JPH11279152A - 8-quinolinol derivative, its metal complex and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound substituted with trifluoromethyl group, used as the ligand of a metal complex which is useful as an intermediate or the like for a pharmaceutical or agrochemical, or useful as a coloring material, an electron transporting material and luminescent material for an EL element, an electrophotographic photoreceptor or the like. SOLUTION: A compound of formula I [R is H, a 1-6C alkyl, acetyl or tosyl; (n) is 0-3; A is H or CF3 , and when A is H, (n)≠0], e.g. 5-trifluoromethyl-8- quinolinol. The compound of formula I is obtained by reacting 2-aminophenol compound of formula II with an acrolein compound of formula III (one of A' is H or CF3 , and the other is H, and when both the two A's are hydrogen atoms, the (n) in formula II is not zero) in an aqueous solution of phosphoric acid and/or arsenic acid. The reaction of the compound of formula I with an appropriate compound of divalent or trivalent metal gives a metal complex of formula IV [M is a divalent or trivalent metal; (m) is 0 or 1].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a trifluoromethyl group-substituted 8 which is effective as a pharmaceutical or agricultural chemical intermediate.
A color former, a quinolinol derivative, and the trifluoromethyl-substituted 8-quinolinol derivative as a ligand;
The present invention relates to a metal complex useful as an electron transporting / emitting material for an element, an electrophotographic photoreceptor, and the like, and a method for producing them.

[0002]

2. Description of the Related Art 8-Quinolinol (also called oxine or 8-hydroxyquinoline) has a pyridine ring type nitrogen atom and a phenol type hydroxyl group in the molecule, and has a three-dimensional structure which is easily coordinated with a metal atom. -1
It acts as a divalent bidentate ligand and forms stable chelate complexes with almost all divalent or trivalent metal ions. Since many of these metal complexes are hardly soluble in water and soluble in organic solvents, it is well known that this property is used for separating and quantifying metals using this property.

[0003] An 8-quinolinol derivative in which a hydrogen atom on an aromatic ring of 8-quinolinol is substituted has the same complex-forming ability. As the 8-quinolinol derivative, a compound in which the substituent is an alkyl group or a halogen atom (eg, chlorine or fluorine) has been reported so far, and a part thereof is commercially available.

The metal complex of 8-quinolinol, especially the aluminum complex, was first proposed by Tang et al. In 1987 as the first organic thin film electroluminescent (EL) device using A.
Since its publication in ppl. Phys. Lett., 51, 913, it has attracted attention as a light emitting material for organic thin film EL.

An organic thin film EL device has an organic fluorescent dye layer.
Single-layer excitation of light-emitting material (fluorescent dye) molecules by having a structure in which a laminated film of (light-emitting layer) and organic semiconductor layer is sandwiched between electrodes, and electrons and holes injected from the electrodes recombine in the light-emitting layer. A state is created, and light emission is used when the state returns to the ground state. E of a double hetero (DH) structure in which an 8-quinolinol complex is sandwiched between a hole transport layer and an electron transport layer
It is known that confinement of the L element in an excited state is effective.

Researches have been made to improve the EL emission characteristics of the 8-quinolinol metal complex. For example, 8
-Doping the quinolinol aluminum complex with a small amount of a suitable organic dye (e.g., quinacridone dye) gives 10 ⁴ cd /
There is a report that high brightness up to m ² can be obtained.

JP-A-6-145146 discloses a metal complex of an 8-quinolinol derivative substituted with a fluorine atom or a cyano group with various metals, which is useful as an EL light emitting material. It describes that yellow to orange luminescence is obtained depending on the type.

[0008]

Problems to be Solved by the Invention 8
When considering a quinolinol metal complex, its durability, especially heat resistance and oxidation resistance are insufficient, and it is advantageous to further improve the electron accepting property in order to enhance the electrical characteristics.

As a means for solving this problem, it is conceivable to replace a hydrogen atom on the aromatic ring of 8-quinolinol with a fluorine atom or a substituent containing fluorine. Since a fluorine atom has a high bond energy with a carbon atom, improvement of heat resistance and oxidation resistance of the molecule can be expected by substitution with a fluorine atom or a fluorine-containing substituent (eg, a trifluoromethyl group). Further, a fluorine atom or a fluorine-containing substituent has a large electron-withdrawing property, and an effect of increasing electron-accepting properties can be expected. Furthermore, if these substituents can be introduced at any positions of the two aromatic rings of 8-quinolinol, it is expected that luminescent materials having different luminescent colors required for a full-color display can be obtained.

