JP2002173607A - Method for producing fluoran compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially and advantageously producing a fluoran compound. SOLUTION: A fluoran compound expressed by general formula (4) (wherein R1 and R2 express each an alkyl, a cycloalkyl, an alkoxyalkyl, a tetrahydrofurfuryl or a phenyl which may have substituents and can form a ring by bonding to each other; X1 expresses H or an alkyl; X2 expresses H, an alkyl, a halogen atom or an amino and X3 express H; X3 together with adjacent X1 or X2 can form a benzene ring by bonding to each other) is produced by reacting a benzophenonecarboxylic acid derivative expressed by general formula (1) (M expresses a sodium atom or a potassium atom) with a phenol derivative expressed by general formula (2) (R3 expresses H or an alkyl) in a condensation agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a fluoran compound useful as a coloring dye for pressure-sensitive recording paper, heat-sensitive recording paper and the like.

[0002]

2. Description of the Related Art Conventionally, fluoran compounds have been synthesized by reacting a benzophenonecarboxylic acid derivative in the form of a free acid with a phenol derivative. For example, a benzophenonecarboxylic acid derivative in the form of a free acid as shown in the following formula (5) is used.

[0003]

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The benzophenonecarboxylic acid derivative in the form of the free acid is produced by reacting an aminophenol compound with phthalic anhydride in a nonpolar organic solvent such as toluene, xylene, o-dichlorobenzene and the like. Since various impurities such as unreacted starting materials and rhodamine-based compounds are present in the reaction system after the completion of the reaction, a general-purpose organic solvent is used for many benzophenonecarboxylic acid derivatives except for special ones. It was relatively difficult to efficiently precipitate as crystals in the form of free acid in the reaction system.
Therefore, conventionally, for benzophenone carboxylic acid derivatives that are difficult to efficiently precipitate crystals in the form of free acid in the reaction system, an aqueous alkali solution is added to the reaction solution, and the desired product is first extracted into the aqueous layer in the form of an alkali metal salt. Then, an alkali metal salt-form crystal is once precipitated from the separated aqueous layer, and then dissolved in water, and neutralized to precipitate the desired product in the form of a free acid (acid precipitation). The method was generally adopted.

[0005] Even in the case of a special benzophenone carboxylic acid derivative which tends to precipitate crystals in the form of free acid in the reaction system as the reaction proceeds, the more the yield of the desired product is improved, the more the reaction system The impurities are taken into the target substance precipitated therein, and the removal of the impurities becomes insufficient only by separating the precipitated target substance by filtration or the like. Therefore, when it is desired to obtain a high-purity target product in good yield, an organic solvent and an aqueous alkali solution are added to the separated crude product in the form of the free acid to convert the target product into an aqueous layer in the form of an alkali metal salt. The target product is extracted into an aqueous layer in the form of an alkali metal salt by directly adding an aqueous alkali solution to the reaction solution in the same manner as described above, and then the target product is once crystallized in the form of an alkali metal salt. A method of precipitating and then performing acid precipitation (Japanese Patent Application Laid-Open Nos. 59-120654 and 61-130) has been adopted.
No. 262, JP-A-62-70350, JP-A-2-20
565, JP-A-5-213840, etc.).

As a method for isolating a benzophenone carboxylic acid derivative in the form of a free acid, various methods other than the above-mentioned methods are known which are modified in consideration of washing and purification operations. In addition, in view of the disadvantages of the method of obtaining the target product in the form of a free acid after passing through the form of an alkali metal salt, that is, in view of the large number of steps and generation of a large amount of neutralized wastewater, for example, the reaction is carried out with an aliphatic lower carboxylic acid. A method in which the reaction is carried out in an acid and then water or an aliphatic lower alcohol is added to the reaction system after the reaction to crystallize the desired product in the form of a free acid has been proposed. (Japanese Patent Laid-Open No. 6
-100512 publication). However, since this method also uses a special aliphatic carboxylic acid, there are new problems such as difficulty in recovering and utilizing the solvent and in treating the waste liquid.

