JPH047333B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula [] (In the formula [], x represents a number in the range of 1 to 2, y represents a number in the range of 1 to 6, and n represents a number in the range of 1 or more.) Regarding the method for synthesizing the brominated acenaphthylene condensate represented by the general formula [] (In the formula [], x, y and n are the above formula []
expresses the same meaning as The present invention relates to a method for producing a brominated acenaphthylene condensate by subjecting the brominated acenaphthene condensate shown in ) to a dehydrobromination reaction. The brominated acenaphthylene condensate (hereinafter abbreviated as Con-BACN) obtained by the method of the present invention is a compound with excellent flame retardancy and radiation resistance. It has the property of being sexual. In addition, since it has a double bond in its molecule, it can be grafted onto resins by subjecting it to free radical generation treatment, and since it is a condensate, it has excellent compatibility with resins, so it can last for a long time. It is attracting attention as a compound that can maintain stable flame retardancy and radiation resistance. (Unexamined Japanese Patent Publication 1983-
(No. 122862) In particular, Con-BACN is used as a coating insulation material for electric wires and cables used in nuclear reactors, breeder reactors, ionizing radiation generators, etc. that are required to have both flame retardancy and radiation resistance, and various resin compositions. It is expected to be used for things. An object of the present invention is to provide a method for industrially producing Con-BACN having excellent radiation resistance and flame retardancy. Con-BACN in the present invention is a compound containing at least one bromine in the naphthalene nucleus, and brominated acenaphthene is formally condensed by Friedel-Crafts reaction to form a multimer with a degree of condensation of 2 or more. , followed by a dehydrobromation reaction to form a condensate of brominated acenaphthylene. That is, it is a compound represented by the general formula [], more specifically, the general formula [] or [] (In the formula, y represents a number from 1 to 6) It is a condensate whose constituent elements are units, and its bonding mode is an intermolecular bond between the benzylic carbon of acenaphthylene and the aryl carbon of acenaphthylene. . The connection points are, for example, 1 (or 2), 5'- or 1 (or 2), 6'- etc., but there are also 1 (or 2),
3'-, 1 (or 2), 4'-, 1 (or 2),
Possible combinations include 7'-, 1 (or 2), and 8'-. Those with a degree of condensation of 3 or more have the number of constituent units increased by any of these bonds. In the present invention, those having a degree of condensation of 10 or less, which have excellent compatibility with the resin, are preferred from a practical standpoint. Con-BACN is generally produced by bromination, condensation and dehydrobromination reactions of acenaphthenes. For example, by adding bromine to acenaphthene in a halogenated hydrocarbon solvent, the benzyl side chain is brominated, condensed, and the naphthalene nucleus is brominated to produce a brominated acenaphthene condensate represented by the general formula [ ]. do. Subsequently, this compound is subjected to a dehydrobromination reaction with a base to produce Con-BACN. The method for dehydrobrominating the brominated acenaphthene condensate includes a method in which a solution of caustic curry ethanol is added dropwise in an aromatic hydrocarbon solvent such as benzene (Japanese Unexamined Patent Publication No. 56-122862), and a method according to the present invention. There is a known method (Japanese Patent Application No. 169,835/1983), which was previously filed by the authors of the present invention, in which a solution of caustic potash-methanol is dropped into a halogenated hydrocarbon such as carbon tetrachloride. In these methods, caustic potash is dissolved in a lower alcohol to perform a dehydrobromation reaction, but a nucleophilic substitution reaction of alkoxy groups occurs competitively with the elimination reaction.
