JPH0753830B2 - Method for producing azo compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an azo compound of phenols or naphthols with high purity and high yield.

(Prior Art) Azo compounds of phenols or naphthols have a wide range of uses as dyes, and are useful compounds used as colored couplers in photographic compounds.

The use of the compound as a photographic compound will be described below.

When the silver halide photographic light-sensitive material is exposed to light and then color-developed, a color-developing agent such as an oxidized aromatic primary amine reacts with a dye-forming coupler to form a color image. Generally, in this method, a color reproduction method by a subtractive color method is used, and in order to reproduce blue, green, and red, yellow, magenta, and cyan color images having complementary colors are formed. In this case, phenols or naphthols are often used as cyan dye-forming couplers.

Cyan dyes formed from cyan couplers should ideally only absorb red light, but generally also have unwanted side absorptions in the green and blue light regions.

A masking method using a colored coupler is known as a method for correcting this secondary absorption.

Typical colored couplers used in combination with cyan couplers are, for example, US Pat. Nos. 4,004,929 and 4,1.
The couplers described in No. 38,258 or No. 4,046,573 are known.

(Problems to be Solved by the Invention) Conventionally, in the synthesis of an azo compound of phenols or naphthols, the reaction condition is extremely controlled because the product is an unstable substance. However, in many cases, in addition to the desired azo compound, oxidation products formed by oxidation or decomposition products thereof and other by-products are considerably produced as by-products. The incorporation of these by-products into the azo compound is particularly serious in the case of colored couplers, resulting in a fatal defect in photographic performance that the sensitivity is lowered. Therefore, some purification steps were required to obtain a highly pure diazo compound, which was not suitable for large-scale synthesis in terms of cost.

Therefore, the present invention provides a method for producing an azo compound of phenols or naphthols industrially useful as a dye or a photographic compound with high purity and high yield, and reducing the load of the purification step. Especially.

(Means for Solving the Problem) As a result of intensive studies conducted by the present inventors in order to overcome the difficulties in the production of such conventional azo compounds of phenols or naphthols as photographic compounds, phenol When synthesizing an azo compound having an azo compound on the 4-position substituent of naphthols or naphthols, a hydroxyl group of phenols or naphthols is protected by diazotization and then deprotected to produce a by-product. It has been found that the production of lactic acid can be controlled and the object can be achieved, and the present invention has been completed based on this finding.

That is, according to the present invention, after reacting a compound represented by the following general formula (I) with a diazotizing agent, a nucleophilic species R ₃ is introduced into the produced diazonium salt by a nucleophilic reaction, and then R ₁ is hydrolyzed. Is provided to obtain a compound represented by the following general formula (II), which provides a process for producing an azo compound.

(In the formula, R ₁ represents a group removable by an acid or an alkali, R ₂ represents a group capable of substituting on a benzene ring, n represents an integer of 0 to 4, and when n is plural, R ₂ represents R ₂ may be the same or different and may combine with each other to form a ring, R ₃ represents a nucleophilic species and L represents a linking group.) In formulas (I) and (II) R ₂ is phenol 2
Substitution at position 5 or 5 is preferred. The carbon number of R ₂ is preferably 1 to 40, more preferably 1 to 25.

Among the compounds represented by the general formula (I), preferred compounds are represented by the general formula (III).