[0007]

The inventor of the present invention questioned the above-mentioned conventional assumption that the benzophenone carboxylic acid derivative used as a raw material of the fluoran compound must be in the form of a free acid. The present inventors have conceived of a method for producing a fluoran compound using a benzophenonecarboxylic acid derivative of the form (1) directly as a raw material, and have intensively studied the method. As a result, they have found that the method for producing a fluoran compound based on the novel idea described above does not merely contribute to the labor saving of the raw material production process, and have further reached the present invention as a result of further research.

[0008]

That is, the present invention firstly comprises reacting a benzophenonecarboxylic acid derivative represented by the general formula (1) with a phenol derivative represented by the general formula (2) in a condensing agent. The present invention relates to a method for producing a fluoran compound represented by the general formula (4).

[0009]

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[Wherein R ¹ and R ² represent an alkyl group, a cycloalkyl group, an alkoxyalkyl group, a tetrahydrofurfuryl group, or a phenyl group which may have a substituent. Also, R ¹ and R ² can be linked to form a ring. M represents a sodium atom or a potassium atom. ]

[0011]

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[In the formula, R ³ represents a hydrogen atom or an alkyl group, X ¹ represents a hydrogen atom or an alkyl group, and X ² represents a hydrogen atom, an alkyl group, a halogen atom or a general formula (3). X ³ represents a hydrogen atom.
Further, X ³ and adjacent X ¹ or X ² can be linked to form a benzene ring. ]

[0013]

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[Wherein R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aralkyl group, or a phenyl group which may have a substituent. ]

[0015]

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[Wherein R ¹ , R ² X ¹ , X ² and X ³ have the same meanings as described above. The present invention is, secondly, in the above-mentioned first invention, R
^{The present} invention relates to a method for producing a fluoran compound, wherein 1 represents an alkyl group having 1 to 5 carbon atoms, and R ² represents a group selected from an alkyl group having 3 to 6 carbon atoms, a methoxypropyl group and an ethoxypropyl group.

The present invention is, in the third aspect of the present invention, a method according to the first aspect, wherein R ¹ and R ² represent an N-ethyl-N-iso-pentylamino group, an N, N-dipentylamino group , A N-methyl-NN-propyl group and a N-ethyl-N-iso-butyl group.

Fourth, the present invention provides the above-mentioned first invention, wherein R ¹ and R ² are adjacent to each other by an N-ethyl-N-iso-pentylamino group or an N, N-dipentylamino group. , Means a group selected from N-methyl-NN-propyl group and N-ethyl-N-iso-butyl group,
X ¹ represents a hydrogen atom or a methyl group, X ² represents a dibenzylamino group, an unsubstituted anilino group, or an anilino group substituted with a methyl group, a chlorine atom or a trifluoromethyl group, and X ³ represents It relates to a method for producing a fluoran compound which means a hydrogen atom.

The benzophenonecarboxylic acid derivative in the form of the free acid used in the conventional method, when introduced into a typical concentrated sulfuric acid as a condensing agent, forms a viscous mass and adheres to each other to form a solution. For a long time. In this regard, the benzophenone carboxylic acid derivative in the form of an alkali metal salt used in the present invention hardly forms a lump when poured into concentrated sulfuric acid and dissolves smoothly.

In the above-mentioned production method of the present invention, in the formulas (1) and (4), R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkyl group having 3 to 6 carbon atoms, a methoxypropyl group, It is more preferably carried out when it means a group selected from ethoxypropyl groups. Furthermore the process of the present invention, in (1) and (4), ^{R 1} and R
² is an adjacent nitrogen atom, and N-ethyl-N-iso-pentylamino group, N, N-dipentylamino group, N-methyl-NN-propyl group and N-ethyl-N-iso-
It is most preferably carried out when it means a group selected from butyl groups.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The fluoran compound of the present invention is prepared by using a benzophenonecarboxylic acid derivative in the form of an alkali metal salt as a starting material instead of the conventional free acid form of the benzophenonecarboxylic acid derivative. And the other is the same. The present invention is different from the conventional method only in that the benzophenone carboxy derivative in the form of an alkali metal salt is used as one of the raw materials as described above, but this raw material is added to concentrated sulfuric acid or the like used as a condensing agent. The temperature tends to rise more easily than in the case of the conventional method. However, this rise in temperature can be controlled relatively easily by adjusting the temperature and flow rate of the cooling water, or by adjusting the rate of addition of the benzophenone carboxy derivative as a raw material. In the present invention, when a benzophenone carboxylic acid derivative is added to concentrated sulfuric acid,
An equimolar amount of sodium sulfate is formed, but this product has no adverse effect on the subsequent condensation reaction with the phenol derivative.

