JPH04187687A - Preparation of fluorane compound - Google Patents

Abstract

PURPOSE:To prepare the subject compound useful as an electron-donating colorless dye which has an indolenine ring in a part of the nucleus and can be developed into a red color, by reacting an alkoxy-substituted indolenine derivative with a hydroxy-substituted aminobenzoylbenzoic acid. CONSTITUTION:A 5-alkoxy-2-R3-3-R4,R5-substituted indolenine derivative (R3-R5 are H, alkyl, aryl, acyl, substituted amino, or R3-R5 may form a ring comprising non-metal atoms at the adjacent positions) (e.g. 5-methoxy-2-methyl-3,3- dimethylindolenine) 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 5B-87094, similar compounds have been actively researched and developed since then. 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 indolenine ring.

The present inventors focused on this point and conducted various studies, and when they attempted to react a substituted indolenine derivative with 2- and 4-substituted aminobenzoylbenzoic acid, they found that the reaction proceeded smoothly. It was recognized that this was the case, and the present invention was completed.

(Object of the Invention) Therefore, the first object of the present invention is to provide a fluoran compound having an indolenine ring partial skeleton. The second objective is to provide a fluorane derivative with improved resistance. The third objective is to provide a fluoran compound that develops a vermilion color.

(Structure of the Invention) The object of the present invention is to react a 5-flucoxy 2-R, -3-R,,R, substituted indolenine derivative with a 2-human O-xy 4-substituted aminohenzoylbenzoic acid. A method for producing a fluoran compound having an indolenine ring in its characteristic partial skeleton.

(However, R, , Ri, R are hydrogen atoms, alkyl groups,
It represents a monovalent group selected from an aryl group, an acyl group, and a substituted amino group, and may form a ring consisting of nonmetallic atoms at adjacent positions. ) was achieved by developing.

This was achieved by developing

5-alkoxy-2-R, -3-R4 used in the present invention
, various compounds are used as the R5-substituted indolenine derivative.

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

R4, R5, and R represent 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. It is selected from a furkyl group or an aryl group that it may have. 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 18 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, diethylamide 7 groups, dibutylamino groups, N-
Ethyl-N-)luidino group, N-ethyl-N=furfuryl-N-methyl group, N-ethyl-N-isobuOvir group,
N-ethyl-N-dimethylanilino group, N-ethyl-N
-isoamyl group, etc. Among these, diethylamino group, dibutylamino group, N-ethyl-N-phenoxyethylamino group, etc. are particularly advantageous in terms of reactivity, handling, and availability of raw materials.

5-Alkoxy-2-R, -3-R4, R5-substituted indolenine derivative 1 can be easily obtained by reaction of a carbonyl compound having a secondary carbon atom at the α-position with 4-alkoxyphenylhydrazine.

Specific examples of substituted indolenine derivatives include the following.

5-methoxy-indolenine, 5-butoxy-indolenine, 5-methoxy-2-methyl-3゜3-diethylindolenine, 5-methoxy-2-methyl-3,3-dimethylindolenine, 5-methoxy-indolenine 2-benzyl-3,
3-diphenylindolenine, 5-methoxy-2-methyl-3,3-pentamethyleneindolenine, 5-methoxy-3゜3-pentamethyleneindolenine, 5-methoxy-3,3-dimethylindolenine, 5- Methoxy-2
-Methyl-3-methyl-3-ethylindolenine, 5-
Methoxy-2-phenyl-3,3-dimethylindolenine, 5-methoxy-2-methyl-3,3-diphenylindolenine, 5-hensyloxy-2-phenyl-3,
Examples include 3-diphenylindolenine.

By the production method of the present invention, a colorless dye that usually develops a magenta to red color can be obtained very easily. The hue changes depending on the color developer used.

Next, the fluoran compound produced in the present invention is indicated by -, although the present invention is not limited to these, R, , R, and, as mentioned above, an aryl group.

Indicates a hydrogen atom or an alkyl group.

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

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.

For example, the reaction conditions, temperature time, post-treatment, etc.
839334.0LS3838374, JP-A-1-21
1591, etc., and you can refer to them.

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

Example 1 0.01 mol of 5-methoxy-2-methyl-3,3-dimethylindolenine and 0.01 mol of 2-hydroxy-4-dibutylamino-benzoylbenzoic acid were cooled in ice.
Measure into 8 milliliters of sulfuric acid and 2 milliliters of fuming sulfuric acid. Stir at room temperature for 2 hours, then mix at 30℃~4
After stirring for 1 hour at 0° C., the product was isolated by pouring with stirring into water-cooled alkaline water in which two molar equivalents of caustic soda had been dissolved.

Column chromatography using silica gel with hexane/ethyl acetate as a developing solvent gave the desired product, which turned vermilion on contact with BPA and had a molecular weight of 508 and a melting point of 218 to 219°C.

Example 2 A fluoran having an indolenine ring in the partial skeleton was prepared in the same manner as in Example 1 except that 2-hydroxy-4-dibutylaminobenzoylbenzoic acid was changed to 2-human Oxy-4-diethylaminobenzoylbenzoic acid. I got it.

The molecular weight was 452.

Upon contact with BPA, it took on a bright vermilion color.

Claims (1)

[Scope of Claims] An indolenine ring in a partial skeleton characterized by reacting a 5-alkoxy-2-R_3-3-R_4, R_5 substituted indolenine derivative with 2-hydroxy-4-substituted amino-benzoylbenzoic acid. A method for producing a fluoran compound having the following. (However, R_3R_4R_5 is a hydrogen atom, an alkyl group,
It represents a monovalent group selected from an aryl group, an acyl group, and a substituted amino group, and may form a ring consisting of nonmetallic atoms at adjacent positions. )