JP3044828B2 - Preparation of hexabromocyclododecane - 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 2,5,6,9,10-hexabromocyclododecane. The 1,2,5,6,9,
10-Hexabromocyclododecane is a compound useful as a flame retardant for polymer compounds.

[0002]

2. Description of the Related Art 1,2,5,6,9,10-Hexabromocyclododecane (hereinafter abbreviated as HBCD) is a flame retardant used for polystyrene resins and the like. This flame retardant converts bromine into 1,5,9-cis, trans, trans-
It is synthesized by a reaction to be added to cyclododecatriene (hereinafter abbreviated as CDT).

When analyzed by high performance liquid chromatography equipped with an ODS reversed phase column, HBCD shows 3
It is known that there are different types of isomers. They are eluted from the column in order of α-HBCD, β-HBC
D, γ-HBCD [E. R. Lars
en and E. L. Ecker, J. et al. FireS
ci. , 4,261 (1986)].

[0004] The inventors of the present invention have isolated each isomer and measured its physical properties. As a result, the melting points of the α-, β-, and γ-isomers were 184 to 186 ° C, 168 to 171 ° C, and 196 to 186 ° C.
198 ° C. Thermogravimetric analysis (in air, heating rate 1
0 ° C / min), the 5% weight loss on heating is 2
At 42 ° C, 217 ° C, and 245 ° C, the 50% heating weight loss temperatures are 255 ° C, 232 ° C, and 258 ° C, respectively. Therefore, the thermal stability is higher in the order of γ-HBCD, α-HBCD, and β-HBCD. HBCD used as a flame retardant is γ-
Although the body is mainly used, the quality of HBCD greatly depends on the difference in the abundance ratio of these isomers. For example, when the abundance ratio of β-HBCD, which has a low melting point and low thermal stability, increases, the melting point of HBCD decreases, and the thermal decomposition of HBCD begins to occur at a low temperature during molding of a polymer. There were problems such as corrosion and coloring of the resin.

[0005] The reaction of adding bromine to CDT results in H
Although BCD has been synthesized, various reaction methods have been disclosed to date.

[0006] German Patent 1 147 574 discloses that bromine is added dropwise to a solution of CDT in ethyl alcohol,
It is described that a bromine addition reaction is performed. However, in this method, an insoluble resinous substance precipitates during the reaction, so that stirring is difficult and scale-up is difficult. Furthermore, the HBCD produced at this time has a drawback that the melting point is low and the heat resistance is inferior.

[0007]

In order to solve the drawback of insoluble resinous substances being precipitated during the reaction, several mixed solvent systems have been disclosed by a similar reaction method. For example, JP-B-49-24474 discloses a mixed solvent system of alcohol and benzene, JP-B-49-24475 discloses a mixed solvent system of alcohol and ester, USP 3,833,675 discloses a mixed solvent system of t-butyl alcohol and benzene. No. 5187 discloses a mixed solvent system of alcohol and halogenated hydrocarbon, and EP 181414 discloses a mixed solvent system of alcohol and dioxane. When the reaction is carried out with these solvents, precipitation of resinous substances during the reaction is eliminated because the solubility of the reaction solvent is high. However, the defect that the HBCD produced has a low melting point and poor heat resistance remains.

Further, Japanese Patent Publication No. 53-12510 discloses a method in which a solvent is charged in a reactor, and CDT and bromine are simultaneously dropped and reacted. However, the generated H
The problem that the heat resistance and melting point of BCD were low remained.

In the above reaction method, γ-H
Not only is the selectivity of BCD low, but in addition to the bromine addition reaction, side reactions such as bromination at the allylic position, dehydrobromination, or bromination of the solvent are liable to occur. There was a problem that it was mixed in the HBCD crystal. It is known that these impurities also cause corrosion of the molding machine and coloring of the resin.

[0010] Among the above-mentioned reaction methods, there is one that discloses a method of recycling a reaction filtrate. However, as the number of times of recycling increases, impurities accumulate in the reaction filtrate.
Impurities adhered to the precipitated crystals and the heat resistance of HBCD was reduced. Therefore, the number of times of recycling could not be increased.

[0011] Then, the present inventors consider that γ has high thermal stability.
-A highly selective production method of HBCD was studied. As a result, the present inventors have found that in a method for producing HBCD by reacting bromine with CDT in the presence of an organic solvent, bromine is dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same while CDT is dissolved. And found a method of reacting by dropping, and already applied for a patent (Japanese Patent Application No. Hei 2-288452).
issue). According to this reaction method, the selectivity of γ-HBCD is remarkably improved, and HBCD having high heat resistance can be produced. However, although slightly different depending on the reaction conditions, a slight side reaction occurs in which bromine reacts with the solvent.