[0022]

EXAMPLES The method of the present invention will be described more specifically with reference to the following examples. Example 1 A. Synthesis of disodium salt of 4- (N-ethyl-N-iso-pentyl) amino-2-hydroxy-2'-carboxybenzophenone 3- (N-ethyl-N represented by the formula (6) in 60 ml of toluene -Iso-pentyl) aminophenol 62.
1 g and 57.8 g of phthalic anhydride were added and reacted at 80 ° C. for 20 hours.

[0023]

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To the reaction mixture, 300 ml of water and 30 g of a 48% aqueous sodium hydroxide solution were added, and the mixture was heated to 80 ° C.
-(N-ethyl-N-iso-pentyl) amino-2-
Hydroxy-2′-carboxybenzophenone (the compound of the formula (10) described later) was dissolved. After separating the toluene layer, the alkaline solution was washed twice with 150 ml of toluene at the same temperature to remove by-product rhodamine-type red dye. After adding water to make 500 ml, 83 g (8% based on the liquid amount) of 48% caustic soda was added at 80 ° C. Thereafter, the mixture was cooled to 20 ° C. while stirring. The precipitated crystals were filtered and 8%
Washing was performed with 450 ml of aqueous sodium hydroxide solution. Drying yielded the disodium salt of 4- (N-ethyl-N-iso-pentyl) amino-2-hydroxy-2'-carboxybenzophenone represented by formula (7). Yield: 107.4 g, purity (HPLC): 89.3%
(Containing about 10% of inorganic substances such as sodium hydroxide),
80.1% yield

[0025]

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B. 2-anilino-3-methyl-6- (N
Synthesis of -ethyl-N-iso-pentyl) aminofluoran 44.7 g of disodium salt of 4- (N-ethyl-N-iso-pentyl) amino-2-hydroxy-2'-carboxybenzophenone in 180 g of concentrated sulfuric acid 20 to 25
Dissolved at ° C. At that time, no lump was formed at all, and it could be dissolved smoothly. Next, 2-methyl-4 represented by the formula (8)
-23.4 g of methoxydiphenylamine at 10 to 15 ° C
And dissolved. Thereafter, the reaction was carried out at 10 to 15 ° C. for 48 hours.

[0027]

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The reaction product was discharged into 500 ml of ice water, and the precipitate was filtered and washed with water. The obtained cake is washed with toluene 15
0 ml, diluted caustic soda, and the pH of the aqueous layer.
And then stirred at 90 ° C. for 1 hour. The toluene layer was separated, added with 2 g of activated carbon, filtered while hot, and then heated at 10 ° C.
The mixture was cooled with stirring until crystallization. After filtering the precipitated crystals,
After drying, pure 2-anilino-3 represented by formula (9)
-Methyl-6- (N-ethyl-N-iso-pentyl)
Aminofluorane was obtained. Yield 46.3 g, 89.4% yield, mp 166
~ 167.5 ° C

[0029]

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Comparative Example 1 A. Preparation of 4- (N-ethyl-N-iso-pentyl) amino-2-hydroxy-2'-carboxybenzophenone (free oxidation of sodium salt) 4- (N-ethyl-N-iso obtained in Example 1 -Pentyl) amino-2-hydroxy-2'-carboxybenzophenone disodium salt (44.7 g of the compound of the formula (7)) was dissolved in 300 ml of water. Dilute sulfuric acid was gradually added thereto at room temperature to neutralize to pH 5.5. The obtained mass was recrystallized from 90 ml of toluene, filtered and dried, and then 4- (N-ethyl-N-iso) represented by the formula (10) was obtained.
-Pentyl) amino-2-hydroxy-2'-carboxybenzophenone crystals were obtained. Yield 33.0 g, purity (HPLC) 99.0%, yield 92.0%, mp 128-130 ° C

[0031]