(In the formula, R ₁ represents a group to be removed by an acid or an alkali, and preferably an acyl group (for example, acetyl, benzoyl, pivalyl), an alkoxycarbonyl group (for example, methoxycarbonyl, hexadecyloxycarbonyl,
Dodecyloxycarbonyl), aryloxycarbonyl group (eg, phenoxycarbonyl, 4-t-amylphenoxycarbonyl), carbamoyl group (eg, methylcarbamoyl), silyl group (eg, trimethylsilyl, di-t-butylmethylsilyl), alkyl Group, imidoyl group, oxazolyl group, sulfonyl group and the like. Among these, an acyl group is particularly preferable. R ₄ ,
R ₅ represents a group capable of substituting for a naphthol ring, preferably a halogen atom (for example, chlorine atom, bromine atom) straight-chain or branched, chain-like or cyclic, saturated or unsaturated, substituted or unsubstituted aliphatic group (for example, Methyl, propyl, t-butyl, trifluoromethyl, tridecyl, 3- (2,4-di-t-amylphenoxy) propyl, 2-dodecyloxyethyl, 3-phenoxypropyl, 2-hexylsulfonylethyl, cyclopentyl, benzyl ), An aryl group (eg, phenyl, 4-t-butylphenyl, 4-tetradecaneamidophenyl), a heterocyclic group (eg, 2
-Furyl, 2-thienyl, 2-pyrimidyl, 2-benzothiazolyl), cyano group, alkoxy group (e.g. methoxy, ethoxy, 2-methoxyethoxy, 2-dodecyloxyethoxy, 2-methanesulfonylethoxy), aryloxy group (e.g. , Phenoxy, 2-methylphenoxy, 4-t-butylphenoxy), heterocyclic oxy group (for example, 2-benzimidazolyloxy), acyloxy group (for example, acetoxy, hexadecanoyloxy), carbamoyloxy group (N-ethyl). Carbamoyloxy), silyloxy group (eg, trimethylsilyloxy), sulfonyloxy group (eg, dodecylsulfonyloxy), acylamino group (eg, acetamide, benzamide, tetradecanamide, α- (2,4-
Di-t-amylphenoxy) butyramide, 2,4-di-
t-amylphenoxyacetamide, α- {4- (4-
(Hydroxyphenylsulfonyl) phenoxy)} decanamide, isopentadecanamide), anilino group (eg, phenylamino, 2-chloroanilino, 2-chloro-5-tetradecanamidoanilino, 2-chloro-5-).
Dodecyloxycarbonylanilino, N-acetylanilino, 2-chloro-5- {α- (2-t-butyl-4-
Hydroxyphenoxy) dodecanamide} anilino),
Ureido group (for example, phenylureido, methylureido, N, N-dibutylureido), imide group (for example, N
-Succinimide, 3-benzylhydantoinyl, 4-
(2-ethylhexanoylamino) phthalimide), a sulfamoylamino group (for example, N, N-dipropylsulfamoylamino, N-methyl-N-decylsulfamoylamino), an alkylthio group (for example, methylthio,
Octylthio, tetradecylthio, 2-phenoxyethylthio, 3-phenoxypropylthio, 3- (4-t-
Butylphenoxy) propylthio), an arylthio group (for example, phenylthio, 2-butoxy-5-t-octylphenylthio, 3-pentadecylphenylthio, 2
-Carboxyphenylthio, 4-tetradecanamidophenylthio), heterocyclic thio group (for example, 2-benzothiazolylthio), alkoxycarbonylamino group (for example, methoxycarbonylamino, tetradecyloxycarbonylamino), aryloxycarbonylamino A group (eg, phenoxycarbonylamino, 2,4-di-t
-Butylphenoxycarbonylamino), a sulfonamide group (for example, methanesulfonamide, hexadecanesulfonamide, benzenesulfonamide, p-toluenesulfonamide, octadecanesulfonamide, 2-methyloxy-5-t-butylbenzenesulfonamide), Carbamoyl group (for example, N-ethylcarbamoyl, N, N-dibutylcarbamoyl, N- (2-dodecyloxyethyl) carbamoyl, N-methyl-N-dodecylcarbamoyl, N- {3- (2,4-di-t) -Amylphenoxy) propyl} carbamoyl), an acyl group (eg, acetyl group, (2,4-di-t-amylphenoxy))
Acetyl, benzoyl), sulfamoyl groups (eg,
N-ethylsulfamoyl, N, N-dipropylsulfamoyl, N- (2-dodecyloxyethyl) sulfamoyl, N-ethyl-N-dodecylsulfamoyl, N, N
-Diethylsulfamoyl), a sulfonyl group (for example,
Methanesulfonyl, octanesulfonyl, benzenesulfonyl, toluenesulfonyl), sulfinyl group (eg octansulfinyl, dodecylsulfinyl, phenylsulfinyl), alkoxycarbonyl group (eg methoxycarbonyl, butyloxycarbonyl, dodecylcarbonyl, octadecylcarbonyl), aryloxy It represents a carbonyl group (eg, phenyloxycarbonyl, 3-pentadecyloxycarbonyl).