Some by-products of ether compounds are observed. If these are mixed into the product Con-BACN, Con
-The method that the present inventors have already applied for (Japanese Patent Application No. 1983-1999)
193145) was required. Furthermore, when caustic soda, which is cheaper than caustic potash, is used, it has disadvantages such as requiring a large amount of alcohol because of its low solubility in alcohol, and slow reaction because the base concentration cannot be increased. Furthermore, in the method in which the dehydrobromination reaction is carried out in an aromatic hydrocarbon, the method of carrying out the bromination and condensation reactions in the previous step in a halogenated hydrocarbon solvent is a required technique. A step of substituting the solvent from halogenated hydrocarbon to aromatic hydrocarbon is required. Therefore, this method inevitably requires a complicated manufacturing process. Therefore, a method in which bromination, condensation, and dehydrobromination reactions are carried out in the same solvent is an advantageous method in terms of the production process. However, when the dehydrobromation reaction was carried out in halogenated hydrocarbons, it became clear that some solvent decomposition occurred. For example, in the case of carbon tetrachloride, the decomposition shown below is observed. CCl ₄ +6KOH→K ₂ CO ₃ +3H ₂ OO + 4KCl In addition, since the alcoholic solution of caustic potash is dropped into the solution of the brominated acenaphthene condensate, it is necessary to dissolve the solid caustic potash in the alcohol, especially in this reaction. In a batch reaction, the work is complicated and solid caustic is handled, which poses problems in terms of labor safety. Furthermore, this reaction progresses with the solution of the brominated acenaphthene condensate and the alcoholic solution of potassium hydroxide forming two phases, but as the reaction progresses, a large amount of potassium bromide salt precipitates, causing damage to the reactor walls and stirring blades. This makes treatment operations after the reaction is complicated. As described above, the known dehydrogenation methods are not completely satisfactory in terms of product quality, economy, and operability as an industrial-scale manufacturing technology. In view of these circumstances, the present inventors conducted extensive studies on the dehydrobromation reaction method, and as a result,
When dehydrobromating a brominated acenaphthene condensate dissolved in a halogenated hydrocarbon solvent with an alkali metal hydroxide, a hydrous alcohol with a water/alcohol weight ratio of 0.1 to 0.5 may be used as a solvent for the alkali metal hydroxide. Specifically, the inventors have discovered that the drawbacks of the above-mentioned known techniques can be significantly overcome, and have completed the present invention. That is, according to the method of the present invention, since the alkali metal hydroxide concentration can be increased, the dehydrobromation reaction can be carried out without reducing the reaction rate due to water addition. Next, when this hydroalcoholic solvent is used, the above-mentioned side reactions are significantly suppressed. In other words, since no nucleophilic substitution reaction by alkoxy groups is observed, the resulting Con−BACN
The quality is excellent. Furthermore, decomposition of the halogenated hydrocarbon solvent is extremely suppressed, which is economically advantageous. In addition, in the method of the present invention, it is possible to prepare an alkaline solution by simply adding an aqueous solution of the alkali metal hydroxide to the alcohol and mixing it, thus eliminating the need for the dissolution operation that is required in the case of solid caustic. , workability is greatly improved. Furthermore, when a hydrous alcohol is used, the alkali metal salt produced as a by-product is dissolved as the reaction progresses, and its precipitation is suppressed, thereby facilitating post-treatment operations after the reaction is completed. As described above, the present invention provides, as part of the process, a method for economically producing Con-BACN from a brominated acenaphthene condensate using simple operations. The present invention will be explained in detail below. The halogenated hydrocarbon used in the present invention is a solvent inert to the bromination/condensation and dehydrobromation reactions of acenaphthene, such as carbon tetrachloride, chloroform, methylene chloride, ethylene dichloride,
Ethylene dibromide, trichloroethane, etc. can be mentioned, but carbon tetrachloride is preferably selected. Although there is no particular limitation on the amount of solvent used, it is desirable that the brominated acenaphthene condensate be completely dissolved in the solvent, so
-BACN concentration is usually about 10 to 70% by weight. Next, as the alkali metal hydroxide used in the method of the present invention, hydroxides such as lithium, sodium, potassium, and cesium are used, but in consideration of economic efficiency, sodium hydroxide and potassium hydroxide are generally used. To be elected. The amount of these alkali metal hydroxides to be used is selected to be 0.8 mol or more, more preferably about 1 to 3 mol, per 1 mol of the structural unit of the brominated acenaphthene condensate as the raw material. In the method of the present invention, a hydrous alcohol is used as a solvent for the alkali metal hydroxide, and therefore, an alcohol having a carbon number of 4 or less and having a high solubility in water is used as the alcohol. For example, methanol, ethanol, n-propanol, i-propanol, n-butanol, sec-butanol, tert-
Examples include butanol, ethylene glycol, propylene glycol, etc. In particular, methanol and ethanol are preferable because the reaction is fast and post-treatment after the reaction is easy. The amount of these lower alcohols to be used is selected to be at least the amount that dissolves the alkali metal hydroxide when water is added. The amount is preferably such that the concentration is high. The amount of water added to the alcohol is selected such that the water/alcohol weight ratio is 0.1 to 0.5. More preferably, the amount is in the range of 0.2 to 0.4.