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B. 2-anilino-3-methyl-6- (N
Synthesis of -ethyl-N-iso-pentyl) aminofluoran 4- (N-ethyl-N-iso-pentyl) amino-2-hydroxy-2'-carboxybenzophenone (formula (10) described above) in 150 g of concentrated sulfuric acid. 33.0)
g was dissolved at 20-25 ° C. Lumps were formed and could not be dissolved smoothly. Then, 2-methyl-4-methoxydiphenylamine (compound of the above formula (8)) 21.
6 g was melted at 10-15 ° C. Thereafter, the same treatment as in Example 1 was carried out, and pure 2-anilino having the same structure as in Example 1 was obtained.
3-Methyl-6- (N-ethyl-N-iso-pentyl) aminofluoran (compound of the above formula (9)) was obtained. Yield 42.5 g, Yield 89.2%, mp 166
~ 167.5 ° C

Example 2 A. Synthesis of dipotassium salt of 4- (N, N-dipentyl) amino-2-hydroxy-2'-carboxybenzophenone 74.7 g of 3-dipentylaminophenol represented by the formula (11) in 60 ml of m-xylene and anhydrous Phthalic acid 5
7.7 g was added and reacted at 80 ° C. for 18 hours.

[0034]

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To the reaction mixture, 300 ml of water and 20 g of potassium hydroxide were added, and heated to 80 ° C. to produce 4- (N,
N-dipentyl) amino-2-hydroxy-2'-carboxybenzophenone (compound of formula (14) described below)
Was dissolved. After separating m-xylene, the product was washed twice with 150 ml of m-xylene at the same temperature to remove by-product rhodamine-type red dye. After making the liquid volume 500 ml and adding 55 g of potassium hydroxide (11% based on the liquid volume) at the same temperature,
The mixture was cooled to 20 ° C. with stirring. The precipitated crystals are filtered,
Washed with 450 ml of 11% aqueous potassium hydroxide solution. After drying, a dipotassium salt of 4- (N, N-dipentyl) amino-2-hydroxy-2'-carboxybenzophenone represented by the formula (12) was obtained. Yield 137.8 g, purity (HPLC) 87.4%
(Containing about 12% of an inorganic substance such as potassium hydroxide), and a yield of 84.9%

[0036]

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B. 2-anilino-3-methyl-6
Synthesis of (N, N-dipentyl) aminofluoran dipotassium salt of 4- (N, N-dipentyl) amino-2-hydroxy-2′-carboxybenzophenone in 180 g of concentrated sulfuric acid (compound of formula (12) above) 54.1)
g was dissolved at 20-25 ° C. At that time, no lump was formed at all, and it could be dissolved smoothly. Next, 2-methyl-4-methoxydiphenylamine (the compound of the above formula (8))
Dissolve 23.4 g at 10-15 ° C, then 10-15
Reaction was carried out at 48 ° C for 48 hours. The reaction product was discharged into 500 ml of ice water, and the precipitate was filtered and washed with water. M the cake obtained
-In 150 ml of xylene, diluted sodium hydroxide was added to adjust the pH of the aqueous layer to 12, and the mixture was stirred at 90 ° C for 1 hour. The xylene layer was separated, added with 2 g of activated carbon, filtered while hot, and cooled to 10 ° C. with stirring to crystallize. The precipitated crystals were filtered and dried to obtain pure 2-anilino-3-methyl-6- (N, N-dipentyl) aminofluoran represented by the formula (13). Yield 49.8 g, Yield 88.9%, mp181-1
82 ° C

[0038]

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Comparative Example 2 A. Preparation of 4- (N, N-dipentyl) amino-2-hydroxy-2′-carboxybenzophenone (free oxidation of potassium salt) 4- (N, N-dipentyl) amino- obtained in Example 2
2-hydroxy-2'-carboxybenzophenone 2
Potassium salt (compound of formula (12) above) 54.1 g
Was dissolved in 300 ml of water. Dilute sulfuric acid was gradually added thereto at room temperature to neutralize to PH5. The resulting lump is treated with Ruen 7
Heated to 0 ml to dissolve. After the solution was concentrated, it was cooled to precipitate crystals. After filtration and drying, crystals of 4- (N, N-dipentyl) amino-2-hydroxy-2′-carboxybenzophenone represented by the formula (14) were obtained. Yield 38.4 g, purity (HPLC) 98.0%,
94.8% yield, mp 116-118 ° C

[0040]