However, there are very few kinds of compounds in which an 8-quinolinol derivative is substituted with fluorine, and there are only commercially available compounds in which the fluorine is substituted in the 5-position. There is only.
There are no reported examples of 8-quinolinol derivatives substituted with a trifluoromethyl group.

The above-mentioned JP-A-6-145146 discloses, for example, compounds in which a fluorine atom is monosubstituted at each of the 2- to 7-positions of 8-quinolinol, and 3,6- or 5,7-disubstituted compounds. A metal complex of the compound is shown. As an actual synthesis example of the metal complex, a commercially available 5-substituted fluorine-substituted product
(I.e., 5-fluoro-8-quinolinol) has only been reacted with a metal.

The fluorine-substituted aromatic compound is obtained by diazotizing an aromatic amino compound obtained by reducing an aromatic nitro compound in the presence of tetrafluroboric acid by a Bartz-Siemann reaction to obtain tetrafluoroboric acid. It is generally synthesized by introducing a fluorine group by thermally decomposing a diazonium salt. However, it is difficult for this method to selectively proceed with high yield in the case of fluorination of 8-quinolinol. Therefore, a fluorine-substituted derivative of 8-quinolinol is actually described in JP-A-6-14 / 1994.
At present, it cannot be used except for the 5-fluoro-substituted product described in JP-A-5146.

Accordingly, if derivatives having substituents containing fluorine introduced at various positions of 8-quinolinol can be produced in good yield, the performance (eg, durability such as oxidation resistance and electron acceptability) of the organic thin film EL display can be improved. , Electron acceptability, change in emission color, etc.). The present invention provides such an 8-quinolinol derivative, a metal complex having the 8-quinolinol derivative as a ligand, and a method for producing the same.

[0014]

According to the present invention, in the synthesis of 8-quinolinol by the condensation reaction of 2-aminophenol (= o-aminophenol) with acrolein (= acrylaldehyde) using an acid catalyst, By using a compound having a trifluoromethyl group introduced into one or both reaction components, 8-position in which various positions are substituted with a trifluoromethyl group (that is, a fluorine-containing substituent) is used.
Quinolinol derivatives can be synthesized.

The condensation reaction between 2-aminophenol and acrylaldehyde has conventionally had a problem of low yield, but it has been found that the use of an aqueous solution of phosphoric acid or arsenic acid as a solvent significantly improves the yield. . The obtained trifluoromethyl-substituted 8-quinolinol derivative is a novel compound. This derivative has a chelate forming ability like 8-quinolinol, and reacts with various divalent or trivalent metals to form a metal complex.

According to the present invention, there is provided an 8-quinolinol derivative substituted by a trifluoromethyl group represented by the following general formula (1). However, in the general formula (1), R is H,
C ₁ -C ₆ alkyl group, an acetyl group or a tosyl group (= p-
Wherein n is 0 or an integer of 1 to 3, A is an H or CF ₃ group, and when A is H, n is not 0.

[0017]

Embedded image

The 8-quinolinol derivative of the general formula (1) is
A 2-aminophenol compound represented by the following general formula (2), an acrolein compound represented by the following general formula (3),
It can be produced by reacting in an aqueous solution of phosphoric acid and / or arsenic acid. However, R and n in the general formula (2) have the same meaning as described above, and the 3-position is unsubstituted, that is, not substituted with a CF ₃ group, and one of A ′ in the general formula (3) is H Or a CF ₃ group, the other being H, two A ′
Are H, n in the general formula (2) is not 0.

[0019]

Embedded image

According to the present invention, a metal complex of a trifluoromethyl-substituted 8-quinolinol derivative represented by the following general formula (4) is also provided. In the general formula (4), n and A have the same meanings as described above, M is a divalent or trivalent metal, and m is 0 or 1.

[0021]

Embedded image

Such a metal complex can be produced by reacting a trifluoromethyl-substituted 8-quinolinol derivative represented by the general formula (1) with a suitable divalent or trivalent metal compound.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The 8-quinolinol derivative of the present invention has a structure in which at least one hydrogen atom on the aromatic ring of 8-quinolinol is substituted with a trifluoromethyl group as shown in the above general formula (1). Compound. This compound is a 2-aminophenol compound represented by the general formula (2),
It can be produced by a ring-closing reaction by condensation with an acrolein compound represented by the above general formula (3), and at least one of the two kinds of reaction components has a trifluoromethyl group. When the 2-aminophenol compound has 1 to 3 trifluoromethyl groups, the general formula (1)
In the case where n is from 1 to 3 and the acrolein compound has a trifluoromethyl group,
In (1), a compound in which A is a trifluoromethyl group is obtained.