Further, Japanese Patent Application No. 2-288453 discloses a method for producing HBCD by reacting bromine with CDT in the presence of an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same, wherein the substrate concentration of CDT to the solvent is determined. To 0.1
It discloses a method of adjusting the content to ２０20 wt / vol%. According to this reaction method, the selectivity of γ-HBCD is remarkably improved, and HBCD having high heat resistance can be produced. However, since the concentration of the reaction substrate is relatively low, HB which can be produced in one reaction
The amount of CD was fairly low, which was not a very favorable method in terms of the reaction process.

Therefore, there has been a demand for a reaction process capable of reducing the amount of excess bromine used and obtaining HBCD having high thermal stability.

[0014]

SUMMARY OF THE INVENTION In view of the above circumstances, the present inventors have reduced the amount of excess bromine used and have found that H has a high thermal stability.
As a result of intensive studies on a reaction process for obtaining BCD, HBCD is produced by dissolving bromine in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same, and then dropping CDT to cause a reaction. In the method, by repeatedly using a reaction filtrate as a reaction solvent, bromine is dropped into a solution of CDT dissolved in an organic solvent, which has been conventionally generally performed, and the reaction filtrate is reacted with the reaction solvent. The selectivity of γ-HBCD is remarkably improved as compared with the method using repetition, the unidentifiable substances which are considered to be generated by side reactions other than the bromine addition reaction are extremely reduced, and the number of times of recycle of the filtrate is reduced. The inventors have found that the amount of bromine can be increased, and furthermore, that the amount of bromine used is only a theoretical amount, and reached the present invention. That is, the present invention provides a method of producing HBCD by dropping CDT while dissolving bromine in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same, thereby producing a reaction filtrate. HB characterized by being used repeatedly
It relates to the manufacturing method of CD.

Hereinafter, the present invention will be described in detail.

The solvent used in the method of the present invention is an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same. As the alcohol having 1 to 4 carbon atoms, methanol,
Ethanol, n-propanol, isopropanol, n
-Butanol, sec-butanol, isobutanol,
tert-Butanol, ethylene glycol, diethylene glycol, propylene glycol and the like.
Among these alcohols, ethanol, n-propanol, tert-butanol and the like are particularly preferred. Examples of the organic solvent to be mixed with the alcohol include ether solvents, halogenated hydrocarbon solvents, and ester solvents. The mixing ratio of each solvent to be mixed with the alcohol is not particularly limited. Specific examples of each solvent include dipropyl ether, diisopropyl ether, tetrahydrofuran (TH
F), dioxane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and the like, and as halogenated hydrocarbon solvents, carbon tetrachloride, chloroform, methylene chloride, ethylene dichloride (EDC)
Examples of the ester solvents include ethyl acetate, methyl acetate, and 2-methoxyethyl acetate. Ethanol-ethyl acetate, ethanol-
THF, ethanol-dioxane, ethanol-ED
C, ethanol-methylene chloride and the like are particularly preferred from the viewpoint of reaction results.

As disclosed in Japanese Patent Application No. 2-288453, the reaction substrate concentration at which the method of the present invention can be carried out is 0.1 to 20 wt / vol%, preferably 0.5 to 20 wt / vol%. When performed in the range of 10 wt / vol% to 10 wt%, the selectivity of γ-HBCD having high heat resistance is improved.
0.1-20 wt / vol%, preferably 0.5-10
A range of wt / vol% is selected. 0.1wt / vol
% Even if the reaction is performed at a concentration lower than 0.1 wt / vol.
%, The selectivity of γ-HBCD is not improved as expected. Also 20wt
When the reaction is carried out in excess of / vol%, the selectivity of γ-HBCD is remarkably reduced, so that it is not selected.

In the reaction method for carrying out the present invention, bromine is dissolved in a reaction solvent, CDT is added dropwise, and the mixture is allowed to react. If necessary, the crystals are aged and separated by filtration. The filtrate obtained here may be replenished with a deficient solvent if necessary. Bromine is dissolved in the reaction filtrate, and CDT is added dropwise to react. This can be achieved by repeating this operation.

The HBCD produced after the completion of the reaction can be isolated as a powder by known means. For example, HBCD crystals can be obtained by filtering the precipitated crystals.

The number of repetitions is not particularly limited because it can vary depending on the concentration of the reaction substrate, the reaction temperature, and the like.
It can be repeated about 1 to 100 times, preferably about 5 to 80 times.