L represents a linking group, and preferably has 6 to 15 carbon atoms, and includes, for example, a substituted or unsubstituted phenylene group (eg, 1,4-phenylene group, 1,3-phenylene group, Aralkylene groups (eg And so on.

In the general formula (III), R ₅ is preferably substituted at the 5-position of naphthol. The carbon number of R ₄ and R ₅ is preferably 1-40, more preferably 1-25.

Among the compounds represented by the general formula (II), preferred compounds are represented by the general formula (IV).

In the formula, R ₄ , R ₅ and L represent the above groups, and R ₃ represents a nucleophilic species capable of attacking a diazonium ion. Preferably,
Represents a phenol or naphthol compound.
Particularly preferably, it is represented by the following general formula (V).

In the formula, R ₆ , R ₇ , and R ₈ represent a group (including an atom) that can be substituted on the naphthol ring, and as a representative example, a halogen atom, a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group or other, Cyano group, aromatic group, heterocyclic group, carbonamido group, sulfonamide group, carbomoyl group, sulfamoyl group, ureido group, acyl group, acyloxy group,
Aliphatic oxy group, aromatic oxy group, aliphatic thio group, aromatic thio group, aliphatic sulfonyl group, aromatic sulfonyl group,
Examples thereof include a sulfamoylamino group, a nitro group, and an imide group, and the carbon number contained in R ₆ , R ₇ , and R ₈ is 0 to 30. In R ₈ , n represents an integer of 0 to 4, and when n is plural, they represent the same or different.

Next, specific examples of the compound represented by the general formula (IV) which can be synthesized by the present invention are shown below. However, it is not limited to these.

The reaction for obtaining the compound represented by the general formula (IV) in high purity and high yield was achieved by protecting the hydroxyl group at the 1-position. The synthesis method constituting the present invention will be described in detail below.

From the general formula (III) to the general formula (IV), first, the general formula (III)
Can be obtained by diazotizing the compound and deprotecting the general formula (VI) obtained by reacting with the general formula (V). The reaction scheme is shown below.

(In the formula, R _{1 to} R ₈ and n have the same meanings as described above.) First, the reaction (A) shown in (Scheme 1) will be described.

A diazotizing agent was added dropwise to the hydrochloride of the compound represented by the general formula (III) to synthesize a diazonium ion, and this solution was added to a solution of the compound represented by the general formula (V) in the presence of a base. By dropping, a compound represented by the general formula (VI) is obtained. Here, sodium nitrite is often used as the diazotizing agent. The amount used is the general formula (II
0.8 mol to 1.8 mol, preferably 0.9 mol to 1.3 mol per 1 mol of the compound of I) is suitable. As the reaction solvent, amides (for example, N, N-dimethylformamide, N, N
-Dimethylacetamide), ethers (e.g. dimethoxyethane, diglyme), sulfonic acids (e.g. dimethyl sulfone, sulfolane), sulfoxides (e.g. dimethyl sulfoxide), alcohols (e.g. 1-methoxy-2-propanol, 2-methoxyethanol, (Methanol, ethanol) is used. These solvents may be used as a mixture. Moreover, you may use it, mixing with water.

The reaction temperature is -20 ° C to 60 ° C, preferably -10 ° C to
20 ° C, particularly preferably -5 ° C to 5 ° C. The charge molar ratio of the compound represented by the general formula (V) is (III)
/(V)=0.5 to 2.0, preferably 0.8 to 1.5, and is appropriately selected. Examples of the base include metal alkoxides (eg, sodium methoxide, t-butoxy potassium), organic bases (eg, 1,5-diazabicyclo [3,4,0] nonene-5,1,4-diazabicyclo [2,2,1] octane). , Triethylamine) or inorganic bases (sodium hydroxide, potassium hydroxide, sodium acetate) are used. The amount used is general formula (V) 1
0.8 mol to 5.0 mol, preferably 1.0 mol to mol
It is properly selected at 3.0 mol.

The reaction temperature of the reaction of the diazonium ion of the general formula (III) with the compound of the general formula (V) is −5 ° C. to 30 ° C.
C., preferably 0.degree. C. to 25.degree.

Next, the reaction conditions of the reaction (B) shown in (Scheme 1) will be described.

