JP3044830B2 - Method for producing 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. 1,2,5,6 obtained by the present invention
9,10-Hexabromocyclododecane is a compound useful as a flame retardant for a polymer compound.

[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 using high performance liquid chromatography equipped with an ODS reverse phase column, it is known that HBCD has three types of isomers. They are eluted from the column in the order of α-HBCD, β-HBCD,
γ-HBCD [E. R. Larsen
and E. L. Ecker, J. et al. Fire Sc
i. , 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 having a low melting point and low thermal stability increases, the melting point and heat resistance of HBCD decrease. Therefore, since thermal decomposition of HBCD starts to occur at a relatively low temperature, there have been problems such as corrosion of the molding machine and coloring of the resin.

[0005] The reaction of adding bromine to CDT results in H
Although BCD has been synthesized, various reaction methods such as the following 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, US Pat. No. 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, problems remain because the HBCD produced has a low melting point and low heat resistance.

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 side reactions such as bromination at the allylic position, dehydrobromination, bromination of the solvent, and the like are liable to occur in addition to the bromine addition reaction. However, there has been a problem that HBCD is mixed into the HBCD crystal. These impurities also corrode the molding machine,
It is known to cause coloring of the resin.

Therefore, the present inventors have proposed that γ having high thermal stability.
-A highly selective production method of HBCD was studied. As a result, the present inventors reacted bromine and CDT in the presence of an organic solvent, and in a method of producing HBCD, bromine was dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same. A method of reacting by dropping CDT has been found, and a patent application has already been filed (Japanese Patent Application No. 2-2884).
No. 52). 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, and the substrate concentration of CDT with respect to the solvent. 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.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies on a reaction process that can reduce the amount of excess bromine used and obtain HBCD having high thermal stability. Alternatively, in a method of producing HBCD by reacting bromine and CDT in an organic solvent containing the same, a reaction method in which bromine and CDT are alternately charged and reacted in a reaction solvent and then crystals are collectively isolated. As a result, the amount of bromine used can be about the theoretical amount, it is very effective in the reaction process as compared with the reaction method of isolating crystals in each reaction, and γ-HB in each reaction.
The present inventors have found that the selectivity of CD does not show a decrease in selectivity or an increase in unknown substances even when the number of times of alternately charging is increased, and the present invention has been reached.

That is, the present invention provides a method for preparing bromine and CDT in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same.
And a method for producing HBCD by reacting bromine and CDT alternately in a reaction solvent.

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 solvent 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:
Examples of ether solvents include dipropyl ether, diisopropyl ether, tetrahydrofuran (THF), dioxane, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, and examples of halogenated hydrocarbon solvents include carbon tetrachloride, chloroform, methylene chloride, and ethylene dichloride (EDC). ), Etc., and ethyl acetate, methyl acetate, 2-
Methoxyethyl acetate and the like can be mentioned. As a mixed solvent, ethanol-ethyl acetate, ethanol-THF,
Ethanol-dioxane, ethanol-EDC, ethanol-methylene chloride and the like are particularly preferable from the viewpoint of the reaction results.

The reaction substrate concentration (CDT / reaction solvent = wt / vol%) at which the method of the present invention can be carried out depends on the charged C
It is preferably about 10 to 40%, preferably about 20 to 30%, calculated from the total amount of DT and the amount of the reaction solvent. When the reaction is carried out at a substrate concentration lower than 10%, the amount of crystals obtained per unit volume is small, and the advantage of practicing the present invention is small. 4
If the reaction is carried out at a substrate concentration of 0% or more, the slurry concentration is too high and stirring becomes difficult, which is not preferable in the process.

[0018] The number of times of alternately charging the reaction varies depending on the concentration of the reaction substrate at each time, and thus cannot be unconditionally specified.
However, as disclosed in Japanese Patent Application No. 2-288453, the concentration of the reaction substrate at each time is 0.1 to 20 wt / vol.
%, Preferably in the range of 0.5 to 10 wt / vol%, the selectivity of γ-HBCD having high heat resistance is improved, so that it is 0.1 to 20 wt / vol%, preferably 0.1 to 20 wt / vol%.
A range of 5 to 10 wt / vol% is selected. Even when the reaction is performed at a concentration lower than 0.1%, the selectivity of γ-HBCD does not improve as expected as compared with the selectivity of γ-HBCD at 0.1 wt / vol%. Also 20wt / v
If the reaction is carried out in excess of ol%, the selectivity of γ-HBCD is remarkably reduced, so that it is not selected. That is, the number of times of alternately charging with the reaction substrate concentration is 0.1 to 20 wt / vo.
400 to 2 times, preferably 0.1 to 1% at a substrate concentration of about 1%.
The present invention can be implemented by repeating about 80 to 4 times at a substrate concentration of about 5 to 10 wt / vol%.