First, a method for producing the 8-quinolinol derivative will be described. Among the reaction components, the 2-aminophenol compound is a compound represented by the general formula (2). That is, a trifluoromethyl group can be substituted at any one to three of the meta and para positions with respect to the amino group (NH ₂ ). However, when the reaction partner acrolein has a trifluoromethyl group, it may not be substituted with a trifluoromethyl group. The R group is hydrogen, an alkyl group having 6 or less carbon atoms, an acetyl group or a tosyl group.

Of these 2-aminophenol compounds, 2-aminophenol (= o-aminophenol)
As such, it is commercially available. The trifluoromethylation of this compound can be easily performed, for example, by reacting a trifluoromethyl agent such as CF ₃ I, N-trifluoromethyl-N-nitrosotrifluoromethanesulfonamide (TNS-Tf). . The compound in which the R group is a group other than H can be obtained by reacting the compound in which the R group is H with a corresponding halide represented by, for example, RX (X is a halogen). When the R group is an alkyl group, other alkylating agents such as dialkyl sulfate and trialkyl phosphate can be used.

Another reaction component to be condensed with the 2-aminophenol compound is an acrolein compound represented by the general formula (3). This compound is acrolein itself or an acrolein derivative in which the α-position or β-position has been substituted with a trifluoromethyl group (ie, one of the two A ′ is a trifluoromethyl group).
The acrolein derivative in which one of A ′ is a trifluoromethyl group can be synthesized, for example, from 1- or 2-trifluoromethylacrylic acid.

The reaction between compounds (2) and (3) is a condensation reaction between an amine and an aldehyde. This condensation reaction is generally performed in a solvent composed of an acidic aqueous solution. Hydrochloric acid, sulfuric acid and the like are generally used as the acidic aqueous solution, but the above (2) used in the present invention is used.
When these acids are used as a solvent in the condensation reaction of the reaction components of (3) and (3), the reaction does not proceed well, and the yield is remarkably low, or a tar-like substance is generated, and the desired product cannot be obtained. It is considered that the acrolein compound is polymerizable, and the polymerization is likely to proceed by heating in a strongly acidic aqueous solution such as hydrochloric acid or sulfuric acid, so that the condensation reaction does not effectively proceed.

On the other hand, when an aqueous solution of a weak acid such as phosphoric acid or arsenic acid is used as the reaction solvent, the condensation reaction between the 2-aminophenol compound and the acrolein compound effectively proceeds, and the desired compound represented by the general formula (1) It has been found that the 8-quinolinol derivative represented by the formula can be produced in good yield. However, when acetic acid, which is an organic acid, is used even for a weak acid, a high yield cannot be obtained for unknown reasons.

A particularly preferred reaction solvent is an aqueous phosphoric acid solution, but an aqueous arsenic acid solution can also be used, or a mixed aqueous solution of phosphoric acid and arsenic acid can be used. The concentration of the aqueous solution is 30 for phosphoric acid
8585 wt%, and in the case of arsenic acid, the range is preferably 30-60 wt%.

The reaction is preferably carried out in the presence of an oxidizing agent centering on a nitro compound and a small amount of a catalyst such as iron sulfate, as conventionally performed. The nitro compound as the oxidizing agent is not particularly limited, but m-nitrobenzenesulfonic acid, nitrobenzene and the like are generally used.

The reaction temperature and the reaction time are not particularly limited, but the reaction is generally carried out at 70 to 150 ° C, preferably at 80 to 110 ° C. The reaction does not proceed effectively below 70 ° C,
In the above, the progress of side reactions increases, and a tar-like substance is generated, and it is difficult to synthesize the target substance substantially effectively. Although the reaction time is not particularly limited, it is generally 0.5 to 8
This is performed for a time, preferably 1 to 4 hours.

The reaction is generally carried out by dissolving a 2-aminophenol derivative, a nitro compound, iron sulfate or the like in an aqueous acid solution of a solvent and dropping an acrolein compound or a solution thereof into the resulting solution. Is also possible.

After completion of the dropwise addition, the reaction is carried out while maintaining the reaction temperature for a predetermined time. The reaction product can be isolated by neutralizing the reaction solution and purifying the resulting precipitate by direct distillation (or sublimation), or by extracting with a suitable solvent and then distilling. By this method, one of the 3rd to 7th positions is
8- or more positions substituted with a trifluoromethyl group
The quinolinol derivative can be obtained in good yield.