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B. 2-anilino-3-methyl-6
Synthesis of (N, N-dipentyl) aminofluoran 4- (N, N-dipentyl) amino-2-hydroxy-2′-carboxybenzophenone (compound of formula (14) described above) in 150 g of concentrated sulfuric acid. 20 to 2
Dissolved at 5 ° C. Lumps were formed and took time to dissolve.
Next, 22.2 g of 2-methyl-4-methoxydiphenylamine (the compound of the above formula (8)) was dissolved at 10 to 15 ° C. Then, the same treatment as in Example 2 was carried out and pure 2-anilino-3-methyl-6- (N,
N-dipentyl) aminofluorane ((13)
A compound of the formula) was obtained. Yield 47.0 g, Yield 88.5%, mp181-
182 ° C

Example 3 A. Synthesis of disodium salt of 4- (N, N-diethyl) amino-2-hydroxy-2'-carboxybenzophenone 3-120 represented by the formula (15) in 120 ml of toluene
49.5 g of (N, N-diethyl) aminophenol and 57.8 g of phthalic anhydride were added and reacted at 90 ° C. for 20 hours.

[0043]

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To the reaction mixture were added 300 ml of water and 60 g of a 48% aqueous sodium hydroxide solution, and the mixture was heated to 80 ° C. to produce 4
-(N, N-diethyl) amino-2-hydroxy-2 '
-Carboxybenzophenone (compound of the formula (19) described later) was dissolved. After separating the toluene layer, the alkaline solution was washed twice with 150 ml of toluene at the same temperature to remove by-product rhodamine-type red dye. 500m with water
Then, 62 g of 48% caustic soda (6% based on the liquid amount) was added at 80 ° C. Thereafter, the mixture was cooled to 20 ° C. while stirring. The precipitated crystals were filtered and washed with 300 ml of a 6% aqueous sodium hydroxide solution. After drying, 4- (N, N-diethyl) amino-2-hydroxy- represented by the formula (16)
The disodium salt of 2'-carboxybenzophenone was obtained. Yield 108.5 g, purity (HPLC) 90.5%
(Containing 9.5% of inorganic substances such as sodium hydroxide),
91.7% yield

[0045]

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B. 2-anilino-3-methyl-6
Synthesis of (N, N-diethyl) aminofluoran 4- (N, N-diethyl) amino-fluoride in 180 g of concentrated sulfuric acid
2-hydroxy-2'-carboxybenzophenone 2
Sodium salt (compound of the above formula (16)) 39.4
g was dissolved at 20-25 ° C. At that time, no lump was formed at all, and it could be dissolved smoothly. Then, 2-methyl-4-methoxydiphenylamine represented by the formula (17) 23.4
g was dissolved at 10-15 ° C. Then at 10-15 ° C 4
The reaction was performed for 8 hours.

[0047]

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The reaction product was discharged into 500 ml of ice water, and the precipitate was filtered and washed with water. The obtained cake is washed with toluene 30
0 ml, diluted caustic soda, and the pH of the aqueous layer.
And then stirred at 90 ° C. for 1 hour. The toluene layer was separated, added with 2 g of activated carbon, filtered while hot, and then heated at 10 ° C.
The mixture was cooled with stirring until crystallization. After filtering the precipitated crystals,
After drying, pure 2-anilino represented by formula (18)
3-Methyl-6- (N, N diethyl) aminofluoran was obtained. Yield 43.5 g, 91.5% yield, mp 195
~ 197 ° C

[0049]

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Comparative Example 3 A. Preparation of 4- (N, N-diethyl) amino-2-hydroxy-2′-carboxybenzophenone (free oxidation of sodium salt) 4- (N, N-diethyl) amino-2 obtained in Example 3
Disodium salt of -hydroxy-2'-carboxybenzophenone (compound of the above formula (16)) 39.4 g
Was dissolved in 300 ml of water. Dilute sulfuric acid was gradually added thereto at room temperature to neutralize to pH 5.5. The obtained crystals are filtered,
Drying yielded 4- (N, N-diethyl) amino-2-hydroxy-2'-carboxybenzophenone represented by the formula (19). Yield 31.2 g, purity (HPLC) 99.0%, yield 98.8%, mp 199-201 ° C

[0051]

