JP3188501B2 - New fluoran compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel fluoran compound, and more particularly to a fluoran compound which is useful as a recording material, for example, a color-forming compound for pressure-sensitive or heat-sensitive recording.

[0002]

2. Description of the Related Art Conventionally, for example, 3-N, N-diethylamino-6-methyl-7-anilinofluoran is a color-forming compound that develops black color, and is useful as a color-forming compound for recording materials. It is known that
8-43296). Also, for example, 3-N, N-
Di-n-butylamino-7- (2'-chlorophenyl)
Aminofluorane is a color-forming compound that develops black color, and is known to be useful as a color-forming compound for recording materials (Japanese Patent Publication No. Sho 60-53069). However, these existing fluoran compounds cannot be said to have sufficient performance in terms of color development performance and storage stability of a color image, and further improvement is strongly desired at present.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel compound having excellent performance in color development and storage stability of a color image, which is useful as a color-forming compound for forming a black color for recording materials. It is to provide a fluoran compound.

[0004]

Means for Solving the Problems The inventors of the present invention have synthesized many compounds in order to achieve the above object, and as a result of intensive studies, they have reached the present invention. That is, the present invention provides a compound represented by the general formula (1):

[0005]

Embedded image (Wherein, R ₁ represents a methyl group or an n-propyl group,
R ₂ and R ₃ represent a methyl group).

The fluoran compound represented by the general formula (1) of the present invention is typically a benzoic acid derivative represented by the following general formula (2)

[0007]

Embedded image (Wherein, R ₁ has the same meaning as in formula (1))
And a diphenylamine derivative represented by the general formula (3)

[0008]

Embedded image (Wherein R ₂ and R ₃ have the same meanings as in the case of the general formula (1), and R ₄ represents an alkyl group having 1 to ₄ carbon atoms) and a dehydrating condensing agent, for example, concentrated sulfuric acid, fuming In the presence of a dehydrating condensing agent such as concentrated sulfuric acid to which sulfuric acid has been added, polyphosphoric acid, phosphorus pentoxide, anhydrous aluminum chloride and the like, particularly preferably, the reaction is carried out in concentrated sulfuric acid, and after discharging into ice water, the resulting cake is obtained. Can be produced by alkali treatment.

The dehydration-condensation reaction is usually carried out in a temperature range of 0 to 100 ° C. for several hours to several tens of hours. When the reaction is performed in concentrated sulfuric acid, the reaction temperature is particularly preferably in the range of 0 to 50 ° C. Since the reaction time depends on the reaction temperature, it is necessary to perform the reaction for a sufficient time. Also,
The alkali treatment to be performed after the dehydration condensation is preferably performed at a temperature of 0 to 100 ° C., preferably 40 to 100 ° C. with an aqueous solution of potassium hydroxide, sodium hydroxide or the like to adjust the pH to about 9 to 13, and the reaction time Depends on the reaction temperature, but usually takes tens of minutes to several hours. In the alkali treatment, the alkali treatment may be performed in the presence of an organic solvent other than water, such as benzene, toluene, xylene, and chlorobenzene. In this case, the generated fluoran compound can be extracted into the organic solvent. The fluoran compound thus produced can be purified, if necessary, by a known purification method such as recrystallization or column chromatography to increase the purity.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 Preparation of 3-N, N-dimethylamino-6-methyl-7- (3′-methylphenyl) aminofluoran compound 2- (4′-N, N-dimethylamino-2′-hydroxybenzoyl) 62 g of benzoic acid is added to 300 ml of concentrated sulfuric acid.
After dissolution at 0 ° C, (2-methyl-4-methoxyphenyl)
50 g of-(3'-methylphenyl) amine [in the formula (3), R ₂ and R ₃ are methyl groups and R ₄ is a methyl group] are added at the same temperature, and the mixture is stirred at 10 to 25 ° C. for 30 hours. . The reaction mixture was discharged into 1500 ml of ice water, and the precipitated solid was collected and washed with water.
% NaOH aqueous solution (600 ml), and toluene 60
After adding 0 ml, the mixture was stirred at 60 to 70 ° C for 3 hours. The toluene layer was separated, washed with warm water until neutral, the toluene layer was separated, and toluene was distilled off under reduced pressure. After 300 ml of methanol was added to the residue and left at room temperature, the precipitated crystals were separated by filtration. Further, the crystals were recrystallized from toluene to give almost colorless crystals of the desired 3-N,
70 g of N-dimethylamino-6-methyl-7- (3′-methylphenyl) aminofluoran compound was obtained. Melting point 205-207 ° C ¹ H-NMR (DMSO-d ₆ ) δ = 2.1 (s, 3H), 2.3 (s, 3H), 2.8
(S, 6H), 6.4-8.1 (m, 14H) This fluoran compound is 45% in 95% acetic acid aqueous solution.
The absorption maximum was shown at 0 nm and 595 nm. The toluene solution of this fluoran compound was colorless and transparent, and quickly developed black on silica gel.

Example 2 Preparation of 3-N, N-di-n-propylamino-6-methyl-7- (3'-methylphenyl) aminofluoran compound In Example 1, 2- (4'-N , N-Dimethylamino-2′-hydroxybenzoyl) benzoic acid is replaced by 2- (4′-N, N-di-n-propylamino-
Other than using 2'-hydroxybenzoyl) benzoic acid,
According to the method described in Example 1, 3-N, N-di-n-
A propylamino-6-methyl-7- (3'-methylphenyl) aminofluoran compound was produced. 138-140 ° C ¹ H-NMR (DMSO-d ₆ ) δ = 0.9-1.8 (m, 10H), 2.1 (s, 3)
H), 2.3 (s, 3H), 3.1 to 3.6 (m, 4
H), 6.4-8.1 (m, 14H) This fluoran compound is 45% in 95% acetic acid aqueous solution.
The absorption maximum was shown at 0 nm and 595 nm. The toluene solution of this fluoran compound was colorless and transparent, and quickly developed black on silica gel.

[0012]

According to the present invention, there is provided a novel fluoran compound which is useful as a color-forming compound for forming a black color for a recording material and has excellent performance in color development and storage stability of a color image. It is.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-163275 (JP, A) JP-A-59-120654 (JP, A) JP-A-61-74883 (JP, A) JP-A-57-120 190049 (JP, A) JP-A-54-34909 (JP, A) JP-A-58-52356 (JP, A) JP-A-53-25106 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C07D 493/10 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A fluoran compound represented by the general formula (1) (formula 1). Embedded image (Wherein, R ₁ represents a methyl group or an n-propyl group,
R ₂ and R ₃ represent a methyl group)