JPH03218330A - Production of hexabromocyclododecane - Google Patents

Abstract

PURPOSE:To obtain gamma-form of title substance in high yield by dropwisely adding 1,5,9-cis, trans, trans-cyclododecatriene to a lower alcohol or organic solvent containing the lower alcohol in which bromine is dissolved to react bromine with the above-mentioned cyclododecatriene. CONSTITUTION:1,5,9-cis, trans, trans-Cyclododecatriene(CDT) is dropwisely added to 1-4C alcohol (preferably ethanol, n-propanol or tert.-butanol) or organic solvent containing the same alcohol in which bromine is dissolved and reacted with bromine at-20-50 deg.C to provide gamma-form of title substance useful as flame- retardant for high polymer compound in high selectivity and yield. The objective compound having excellent hue and heat stability is obtained, because the production of impurities is reduced. Molar ratio of bromine/CDT is preferably 3.0-10.0 and CDT concentration to the organic solvent is preferably 0.1-40wt./vol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing 1,2,5,6.910-hexabromocyclododecane, which has excellent heat resistance. 1,2
,5,6,9.10-hexabromocyclododecane is
It is a compound useful as a flame retardant for polymeric compounds.

(Prior Art) 1,2,5,6,9.10-hexabromocyclododecane (hereinafter abbreviated as HBCD) is a commonly known flame retardant and is used in polystyrene resins and the like. This flame retardant is synthesized by a reaction in which bromine is added to 1,5.9-cis, trans, trans-cyclododecatriene (hereinafter abbreviated as CDT).

German Patent No. 1147574 describes that a 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 also been proposed using similar reaction methods. For example, in Japanese Patent Publication No. 49-24474, a mixed solvent system of alcohol and benzene is used, and in Japanese Patent Publication No. 49-24475, a mixed solvent system of alcohol and ester is used, USP383
No. 3675 proposes a mixed solvent system of t-butyl alcohol and benzene, Japanese Patent Publication No. 50-5187 proposes a mixed solvent system of alcohol and a halogenated hydrocarbon, and EP 181414 proposes a mixed solvent system of alcohol and dioxane.

In addition, Japanese Patent Publication No. Sho 53-12510 discloses a method in which a solvent is charged in a reactor and CDT and bromine are simultaneously added dropwise to react.

(Problem to be solved by the invention) HBCD produced by the bromine addition reaction of CDT includes:
It is known that there are three types of isomers with different physical properties (E.R. Larsenand and E.L.E.
Kerr, J. FireSc i. ,4,261
(1986)). That is, when analyzed using an ODS reverse phase column in high performance liquid chromatography, a-HBCD, 73-HBCD, and 7-H are eluted from the column in the order of
It has been stated that an isomer named BCD exists.

The present inventors isolated each isomer and measured their physical properties. According to the results, the respective melting points of α-, β-, and γ were 184-186°C, 168-1716°C, and 196-1716°C.
The temperature is 198°C. In addition, thermogravimetric analysis (in air, heating rate 1
0°C/min), the 5% heating weight loss temperature is 2
42°0.217°C and 245°C, the 50% weight loss temperature was 255°C, respectively. 232°C and 258°C. Therefore, the thermal stability is higher in the order of γ-HBCD, α-HBCD, and β-HBCD.

HBCD used as a flame retardant is mainly composed of gamma monomer, but due to the difference in the abundance ratio of these isomers, HBCD
The quality of the CD is greatly affected.

For example, if the abundance ratio of β-HBCD, which has a low melting point and low thermal stability, increases, the melting point of HBCD will decrease, and during polymer molding, thermal decomposition of HBCD will begin to occur at low temperatures, so the molding machine will There were problems such as corrosion and discoloration of the resin.

Furthermore, in the method described in German Patent No. 1,147,574, a resin-like substance insoluble in the solvent precipitates during the reaction, making stirring difficult and making scale-up difficult. Furthermore, HBC generated at this time
Since D had a low melting point, it had the disadvantage of poor heat resistance.

When the reaction is carried out using 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.

However, since the melting point of the produced HBCD is low, there still remains a problem in terms of heat resistance.

Furthermore, even in the method described in Japanese Patent Publication No. 53-12510, there remained a problem in terms of heat resistance because the melting point of the produced HBCD was low.

Furthermore, in the conventional reaction method described above, in the bromination reaction of CDT, in addition to the addition reaction of bromine to the double bond of CDT, bromination of the allylic position, dehydrobromination, or bromination of the solvent, etc. There were problems such as side reactions occurring, resulting in lower yields, and impurities being mixed into the HBCD crystals. These impurities also cause corrosion of molding machines and coloration of resin.

Therefore, a method for selectively producing γ-HBCD with high thermal stability has been desired.

(Means for Solving the Problems) In view of the above circumstances, the present inventors have developed a method for γ-H which has high thermal stability.
As a result of intensive studies on highly selective manufacturing methods for BCD,
In the presence of an organic solvent, in which bromine is dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing it, CDT is added.
The conventional method of reacting by dropping bromine into a solution of CDT in an organic solvent, or the method of reacting by adding bromine dropwise to a reaction vessel in advance, or Compared to a reaction method in which bromine and bromine are simultaneously added dropwise into the reactor, the selectivity of γ-HBCD is significantly improved, and furthermore, unidentified unknown substances that are thought to be produced by side reactions other than the bromine addition reaction are eliminated. The present invention was achieved based on the discovery that the

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

The present invention will be explained in detail below.

