why the reaction between hydrogen bromide generated in the bromination reaction and the alcohol as the solvent is suppressed is that the reaction temperature is set to 20 ° C. or less and the aging step is performed. It is considered that the addition of water in the above causes the equilibrium shown by the following reaction formula-2 to be biased toward the original system. For example, in the case of methanol, which is frequently used as a reaction solvent, the substance by-produced according to Reaction Formula-2 is methyl bromide. Methyl bromide is an extremely toxic substance, and reducing its generation is extremely useful in terms of working environment and safety.

[0022]

Embedded image The gist of the present invention is a method for brominating BPA with bromine in alcohol, wherein the reaction temperature is -10 to 20 ° C and water is added in the aging step. Quality TB with reduced color and improved hue
A in the manufacturing method. The details will be described below.

The reaction solvent used in the method of the present invention is an alcohol having 1 to 4 carbon atoms, preferably methanol. Further, the concentration of the BPA substrate in the alcohol is not particularly limited, but is usually about 5 to 30% by weight.

The reaction temperature in the method of the present invention is -10
-20 ° C, preferably 0-15 ° C. -1
If the temperature is lower than 0 ° C., the reaction rate becomes extremely slow. If the temperature exceeds 20 ° C., there is no effect on the reduction of hydrolyzable bromine, which is not preferable.

The amount of bromine used in the method of the present invention is 4.0 to 5.0 (molar ratio), preferably 4.1 to 4.5, based on BPA. If it is less than 4.0, the yield of TBA is low, and if it exceeds 5.0, side reactions due to excess bromine tend to occur, which is not preferable.

The bromine is usually gradually added over 0.5 to 10 hours. After completion of the addition of bromine, aging is usually performed for about 0.5 to 5 hours while adding water to complete the reaction. The amount of water to be added is usually 2 to the reaction solvent.
-15% by weight, preferably 3-10% by weight. If it is less than 2% by weight, the effect of reducing hydrolyzable bromine is not effective, and if it exceeds 15% by weight, the obtained TBA is undesirably colored. There is no particular limitation on the method of adding water. That is, they may be added all at once or continuously.

After completion of the reaction, water is added to the reaction solution in order to crystallize TBA dissolved in the reaction solution. The amount of water to be added is usually about 30 to 100% by weight based on the reaction solvent. If it is less than 30% by weight, the crystallization amount of TBA is small, and
If it exceeds 0% by weight, the purity of TBA is undesirably reduced.

In the method of the present invention, TBA crystals are separated from the reaction solution by filtration, washed with water and dried to obtain a product.

The TBA obtained by the method of the present invention is a high quality TBA containing only 2 to 50 ppm of hydrolyzable bromine and having improved hue.

[0030]

As is apparent from the above description, according to the present invention, it was impossible to obtain by the conventional method by setting the reaction temperature to -10 to 20 ° C. and adding water in the aging step. High-quality TBA with reduced hydrolyzable bromine content and improved hue can be produced with high yield.

Therefore, the TBA obtained by the method of the present invention
Does not require a special purification step,
It can be used as a flame retardant for resins for electric and electronic materials such as sealants.

Further, in the method of the present invention, the reaction between hydrogen bromide generated by the bromination reaction and the alcohol of the solvent is significantly suppressed as compared with the conventional method using alcohol alone as the reaction solvent. The amount of recovered alcohol and hydrogen bromide is greatly improved.

Therefore, by practicing the method of the present invention, high quality TBA can be industrially advantageously produced by simplifying the conventional process.

[0034]

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

Example 1 54.8 g (0.24 mol) of BPA was placed in a four-neck flask having a capacity of 1000 ml having a thermometer, a stirring blade and a cooling tube.
l) was charged, and 320 g of methanol was added thereto to dissolve.

Next, while maintaining the reaction solution at 10 ° C., 163.0 g (1.02 mol) of bromine was added dropwise over 3 hours. After completion of the bromine addition, the mixture was aged at the same temperature for 15 minutes,
5 g was added, and aging was further performed for 2 hours.

After aging, the remaining excess bromine was reduced by adding an aqueous hydrazine solution, and 250 g of water was added thereto over 1 hour to crystallize the soluble TBA.

Subsequently, the precipitated crystals were collected by filtration, washed with water and dried to obtain 126.9 g of TBA white crystals.

When the isolated TBA crystal was analyzed by high performance liquid chromatography, the crystal purity was 99.3%. Further, when potentiometric titration was performed using an aqueous silver nitrate solution, it was found to contain 40 ppm of hydrolyzable bromine.
Further, as a result of analysis using a color difference meter, the hue of this isolated crystal was 96.4 in Hunter whiteness.

The reaction conditions are shown in Table 1, and the obtained results are shown in Table 2.

Examples 2 to 7 According to Example 1, the reaction was carried out under the conditions shown in Table 1.
Table 2 shows the results.

Comparative Examples 1 to 6 According to Example 1, the reaction was carried out under the conditions shown in Table 1.
Table 2 shows the results.

[0043]

[Table 1]

[0044]

[Table 2]

[Table 2 Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 37/62 C07C 37/68-37/88 C07C 39/24-39/44

Claims (1)

(57) [Claims] 1. A method for producing tetrabromobisphenol A by brominating bisphenol A with bromine in alcohol, wherein the reaction temperature is -10 to 20 ° C. and water is added in the aging step. For producing high quality tetrabromobisphenol A.