KR20190050646A - Method for preparing 3-aminofluorene - Google Patents

Abstract

The present invention relates to a method for manufacturing 3-aminofluorene having a specific structure. Specifically, provided are the method for manufacturing 3-aminofluorene having the specific structure and an organic light emitting compound synthesized using the 3-aminofluorene, wherein the method comprises following steps of: acetylation of an amine group with the specific structure of 2-aminofluorene and nitration of the acetylated compound; de-acetylation of the acetylated amine group of the nitrated product; replacing the de-actylated amine group with hydrogen by conducting a reaction with nitrous acid and hypophosphorous acid; and reducing a nitro group of the hydrogen substitution product. The 3-aminofluorene can be manufactured at a low cost and a high yield.

Description

METHOD FOR PREPARING 3-AMINOFLUORENE < RTI ID = 0.0 >

The present invention relates to a process for the preparation of 3-aminopurienes. More particularly, it relates to a method for substituting an amine group at the 3-position of fluorene.

The derivatives of 3-aminoprene are useful compounds as organic light emitting materials.

The organic light emitting material functions to convert electrical energy into light energy through organic light emitting phenomenon.

When a voltage is applied to a circuit, electrons and holes generated from the anode and the cathode, respectively, are transferred to the organic light emitting layer formed from the organic light emitting material and recombine, and the band gap between the LUMO and the HOMO of the organic light emitting material It is a phenomenon that the light of the corresponding energy is emitted.

OLEDs (organic light emitting diodes) generally have a multi-layer structure including a transparent electrode, an organic light emitting layer, a light emitting auxiliary layer, a hole transporting layer, and an electron transporting layer.

When the OLED has a structure in which the hole transport layer and the organic emission layer are in contact with each other, organic light emission may occur at the interface between the hole transport layer and the organic emission layer.

When an organic light emitting phenomenon occurs at the interface between the hole transporting layer and the organic light emitting layer, the color purity and efficiency of the OLED are lowered and the lifetime is also shortened.

To solve this problem, a light emitting auxiliary layer is introduced between the hole transporting layer and the organic light emitting layer. The light emission assisting layer is formed of a material in which the energy level of HOMO is located between the HOMO of the hole transporting layer and the HOMO of the organic light emitting layer.

The 3-aminopyrrolene derivative is a compound that can be applied to the light emission-assisting layer. For example, Korean Patent Laid-Open Publication No. 10-2015-0006199 discloses a method for synthesizing 3-aminopyrrolene. However, since the above synthesis method is a high-cost process using expensive reagents, it is necessary to develop a method for synthesizing 3-aminopurien derivatives more economically.

Korean Patent Publication No. 10-2015-0006199

An object of the present invention is to provide a process for producing 3-aminoprene which is simple in process and high in yield.

1. acetylating an amine group of 2-aminopyrrolene represented by the general formula (1); Nitrating the acetylated compound; Deacetylating the acetylated amine group of the nitrated product; Reacting the de-acetylated amine group with nitrous acid and hypophosphorous acid to replace with hydrogen; And reducing the nitro group of the hydrogen substitution product. 2. The process according to claim 1,

[Chemical Formula 1]

(2)

(In the above formulas (1) and (2), R ¹ and R ² are independently of each other hydrogen or an alkyl group having 1 to 8 carbon atoms.)

2. The process of claim 1, wherein the acetylation comprises reacting the amine group with an acetic acid derivative.

3. The method of claim 1, wherein the nitration comprises reacting the acetylated compound with nitric acid and sulfuric acid.

4. The process of claim 1, wherein the de-acetylation comprises reacting the acetylated amine group with a metal hydroxide salt.

5. The process of claim 1, wherein the nitrite is formed by the reaction of sodium nitrite and sulfuric acid.

6. The process of claim 1, wherein said reduction comprises reacting said nitro group with iron powder, ammonium chloride and water.

7. An organic light-emitting compound synthesized by using 3-aminoprene produced by any one of the above-mentioned 1 to 6 production methods.

According to the embodiments of the present invention, 3-aminoprene can be economically produced by using 2-aminophorene which is easily available.

In addition, 3-aminoprene can be produced at low cost by using inexpensive compounds such as acetic anhydride, nitric acid, sulfuric acid, and potassium hydroxide.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be obvious to those skilled in the art that such modifications and variations are within the scope of the appended claims.

