JPH0218348B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel fluoran compound and a method for producing the same. More specifically, the present invention relates to the general formula () (In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 8 carbon atoms, and R ₃ represents an alkyl group, an alkoxyalkyl group, or a phenyl alkyl group having 1 to 8 carbon atoms. R ₄ represents an alkyl group having 1 to 8 carbon atoms. ~10 alkyl groups, alkoxyalkyl groups, alkoxyalkoxyalkyl groups,
Cycloalkoxyalkyl group, cycloalkoxyalkoxyalkyl group, phenylalkoxyalkyl group, phenylalkoxyalkoxyalkyl group, phenoxyalkyl group, phenoxyalkoxyalkyl group, cycloalkyl group, phenylalkyl group, acylalkyl group, cyanoalkyl group,
It represents a carboamide alkyl group, furyl alkyl group, furyl alkyloxyalkyl group, tetrahydrofuryl alkyl group or tetrahydrofuryl alkyloxyalkyl group, and the phenyl group contained in R ₃ or R ₄ is substituted with an alkyl group or a halogen. Good too. Further, R ₃ and R ₄ may be combined with -CH to form a cycloalkyl group, a tetralinyl group or an indanyl group. X is hydrogen, halogen or nitro group, n is 1
Or represents the number 2. ) A fluoran compound and its production method. Pressure-sensitive recording paper and heat-sensitive recording paper, which utilize a coloring reaction caused by the contact between an almost uncolored electron-donating substance and an almost uncolored electron-accepting substance, have evolved rapidly with the development of the current information age. Demand is increasing. Generally, pressure-sensitive recording paper is produced by dissolving an electron-donating white dye (hereinafter referred to as a coloring agent) in an organic solvent.
The top paper is emulsified into a few microns and microencapsulated with a polymer compound such as gelatin, and this is coated on a support, and the other side is coated with an electron-accepting substance (hereinafter referred to as a color developer) on the support. The microcapsules are destroyed by applying pressure such as pen pressure or hammer pressure, with the coated surfaces of the two facing each other.
This is a recording method in which the color forming agent in the capsule is released and transferred to the surface of the color developing agent to cause a color reaction and obtain a copied image. In addition, in thermal recording paper, a color forming agent and a color developing agent are supported in a binder (for example, a polymeric material such as polyvinyl alcohol) together with a solid flux, if necessary, so that the two do not come into contact with each other. The most common type of recording method is one in which at least one of a fluxing agent, a color former, and a color developer is melted by heating, and the color former and the color developer come into contact with each other, causing a color reaction to occur, thereby obtaining a recorded image. In addition, current-carrying heat-sensitive recording paper has a conductive layer containing a conductive agent between the support and the color forming layer (containing a color forming agent, a color developer, and a fluxing agent if necessary), and a voltage can be applied thereto. Therefore, this is a recording method in which a recorded image is obtained by generating a coloring reaction due to heat generation. In recent years, there has been an increasing demand for color formers that can produce black images due to the need to make copies from recording paper on which images have been obtained by the color reaction between the color former and the color developer under pressure or heat as described above. It's here. In principle,
A black image can also be obtained by mixing several suitable color formers of different hues, but
Since the speed of color development differs depending on the type of color former, and the light fastness, water resistance, etc. of the image also differ, there are drawbacks such as a change in hue depending on the storage condition of the recording paper. Therefore, efforts have been made to develop dyes that can produce black images using a single coloring agent, but no dye has yet been found that produces black images that are satisfactory in all aspects, including hue, fastness, self-color development, and cost. The current situation is that this is not the case. The present inventor has discovered that the fluoran derivative represented by the general formula () is itself a white crystal with no coloration, but when it comes into contact with an acidic substance, it develops a blackish color, and is highly durable and has excellent light resistance and water resistance. It has been found that this dye is useful as a coloring agent for highly sensitive pressure-sensitive or heat-sensitive recording paper. The fluoran compound of the present invention can be produced, for example, as follows. (A) General formula () (In the formula, R ₁ , R ₂ , X, and n have the above-mentioned meanings.) A compound represented by the general formula () (In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and R ₃ and R ₄ have the above-mentioned meanings.) React for several hours to several tens of hours at around ℃. Next, the mixture is poured into water, made alkaline, and further heat-treated if necessary to obtain slightly colored white crystals. When this is separately dried and recrystallized, the fluoran derivative represented by the general formula () is obtained as white crystals. Sulfuric acid, phosphoric acid, polyphosphoric acid, etc. are used as the dehydrating agent when synthesizing the compound of general formula () from the compound of general formula () and the compound of general formula (). Sulfuric acid with a concentration of 85% to 100% is used. Further, as the recrystallization solvent, n-hexane, toluene, monochlorobenzene, chloroform, methyl isobutyl ketone, methyl cellosolve, isobutanol, isopropanol, dioxane, ethylene glycol dimethyl ether, etc. are used. Pressure-sensitive or pressure-sensitive recording paper can be produced by a conventional method using one or more of the color formers obtained in this way, or in combination with other color formers. The fluoran derivative represented by the general formula () of the present invention is a novel compound itself, and the recording paper using this compound is also novel. The fluoran derivative represented by the general formula () contains chlorine as a substituent at the 6-position and at the same time
In this position, there is an imino group bonded to the tertiary carbon, i.e.

