JPH04338344A - Production of hexabromocyclododecane - Google Patents

Abstract

PURPOSE:To provide selectively gamma-1,2,5,6,9,10-hexabromocyclododecane excellent in heat resistance. CONSTITUTION:The objective 1,2,5,6,9,10-hexabromocyclododecane can be obtained by adding 3-30wt./vol.%, based on the alcohol in the reaction solvent, of a hydrohalogenic acid to said solvent followed by reaction of bromine with 1,5,9-cis, trans, trans-cyclododecatriene.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to 1, 2 with excellent heat resistance.
, 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 polymeric compounds.

0002

2. Description of the Related Art 1,2,5,6,9,10-hexabromocyclododecane (hereinafter abbreviated as HBCD) is a flame retardant used in polystyrene resins and the like. This flame retardant contains bromine in 1,5,9-cis, trans, trans-
It is synthesized by an addition reaction to cyclododecatriene (hereinafter abbreviated as CDT).

[0003] When analyzed using high performance liquid chromatography equipped with an ODS reverse phase column, it is known that HBCD exists in three types of isomers. They are α-HBCD, β-HBCD,
It has been named γ-HBCD [E. R. Larsen
and E. L. Ecker, J. Fire
Sci. , 4, 261 (1986)].

[0004] The present inventors isolated each isomer and measured their physical properties. According to the results, the melting points of α-, β-, and γ-isomers are 184-186°C, 168-171°C, and 196-196°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
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-
The quality of HBCD is largely influenced by 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 and heat resistance of HBCD decrease. Therefore, thermal decomposition of HBCD begins to occur at a relatively low temperature, resulting in problems such as corrosion of the molding machine and coloring of the resin.

By the reaction of adding bromine to CDT, H
BCD has been synthesized, and various reaction methods such as those described below have been disclosed to date.

German Patent No. 1147574 describes that a bromine addition reaction is carried out by dropping bromine into an ethyl alcohol solution of CDT. However, in this method, insoluble resinous substances precipitate during the reaction, making stirring difficult and making scale-up difficult. Furthermore, the HBCD produced at this time has a low melting point and poor heat resistance.

[0007]

Problems to be Solved by the Invention In order to overcome the drawback that insoluble resinous substances precipitate during the reaction, several mixed solvent systems have been disclosed for similar reaction methods. For example, in Japanese Patent Publication No. 49-24474, a mixed solvent system of alcohol and benzene, in Japanese Patent Publication No. 49-24475, a mixed solvent system of alcohol and ester, and in US Pat. No. 3,833,675, a mixed solvent system of t-butyl alcohol and benzene; No. 5187 uses a mixed solvent system of alcohol and a halogenated hydrocarbon, and EP 181414 uses a mixed solvent system of alcohol and dioxane. When the reaction is carried out in these solvents, the solubility of the reaction solvent is high, so there is no precipitation of resinous substances during the reaction. However, problems remained due to the low melting point and low heat resistance of the HBCD produced.

Furthermore, Japanese Patent Publication No. 53-12510 discloses a method in which a solvent is charged in a reactor and CDT and bromine are simultaneously added dropwise to react. However, the H
Problems remained that the heat resistance and melting point of BCD were low.

In the above reaction method, γ-H, which has high heat resistance,
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 tend to occur, resulting in lower yields and the presence of impurities. There were problems such as mixing into the HBCD crystal. These impurities also cause corrosion of the molding machine,
It is known to cause discoloration of resin.

[0010] Therefore, a highly selective production method of γ-HBCD with high thermal stability was required.

[0011].

[Means for Solving the Problems] In view of the above circumstances, the present inventors have conducted intensive studies on a highly selective production method of γ-HBCD with high thermal stability, and have developed an alcohol having 1 to 4 carbon atoms or an alcohol containing γ-HBCD. bromine and CDT in an organic solvent containing
In the method for producing HBCD by reacting, 3 to 30w of hydrohalic acid is added to the alcohol in the reaction solvent.
When t/vol% is added and reacted, the selectivity of γ-HBCD is significantly improved compared to when it is not added, side reactions with the reaction solvent can be suppressed, and the amount of impurities produced is significantly reduced. This discovery led to the present invention.

That is, the present invention deals with the treatment of bromine with CDT in an alcohol having 1 to 4 carbon atoms or an organic solvent containing it.
In a method for producing HBCD by reacting with bromine,
Before starting the reaction between CDT and bromine, add 3 to 30 wt/vol of hydrohalic acid to the alcohol in the reaction solvent.
% of HBCD.