When the water/alcohol weight ratio is 0.1 or less, the aforementioned side reactions, ie, nucleophilic substitution reactions with alkoxy groups and decomposition of the halogenated hydrocarbon solvent, are often observed during the dehydrobromation reaction. On the other hand, if it is 0.5 or more,
The reaction becomes extremely slow and does not go to completion. At the amount of water added according to the present invention, the reaction proceeds sufficiently quickly to completion, and the yield is quantitative. Furthermore, the aforementioned side reactions are also greatly suppressed. Since the reaction is generally carried out under normal pressure, the reaction temperature is below the boiling point of the solvent, and is usually about 30 to 100°C. Generally, it is preferable to carry out the reaction at a higher temperature because the reaction proceeds quickly and quantitatively. Reaction time may vary depending on reaction temperature, etc., but usually
It takes about 10 minutes to about 8 hours. After the reaction is completed, the generated Con-BACN can be isolated as a powder by known means. for example,
Con-BACN can be obtained as a powder by washing the reaction mixture with water and adding the organic layer to a poor solvent such as acetone to reprecipitate and separate Con-BACN. As described above, according to the present invention, high-quality Con
-BACN can be produced economically. Therefore, it is an industrially advantageous method that simplifies the conventional process.
A method for producing Con-BACN has become possible. Next, the method of the present invention will be explained in more detail with reference to Examples, but the method is not limited thereto. Example 1 308 g of acenaphthene and 6.6 g of 2.2'-azobisisobutyronitrile were added to 950 ml of carbon tetrachloride at 77°C.
The mixture was heated to reflux. A solution prepared by dissolving 320 g of bromine in 470 ml of carbon tetrachloride was added dropwise to this solution over 1.5 hours with stirring, and the mixture was reacted for an additional 0.5 hour. After the reaction,
The reaction solution was cooled, 38 g of titanium tetrachloride was added to the reaction solution at 25° C., and the reaction was continued for 1 hour. Subsequently, 1120 g of bromine was added dropwise at 25°C for 4 hours, and then
The temperature was raised to 75°C, and the mixture was heated to reflux and reacted for 3 hours. After the reaction, an aqueous sodium hydrogen sulfite solution was added to the reaction solution to remove unreacted bromine, and the reaction solution was washed with water to obtain a mixture containing 840 g of brominated acenaphthene condensate (equivalent to 2.0 mol per raw acenaphthene monomer unit). , 1500 ml of carbon tetrachloride solution was obtained. This brominated acenaphthene condensate was a compound with a bromine content of 64.3%. From this carbon tetrachloride solution, 300 ml of a solution containing 168 g of brominated acenaphthene condensate was used in the next dehydrobromation reaction. Under a nitrogen stream, add 31.4 g of caustic potassium to the above reaction solution,
A solution containing 80 g of methanol and 32 g of water was added dropwise, and the reaction was carried out under reflux at 58°C. The time course of the reaction was tracked by H ¹ -NMR spectrum measurement, and the conversion rate from general formula [] to general formula [] was determined. Figure 1 shows H ¹ -NMR charts before and after the reaction. In both spectra, a peak of ¹ H bonded to the naphthalene ring is observed at δ _H =7.0 to 7.9PPm. For the intermediate (spectrum (a)), δ _H =5.65~
