JP2897372B2 - Production method of high quality tetrabromobisphenol A - Google Patents

Description

The present invention relates to a high-quality tetrabromobisphenol A (hereinafter referred to as TBA) having a reduced hydrolyzable bromine content and an improved hue.
Abbreviated. ).

TBA is a compound useful as a flame retardant such as an epoxy resin and an ABS resin.

[Prior 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. In particular, methanol is industrially selected as a reaction solvent because of relatively low generation of impurities. But,
The TBA crystals produced by the conventional method as described above usually have about 1
Contains 00-2000 ppm hydrolysable bromine.

TBA is used in a large amount in an epoxy resin composition as a reactive flame retardant, and is blended in the form of TBA alone or an epoxy resin having TBA as a skeleton. However, in these epoxy resin applications, a problem arises because hydrolysable bromine contained in TBA adversely affects the curing reaction of the resin and the properties of the resin after curing.

In particular, in an epoxy resin used for electric and electronic materials such as a laminate and a sealant, its presence is a very important problem. In other words, when TBA with a high content of hydrolyzable bromine is used for epoxy resins 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, which 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 in these applications requires purification by recrystallization or the like in order 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, it can be obtained.
TBA contains about 50 to 100 ppm of hydrolyzable bromine, which is not always satisfactory for use in electric and electronic materials. Furthermore, this method is industrially complicated and uneconomical, since it requires a special purification step.

On the other hand, the present inventors, in a method for producing TBA,
It has been found that the use of methanol containing 5 to 15% by weight of water as a reaction solvent provides a TBA having a reduced hydrolyzable bromine content, and was filed earlier (Japanese Patent Application No. 1-328168).
issue).

Since the method is industrially simple, it is effective as a method for reducing the content of hydrolyzable bromine, but the obtained TBA is slightly colored, so that it is not yet satisfactory as a method for producing high-quality TBA. .

That is, when water is contained in the reaction solvent, the reaction formula-1
In the reaction system, there is a problem that the oxidation reaction occurs simultaneously with the bromination reaction and the product is slightly colored, for example, because hypobromite is generated in the system by the reaction shown in (1).

[Problems to be Solved by the Invention] An object of the present invention is to provide a high-quality TBA having a reduced hydrolyzable bromine content and an improved hue, which were not satisfied by the conventional methods.
Is to submit a method of manufacturing. In addition, another object of the present invention is to provide an industrial method which is economically advantageous and simplifies the conventional process in a manufacturing method which is conventionally complicated and economically problematic in the manufacturing process.

The hydrolyzable bromine referred to in the present invention is the amount of bromine ion desorbed by heating and refluxing for 15 minutes after dissolving TBA in a potassium hydroxide-methanol solution, expressed by the weight ratio of TBA. .

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

Means for Solving the Problems In view of the above circumstances, the present inventors have conducted intensive studies to industrially produce a high-quality TBA with a reduced hydrolyzable bromine content and an improved hue. In the method of brominating BPA with bromine, by using a mixed solvent of hydrohalic acid and alcohol as a reaction solvent, high-quality TBA with reduced hydrolyzable bromine content and improved hue can be obtained. I found that.

In addition, the method of the present invention has also found that the amount of by-produced methyl bromide can be significantly reduced as compared with the case where methanol is used alone as the reaction solvent, thereby completing the present invention.

Methyl bromide is an extremely toxic substance by-produced by the reaction between hydrogen bromide generated in the BPA bromination reaction and methanol as a solvent, as shown in Reaction formula-2. Therefore, reduction of the generation amount is extremely useful in working environment and safety.

[Action] In the method of producing TBA, by using a mixed solvent of hydrohalic acid and alcohol as a reaction solvent, it is possible to produce high quality TBA with reduced hydrolyzable bromine content and improved hue. Becomes Further, the method of the present invention can significantly reduce the amount of by-produced methyl bromide.

Hydrolysable bromine is believed to arise from impurities in BPA and / or alkyl bromides with relatively weak carbon-bromine bonds where the side chain alkyl groups of TBA are brominated.
Therefore, it is considered that bromine radicals are involved in the formation.

The reason why hydrolysable bromine is reduced when a mixed solvent of hydrohalic acid and alcohol is used as the reaction solvent is not always clear, but the addition of hydrohalic acid suppresses the generation of bromine radicals, As a result, it is considered that the generation of alkyl bromides that cause hydrolyzable bromine is suppressed.

On the other hand, in the method of the present invention, TBA with improved hue
The reason why is obtained is considered that addition of hydrohalic acid suppresses the oxidation reaction in the reaction system, and as a result, product coloring is suppressed. That is, it is considered that the addition of hydrohalic acid causes the equilibrium of the above-mentioned reaction formula-1 to be biased toward the original yarn, and thus the oxidation reaction in the reaction system is suppressed.

