JPH04187688A - Preparation of fluorane compound - Google Patents

Abstract

PURPOSE:To prepare the subject compound useful as an electron-donating colorless dye and having an indole ring in a part of the nucleus, by reacting an alkoxy-substituted indole derivative with a hydroxy-substituted aminobenzoylbenzoic acid. CONSTITUTION:A 5-alkoxy-1-R3-2-R4-3-R5-substituted indole derivative (R3-R5 are H, alkyl, aryl, acyl, amino, or R3-R5 may form a ring comprising non-metal atoms at the adjacent positions) (e.g. 6-methoxy-9-methyl-1,2,3,4- tetrahydrocarbozole) is reacted with a 2-hydroxy-4-substituted amino- benzoylbenzoic acid (e.g. 2-hydroxy-4-dibuthylamino-benzoylbenzoic acid) preferably in a molar ratio of 1.1/1 to 1/1.1 in the presence of a dehydrative catalyst to provide the objective compound of the formula (R1, R2 are aryl, H, alkyl).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing fluoran compounds useful as electron-donating colorless dyes.

(Prior Art) Recording materials using an electron-donating colorless dye and an electron-accepting compound are known as pressure-sensitive paper, heat-sensitive paper, light-sensitive pressure-sensitive paper, electrically conductive heat-sensitive recording paper, and the like. For example, UK patent 214044
9. U.S. Pat. No. 4,480,052, U.S. Pat.
0-123556, 60-123557, etc. are detailed.

In recent years, as recording systems have become faster and more diverse, attempts have been made to improve the sensitivity, functionality, and durability of recording materials.

For example, regarding thermofusible agents for increasing sensitivity, Japanese Patent Application Laid-Open No. 58
In addition to basic inventions such as -57989 and 58-87094, similar compounds have since been actively researched and developed. On the other hand, various skeletons of electron-donating colorless dyes are being studied with the aim of improving sensitivity and durability.

In particular, when it comes to fluoran compounds, which are one of the typical electron-donating colorless dyes that exhibit black color, we introduce long-chain alkyl groups into the fluoran ring, or replace the alkyl groups of dialkylamino groups with long-chain alkyl groups or branches. By changing to an alkyl group or making it a bis body,
Many attempts have been made to utilize the decrease in solubility in solvents.

In the past, there have been several studies on fluorane having a hydroquinoline ring structure, and interesting properties such as robustness and light resistance have been recognized. However, there have been almost no studies on fluorane having an indole ring or a hydrocarbazole ring.

The present inventors paid attention to this point, made various studies, and attempted to react a substituted indole derivative with a 2-hydroxy-4-substituted amino-benzoylbenzoic acid. Contrary to expectations, it was found that the reaction proceeded smoothly, leading to the present invention.

After further investigation, it was discovered that even if the indole ring has a cyclic structure like a hydrocarbazole ring, the formation of a fluorane ring proceeds smoothly.

(Object of the Invention) Therefore, the object of the present invention is to provide a fluoran compound having an indole ring partial skeleton.

The second object is to provide a fluoran compound having a hydrocarbazole ring partial skeleton.

(Structure of the Invention) An object of the present invention is to react a 5-alkoxy-1-R, -2-R, -3-R2-substituted indole derivative with a 2-hydroxy-4-substituted amino-benzoylbenzoic acid. A method for producing a fluoran compound having an indole ring in its partial skeleton (where R, R, Fl are hydrogen atoms, alkyl groups,
It represents a monovalent group selected from an aryl group, an acyl group, and an amino group, and may form a ring consisting of nonmetallic atoms at adjacent positions. ) was achieved by developing.

5-alkoxy-1-R, -2-R, used in the present invention,
Various compounds can be used as the -3-R, substituted indole derivative.

The 5-alkoxy group is conveniently a group derived from a lower alkyl group, for example an alkoxy group derived from an alkyl selected from methyl, ethyl, butyl and the like.

R3, R4, and R5 each have a hydrogen atom, an acyl group, a substituent such as a halogen atom, a hydroxy group, an acyl group, an alkoxy group, an aryloxy group, a cyano group, an alkyl group, an alkenyl group, a nitro group, an unsaturated bond, etc. selected from optionally alkyl groups or aryl groups. These are 5 atoms consisting of non-metallic atoms interconnected at adjacent positions.
A ring having 1 to 12 members may be formed.

On the other hand, as the 2-hydroxy-4-substituted amino-benzoylbenzoic acid, a compound having a substituted amino group having 13 or less carbon atoms, especially a di-substituted amino group is preferable.