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 likely to occur, so that impurities increase, and the reaction between the reaction solvent and bromine tends 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 method for carrying out the present invention is a reaction method in which CDT is dissolved in a reaction solvent and then bromine is added dropwise to cause a reaction, and CDT is newly dissolved in the reaction solution and bromine is added dropwise to carry out the reaction. Alternatively, any reaction method can be achieved in which bromine is dissolved in the reaction solvent and then CDT is added dropwise to cause a reaction, and bromine is newly dissolved in the reaction solution and CDT is added dropwise to carry out the reaction.

In practicing the present invention, the reaction time, aging time, and dissolution time of each time can vary depending on the reaction temperature, the charged amount, and the like. However, the reaction may be carried out by dropping CDT or by dropping bromine. The reaction time is usually about 10 minutes to 10 hours. After the reaction is completed, the next C
The aging time until DT or bromine is dissolved in the reaction solvent is usually about 0 to 5 hours. The dissolution time for dissolving CDT and bromine in the reaction solvent is usually about 10 minutes to 5 hours. Further, the aging time after repeating the reaction a predetermined number of times can be usually achieved by reacting for about 0 to 5 hours.

The amount of bromine relative to the CDT calculated from the total amount of the charged CDT and bromine is 3.0 or more, preferably 3.0 to 5.0, in terms of Br ₂ / CDT (molar ratio).
If it is less than 3.0, the reaction is not completed because bromine is insufficient for CDT. If it exceeds 5.0, side reactions due to excess bromine remaining in the reaction system are likely to occur, and this is not preferable from an economic viewpoint.

The HBCD produced after completion of the reaction can be isolated as a powder by known means. For example, a method of filtering the precipitated crystals as they are, a method of taking the crystals by pouring the reaction solution at the end of the reaction into a poor solvent, and a method of pouring a poor solvent into the reaction solution at the end of the reaction can be considered. Further, the solvent recovered as a filtrate can be repeatedly used as a reaction solvent by replenishing a new solvent.

[0024]

By carrying out the method of the present invention, it has become possible to produce a γ-isomer of HBCD having a high stoichiometric amount of bromine and excellent in hue and thermal stability with high selectivity and high yield. .
It is also very effective in the reaction process.

[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.

Examples 1 to 6 In a round-bottomed flask equipped with a reflux condenser and stirring blades,
The reaction solvent having the composition shown in the following was charged. In that, CDT and bromine in the amounts shown in Table 1 were divided into the number of times shown in Table 1 and charged alternately. The reaction temperature was set to 15 ° C. for each reaction, and the reaction was performed by dropping over 2 hours. After completion of the dropwise addition, the mixture was aged for 2 hours.

After the completion of the reaction, the reaction slurry was subjected to high performance liquid chromatography (column TSK gel-ODS80T).
M, eluent acetonitrile / water = 80/20 vol
%, Detector UV 215 nm) and the results are summarized in Table 1. Components that could not be identified were determined as unknown. DBCD (dibromocyclododecadien) and TBCD (tetrabromocyclododecene) in Table 1
Is a reaction intermediate of HBCD. Since TBCD has an isomer, OCD is determined by high performance liquid chromatography.
Analysis was performed using a DS reversed-phase column, and they were named α-TBCD and β-TBCD in the order of elution from the column.

The selectivity of γ-HBCD was represented by the value obtained by dividing the amount of γ-HBCD produced by the total amount of HBCD isomers [γ-HBCD / (α-TBCD + β-TBCD + γ-
HBCD)].

At the end of the reaction, the reaction solution was filtered, the obtained crystals were dried, and the melting points were measured. The results are shown in Table 1.

[0030]

[Table 1] Comparative Examples 1 and 2 Table 2 was placed in a round bottom flask equipped with a reflux condenser and a stirring blade.
The reaction solvent having the composition shown in the following was charged. The CDT and bromine in the amounts shown in Table 2 were separately charged in the number of times shown in Table 2. The reaction temperature was set to 15 ° C. for each reaction, and the reaction was performed by dropping over 2 hours. After completion of the dropwise addition, the mixture was aged for 2 hours. Thereafter, post-processing and analysis were performed in the same manner as in the examples, and the results are shown in Table 2.

[0031]

[Table 2]

Claims (1)

(57) [Claims] 1. A bromine is reacted with 1,5,9-cis, trans, trans-cyclododecatriene in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same,
In a method for producing 1,2,5,6,9,10-hexabromocyclododecane, bromine and 1,5,9-cis,
Characterized in that trans and trans-cyclododecatriene are alternately charged into a reaction solvent and reacted.
A method for producing 5,6,9,10-hexabromocyclododecane.