The present invention relates to a process for preparing 3-aminopyrrolene represented by the general formula (2), which comprises acetylating an amine group of 2-aminopyrrolene represented by the general formula (1), nitrating the acetylated compound, Deacetylating the acetylated amine group of the nitrated product, reacting the de-acetylated amine group with nitrous acid and hypophosphoric acid to replace with hydrogen, and reducing the nitro group of the hydrogenated product (2), and an organic light emitting compound synthesized using the 3-aminoprene. The 3-aminoprene can be produced at a low cost and a high yield.

[Chemical Formula 1]

(2)

In the general formulas (1) and (2), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms.

For example, R ¹ and R ² may be, independently of each other, hydrogen or an alkyl group having 1 to 4 carbon atoms.

In addition, the alkyl group may be linear, barnished or cyclic.

First, the amine group of 2-aminopyrrolene represented by Formula 1 is acetylated.

The acetylation may be performed using an acetic acid derivative such as acetyl chloride or acetic anhydride. Preferably, acetic anhydride can be used.

Acetamido (AcNH-) group can be produced by acyl substitution of the acetic acid derivative and the amine group.

By the above acetylation, a compound represented by the following general formula (3) can be produced.

(3)

In Formula 3, R ¹ and R ² are the same as those of the formula 1 and 2 R ¹ and R ^2.

By the acetylation, the nitration of the 2-aminopurienol can be facilitated.

For example, in the case of direct nitration of the 2-aminopyrrolene without the above acetylation, the protonation of the amine group by an acid (for example, nitric acid or sulfuric acid) used in the nitration reaction (-NH ₃ ⁺ , Ammonium ion) is generated as protonation occurs, and the ammonium ion acts as an electron withdrawing group to reduce the reactivity of the nitration reaction.

The acetylated compound may be nitrated.

The nitration may be performed by reacting the acetylated compound with nitric acid and sulfuric acid.

The product according to the nitration can be represented by the following formula (4).

[Chemical Formula 4]

In Formula 4, R ¹ and R ² are the same as those of the formula 1 and 2 R ¹ and R ^2.

As the nitric acid, concentrated nitric acid having a moisture content of less than 70% may be used.

As the sulfuric acid, concentrated sulfuric acid having a moisture content of less than 95% may be used.

The nitration can be carried out at a temperature of 10 ° C or lower. When the temperature exceeds 10 ° C, the yield of the nitration decreases as the side reactions of the electrophilic aromatic substitution become active. can do. The lower limit of the temperature at which the nitration is performed is not limited, and preferably, when performed at 0 ° C or higher, the decrease in reactivity due to the low temperature can be prevented.

The nitration may be performed by first adding nitric acid to the acetylated compound, followed by dropwise addition of sulfuric acid.

If the sulfuric acid is added dropwise, it may be easy to control the temperature during the reaction so as not to exceed 10 ° C.

For example, the acetamido group generated by the acetylation is an electron donating group, and the reactivity of the acetamido-substituted aromatic ring in the electrophilic aromatic substitution reaction may be increased.

The acetamido group may also be an ortho-para director, and the nitration may occur at the 1- or 3- position of the acetylated compound (Formula 3).

In one embodiment, when R ¹ and R ² are each an alkyl group having 1 to 8 carbon atoms, the steric hindrance of R ¹ and R ² limits the nitration reaction at the 1- , A nitration reaction may occur at the 3-position of the above-mentioned formula (3).

The acetylated amine group of the nitration product is de-acetylated.

The de-acetylation can be carried out by hydrolysis of the acetamido group.

The hydrolysis can be carried out under acidic or basic conditions.

When the hydrolysis is carried out under acidic conditions, the amine group generated by the hydrolysis is protonated by hydrogen ions (H ⁺ , proton) contained in the solution of the acidic conditions to form ammonium ions, Can undergo hydrolysis under basic conditions.

As a non-limiting example of the basic conditions, metal hydroxides such as potassium hydroxide, sodium hydroxide and the like can be used.

The acetamido group may be hydrolyzed by the de-acetylation to produce the amine group.

The de-acetylation product may be represented by the following general formula (5).

[Chemical Formula 5]

In formula 5, R ¹ and R ² are the same as those of the formula 1 and 2 R ¹ and R ^2.

The amine group of the de-acetylation product (Formula 5) may be substituted with hydrogen by reaction with nitrous acid and hypophosphorous acid.