The thus synthesized 8-quinolinol derivative has the same complex-forming ability as 8-quinolinol, and can form a complex with various metals. As the metal, any of a monovalent alkali metal and a polyvalent metal is possible, but a polyvalent metal is preferable. Particularly, attention has been paid to a light emitting material for an EL element, such as aluminum.
Valent metals are preferred. However, it can form a complex with a divalent metal, and specific examples of the divalent metal include Zn and Be. A trivalent metal is a tricoordinate (ie, m in the general formula (4))
And a divalent metal forms a bi-coordinated metal complex (that is, m is 0 in the general formula (4)).

The complex is readily formed by reacting 8-quinolinol with a suitable metal compound (eg, a divalent or trivalent metal compound) in an organic solvent. The metal compound only needs to be soluble in the organic solvent used. For example, an alkylated metal compound (eg, triethylaluminum) may be used. In addition, a halide such as aluminum chloride may be used. Examples of the solvent include hydrocarbons such as toluene and ethers such as tetrahydrofuran, but are not limited thereto.

The complex formation reaction is carried out, for example, by using an inert gas.
In an atmosphere (eg, nitrogen), the 8-quinolinol derivative can be dissolved in an anhydrous organic solvent, and an organic solvent solution of the metal compound can be added dropwise to the resulting solution using a syringe.
The reaction temperature and reaction time are not particularly limited, but the reaction temperature is preferably room temperature to 50 ° C, and the reaction time will be about 3 to 10 hours.

The structures of the trifluoromethyl-substituted 8-quinolinol derivative of the present invention and the metal complex coordinated with the derivative are represented by MS (mass spectrum), elemental analysis, IR and NMR.
And so on. In particular, the measurement of the molecular weight by MS makes a large judgment on whether or not the target substance is generated.

[0038]

【Example】

[0039]

Example 1 10.0 g of 2-amino-4-trifluoromethylphenol, 6.0 g of m-nitrobenzenesulfonic acid (oxidizing agent) were placed in a 200 ml three-necked flask equipped with a magnetic stirrer, a reflux condenser, a thermometer, and a dropping funnel. Add 50 ml of 85 wt% phosphoric acid aqueous solution (solvent) and 0.1 g of ferrous sulfate (catalyst),
Heated to 80 ° C. in oil bath. Subsequently, 10 ml of acrolein was added dropwise from the dropping funnel over 1 hour. After dropping, 2 at 100 ° C
The mixture was heated and stirred for hours. Thereafter, the reaction solution was poured into water and neutralized to pH 7 with aqueous ammonia. The neutralized solution was extracted with dichloromethane, and then the dichloromethane was removed under reduced pressure.
The remaining brown solid was directly sublimated and purified under reduced pressure to obtain 4.3 g of 5-trifluoromethyl-8-quinolinol as a white solid.

DI-MS (direct mass spectrum) Fragment: 213 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 56.3, H 2.8, N 6.6, F 26.8 Actual value: C 56.7, H 2.5, N 6.4, F 26.0

[0041]

Example 2 By the same operation as in Example 1, 4.5 g of a white solid of 6-trifluoromethyl-8-quinolinol was obtained from 10.0 g of 2-amino-5-trifluoromethylphenol and 10 ml of acrolein.

DI-MS fragment: 213 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 56.3, H 2.8, N 6.6, F 26.8 Actual value: C 56.5, H 2.6, N 6.7, F 26.2

[0043]

Example 3 The procedure of Example 1 was repeated, except that the amount of m-nitrobenzenesulfonic acid was changed to 4.5 g.
Amino-4,5-ditrifluoromethylphenol 10.0 g
And 10 ml of acrolein, 4.1 g of a white solid of 5,6-ditrifluoromethyl-8-quinolinol was obtained.

DI-MS fragment: 281 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 47.0, H 1.8, N 5.0, F 40.6 Actual value: C 46.5, H 2.1, N 5.2, F 40.3

[0045]

Example 4 By the same operation as in Example 1, except that the solvent was
Changing to a 50 wt% arsenic acid aqueous solution, 3.9 g of a white solid of 5-trifluoromethyl-8-quinolinol was obtained from 10.0 g of 2-amino-4-trifluoromethylphenol and 10 ml of acrolein.

DI-MS fragment: 213 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 56.3, H 2.8, N 6.6, F 26.8 Actual value: C 56.5, H 2.9, N 6.5, F 26.3 In each of the above examples, the R group of 2-aminophenol (2) is H. However, even when the R group is a lower alkyl group other than H, an acetyl group or a tosyl group, the same applies to the above. One skilled in the art will appreciate that the corresponding trifluoromethyl substituted derivative can be synthesized by Alternatively, by reacting the product of Examples 1 to 4 with a suitable alkylating agent, acetylating agent or tosylating agent (eg, the above-mentioned halides and the like), a compound of the present invention in which the R group is other than hydrogen is obtained. Those skilled in the art will understand that they can also be synthesized.