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B. 2-anilino-3-methyl-6
Synthesis of (N, N-diethyl) aminofluoran 4- (N, N-diethyl) amino-fluoride in 150 g of concentrated sulfuric acid
31.2 g of 2-hydroxy-2′-carboxybenzophenone (the compound of the above formula (19)) is added at 20 to 25 ° C.
And dissolved. Lumps were formed and could not be dissolved smoothly. Then, 23.2 g of 2-methyl-4-methoxydiphenylamine (the compound of the above formula (17)) was added to 10-1.
Dissolved at 5 ° C. Thereafter, the same treatment as in Example 3 was carried out to obtain pure 2-anilino-3-methyl-6 having the same structure as that of Example 3.
Thus,-(N, N-diethyl) aminofluoran (the compound of the above formula (18)) was obtained. Yield 42.8 g, 91.1% yield, mp 195
~ 197 ° C

Examples 4 to 26 By operating in the same manner as in Examples 1 to 3, fluoran compounds shown in the following table were synthesized. Shown together with the color hue and melting point of acid clay.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

[Table 5]

[0059]

According to the present invention, since a benzophenone carboxylic acid derivative in the form of an alkali metal salt is used as a raw material, almost no lumps are formed during dissolution in concentrated sulfuric acid, and smooth dissolution is possible. Further, the benzophenone carboxylic acid derivative is separated and purified as an alkali metal salt as in the related art, and can be used in the production of a fluoran compound as an alkali metal salt without being neutralized again and separated in the form of a free acid. Therefore, not only is it advantageous in terms of labor saving of the process, but also because there is no loss in the case of separation in the form of free acid, the yield is better than before, and it is industrially extremely advantageous.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C07D 493/10 B41M 5/18 105 F term (reference) 2H026 AA07 BB13 BB14 2H085 AA07 BB13 BB14 4C071 AA04 AA07 BB01 CC12 DD19 EE05 FF17 HH09 4H056 BA02 BB05 BB14 BC01 BD03 BF02F BF07F BF26F BF28E BF38F

Claims (4)

[Claims] A benzophenonecarboxylic acid derivative represented by the general formula (1) and a phenol derivative represented by the general formula (2) are reacted in a condensing agent. For producing fluoran compounds. Embedded image [Wherein, R ¹ and R ² represent an alkyl group, a cycloalkyl group,
It means an alkoxyalkyl group, a tetrahydrofurfuryl group, or a phenyl group which may have a substituent. Also, R ¹
And R ² may be linked to form a ring. M represents a sodium atom or a potassium atom. [Chemical formula 2] [Wherein, R ³ represents a hydrogen atom or an alkyl group, X ¹ represents a hydrogen atom or an alkyl group, and X ² represents a hydrogen atom, an alkyl group, a halogen atom, or an amino group represented by the general formula (3). And X ³ represents a hydrogen atom. Further, X ³ and adjacent X ¹ or X ² can be linked to form a benzene ring. [Chemical formula 3] [In the formula, R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aralkyl group, and a phenyl group which may have a substituent. [Formula 4] [Wherein, R ¹ , R ² , X ¹ , X ² , and X ³ have the same meaning as described above. ] 2. R ¹ is an alkyl group having 1 to 5 carbon atoms,
The method for producing a fluoran compound according to claim 1, wherein R ² represents a group selected from an alkyl group having 3 to 6 carbon atoms, a methoxypropyl group, and an ethoxypropyl group. 3. The method according to claim 1, wherein R ¹ and R ² are adjacent nitrogen atoms, and N-ethyl-N-iso-pentylamino, N, N-dipentylamino, N-methyl-NNn-propyl and N
The method for producing a fluoran compound according to claim 1, which means a group selected from -ethyl-N-iso-butyl group. 4. A compound according to claim 1, wherein R ¹ and R ² are adjacent nitrogen atoms, and N-ethyl-N-iso-pentylamino, N, N-dipentylamino, N-methyl-NNn-propyl and N
-Ethyl-N-iso-butyl group, X ¹ represents a hydrogen atom or a methyl group, X ² represents a dibenzylamino group, an unsubstituted anilino group, or a methyl group,
2. An anilino group substituted by a chlorine atom or a trifluoromethyl group, and X ³ represents a hydrogen atom.
A method for producing the fluoran compound as described above.