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. Alcohols having 1 to 4 carbon atoms include methanol,
Ethanol, n-propanol, isopropanol, n
-butanol, sec-butanol, isobutanol,
Examples include 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 organic solvents that can be mixed with alcohol include ether solvents,
Examples include halogen-based hydrocarbon solvents and ester-based solvents. The mixing ratio of each solvent to be mixed with alcohol is not particularly defined. 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., but examples of ester solvents include ethyl acetate, methyl acetate, 2-
Examples include methoxyethyl acetate. Mixed solvents include ethanol-ethyl acetate, ethanol-THF,
Ethanol-dioxane, ethanol-EDC, ethanol-methylene chloride, etc. are particularly preferred from the viewpoint of reaction results.

[0015] The method of dissolving the hydrohalic acid in the reaction solvent is not particularly limited. Examples include a method in which hydrohalic acid gas is directly blown into the reaction solvent, a method in which a reaction solvent containing hydrohalic acid is used, and a method in which a substance that reacts with bromine to generate hydrobromic acid is used. There are methods such as adding it to the system.

Regarding the timing of addition of hydrohalic acid,
When reacting by dropping CDT into bromine dissolved in a reaction solvent, add CDT to the reaction solvent before dissolving bromine in the reaction solvent to suppress side reactions between the reaction solvent and bromine.
When reacting by dropping bromine into a solution of bromine, add hydrohalic acid before dropping bromine, and when reacting by dropping bromine and CDT at the same time, add hydrohalic acid before dropping bromine and CDT. Just do it.

The amount of hydrohalic acid added is preferably 3 to 30 wt/vol% (hydrohalic acid/alcohol) relative to the alcohol in the reaction solvent, preferably 5 to 20 wt/v.
ol% is selected. If the addition amount is less than 3wt/vol%, the effect of adding hydrohalic acid is small, and the addition amount is less than 3wt/vol%.
Even if more than /vol% is added, the addition effect does not improve any further,
It is also unfavorable from an economic point of view.

The type of hydrohalic acid used in this reaction is hydrofluoric acid, hydrochloric acid, hydrogen bromide, hydroiodic acid, etc., or a mixture thereof, and preferably hydrochloric acid and hydrobromic acid. be.

The reaction method for carrying out the present invention is a method in which bromine is added dropwise to a solution of CDT in a reaction solvent, or a method in which CDT is added dropwise to a solution of bromine in a reaction solvent. , a method of simultaneously dropping CDT and bromine into the reaction solvent to cause the reaction is possible, and any method may be used, but a method of simultaneously dropping CDT and bromine into the reaction solvent to cause the reaction is a highly heat-resistant γ- HBCD
This is preferable because the selectivity of

CD for carrying out the method of the present invention
The substrate concentration of T (CDT/reaction solvent = wt/vol%) can be determined by adding bromine dropwise into a solution of CDT in a solvent, or dropping CDT into a solution of bromine in a solvent. In the case of the method, as disclosed in Japanese Patent Application No. 2-288453, 0.1 to 20 w of organic solvent is used.
t/vol%, preferably 0.5-10wt/vol%
is selected. Even if the reaction is carried out at a concentration lower than 0.1%,
Compared to the selectivity of γ-HBCD at 0.1 wt/vol%, the selectivity of γ-HBCD is not improved as expected and is not useful from an economic standpoint. Also 20wt
If the reaction is carried out in excess of /vol%, the selectivity of γ-HBCD will decrease significantly, so it is not selected. Furthermore, in the case of a method in which CDT and bromine are simultaneously added dropwise into the reaction solvent, the amount is selected to be 0.1 to 50 wt/vol%, preferably 0.5 to 40 wt/vol%, based on the organic solvent. Even if the reaction is carried out at a concentration lower than 0.1%, it is not useful from an economical point of view, and when it exceeds 40%, the slurry concentration becomes too high, which is not preferable.

[0021] There is no particular limitation on the reaction temperature when carrying out the method of the present invention, but if the reaction is carried out at a high temperature,
This is not very preferable because substitution reactions other than bromine addition reactions tend to occur, resulting in an increase in impurities, and reactions between the reaction solvent and bromine tend to 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 is usually about -20℃~
The temperature range is approximately 50°C.

[0022] The reaction time in carrying out the present invention may vary depending on the reaction method, reaction temperature, amount charged, etc.
In the case of a method of reacting by dropping bromine into CDT dissolved in a solvent, the dropping time of bromine is usually about 10 minutes to 10 minutes.
Approximately 0 to 3 hours, and approximately 0 to 3 hours after CDT has finished dropping.
This can be accomplished by reacting for about an hour. In the case of a method of reacting by dropping CDT into a solution of bromine in a solvent, the dropping time of CDT is usually about 10 minutes to 10 hours, and the reaction is continued for about 0 to 3 hours after the dropping of CDT is finished. It can be achieved by doing this. CDT in reaction solvent
In the case of the method of dropping bromine and bromine at the same time, bromine and CD
The time for dropping T is usually about 10 minutes to 20 hours, and the reaction can be completed for about 0 to 3 hours after the dropping of CDT is completed.