When the amine group reacts with the nitrite, a diazonium cation (-N ₂ ⁺ ) is formed by a diazotization reaction, and the diazonium ion may be substituted with hydrogen by reacting with a hypophosphorous acid.

In one embodiment, the nitrite may be formed by the reaction of sodium nitrite with sulfuric acid. The nitrite is easily decomposed into nitric acid, nitrogen oxide, or water. By adding the sodium nitrite and the sulfuric acid to the reaction solution, it is possible to participate in the diazotization reaction before the nitrite is decomposed.

The diazonium ion is preferably reacted at a temperature of 10 ° C or lower in order to suppress the side reaction which is very reactive and to cause the hydrogen substitution reaction. The lower limit of the hydrogen substitution reaction temperature is not limited, and preferably, when the reaction is carried out at 0 ° C or higher, the decrease in reactivity due to the low temperature can be prevented.

When sulfuric acid is first added to the reaction solution and the sodium nitrite is added dropwise, it may be easy to maintain the temperature of the reaction solution at 10 ° C or lower.

The hydrogen substitution product may be represented by the following formula (6).

[Chemical Formula 6]

In Formula 6, R ¹ and R ² are the same as those of the formula 1 and 2 R ¹ and R ^2.

The nitro group of the hydrogen substitution product (Formula 6) may be reduced to produce the 3-aminopyrrolene represented by Formula 2. [

As a non-limiting example of the reducing catalyst or the reducing agent used for the reduction, ammonium chloride, water or hydrogen is used with Ni, Fe, Zn, Sm, Pd / C, PtO ₂ , SnCl ₂ , TiCl ₃ , Raney Ni or zeolite .

In one embodiment, the hydrogen displacement product can be reduced using iron (Fe) powder, ammonium chloride, and water to reduce the nitroxide in high yield.

In one embodiment, the organic light emitting compound may be synthesized by using 3-aminoprene produced by the process for producing 3-aminoprene. For example, the substituent which increases the resonance effect of an aryl group, a heteroaryl group or the like in the amine group of the 3-aminopyrrolene may be substituted to form an organic light emitting compound.

The organic light emitting compound may be used as a material of an OLED.

Hereinafter, a method of producing 3-aminoprene according to embodiments of the present invention will be described in detail with reference to specific experimental examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiment within the scope and spirit of the present invention, It is to be understood that such variations and modifications are intended to fall within the scope of the appended claims.

Example

2- Acetamido -9,9- dimethylfluorene  synthesis

25 g of 2-amino-9,9-dimethylfluorene was added to 80 ml of dichloromethane, and 12.8 ml of acetic anhydride was added dropwise while stirring. After stirring for about 3 hours, analysis of thin layer chromatography (Ethyl acetate / Hexane = 1/2) showed that the raw material was exhausted.

2- Acetamido -3-nitro-9,9- dimethylfluorene  synthesis

The reaction solution was cooled to 5 캜 and dissolved by adding 10.8 ml of 70% nitric acid. 10 ml of 95% sulfuric acid was added dropwise while keeping the reaction solution at 10 캜 or lower. After stirring at room temperature for 2 hours, 2-Acetamido-9,9-dimethylfluorene disappeared by thin layer chromatography (Ethyl acetate / Hexane = 1/2) analysis. Dichloromethane (800 ml) and water (350 ml) were added to dissolve in the reaction mixture and then the layers were separated. The organic layer was washed with 300 ml of water and then layered. The organic layer was concentrated by heating to about 200 ml, then 150 ml of isopropanol was added, and about 100 ml of solvent was distilled off by heating. The solid obtained by cooling and filtration was recrystallized in the same manner with dichloromethane and isopropanol. The precipitated yellow crystals were filtered and dried to obtain 16.2 g of 2-acetamido-3-nitro-9,9-dimethylfluorene of 99.4% purity by gas chromatography analysis.

The MS data appeared as follows.

296.1, 254.1, 240, 224, 193.1, 165.1, 43.1

2-Amino-3-nitro-9,9- dimethylfluorene  synthesis

2-Acetamido-3-nitro-9,9-dimethylfluorene was added to 150 ml of ethanol, followed by the addition of 8.1 g of potassium hydroxide, followed by refluxing with heating. After 4 hours of reaction, it was confirmed by thin layer chromatography (Ethyl acetate / Hexane = 1/6) that the raw material was exhausted, and 100 ml of ethanol was added thereto, followed by recovery by heating distillation. To the residue was added 60 ml of water, cooled, and then filtered. GC and MS analysis confirmed that 2-Amino-3-nitro-dimethylfluorene was prepared.