A peak due to ¹ H at the benzyl position of 5.9PPm was observed, and the final product (spectrum (b) shows double bond formation due to dehydrobromation reaction, and this peak is due to δ _H
= 6.7 to 7.0PPm, and the strength also decreases. After the reaction was completed, no peak indicating methyl ether by-product was observed. After the reaction was completed, water was added to the reaction solution under a nitrogen atmosphere to wash the organic phase three times with water. The amount of carbonate ions in the aqueous phase was determined by the Orsatto analysis method, and the decomposition rate of carbon tetrachloride was determined. Table 1 shows these reaction conditions and analysis results. The obtained organic phase was added to i-octane 1.2 with stirring to reprecipitate Con-BACN, and the precipitated powder was separated and dried to obtain a reddish brown powder with a bromine content of 56.1% and a melting point of 125-147°C. Con-BACN110g
I got it. High performance liquid chromatography (GPC)
Analysis of the degree of condensation shows that monomer is 22% and dimer is 25%.
%, and 53% was 3-8mer. In addition, the liquid contains 26
g of Con-BACN is included, and after the completion of the reaction,
The yield of Con-BACN is almost quantitative. Example 2 A solution containing 31.4 g of caustic potassium, 105 g of methanol, and 21 g of water was added dropwise to 300 ml of a carbon tetrachloride solution containing 168 g of the brominated acenaphthene condensate produced in Example 1, and the reaction was carried out under reflux at 58°C. Ta. The results obtained are shown in Table 1. Example 3 A mixed solution of 56 g of 40% caustic soda aqueous solution (containing 22.4 g of caustic soda) and 80 g of methanol was added dropwise to 300 ml of carbon tetrachloride solution containing 168 g of the brominated acenaphthene condensate produced in Example 1, and the mixture was refluxed at 58°C. The reaction was carried out below. The results obtained are shown in Table 1. Comparative Example 1 31.4 g of solid caustic potassium dissolved in 120 g of methanol was added dropwise to 300 ml of carbon tetrachloride solution containing 168 g of the brominated acenaphthene condensate produced in Example 1, and the reaction was carried out under reflux at 58°C. After the reaction
According to H ¹ -NMR analysis, a peak derived from the methyl ether bond was observed at δ _H =4.0 to 4.3PPm. The results obtained are shown in Table 1. Comparative Example 2 Caustic potassium was added to 300 ml of carbon tetrachloride solution containing 168 g of the brominated acenaphthene condensate produced in Example 1.
A solution containing 31.4 g of methanol, 75 g of methanol, and 45 g of water was added dropwise, and the reaction was carried out under reflux at 58°C. The results obtained are shown in Table 1.

[Table] ○, those that are not approved are indicated by ×.

[Brief explanation of drawings]

Figure 1 shows the intermediate brominated acenaphthene condensate (a) and the final product Con-BACN (b).
FIG. 1 is a diagram showing a ¹ H-NMR spectrum.

Claims (1)

[Claims] 1 General formula dissolved in a halogenated hydrocarbon solvent [] (In formula [], x represents a number in the range of 1 to 2, y represents 1 to 6, and n represents a number in the range of 1 or more.) An alkali metal hydroxide prepared by dissolving a brominated acenaphthene condensate represented by The dehydrogenation reaction is carried out by the general formula [] (In the formula [], x, y and n are the above formula []
expresses the same meaning as ) When producing a brominated acenaphthylene condensate represented by Method for synthesizing acenaphthylene condensate.