[0047]

Example 5 A solution prepared by dissolving 0.72 g of 5-trifluoromethyl-8-quinolinol in 60 ml of dehydrated THF was placed in a 200 ml four-necked flask equipped with a magnetic stirrer, a reflux condenser, a thermometer, and a silicon stopper. The mixture was introduced into the flask from a silicon stopper with a syringe, and 1.25 ml of a 13 wt% triethylaluminum solution in toluene was similarly placed in the flask. Thereafter, the reaction mixture was stirred at room temperature for 5 hours, and the precipitated crystals were separated by filtration, washed with THF, dried under reduced pressure, and three molecules of 5-trifluoromethyl-8-quinolinol were coordinated to one atom of Al. 0.65 g of an aluminum complex of a trifluoromethyl-substituted 8-quinolinol derivative was obtained.

DI-MS fragment: 663 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 54.3, H 2.3, N 6.3, F 25.8 Actual value: C 53.8, H 2.2, N 5.9, F 26.2

[0049]

Example 6 0.72 g of 6-trifluoromethyl-8-quinolinol was reacted with triethylaluminum in the same manner as in Example 5 to give a three-coordinated aluminum complex of 0.55 g.
g was obtained.

DI-MS fragment: 663 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 54.3, H 2.3, N 6.3, F 25.8 Actual value: C 54.1, H 2.5, N 6.5
F 25.5

[0051]

Example 7 In the same manner as in Example 5, 0.96 g of 5,6-ditrifluoromethyl-8-quinolinol was reacted with triethylaluminum to form a three-coordinate aluminum complex.
0.65 g was obtained.

DI-MS fragment: 867 (M ⁺ ) Elemental analysis result (unit: wt%) Theoretical value: C 45.7, H 1.4, N 4.8, F 39.4 Actual value: C 46.3, H 1.5, N 5.0, F 38.9 In Examples 5 to 7, the trifluoromethyl-substituted 8-quinolinol derivative in which the R group is H was used, but the corresponding derivative in which the R group is a lower alkyl group, an acetyl group, or a tosyl group may be used. Metal complexes can be formed in substantially the same manner.

[0053]

Comparative Example 1 The same operation as in Example 1 was performed except that concentrated hydrochloric acid was used as a solvent. A tar-like substance was produced, and the desired product was not obtained.

[0054]

Comparative Example 2 The same operation as in Example 1 was performed except that concentrated sulfuric acid was used as a solvent. A tar-like substance was produced, and the desired product was not obtained.

[0055]

According to the present invention, a trifluoromethyl-substituted 8-quinolinol derivative having excellent durability, especially heat resistance and oxidation resistance, and a metal complex having the ligand as a ligand can be synthesized with high yield. The obtained trifluoromethyl-substituted 8-quinolinol derivative is extremely useful as an intermediate for pharmaceuticals, agricultural chemicals, and the like, and a metal complex using this as a ligand can be used as an electron transporting material or luminescent material for EL devices, electrophotographic photosensitive materials. It is extremely useful as an electron transport material in the body. In particular, since the metal complex is introduced with a trifluoromethyl group, which is known to improve heat resistance, oxidation resistance, and electron acceptability, it is possible to provide a product with further improved performance compared to conventional products. It is expected to be able to.

Claims (4)

[Claims] 1. An 8-quinolinol derivative substituted by a trifluoromethyl group represented by the following general formula (1). Embedded image Herein, R is H, C ₁ -C ₆ alkyl group, an acetyl group or a tosyl group, n is an integer of 0 or 1 to 3,
A is H or a CF ₃ group, provided that when A is H, n is 0;
is not. 2. A 2-aminophenol compound having a 3-position unsubstituted compound represented by the following general formula (2) and an acrolein compound represented by the following general formula (3) in an aqueous solution of phosphoric acid and / or arsenic acid: A method for producing an 8-quinolinol derivative, wherein one or more positions other than the 2-position are substituted with a trifluoromethyl group. Embedded image In the above formula, R and n in the general formula (2) have the same meaning as in claim 1, and one of A ′ in the general formula (3) is H or CF ₃ group,
The other is H, and when both A ′ are H, the general formula
N in (2) is not 0. 3. A metal complex of a trifluoromethyl-substituted 8-quinolinol derivative represented by the following general formula (4). Embedded image In the above formula, A and n have the same meaning as in claim 1, M is a divalent or trivalent metal, and m is 0 or 1. 4. A method for producing a metal complex, comprising reacting the trifluoromethyl-substituted 8-quinolinol derivative according to claim 1 with a divalent or trivalent metal compound.