The production methods for these are already well known, and many compounds are known. Examples of the di-substituted amino group include those substituted with groups selected from alkyl groups and aryl groups. They may also be bonded to each other to form a piperidine ring, a piperazine ring, a morpholine ring, or the like.

For example, diethylamino group, dibutylamino group, N-
Ethyl-N-toluidino group, N-ethyl-N-furfuryl-N-methyl group, N-ethyl-N-isobrobyl group,
N-ethyl-N-dimethylanilino group, N-ethyl-N
-isoamyl group, etc. Among these, diethylamino group and dibutylamino group are particularly advantageous in terms of reactivity, handling, and availability of raw materials.

5-alkoxy-1-R, -2-R, -3-R.

Specific examples of substituted indole derivatives include the following.

5-Metho-cow sea-indole, 5-buto-cow sea-indole, 5-methoxy-1-ethylindole, 5-methoxy-1-benzylindole, 5-methoxy-1-benzyl-2-methylindole, 5-methoxy-1 -Methylbenzyl-2-ethylindole, 5-methoxy-1-
Octylindole, 5-methoxy-1-benzyl-2
-butylindole, 5-methoxy-1-methyl-2-
Phenylethylindole, 5-methoxy-1,2-di-phenylindole, 5-methoxy-1-benzoylindole, 5-methoxy-1-benzoyl-2-methylindole, 5-methoxy-1-methoxybenzoyl-2- Ethylindole, 5-methoxy-1-octanoyl-2-phenylindole, 6-medoxy 1-ethyltetrahydrocarbazole, 6-medoxy 1-phenyltetrahydrocarbazole, 6-medoxy 1-
Acetyltetrahydrocarbazole, 5-methoxy-3
, 2-di-phenylindole, 6-ptoxy-1-toluidino-tetrahydrocarbazole and the like.

The condensation reaction is carried out in the presence of a dehydration catalyst according to a normal fluorane ring formation reaction. The molar ratio of the reaction is 1/2 to 2
/1, particularly preferably 1.1/1 to 1/1.1.

Reaction conditions, temperature and time, post-treatment, etc. are described, for example, in U.S. Pat.
839334.0LS3838374, JP-A-1-21
1591, etc., and you can refer to them.

In the method of the present invention, it is possible to easily obtain a colorless dye that usually develops a color from magenta to red.

Next, the fluoran compounds produced in the present invention are indicated by -, but the present invention is not limited thereto.As mentioned above, R, , and R indicate an aryl group, a hydrogen atom, or an alkyl group. .

R,, Rt, and R represent the groups described above.

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

Example 1 0.01 mol of 6-medoxy-9-ethyl-1,2,3,4-titrahydrorubazole and 2-hydroxy-4-
0.01 mol of dibutylamino-benzoylbenzoic acid,
Weigh it into 8 ml of ice-cold concentrated sulfuric acid and 2 ml of fuming sulfuric acid. The product was stirred at room temperature for 2 hours, then at 30°C to 40°C for 1 hour, and then poured into water-cooled alkaline water in which twice the molar equivalent of caustic soda had been dissolved, with stirring, to isolate the product.

Column chromatography using silica gel with hexane/ethyl acetate as the developing solvent revealed a magenta color upon contact with BPA, a molecular weight of 548 and a melting point of 199-200°.
The target product C was obtained.

Example 2 6-medoxy-9-ethyl-1,2,3, of Example 1
4-tetrahydrocarbazole, 6-medoxy 1.
2.3. In the same manner as above, except that 4-tetrahydrocarbazole was used and 2-hydroxy-4-dibutylamino-benzoylbenzoic acid was changed to 2-hydroxy-4-diethylamino-benzoylbenzoic acid, an indole ring was added to the partial skeleton. A fluorane having the following properties was obtained. Melting point: 305℃ All of these have a 6-tetrahydrocarbazole ring.
It was a fluoran cyclized at the 7- and 7-positions.

Example 3 6-medoxy-9-ethyl-1,2,3, of Example 1
4-tetrahydrocarbazole, 6-medoxy9-
A fluoran having an indole ring in the partial skeleton was obtained in the same manner except that phenyl-1,2,3,4-tetrahydrocarbazole was used. The compound with a melting point of 226° took on a deep purple color upon contact with BPA.

Claims (1)

[Claims] 5-alkoxy-1-R_3-2-R_4-3-R_5
1. A method for producing a fluoran compound having an indole ring in a partial skeleton, the method comprising reacting a substituted indole derivative with 2-hydroxy-4-substituted amino-benzoylbenzoic acid. (However, R_3, R_4, and R_5 represent a monovalent group selected from a hydrogen atom, an alkyl group, an aryl group, an acyl group, and an amino group, and may form a ring consisting of a nonmetallic atom at the adjacent position. .)