Furthermore, in the method of the present invention, the reason why the amount of by-produced methyl bromide can be significantly reduced is considered to be due to the effect of water contained in the added hydrohalic acid. That is, when hydrohalic acid is added, the amount of water in the reaction system increases, so that the equilibrium of the reaction formula-2 is biased toward the original yarn, and the by-product of methyl bromide is considered to be suppressed.

The gist of the present invention is to provide a method for brominating with bromine, characterized in that a mixed solvent of hydrohalic acid and alcohol is used as a reaction solvent to reduce the content of hydrolyzable bromine and improve the hue. It is in the manufacturing method of quality TBA.
The details will be described below.

The reaction solvent used in the method of the present invention is a mixed solvent of hydrohalic acid and alcohol. The hydrohalic acid referred to in the method of the present invention is hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid or a mixture thereof having a concentration of 5% by weight or more, preferably hydrochloric acid and Hydrobromic acid. It is not preferable to use a hydrohalic acid having a concentration of less than 5% by weight because the TBA formed is colored. The alcohol in the method of the present invention is an alcohol having 1 to 4 carbon atoms, and is preferably methanol.

Further, the mixing ratio of the hydrohalic acid and the alcohol varies depending on the concentration of the hydrohalic acid used.
It is preferable to mix the mixture so that the concentration of water in the mixed solvent is 3 to 20% by weight. If the concentration of water is less than 3% by weight, there is no effect in reducing hydrolysable bromine, and if it exceeds 20% by weight, the purity of the generated TBA is undesirably reduced. still,
The substrate concentration of BPA in the reaction solvent is not particularly limited,
Usually, it is carried out at about 5 to 30% by weight.

The amount of bromine used in the method of the present invention is BP
4.0 to 5.0 (mol ratio) to A, preferably 4.1 to 5.0
4.5. If it is less than 4.0, the yield of TBA is low, and if it exceeds 5.0, a side reaction due to excess bromine tends to occur, which is not preferable.

Bromine is usually added gradually over 0.5 to 10 hours.
The reaction temperature at the time of adding bromine is about -10 to 50 ° C, and particularly preferably about 0 to 30 ° C. If the temperature is lower than -10 ° C, the reaction rate becomes extremely slow. If the temperature exceeds 50 ° C, side reactions such as decomposition of TBA occur, which is not preferable.

After completion of the bromine addition, usually 0.5 to complete the reaction.
Aging is performed for about 5 hours. The reaction temperature during aging is not particularly limited, but is usually selected to be about 0 to 30 ° C. in order to suppress by-product of methyl bromide.

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 add is usually
It is about 30 to 100% by weight based on the reaction solvent. If the amount is less than 30% by weight, the crystallization amount of TBA is small.
Is not preferred because the purity of

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 hydrolysable bromine and having improved hue.

[Effects of the Invention] As is apparent from the above description, according to the present invention, by using a mixed solvent of hydrohalic acid and an alcohol as a reaction solvent, hydrolyzable bromine that cannot be obtained by the conventional method can be obtained. High quality TBA with reduced content and improved hue can be produced.

Therefore, the TBA obtained by the method of the present invention can be used as it is as a flame retardant for resins for electric and electronic materials such as laminates and sealants without requiring a special purification step.

Further, in the method of the present invention, since the generation of methyl bromide is significantly suppressed, the recovered amounts of methanol and hydrogen bromide after the reaction are greatly improved. In addition, safety is significantly improved by reducing the chance of exposure to methyl bromide in the work environment.

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

[Examples] Hereinafter, the method of the present invention will be specifically described 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 charged into a four-neck flask having a capacity of 1000 ml having a thermometer, a stirring blade and a cooling tube, and 300 g of methanol and 40.6 g of 36% by weight hydrochloric acid were added thereto and dissolved. .

Next, while maintaining the reaction solution at 25 ° C., 163.0 g (1.02
mol) was added dropwise over 4 hours, followed by aging at the same temperature for 1 hour.

After aging, the remaining excess bromine was reduced by adding an aqueous hydrazine solution, and then 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, dried, and dried.
7.1 g of TBA white crystals were obtained.

When the isolated TBA crystal was analyzed by high performance liquid chromatography, the crystal purity was 98.7%. Further, when potentiometric titration was performed using an aqueous silver nitrate solution, it contained 21 ppm of hydrolyzable bromine. Further, as a result of analysis using a color difference meter, the hue of this isolated crystal was 95.9 in Hunter whiteness.

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

(Examples 2 to 7) The reaction was carried out under the conditions shown in Table 1 according to Example 1. The results are shown in Table 2.

(Comparative Examples 1 to 4) The reaction was carried out under the conditions shown in Table 1 according to Example 1. The results are shown in Table 2.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 39/367 C07C 37/62

Claims (1)

(57) [Claims] 1. A bromine of bisphenol A with bromine,
A process for producing tetrabromobisphenol A, wherein a mixed solvent of hydrohalic acid and alcohol is used as a reaction solvent.