The MS data appeared as follows.

254.1, 237.1, 209.1, 193.1, 165.1, 127.1, 96.5, 76, 51.1, 30.1

3-Nitro-9,9- dimethylfluorene  synthesis

The filtrate was washed with 100 ml of water and then added to 80 ml of THF to obtain a filtrate. To the solution was added 4.8 ml of 95% sulfuric acid and 11.4 ml of 50% hypophosphoric acid was added with stirring. The solution was cooled to 0 占 폚 and 5.7 g of sodium nitrite was dissolved in 40 ml of water, and the solution was dropped while maintaining the temperature at 10 占 폚 or lower. Thin layer chromatography (Ethyl acetate / Hexane = 1/10) analysis showed that the raw material was exhausted. Dichloromethane (300 ml) was added, and the mixture was stirred. Then, 200 ml of water was added thereto and washed. The organic layer was separated, washed with 100 ml of water, and layered.

3-Amino-9,9- dimethylfluorene  synthesis

The separated organic layer was completely concentrated by distillation under reduced pressure, dissolved in 60 ml of dioxane, and then 12 g of iron powder, 1.5 g of ammonium chloride and 10 ml of water were added in order. The reaction mixture was heated under reflux for 8 hours and analyzed by thin layer chromatography (Ethyl acetate / Hexane = 1/10), and analyzed by gas chromatography to find that 89.5% of 3-Amino-9,9-dimethylfluorene was contained Solution.

The reaction mixture was concentrated, 200 ml of dichloromethane and 200 ml of water were added thereto, followed by thorough stirring and layer separation. The organic layer was separated, dried over anhydrous magnesium sulfate (Na ₂ SO ₄ ) and filtered. The filtrate was completely concentrated and chromatographed on silicagel with Ethyl acetate / Hexane = 1/10 solution. The separated solution was concentrated to give 6.2 g of 3-Amino-9,9-dimethylfluorene as a pale white powder at 98.7% purity.

≪ 1 > H NMR (DMSO) data appeared as follows.

(D), 7.14 to 7.17 ppm 1H (d), 7.24 to 7.29 ppm 2H (m), 7.45 to 7.27 ppm 2H (s), 2.52 to 6.56 ppm 7.47 ppm 1H (d), 7.59-7.62 ppm 1H (d)

MS analysis showed that 2-Acetamido-3-nitro-9,9-dimethylfluorene and 2-Amino-3-nitro-9,9-dimethylfluorene were synthesized. By NMR analysis, the target 3-Amino-9 , 9-dimethylfluorene were synthesized. According to the present invention, 3-aminoprene can be synthesized with high yield by using 2-aminoprene, acetic anhydride, nitric acid, sulfuric acid, potassium hydroxide and the like, which are easy to obtain and cheap.

Claims (7)

Acetylating an amine group of 2-aminopyrrolene represented by Formula 1;
Nitrating the acetylated compound;
Deacetylating the acetylated amine group of the nitrated product;
Reacting the de-acetylated amine group with nitrous acid and hypophosphorous acid to replace with hydrogen; And
And reducing the nitro group of the hydrogen substitution product. 2. A process for producing 3-aminopyrrolene represented by the formula (2)
[Chemical Formula 1]

(2)

(In the above formulas (1) and (2), R ¹ and R ² are independently of each other hydrogen or an alkyl group having 1 to 8 carbon atoms.)
The method of claim 1, wherein the acetylation comprises reacting the amine group with an acetic acid derivative.
The method of claim 1, wherein the nitration comprises reacting the acetylated compound with nitric acid and sulfuric acid.
2. The process of claim 1, wherein the de-acetylation comprises reacting the acetylated amine group with a metal hydroxide salt.
The method of claim 1, wherein the nitrite is formed by the reaction of sodium nitrite and sulfuric acid.
The process according to claim 1, wherein the reduction comprises reacting the nitro group with iron powder, ammonium chloride and water.
An organic light-emitting compound synthesized by using 3-aminoprene produced by any one of claims 1 to 6.