The reaction temperature for carrying out the method of the present invention is not particularly limited, but when the reaction is carried out at a high temperature,
Substitution reactions other than the bromine addition reaction are apt to occur, so that impurities increase, and the reaction between the reaction solvent and bromine is apt to occur. Further, when the reaction is carried out at an extremely low temperature, the reaction rate is slow, so that the reaction is not completed and stops at a reaction intermediate, which is not preferable. Reaction temperatures are usually in the range of about -20C to about 50C.

The reaction time for carrying out the present invention can vary depending on the reaction temperature, the charged amount and the like.
Is usually about 10 minutes to 10 hours, and ripening time after completion of the dropping of CDT is about 0 to 5 hours.

The amount of bromine used for CDT is Br ₂ /
The CDT (molar ratio) is 3.0 or more, preferably 3.0 to 3.0.
5.0. If it is less than 3.0, the reaction is not completed because bromine is insufficient for CDT. If it exceeds 5.0, it is not preferable from an economic viewpoint.

[0024]

By implementing the method of the present invention, H
It has become possible to produce a γ-isomer of BCD with high selectivity and high yield. As a result, it has become possible to produce HBCD having excellent hue and thermal stability. Further, since the amount of accumulated impurities is small, the number of times of recycling can be increased dramatically.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 A round-bottomed flask equipped with a reflux condenser and stirring blades was prepared as shown in Table 1.
A reaction solvent having the composition shown in the following and bromine were charged. Table 1 in it
The reaction was carried out by dropping the amount of CDT shown in (1) at 30 ° C. over 2 hours. After completion of the dropwise addition, the mixture was aged for 2 hours. After completion of the reaction, the precipitated crystals were separated by filtration, and after drying the crystals, the melting point and purity were measured. Purity was determined by high performance liquid chromatography (column TSK gel-ODS80TM, eluent acetonitrile / water = 80/20 vol%, detector UV2
15 nm). The reaction filtrate is shown in Table 1 or Table 2.
Was used as a reaction solvent, bromine was dissolved, and CDT was added dropwise at 15 ° C. over 2 hours to carry out a reaction. Similarly, the recycle reaction of the reaction filtrate was repeated 20 times. The results are collectively shown in Tables 1 and 2, respectively. γ
The selectivity of HBCD is determined by determining the amount of γ-HBCD produced by HBC.
It was shown by the value divided by the total amount of D isomer [γ-HBCD /
(Α-TBCD + β-TBCD + γ-HBCD)].

[0027]

[Table 1]

[0028]

[Table 2] Example 2 The same procedure as in Example 1 was carried out except that a reaction solvent and bromine having the composition shown in Table 3 were charged, and the amount of CDT shown in Table 3 was dropwise added at 30 ° C. over 2 hours. The reaction and analysis were performed by the method. The reaction filtrate was prepared by adding a solvent in an amount shown in Table 3 or Table 4 to obtain a reaction solvent and dissolving bromine.
T was added dropwise at 15 ° C. over 2 hours to react. Similarly, the recycle reaction of the reaction filtrate was repeated 20 times. The results are collectively shown in Tables 3 and 4, respectively.

[0029]

[Table 3]

[0030]

[Table 4] Example 3 A reaction solvent similar to that of Example 1 was prepared except that a reaction solvent and a bromine having the composition shown in Table 5 were charged, and the amount of CDT shown in Table 5 was dropped therein at 30 ° C. over 2 hours. The reaction and analysis were performed by the method. The reaction filtrate was prepared by adding a solvent in an amount shown in Table 5 or Table 6 to obtain a reaction solvent, dissolving bromine, and then adding CD.
T was added dropwise at 15 ° C. over 2 hours to react. Similarly, the recycle reaction of the reaction filtrate was repeated 20 times. The results are collectively shown in Tables 5 and 6, respectively.

[0031]

[Table 5]

[0032]

[Table 6] Comparative Example 1 A round-bottomed flask equipped with a reflux condenser and stirring blades was prepared as shown in Table 7
A reaction solvent having the composition shown in Table 1 and CDT were charged. The reaction was carried out by dropping bromine in the amount shown in Table 7 at 15 ° C. over 2 hours. After completion of the dropwise addition, the mixture was aged for 2 hours. Thereafter, the reaction and analysis were performed in the same manner as in Example 1.
The results are summarized in Table 7.

[0033]

[Table 7]

Claims (1)

(57) [Claims] 1. A method in which bromine is dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same.
In a method of producing 1,2,5,6,9,10-hexabromocyclododecane by dropping and reacting cis, trans, trans-cyclododecatriene, the reaction filtrate is repeatedly used as a reaction solvent. A process for producing 1,2,5,6,9,10-hexabromocyclododecane, characterized in that: