JPH06128497A - Fluoran compound and its production - Google Patents

Abstract

PURPOSE:To obtain a new compound, syhthesized from an indoline derivative and a 2-hydroxybenzoylbenzoic acid derivative, good in shelf life, light and chemical resistance and useful as an electron donative colorless dye, etc., for heat-sensitive paper, pressure-sensitive paper, photosensitive pressure-sensitive paper, etc. CONSTITUTION:An indoline derivative expressed by formula I [R5 to R<8> are H, (substituted)alkyl, aryl, etc.; R10 are lower alkyl; R6 is H, halogen, alkyl, aryl or alkoxy] (e.g. 2-methyl-3,3-dimethyl-5-methoxyindoline) is made to react with a 2-hydroxybenzoylbenzoic acid derivative expressed by formula II [R1 and R2 are H, (substituted)alkyl or aryl; R3 and R4 are H, acyl, alkyl, alkoxy, halogen, nitro or aryl; Ra is H, halogen, alkyl, aryl or alkoxy] (e.g. 2-hydroxy-4- diethylaminobenzoylbenzoic acid) to afford the objective fluoran compound expressed by formula III (X is alkylene required to form a 5-membered ring).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a fluoran compound useful as an electron-donating colorless dye for various recording materials such as thermal paper, pressure-sensitive paper, and light-sensitive pressure-sensitive paper, and a method for producing the same.

[0002]

2. Description of the Related Art Recording materials using an electron-donating colorless dye and an electron-accepting compound are pressure-sensitive paper, thermal paper, photosensitive pressure-sensitive paper,
It is already well known as a multicolor recording film and the like. For example, British Patents 2140449, 2165953, and 2
166882, 2174504, U.S. Pat.
No. 52, No. 4436920, Japanese Patent Publication No. 60-23992, JP-A No. 57-179836, No. 60-123556, and No. 6
0-123557, 61-230134 and so on. The recording material should have (1) sufficient color density and color sensitivity, (2) no fog, (3) sufficient fastness of the color body after color development, 4) Color hue is appropriate and copier suitability,
(5) The S / N ratio is high, and (6) the color-developing body has sufficient chemical resistance. In recent years, with the speeding up of recording systems and the diversification of requirements, research has been earnestly conducted to improve these characteristics. The present inventors have found a new material in which the characteristics of the recording material are significantly improved by incorporating a unique device into the electron-donating colorless dye.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluoran compound which is thermally stable and has excellent storage stability and light resistance, and a method for producing the same.

[0004]

The above object has been achieved by developing a fluoran compound represented by the general formula (1). General formula (1)

[0005]

[Chemical 5]

In the formula, R ₁ and R ₂ represent a hydrogen atom, an optionally substituted alkyl group or an aryl group, and R ₃ and R 2
₄ represents a hydrogen atom, an acyl group, an alkyl group, an alkoxy group, a halogen atom, a nitro group or an aryl group, and R ₅
Represents a hydrogen atom, an optionally substituted alkyl group, or an aryl group. R _a and R _b represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. X represents an alkylene group necessary for forming a 5-membered ring. General formula (1)
The compound of 1 is obtained by reacting the indoline derivative represented by the general formula (3) with the 2-hydroxybenzoylbenzoic acid derivative represented by the general formula (4). General formula (3)

[0007]

[Chemical 6]

In the formula, R _{5 to} R ₉ represent a hydrogen atom, an optionally substituted alkyl group or an aryl group, and R ₈ and R ₉
May combine with each other to form a 5- or 6-membered ring. R
₁₀ represents a lower alkyl group. R _b represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. General formula (4)

[0009]

[Chemical 7]

In the formula, R ₁ and R ₂ represent a hydrogen atom, an optionally substituted alkyl group or an aryl group, and R ₃ and R 2
₄ represents a hydrogen atom, an acyl group, an alkyl group, an alkoxy group, a halogen atom, a nitro group or an aryl group. _Ra
Represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. The electron-donating colorless dye according to the present invention has an advantage that its solubility in an organic solvent can be easily controlled, and that it rapidly develops color when brought into contact with an electron-accepting substance. The colored dye is remarkably stable as compared with the dyes generated from the existing color formers, and hardly discolors due to long-term light irradiation or heating, which is particularly advantageous from the viewpoint of long-term storage of records. Further, the stability of the color forming agent is excellent, it does not cause deterioration even after long-term storage and has a sufficient color forming ability, and it has a performance close to ideal as a color forming agent for recording materials such as pressure sensitive paper and thermal paper.

Specific examples of the indoline derivative represented by the general formula (3) used in the present invention are shown below.

[0012]

[Chemical 8]

4-substituted amino-represented by the general formula (4)
Specific examples of the 2-hydroxybenzoylbenzoic acid derivative include 2-hydroxy-4-diethylaminobenzoylbenzoic acid, 2-hydroxy-4-dibutylaminobenzoylbenzoic acid, 2-hydroxy-4-N-ethyl-p-.
Toluidino-benzoylbenzoic acid, 2-hydroxy-4
-N-ethyl-N-isobutyl-benzoylbenzoic acid,
2-Hydroxy-4-N-ethyl-N-tetrahydroxyfurfurylmethyl-benzoylbenzoic acid, 2-hydroxy-4-N-ethyl-N-isoamyl-benzoylbenzoic acid, 2-hydroxy-4-N-ethyl- N-γ-phenoxypropyl-benzoylbenzoic acid, 2-hydroxy-4-N-propyl-N-γ-p-ethylphenoxypropyl-benzoylbenzoic acid, 2-hydroxy-4-
N-ethyl-N-cyclohexylamino-benzoylbenzoic acid and the like can be mentioned.

The compound of the present invention is synthesized by various production methods. For example, a method using the indoline derivative represented by the general formula (3) and the compound represented by the general formula (4) is a preferable example. In this case, the compound of the general formula (3) and the general formula (4)
It is preferable to prepare the compound of 1) in an acidic solvent using 1: 1 to 1: 1.5 molar equivalent. These are -10 to 50 ℃
The reaction is preferably carried out for 2 to 8 hours, and when the acidic solvent is sulfuric acid, 60% or more, and the sulfuric acid concentration is preferably 80 to 100%. Higher concentrations than more dilute acids are effective in keeping the reaction liquid. Other acidic condensation solvents may also be used, for example mixtures of sulfuric acid with fuming sulfuric acid, phosphoric anhydride, polyphosphoric acid and certain Lewis acids such as zinc chloride, phosphorus oxychloride. Sulfuric acid is the preferred condensing agent because of its low cost, ease of handling and non-volatility, and the fact that the reaction can be easily cooled and diluted in ice water and then the reaction product can be directly processed. In addition, aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as monochlorobenzene, dichlorobenzene and chloroform, and alcohols such as methanol, ethanol and propanol are used as recrystallization solvents as needed. Alternatively, ethyl acetate, hexane or the like is used. Specific examples of the compound of the present invention are shown below.

[0015]

[Chemical 9]

[0016]

[Chemical 10]

[0017]

[Chemical 11]

[0018]

[Chemical 12]

Examples will be shown below, but the present invention is not limited to these examples.

[0020]

【Example】

Example 1 Synthesis of compound represented by specific example (1) (Synthesis of 2-methyl-3,3-dimethyl-5-methoxyindoline) 25 g of 4-methoxyphenylhydrazine hydrochloride, 15 g of methyl isopropyl ketone and 190 acetic acid
cc and 20 cc of water are reacted at 70 ° C. for 3 hours and then at 95 ° C. for 2 hours. Slowly pour the reaction solution into diluted aqueous sodium hydrogen carbonate to neutralize, extract with ethyl acetate, and perform column chromatography using silica gel with hexane / ethyl acetate as a developing solvent to give 5-methoxy-2-methyl-3,
3-Dimethylindolenine was isolated. The isolated 5
Raney nickel [Kawaken Fine Chemical Co., Ltd. (Raray NDNT-90)] catalyst amount of -methoxy-2-methyl-3,3-dimethylindolenine was weighed in 200 cc of ethanol and stirred under hydrogen pressure at 80 ° C for 8 hours. Raney nickel in the reaction solution is carefully filtered to remove hexane /
By column chromatography using silica gel with ethyl acetate as a developing solvent, 5-methoxy-2-methyl-
Obtained 3,3-dimethylindoline. The NMR spectrum is shown below. (Solvent, deuterated chloroform) (δ, pp
m) 1.05 (s) 3H, 1.15 to 1.20 (d) 3
H, 1.30 (s) 3H, 3.45-3.55 (q) 1
H, 6.55-6.70 (m) 3H. Next, 5 g of 5-methoxy-2-methyl-3,3-dimethylindoline obtained above and 8.5 g of 2-hydroxy-4-diethylaminobenzoylbenzoic acid were ice-cooled in 40 cc of concentrated sulfuric acid and 5 cc of fuming sulfuric acid. Weigh in. The mixture was stirred at room temperature for 4 hours and then reacted at 30 ° C. for 2 hours. Then, the product was isolated by pouring while stirring in twice the molar equivalent of caustic soda dissolved in ice-alkali water. By column chromatography using silica gel with hexane / ethyl acetate as a developing solvent, a target compound having a melting point of 238 ° C., which is black in contact with BPA and represented by specific example (1), was obtained.

Example 2 Synthesis of Compound Represented in Specific Example (2) Instead of 2-hydroxy-4-diethylaminobenzoylbenzoic acid of Example 1, 2-hydroxy-4-N-ethyl-p-toluidino- Benzoylbenzoic acid was used. Other than the above, the same method as in Example 1 was used to obtain the target product having a melting point of 230 ° C., which is represented by a specific example (2) and exhibits a black color when contacted with BPA.

Example 3 Synthesis of Compound Represented by Specific Example (14) In place of 2-hydroxy-4-diethylaminobenzoylbenzoic acid of Example 1, 2-hydroxy-4-diethylaminobenzoylbenzoic acid was used. Other than the above, the same method as in Example 1 was carried out to obtain the target product represented by the specific example (14) which exhibited a black color upon contact with BPA.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C07D 491/20 7019-4C

Claims (3)

[Claims] 1. A fluoran compound represented by the general formula (1): In the formula, R ₁ and R ₂ represent a hydrogen atom, an optionally substituted alkyl group and an aryl group, R ₃ and R ₄ represent a hydrogen atom,
Acyl group, alkyl group, alkoxy group, halogen atom,
It represents a nitro group or an aryl group, and R ₅ represents a hydrogen atom, an optionally substituted alkyl group or an aryl group. R _a , R _b
Represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. X represents an alkylene group necessary for forming a 5-membered ring. 2. A fluorane compound represented by the general formula (2): In the formula, R ₁ and R ₂ represent a hydrogen atom, an optionally substituted alkyl group and an aryl group, R ₃ and R ₄ represent a hydrogen atom,
Acyl group, alkyl group, alkoxy group, halogen atom,
Represents a nitro group, an aryl group, R _{5 to} R ₉ represent a hydrogen atom, an optionally substituted alkyl group, an aryl group,
They may be joined at positions adjacent to each other to form a 5 or 6 membered saturated or unsaturated ring. R _a and R _b represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. 3. A method for synthesizing a fluorane compound according to claim 1, wherein the indoline derivative represented by the general formula (3) is reacted with the 2-hydroxybenzoylbenzoic acid derivative represented by the general formula (4). . General formula (3) In the formula, R _{5 to} R _{8 each} represent a hydrogen atom, an optionally substituted alkyl group or an aryl group, which are bonded at positions adjacent to each other to form a 5- or 6-membered saturated or unsaturated ring. You may form. R ₁₀ represents a lower alkyl group. R
_b represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group. General formula (4) In the formula, R ₁ and R ₂ represent a hydrogen atom, an optionally substituted alkyl group and an aryl group, and R ₃ and R ₄ represent a hydrogen atom, an acyl group, an alkyl group, an alkoxy group, a halogen atom and a nitro group. Group represents an aryl group. Ra represents _a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkoxy group.