The solvent used in the method of the present invention is an alcohol having 1 to 4 carbon atoms or an organic solvent containing it. Carbon number 1
~4 alcohols include methanol, ethanol,
Examples include n-propanol, imbropanol, n-butanol, see-butanol, inbutanol, tert-butanol, ethylene glycol, diethylene glycol, propylene glycol, and the like. Among these solvents, ethanol, n-probanol, tert-butanol and the like are particularly preferred. Examples of solvents that can be mixed with alcohol include ether solvents, halogenated hydrocarbon solvents, and ester solvents. Specific examples of each solvent include dipropyl ether, diisopropyl ether, tetrahydrofuran (THF), dioxane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and halogen-based hydrocarbons. As a solvent, carbon tetrachloride, chloroform, methylene chloride, ethylene dichloride (EDC)
Examples of ester solvents include ethyl acetate, methyl acetate, and 2-methoxyethyl acetate. Mixed solvents include ethanol-ethyl acetate, ethanol-THF, ethanol-dioxane, and ethanol-EDC.
, ethanol-methylene chloride, etc. are particularly preferred from the viewpoint of reaction results.

There are no particular limitations on the reaction temperature when carrying out the method of the present invention, but if the reaction is carried out at a high temperature, substitution reactions other than bromine addition reaction will likely occur, resulting in an increase in impurities or a reaction between the reaction solvent and bromine. This is not very desirable as it can easily occur. Furthermore, when the reaction is carried out at an extremely low temperature, denaturation of the solvent can be suppressed, but the reaction rate is slow and the reaction is not completed and remains as a reaction intermediate, which is not preferable. The reaction temperature usually ranges from about -20°C to about 50°C.

8 The reaction time in carrying out the present invention may vary depending on the reaction temperature, amount of preparation, etc., but the dropwise addition time of CDT is usually about 10 minutes to 10 hours, and the reaction time is about 3 hours after the completion of dropping CDT. It can be achieved by letting it happen.

The amount of bromine used for CDT is B r 2 / C
DT (molar ratio) is 3.0 or more, preferably 3.0 to 10
．． It is 0. If it is less than 3.0, the reaction will not be completed due to the lack of bromine relative to CDT.

If it exceeds 10.0, side reactions due to excess bromine tend to occur, which is not preferable.

There is no particular limitation on the concentration of CDT in the reaction solvent, but
It is usually about 0.1 to 40 wt/vol%. When the substrate concentration is lower than 0.1wt/vol%, it is difficult to consider from an economical point of view, and 40wt/vol%
If v o is 1% or more, side reactions are likely to occur.

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

(Effects of the Invention) By carrying out the method of the present invention, it has become possible to produce γ-integrated HBCD with high selectivity and high yield. Furthermore, compared to the usual reaction method in which bromine is added, the production of impurities derived from CDT was significantly reduced. Therefore, it has become possible to selectively produce HBCD with excellent hue and thermal stability.

(Examples) The present invention will be explained in more detail below according to Examples, but the present invention is not limited thereto.

Examples 1 to 9 Table 1 was added to a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent having the composition shown in 2 and bromine were charged. The amount of CDT shown in Tables 1 and 2 was added dropwise into the mixture at 30° C. over 2 hours to cause a reaction. After the addition of CDT, the mixture was further aged at 30° C. for 2 hours. After the completion of the reaction, the reaction solution was analyzed by high performance liquid chromatography (column: TSK gel-ODS-80T, manufactured by Tosoh, eluent: acetonitrile/water-80/20 vol. 1%, detector: UV 215 nm), The results are summarized in Tables 1 and 2. For components that cannot be identified,
It was marked as unknown. DBCD (dibromosic dodecadiene) and TBCD (tetrabu-dodecadiene) in the table are reaction intermediates during the production of HBCD. Regarding TBCD, since isomers exist, it was analyzed using an ODS reverse phase column in high performance liquid chromatography, and α-TBCD, β-TBCD were eluted from the column in the order of
It was named D.

The yield and yield of HBCD were calculated by summing the isomers of HBCD. In addition, the selectivity of γ-HBCD is γ
The amount of HBCD produced was divided by the total amount of HBCD isomers (γ-HBCD11/(αHBCD+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 summarized in Tables 1 and 2.

Comparative Examples 1 to 3 Table 3 was added to a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent having the composition shown below and CDT were charged. The amount of bromine shown in Table 3 was added dropwise into the solution at 30° C. over 2 hours to cause a reaction. After the addition of bromine, the mixture was further aged at 30° C. for 2 hours. After the reaction was completed, post-treatment and analysis were performed in the same manner as in Examples, and the results are summarized in Table 3.

Comparative Example 4 Table 3 was added to a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent having the composition shown in was charged. Bromine and CDT in the amounts shown in Table 3 were simultaneously dropped into the solution at 30° C. over 2 hours to cause a reaction. After the addition of bromine 1 2 and CDT, the mixture was further aged at 30° C. for 2 hours. After the reaction was completed, post-treatment and analysis were performed in the same manner as in Examples, and the results are summarized in Table 3.

Claims (1)

[Claims] In the presence of an organic solvent, bromine and 1,5,9-cis, trans, trans-cyclododecatriene are reacted to form 1,2
, 5,6,9,10-hexabromocyclododecane, in which bromine is dissolved in an alcohol having 1 to 4 carbon atoms or an organic solvent containing it, 1,
1,2, characterized by reacting by dropping 5,9-cis, trans, trans-cyclododecatriene;
A method for producing 5,6,9,10-hexabromocyclododecane.