The amount of bromine used for CDT is Br2/
CDT (molar ratio) of 3.0 or more, preferably 3.0 to 5
．． 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 5.0, side reactions due to excess bromine are likely to occur and it is also unfavorable from an economic standpoint.

[0024] After the completion of the reaction, the HBCD produced can be isolated as a powder by known means. For example, there may be a method in which the precipitated crystals are directly filtered, a method in which the reaction solution at the end of the reaction is poured into a poor solvent to pick up the crystals, a method in which a poor solvent is introduced into the reaction solution at the end of the reaction, and the like. Furthermore, the solvent recovered as a filtrate can be repeatedly used as a reaction solvent by replenishing it with new solvent.

[0025]

Effect of the invention: By carrying out the method of the present invention, H
It has become possible to produce the γ-form of BCD with high selectivity and high yield. In addition, it has become possible to manufacture HBCD with excellent hue and thermal stability.

[0026]

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 4 A round-bottomed flask equipped with a reflux condenser and a stirring blade was filled with
The reaction solvent and HBr were charged so as to have the composition shown below. CDT and bromine in the amounts shown in Table 1 were added dropwise thereto at 15° C. over 2 hours to cause a reaction. After the addition was completed, the mixture was further aged for 2 hours. After the reaction, the reaction slurry was subjected to high performance liquid chromatography (column TSK gel-ODS).
80TM, eluent acetonitrile/water = 80/20
vol%, detector UV 215 nm) and the results are summarized in Table 1. In addition, components that could not be identified were classified as unknown. DBCD (dibromocyclododecadiene) and TBCD (tetrabromocyclododecene) in Table 1 are reaction intermediates of HBCD. Furthermore, TBCD
Since there are isomers, they were analyzed by high-performance liquid chromatography using an ODS reverse phase column and named α-TBCD and β-TBCD in the order of elution from the column.

The selectivity of γ-HBCD was expressed as the amount of γ-HBCD produced divided by the total amount of HBCD isomers [
γ-HBCD/(α-TBCD+β-TBCD+γ-H
BCD)].

[0029] 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 Table 1.

Examples 5 to 8 Table 1 was added to a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent, HBr, and bromine were charged so as to have the composition shown below. The amount of CDT shown in Table 1 was added dropwise into the solution at 15° C. over 2 hours to cause a reaction. After the addition was completed, the mixture was further aged for 2 hours. After the reaction was completed, post-treatment and analysis were performed in the same manner as in the examples, and the results are summarized in Table 1.

Example 9 In a round bottom flask equipped with a reflux condenser and a stirring blade,
A reaction solvent, HBr, and CDT were charged so as to have the composition shown below. Bromine in the amount shown in Table 1 was added dropwise thereto at 15° C. over 2 hours to cause a reaction. After the addition was completed, the mixture was further aged for 2 hours. After the reaction was completed, post-treatment and analysis were performed in the same manner as in the examples, and the results are summarized in Table 1.

[0032]

[Table 1] Comparative Example 1 Table 2 was placed in a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent having the composition shown in was charged. CDT and bromine in the amounts shown in Table 2 were added dropwise thereto at 15° C. over 2 hours to cause a reaction. After the addition was completed, the mixture was further aged for 2 hours. After the reaction was completed, post-treatment and analysis were carried out in the same manner as in the examples, and the results are summarized in Table 2.

Comparative Examples 2 and 3 Table 2 was placed in a round bottom flask equipped with a reflux condenser and a stirring blade.
A reaction solvent with the composition shown below and bromine were charged. Table 2 in it
The reaction was carried out by adding dropwise the amount of CDT shown in the figure over a period of 2 hours at 15°C. After the addition was completed, the mixture was further aged for 2 hours. After the reaction was completed, post-treatment and analysis were carried out in the same manner as in the examples, and the results are summarized in Table 2.

Comparative Example 4 Table 2 was placed in 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. Bromine in the amount shown in Table 2 was added dropwise thereto at 15° C. over 2 hours to cause a reaction. After the addition was completed, the mixture was further aged for 2 hours. After the reaction was completed, post-treatment and analysis were carried out in the same manner as in the examples, and the results are summarized in Table 2.

[0035]

[Table 2]

Claims (1)

[Claims] Claim 1: Reacting bromine with 1,5,9-cis,trans,trans-cyclododecatriene in an alcohol having 1 to 4 carbon atoms or an organic solvent containing it,
A method for producing 2,5,6,9,10-hexabromocyclododecane, characterized in that 3 to 30 wt/vol% of hydrohalic acid is added to the alcohol in the reaction solvent. , 5,6,9,10-hexabromocyclododecane manufacturing method.