In the reaction (B), deprotection is performed in the presence of a base. Examples of the base include metal hydroxides (eg potassium hydroxide, sodium hydroxide), metal alkoxides (eg sodium methoxide, t-butoxy potassium), metal hydrides (eg sodium hydride) or organic bases (eg triethylamine, 1,5). -Diazabicyclo [3,4,0] nonene-5,1,4-diazabicyclo [2,2,2,] octane) and the like are used. Preferably, a metal hydroxide or a metal alkoxide is used. When metal hydroxide is used, the amount used is 1.0 with respect to 1 mol of the general formula (VI).
Mol to 30.0 mol, preferably 5.0 mol to 20.0 mol, and when a metal alkoxide is used, 1.0 mol to 10.0 mol, preferably 1.0 mol to 4.0 mol.

As the reaction solvent, amides (for example, N, N-dimethylformamide, N, N-dimethylacetamide), ethers (for example, dimethoxyethane, diglyme), sulfones (for example, dimethylsulfone, sulfolane), sulfoxides (for example, Dimethyl sulfoxide) and alcohols (eg, 1-methoxy-2-propanol, methanol, ethanol) are used. These solvents may be used as a mixture. Alternatively, it may be used as a mixture with water. The reaction temperature is -20 ° C to 80 ° C, preferably 10 ° C to 60 ° C. The reaction time varies depending on the amount used and the reaction temperature.

(Effect of the Invention) According to the method of the present invention, an azo compound can be obtained in high purity and high yield by diazotizing phenols or naphthols useful as photographic compounds. The method of the present invention is particularly suitable as a method for producing an azo compound useful as a colored coupler.

(Example) A typical synthesis example carried out by the present invention will be specifically shown below.

Example 1 Synthesis of Exemplified Compound (1) 64.1 g of compound (29) was dissolved in 200 ml of dimethylformamide, and 21.7 ml of 36% hydrochloric acid aqueous solution was added. The reaction temperature was kept at 5 ° C., and an aqueous solution prepared by dissolving 6.2 g of sodium nitrite in 30 ml of water was added dropwise. After stirring for about 30 minutes, this solution was dissolved in 34.4 g of compound (30), 8.4 g of sodium hydroxide in 200 ml of dimethylformamide and 60 ml of water, and the reaction temperature was 15 ° C.
Was maintained for 1 hour and added dropwise for 1 hour. After stirring for about 1 hour, 1000 ml of acetonitrile was added to precipitate crystals.

The crystals were filtered off to obtain 100.2 g of compound (31).
The yield was almost quantitative.

100 g of the obtained compound (31) and 172 g of sodium hydroxide were dissolved in 500 ml of methanol and 825 ml of water, the reaction temperature was kept at 50 ° C., and the mixture was stirred under a nitrogen atmosphere for 1 hour. After the reaction, acetic acid 156m
l was added, and the precipitated crystals were filtered off. The crystals thus obtained are washed by boiling with a solution of 276 ml of methanol, 65 ml of toluene and 49 ml of water, and filtered to separate the desired exemplified compound (1).
Was obtained (77.2 g, yield 83.2%). As a result of analysis by high performance liquid chromatography, the purity was 99.1% in terms of peak area intensity ratio.

High-performance liquid chromatography measurement conditions Column: 15 cm x 0.6 cmφ DDS column Eluent: Methanol / water / triethylamine-acetic acid = 95
/5/0.2 (vol%) Example 2 Synthesis of Exemplified Compound (5) 11.6 g of compound (32) was dissolved in 40 ml of dimethylformamide, and 4.9 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 1.40 g of sodium sulfite aqueous solution was added dropwise.
After stirring for about 30 minutes, the solution (8.9 g), sodium hydroxide (1.8 g), dimethylformamide (45 ml) and water (20 g) were added to the solution.
The reaction temperature was kept at 15 ° C. and the solution was added dropwise to the solution dissolved in ml in 30 minutes.

After stirring for about 1 hour, 120 ml of acetonitrile was added to precipitate crystals. The crystals were filtered off to obtain 18.7 g of compound (33). Next, to a solution of 18.7 g of the obtained compound (33) in 90 ml of dimethylacetamide, 12.0 ml of a 28% methanol solution of sodium methoxide was added. After the reaction, the reaction mixture was neutralized with hydrochloric acid, and the crystals were separated by filtration to obtain 17.2 g (yield 90.0%) of the target exemplified compound (5). As a result of analysis by high performance liquid chromatography, the peak area intensity ratio was 95.6.
% Purity.

