JPH0517458A - Aromatic compound and method for producing the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a novel aromatic compound having an oxazole ring and a carbonyl group in one molecule, which is preferably used as a raw material for producing a polymer having excellent heat resistance. [Structure] Expression An aromatic compound represented by: (wherein X represents a fluorine atom or a chlorine atom).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic compound having an oxazole ring and a carbonyl group in one molecule, which is preferably used as a raw material for producing a polymer having excellent heat resistance and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with advances in technology, polymers having excellent heat resistance have been required. As a method of improving the heat resistance of a polymer, a method of introducing an oxazole ring into a polymer chain of a polyether or the like using a compound represented by the following formula as a monomer raw material is known.
A monomer compound capable of introducing an oxazole ring and a carbonyl group into a polymer chain has not been known.

[0003]

[Chemical 2]

[0004]

DISCLOSURE OF THE INVENTION The present invention is a novel compound having an oxazole ring and a carbonyl group in one molecule, which is suitably used as a raw material for producing a polymer having excellent heat resistance and has high activity in the synthetic reaction of the polymer. The object is to provide a novel aromatic compound.

[0005]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that a novel aromatic compound having an oxazole ring and a carbonyl group in one molecule has excellent heat resistance. It has been found that it is suitable as a raw material for polymers, and particularly has high activity in the synthesis reaction of polyether, and based on this finding, the present invention has been completed.

That is, the present invention has the formula

[Chemical 3] And a novel aromatic compound represented by the formula (wherein X represents a fluorine atom or a chlorine atom).

Specific examples of the novel aromatic compound of the present invention include 2- (4-fluorophenyl) -5- (4-fluorobenzoyl) benzoxazole and 2- (4-chlorophenyl) -5- (4- Chlorobenzoyl) benzoxazole may be mentioned.

The novel aromatic compounds of the present invention include, for example, 2
It can be produced by reacting-(4-halophenyl) -5-carboxylbenzoxazole and halobenzene by Friedel-Crafts reaction. 2- (4-halophenyl) -5-carboxylbenzoxazole is obtained by performing an amidation reaction between 3-amino-4-hydroxybenzoic acid and 4-halobenzoyl chloride, as represented by the following formula. It is obtained by subjecting the above amidated product to a dehydration cyclization reaction in a solvent such as 1-cyclohexyl-2-pyrrolidone.

[0009]

[Chemical 4] (In the formula, X represents a fluorine atom or a chlorine atom)

The amidation reaction is carried out by reacting 3-amino-4-hydroxybenzoic acid with 4-halobenzoyl chloride in the presence of an acid acceptor of hydrochloric acid generated during the reaction. As the acid acceptor of hydrochloric acid, pyridine, triethylamine and the like are usually used. Used 4
-The amount of halobenzoyl chloride is usually 3-amino-
For 4-hydroxybenzoic acid, preferably 1.0 to
The molar ratio is 1.5 times, and more preferably 1.05 to 1.15 times.

The amidation reaction is usually carried out using an amide solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide.

The reaction temperature is usually 0 to 80 ° C., preferably 0.
It is carried out at -30 ° C. There are no particular restrictions on the reaction pressure, and the reaction pressure is usually around normal pressure. Reaction time is usually 1 to 10
It's time. The reaction is preferably carried out in an atmosphere of an inert gas such as argon.

After completion of the amidation reaction, the reaction solution is poured into water to precipitate a product, which is washed with water and dried to obtain an amide compound. The obtained amide compound can be used for the next dehydration cyclization reaction without further purification.

The dehydration cyclization reaction of the obtained amide compound is
The amide compound is heated in a solvent and the produced water is removed by azeotropic distillation or the like. Toluene or the like is preferably used as an azeotropic solvent used for azeotropic removal of water, and the reaction is preferably carried out in an atmosphere of an inert gas such as argon. The dehydration cyclization reaction is usually performed using a high boiling amide solvent such as 1-cyclohexylpyrrolidone.

The reaction temperature is usually 240 to 300 ° C, preferably 250 to 270 ° C. There are no particular restrictions on the reaction pressure, and the reaction pressure is usually around normal pressure. The reaction time is usually 20 to 30 hours.

After completion of the reaction, the reaction solution is poured into methanol or the like to precipitate a product, which is washed with methanol or the like and dried to obtain 2- (4-halophenyl) -5-carboxyloxazole. The obtained 2- (4-halophenyl) -5-carboxyloxazole can be used in the next reaction without further purification.

The desired novel aromatic compound is 2- (4-halophenyl) -5 obtained by the above dehydration cyclization reaction.
-Carboxyloxazole is obtained by converting it to an acid chloride with a reagent such as thionyl chloride as shown in the following formula, and then performing Friedel-Crafts reaction with halobenzene in the presence of a Lewis acid.

[0018]

[Chemical 5]

In the Friedel-Crafts reaction, 1.01 to 5 mol of halobenzene is usually added to 1 mol of acid chloride.
It is carried out using 1.01 to 10 mol of Lewis acid catalyst. Chlorobenzene and fluorobenzene are used as the halobenzene. As the Lewis acid catalyst, aluminum trichloride, boron trifluoride, tin tetrachloride and the like are preferably used.

