JP2844899B2 - Method for producing hexabromocyclododecane - Google Patents

Description

The present invention relates to a method for producing 1,2,5,6,9,10-hexabromocyclododecane having excellent heat resistance. 1,2,5,6,9,10−
Hexabromocyclododecane is a compound useful as a polymer compound flame retardant.

(Prior art) 1,2,5,6,9,10-hexabromocyclododecane (hereinafter referred to as HB
(Abbreviated as CD) is a well-known flame retardant, and is used for polystyrene resin and the like. This flame retardant is 1,5,
It is synthesized by adding bromine to 9-cis, trans, trans-cyclododecatriene (hereinafter abbreviated as CDT).

German Patent No. 1147574 describes that bromine addition reaction is carried out by dropping bromine into an ethyl alcohol solution of CDT using ethyl alcohol as a reaction solvent.

Several mixed solvent systems have been proposed in a similar reaction method. For example, JP-B-49-24474 describes a mixed solvent system of alcohol and benzene, JP-B-49-24475 describes a mixed solvent system of alcohol and ester, USP3833675 describes a mixed solvent system of t-butyl alcohol and benzene, and JP-B-50-5187.
In the issue, a mixed solvent system of alcohol and halogenated hydrocarbon,
EP181414 proposes a mixed solvent system of alcohol and dioxane, respectively.

In addition, Japanese Patent Publication No. 53-12510 discloses a method in which a solvent is charged into a reactor, and CDT and bromine are simultaneously dropped and reacted.

(Problems to be Solved by the Invention) It is known that three kinds of isomers having different physical properties exist in HBCD produced by bromine addition reaction of CDT (ERLarsen and ELEcker, J. Fire Sci. , 4,26
1 (1986)). That is, O
Analysis using a DS reversed-phase column states that there are isomers named α-HBCD, β-HBCD, and γ-HBCD in the order of elution from the column.

The present inventors have isolated each isomer and measured its physical properties. As a result, the melting point of each of the α-, β-, and γ-isomers was 184.
-186 ° C, 168-171 ° C, 196-198 ° C. In thermogravimetric analysis (in air, heating rate 10 ° C / min), 5% weight loss on heating was 242 ° C, 217 ° C, 245 ° C, and 50% weight loss on heating was 255 ° C, 232 ° C, respectively. 258 ° C. Therefore γ-H
The thermal stability is higher in the order of BCD, α-HBCD, β-HBCD.

HBCD used as a flame retardant is mainly composed of a γ-isomer, but the quality of HBCD is greatly affected by the difference in the 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.

In addition, in the method described in German Patent No. 1147574, a resinous substance insoluble in a solvent is precipitated during the reaction, so that stirring is difficult and scale-up is difficult. Furthermore, the HBCD produced at this time has a disadvantage that the melting point is low and the heat resistance is inferior.

When the reaction is carried out in the above-mentioned mixed solvent system proposed to solve these drawbacks, precipitation of resinous substances during the reaction is eliminated due to the solubility of the mixed solvent. But HBCD to produce
Has a low melting point, so that there still remains a problem in terms of heat resistance.

Also, the method described in JP-B-53-12510 still has a problem in terms of heat resistance because the HBCD produced has a low melting point.

Furthermore, in the conventional reaction method described above, in addition to the bromine addition reaction to the double bond of CDT, bromination at the allylic position, dehydrobromination, bromination of the solvent, etc. Side reactions are likely to occur, lowering the yield and
There were problems such as being mixed into the HBCD crystal. These impurities also cause corrosion of the molding machine and coloring of the resin.

Thus, there has been a demand for a method for selectively producing γ-HBCD having high thermal stability.

(Means for Solving the Problems) In view of the above circumstances, the present inventors have considered that γ-
As a result of intensive studies on a highly selective production method of HBCD, 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, and CDT is dropped and reacted. By doing so,
Compared to a method in which bromine is added dropwise to a reaction in which CDT is dissolved in an organic solvent, or a reaction method in which a reaction solvent is charged in a reaction vessel in advance and CDT and bromine are added simultaneously to the reactor while reacting. As a result, it has been found that the selectivity of γ-HBCD is remarkably improved, and further, unidentified unidentifiable substances which are considered to be generated by a side reaction other than the bromine addition reaction are extremely reduced, and the present invention has been reached.

That is, the present invention relates to a method for producing HBCD by reacting bromine and CDT in the presence of an organic solvent, wherein bromine is dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same, and The present invention relates to a method for producing HBCD, which is characterized by reacting dropwise.