Example 3 Synthesis of Exemplified Compound (10) 10.0 g of the compound (34) was dissolved in 40 ml of dimethylformamide, and 3.9 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 1.20 g of a sodium nitrite aqueous solution was added dropwise.
After stirring for about 30 minutes, 7.1 g of the compound (30), 1.7 g of potassium hydroxide, 40 ml of dimethylformamide, and 20 ml of water were added to this solution.
The reaction temperature was maintained at 15 ° C and the solution was added dropwise to the solution dissolved in 30 minutes. After stirring for about 1 hour, 100 ml of acetonitrile was added to precipitate crystals. The crystals were filtered off to obtain 15.3 g (yield 92.0%) of compound (35). Then, 8.6 ml of a 28% methanol solution of sodium methoxide was added to 75 ml of a solution of 15.3 g of the obtained compound (35) in dimethylacetamide. After the reaction, the product was neutralized with hydrochloric acid, and the crystals were separated by filtration to give 13.3 g of the desired exemplary compound (10) (yield: 93.3
%)Obtained. As a result of analysis by high performance liquid chromatography, the peak area intensity ratio was 96.8%.

Example 4 Synthesis of Exemplified Compound (15) 52.4 g of compound (36) was dissolved in 220 ml of dimethylformamide, and 19.6 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 5.6 g of sodium nitrite aqueous solution was added dropwise. about
After stirring for 30 minutes, this solution was added dropwise to a solution prepared by dissolving the compound (30), 6.9 g of sodium hydroxide in 170 ml of dimethylformamide, and 70 ml of water while keeping the reaction temperature at 15 ° C for 30 minutes. After stirring for about 1 hour, 600 ml of acetonitrile was added to precipitate crystals. The crystals (3
71.2) was obtained. Then, to a solution of the obtained compound (37) (81.2 g) in dimethylacetamide (400 ml) was added sodium methoxide (28% methanol solution, 50 ml). After the reaction, the reaction mixture was neutralized with hydrochloric acid, and the crystals were separated by filtration to obtain 76.6 g (yield 95.3%) of the desired exemplified compound (15). As a result of analysis by high performance liquid chromatography, the peak area intensity ratio was 9
It was 6.0% pure.

Example 5 Synthesis of Exemplified Compound (20) 69.1 g of compound (38) was dissolved in 200 ml of dimethylformamide, and 21.7 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 6.2 g of sodium nitrite aqueous solution was added dropwise. about
After stirring for 30 minutes, the solution (30) (34.4 g), sodium hydroxide (8.4 g), dimethylformamide (200 ml) and water (9 g) were added.
The reaction temperature was kept at 15 ° C and the solution was added dropwise to the solution dissolved in 0 ml in 30 minutes. After stirring for about 1 hour, 1000 ml of acetonitrile
It was added to precipitate crystals. The crystals were filtered off to obtain 100.6 g of compound (39). Next, 100.6 g of the obtained compound (39) and 144 g of potassium hydroxide were added to 500 m of methanol.
1, dissolved in 500 ml of water, kept at a reaction temperature of 50 ° C., and stirred for 1 hour under a nitrogen atmosphere. After the reaction, 156 ml of acetic acid was added, and the precipitated crystals were separated by filtration. The crystals obtained were washed by boiling with a solution of 276 ml of methanol, 65 ml of toluene and 49 ml of water, and filtered to obtain 84.4 g of the desired exemplified compound (20) (yield 88.5%).
Obtained. As a result of analysis by high performance liquid chromatography,
The purity of the peak area intensity ratio was 95.4%.