The above reaction is usually carried out in the presence of a solvent. The solvent is not particularly limited, but methylene chloride, carbon disulfide, nitrobenzene, tetrachloroethane and the like are preferably used, and methylene chloride is particularly preferably used.

The reaction temperature is usually -20 to 80 ° C, preferably 0 to 50 ° C. There are no particular restrictions on the reaction pressure, and the reaction pressure is usually around normal pressure. The reaction time is usually 1 to
10 hours. The reaction is preferably carried out under an atmosphere of an inert gas such as argon.

After completion of the reaction, the reaction product is washed with water and an aqueous alkali solution, and then recrystallized from a toluene-ethanol mixed solvent or the like to obtain the desired novel aromatic compound.

The novel aromatic compounds obtained by the present invention are dihydric phenols such as hydroquinone, resorcin, biphenol, phenolphthalein, dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane and 2,2-. It reacts with bis (4-hydroxyphenyl) butane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, etc. with high activity to form an oxazole ring and a carbonyl group. It is possible to provide an aromatic polyether having excellent heat resistance. In this case, the polymerization reaction may be carried out using a neutral polar solvent in the presence of potassium carbonate, sodium carbonate or the like.

[0024]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto. Example 1 1 equipped with an argon gas introduction tube, a stirrer, and a dropping funnel
Into a liter four-necked flask, 101.4 g (0.662 mol) of 3-amino-4-hydroxybenzoic acid, 55.8 g (0.705 mol) of pyridine, and 350 ml of N, N-dimethylacetamide were placed.

While flowing argon gas, under water cooling, 4-
Fluorobenzoyl chloride 115.4 g (0.72
(8 mol) and then stirred at room temperature for 7 hours. After completion of the reaction, the reaction solution is poured into 5 liters of water and the precipitate is collected. The precipitate was washed with 2 liters of water 5 times and then dried, and the obtained solid was 1-cyclohexyl-2-pyrrolidone 40.
The mixture is heated and stirred in 0 ml at 260 ° C. for 24 hours to perform dehydration ring closure. Water generated by the dehydration ring closure reaction was removed by azeotropic distillation with toluene. Then, the reaction solution was poured into methanol, and the obtained solid was washed with methanol three times to obtain 2
120.0 g of-(4-fluorophenyl) 5-carboxylbenzoxazole are obtained.

Next, 120.0 g (0.504) of the obtained 2- (4-fluorophenyl) -5-carboxylbenzoxazole was placed in a 1-liter four-necked flask equipped with an argon gas introduction tube, a stirrer and a Dimroth. Mol) and 300 ml of thionyl chloride, 1 drop of N, N-dimethylformamide as a catalyst is added, and the mixture is refluxed for 4 hours. The remaining thionyl chloride is removed under reduced pressure, and the obtained acid chloride is dissolved in 450 ml of methylene chloride. 162.0 g of anhydrous aluminum chloride in the obtained acid chloride solution
(1.21 mol) was added, and fluorobenzene was 50.0 m.
1 (0.534 mol) is added dropwise, and the mixture is stirred at room temperature for 7 hours. After completion of the reaction, the reaction solution is poured into a 2 liter beaker containing ice and 150 ml of concentrated hydrochloric acid, and the organic layer is washed with water, 10% aqueous sodium hydroxide solution and water. After the washed organic layer is dried over anhydrous magnesium sulfate, methylene chloride is removed under reduced pressure. By recrystallizing the obtained solid with a toluene-ethanol mixed solvent, 75.1 g of a product is obtained. The yield was 33.7% (reference: 3-amino-4-hydroxybenzoic acid), and the melting point was 158 ° C.

As a result of elemental analysis, the theoretical value and the calculated value agree with each other. As a result of ¹ H-NMR analysis and IR analysis, 2- (4-fluorophenyl) -5- (4-fluorobenzoyl) represented by the following formula: It was found to be benzoxazole. The infrared absorption spectrum of the obtained compound is shown in FIG. Elemental analysis calculated value C: 71.6%, H: 3.31%, N: 4.1
8% measured value C: 71.5%, H: 3.30%, N: 4.2
0%

[0028]

[Chemical 6]

[0029]

INDUSTRIAL APPLICABILITY According to the present invention, a novel aromatic compound having excellent reactivity, which is preferably used as a raw material for producing a polymer having excellent heat resistance and having an oxazole ring and a carbonyl group in one molecule, can be obtained industrially at low cost. I can do it now.

[Brief description of drawings]

FIG. 1 is a chart of infrared absorption spectrum of the compound obtained in Example 1.

Claims (2)

[Claims] 1. The formula: An aromatic compound represented by: (wherein X represents a fluorine atom or a chlorine atom). 2. The method for producing an aromatic compound according to claim 1, wherein 2- (4-halophenyl) -5-carboxylbenzoxazole and halobenzene are reacted by a Friedel-Crafts reaction.