 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. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, ethylene glycol, diethylene glycol,
Propylene glycol and the like. Among these solvents, 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. Specific examples of each solvent include dipropyl ether, diisopropyl ether, tetrahydrofuran (TH
F), dioxane, diethylene glycol dimethyl ether, dimethylene glycol diethyl ether, etc., halogenated hydrocarbon solvents include carbon tetrachloride, chloroform, methylene chloride, ethylene dichloride (EDC), etc., and ester solvents include ethyl acetate. , Methyl acetate, 2-
Methoxyethyl acetate and the like can be mentioned. As the 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 temperature for carrying out the method of the present invention is not particularly limited, but when the reaction is performed at a high temperature, a substitution reaction other than the bromine addition reaction is likely to occur, so that impurities increase, or the reaction between the reaction solvent and bromine. Is not preferred because it is likely to occur. When the reaction is carried out at an extremely low temperature, the denaturation of the solvent is suppressed, but the reaction is not completed because the reaction rate is slow, and the reaction 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 may vary depending on the reaction temperature, the charged amount, etc., but the dropping time of CDT is usually about 10 minutes to about 10 hours, and the reaction is further performed for about 3 hours after the completion of the dropping of CDT. Can be accomplished by doing

The amount of bromine relative to the CDT, 3 Br ₂ / CDT (molar ratio).
It is 0 or more, preferably 3.0 to 10.0. Below 3.0, CDT
The reaction is not complete because of the lack of bromine.
If it exceeds 10.0, side reactions due to excess bromine are likely to occur, which is not preferable.

The concentration of CDT with respect to the reaction solvent is not particularly limited,
Usually, it is about 0.1 to 40 wt / vol%. When the substrate concentration is lower than 0.1 wt / vol%, it is difficult to think from an economical point of view, and
When the content is 40 wt / vol% or more, a side reaction easily occurs.

After completion of the reaction, HBCD produced can be isolated as a fraction by known means. For example, by filtering the precipitated crystals, HB
CD crystals can be obtained. Further, the solvent recovered as a filtrate can be repeatedly used as a reaction solvent by replenishing it with a new solvent. Alternatively, the crystals may be taken up by pouring the reaction solution at the end of the reaction into a poor solvent.

(Effect of the Invention) By carrying out the method of the present invention, it has become possible to produce the γ-form of HBCD with high selectivity and high yield. In addition, the generation of impurities derived from CDT was significantly reduced as compared with the usual reaction method in which bromine was added. Therefore, the hue,
HBCD with excellent thermal stability can be selectively produced.

(Examples) Hereinafter, the present invention will be described in more detail according to examples.
The present invention is not limited by these.

Examples 1 to 9 A round bottom flask equipped with a reflux condenser and a stirring blade was charged with a reaction solvent having the composition shown in Tables 1 and 2 and bromine. The amount of CDT shown in Tables 1 and 2 was dropped therein at 30 ° C. over 2 hours for reaction. After completion of the preparation of CDT, the mixture was further aged at 30 ° C. for 2 hours. After completion of the reaction, the reaction solution was subjected to high performance liquid chromatography (column: TSK gel-ODS-80T,
Eluent: acetonitrile / water = 80 / 20v, manufactured by Tosoh Corporation
ol%, detector: UV215 nm), and the results are summarized in Tables 1 and 2. Components that could not be identified were determined to be unknown. DBCD (dibromocyclododecadiene) and TBCD (tetrabromocyclododecaene) in the table
Is a reaction intermediate during the production of HBCD. Since TBCD has an isomer, it was analyzed by high performance liquid chromatography using an ODS reverse phase column, and named as α-TBCD and β-TBCD in the order of elution from the column.

HBCD yield and yield were calculated on the sum of the isomers of HBCD. The selectivity of γ-HBCD was represented by a value obtained by dividing the amount of γ-HBCD produced by the total amount of HBCD isomers (γ-HBCD).
CD / (α-HBCD + β-HBCD + γ-HBCD)).

At the end of the reaction, the reaction solution was filtered, the obtained crystals were dried and the melting point was measured. The results are shown in Tables 1 and 2.

Comparative Examples 1 to 3 A round bottom flask equipped with a reflux condenser and a stirring blade was charged with a reaction solvent having the composition shown in Table 3 and CDT. The reaction was carried out by dropping bromine in the amount shown in Table 3 at 30 ° C. over 2 hours. After completion of the bromine charging, the mixture was further aged at 30 ° C. for 2 hours. After completion of the reaction, post-treatment and analysis were carried out in the same manner as in the examples, and the results are summarized in Table 3.

Comparative Example 4 A reaction solvent having a composition shown in Table 3 was charged into a round bottom flask equipped with a reflux condenser and a stirring blade. The reaction was conducted by simultaneously dropping bromine and CDT in the amounts shown in Table 3 at 30 ° C. over 2 hours. After completion of the preparation of bromine and CDT, the mixture was further aged at 30 ° C. for 2 hours. After completion of the reaction, post-treatment and analysis were carried out in the same manner as in the examples, and the results are summarized in Table 3.

Claims (1)

(57) [Claims] (1) bromine and 1,5,9-cis, in the presence of an organic solvent;
In a method for producing 1,2,5,6,9,10-hexabromocyclododecane by reacting trans, trans-cyclododecatriene, bromine is converted into an alcohol having 1 to 4 carbon atoms or an organic solvent containing the same. 1,5,9 while dissolved
1,2,5,6,9,10- characterized by reacting cis, trans, trans-cyclododecatriene dropwise
A method for producing hexabromocyclododecane.