Example 6 Synthesis of Exemplified Compound (25) 75.1 g of compound (40) was dissolved in 200 ml of 2-methoxyethanol, and 23.0 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 7.6 g of sodium nitrite aqueous solution was added dropwise. about
After stirring for 30 minutes, 55.9 g of the compound (30), 33.2 g of sodium acetate, 200 ml of dimethylacetamide and 70 parts of water were added.
The reaction temperature was kept at 15 ° C. and the solution was added dropwise over 30 minutes. About 1
After stirring for 1 hour, 1100 ml of acetonitrile was added to precipitate crystals. The compound (41) was obtained by separating the crystals by filtration.
Was obtained in an amount of 109.5 g. Next, 109.5 g of (41) obtained was dissolved in 600 ml of dimethylacetamide, and sodium methoxide 28% was added.
55.9 ml of a methanol solution of was added. After the reaction, the reaction mixture was neutralized with hydrochloric acid, and the crystals were separated by filtration to obtain 88.7 g (yield 86.0%) of the desired exemplified compound (25). As a result of analysis by high performance liquid chromatography, the peak area intensity ratio was 98.9.
% Purity.

Comparative Example 1 39.5 g of compound (42) was dissolved in 300 ml of 2-methoxyethanol, and 15.3 ml of 36% hydrochloric acid aqueous solution was added. Reaction temperature 5 ℃
Then, 5.0 g of sodium nitrite aqueous solution was added dropwise. 50
After stirring for a minute, this solution was added dropwise to a solution of the compound (30) (36.7 g), sodium acetate (21.8 g) in dimethylacetamide (220 ml) and water (73 ml) over 10 minutes while maintaining the reaction temperature at 15 ° C. After stirring for 1 hour, 800 ml of acetone was added to precipitate crystals.
The obtained crystals were washed with a (acetone-methanol) solvent by boiling, filtered, and then washed with a (methanol-toluene-water) solvent by boiling. The crystals were filtered off to obtain 14.8 g (yield 22.3%) of the target Exemplified compound (1). As a result of analysis by high performance liquid chromatography, the purity was 75.4%.

Comparative example 2 Compound (43) 10.0 g was dissolved in dimethylacetamide 50 ml, and 36% hydrochloric acid aqueous solution 3.4 ml was added. The reaction temperature was kept at 5 ° C., and 1.2 g of sodium nitrite aqueous solution was added dropwise. After stirring for 15 minutes, this solution was added dropwise to a solution of 6.0 g of compound (30) and 2.4 g of sodium hydroxide in 50 ml of methanol at a reaction temperature of 15 ° C over 10 minutes. After stirring for 1 hour, acetone 10
0 ml was added to precipitate crystals. The obtained crystals were washed by boiling with an acetone-methanol solvent, filtered, and further washed by boiling with a methanol-toluene-water solution. The crystals were separated by filtration to obtain 3.8 g (yield 25.0%) of the target exemplified compound (25). As a result of analysis by high performance liquid chromatography, the purity was 81.6%.

When the diazotization reaction was carried out without protecting the hydroxyl group, as can be seen by comparing the comparative example with the corresponding example, both the yield and the purity were low. The main by-products produced in the reaction are
It is the following compound (44), and it is presumed that this generation was caused by oxidative decomposition under the reaction conditions. That is, when a substituent such as alkoxy is introduced at the 4-position of naphthol, the oxidation potential is generally low and the naphthol is susceptible to oxidative decomposition. On the other hand, in the examples, by protecting the hydroxyl group, the decomposition could be prevented by raising the oxidation potential, and the azo compound of naphthols could be obtained with high yield and high purity.

Claims (2)

[Claims] 1. A compound represented by the following general formula (I) is reacted with a diazotizing agent, a nucleophilic species R ₃ is introduced into the produced diazonium salt by a nucleophilic reaction, and then hydrolysis is carried out to form R _1. Is removed to obtain a compound represented by the following general formula (II). (In the formula, R ₁ represents a group removable by an acid or an alkali, R ₂ represents a group capable of substituting on a benzene ring, n represents an integer of 0 to 4, and when n is plural, R ₂ represents R ₂ may be the same or different, and R ₂ may combine with each other to form a ring, R ₃ represents a nucleophilic species, and L represents a linking group.) 2. The production of an azo compound according to claim 1, wherein the compounds of the general formulas (I) and (II) are compounds represented by the following general formulas (III) and (IV), respectively. Method. (In the formula, R ₄ and R ₅ represent groups substitutable on the naphthalene ring, and n represents an integer of 0 to 4. When n is plural, R ₅ may be the same or different. )