[Formula] is characterized by containing a group. Recording paper obtained by using a fluoran derivative with such a novel and unique chemical structure as a coloring agent develops a deep black color.
It has particularly excellent storage stability, color development, light resistance, and water resistance. In other words, in pressure-sensitive paper using this coloring agent, there is less discoloration due to light in capsule-coated paper, and the light fastness of the colored image is excellent, and in thermal paper, uncolored paper is less discolored due to temperature and humidity, and coloring is less A major feature is that the image is less likely to change color due to temperature and humidity, or to fade due to light. Furthermore, when applied to multicolor thermosensitive recording paper, it develops vivid colors when heated, develops multiple colors without mixing colors, and is stable in storage. Furthermore, this color former has an extremely high solubility in organic solvents used in the production of pressure-sensitive recording paper. As described above, it is clear from an industrial perspective that the fluoran compound of the present invention greatly improves the drawbacks of color formers currently used in the market as color formers for use in pressure-sensitive recording paper or heat-sensitive recording paper. It is of high value. Next, examples of the compound represented by the general formula () used in the production of the fluoran compound of the present invention include the following. 2-(4'-N,N-diethylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-(4'-N,N-dimethylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-( 4'-N,N-dipropylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-(4'-N,N-dibutylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-(4 '-N,N-diamylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-(4'-N,N-dihexylamino-2'-hydroxybenzoyl)-3-naphthoic acid 2-(4'-N -ethyl-N-butylamino-
2'-Hydroxybenzoyl)-3-naphthoic acid 2-(4'-N,N-diethylamino-2'-hydroxybenzoyl)-5 or 8-chloro-3-
Naphthoic acid 2-(4'-N,N-diethylamino-2'-hydroxybenzoyl)-5 or 8-bromo-3-
Naphthoic acid 2-(4'-N,N-diethylamino-2'-hydroxybenzoyl)-5 or 8-nitro-3-
Naphthoic acid Examples of the compound represented by the general formula () include the following. Next, some examples of the fluoran compound represented by the general formula () of the present invention are described, and the hue when the color is developed on a thin silica gel layer is shown.

【table】

【table】

[Table] The present invention will be explained in more detail with reference to Examples below. Example 1 2-(4'-diethylamino-2'-) in 60 g of concentrated sulfuric acid
Hydroxybenzoyl)-3-naphthoic acid 7.28g
2-chloro-4-hydroxy-N-cyclohexylaniline (melting point
116-117℃) and stirred at 30℃ for 36 hours. After pouring into 300g of ice water, make alkaline with caustic soda solution, raise the temperature to 70℃, and separate the precipitate. Wash with water and dry. 4.50 g of 3-diethylamino-6-chloro-7-cyclohexylamino-benzofluorane having the above structural formula was obtained. Recrystallization from isopropyl alcohol gave white crystals with a melting point of 172-173°C. Example 2 In place of 2-chloro-4-hydroxy-N-cyclohexylaniline in Example 1, 4.23 g of 2-chloro-4-hydroxy-N-cyclopentylaniline (melting point 68-69°C) was used, and the same procedure was carried out. . 3-diethylamino-6 of the above structural formula
4.23 g of -chloro-7-cyclopentylamino-benzofluorane were obtained and recrystallized from isopropanol to give white crystals with a melting point of 210-211°C. Example 3 60 g concentrated sulfuric acid, 2-(4'-diethylamino-2'-
Hydroxybenzoyl)-3-naphthoic acid 7.28g
and 3.71 g of 2-chloro-4-hydroxy-N-isopropylaniline (melting point: 80-81°C), reacted at 30°C for 36 hours in the same manner as in Example 1, and post-treated in the same manner. 5.15 g of 3-diethylamino-6-chloro-7-isopropylamino-benzofluorane having the above structural formula was obtained and recrystallized from isopropanol to obtain white crystals with a melting point of 216-217.5°C. Example 4 Instead of 2-chloro-4-hydroxy-N-isopropylaniline in Example 3, 4.55 g of 2-chloro-4-hydroxy-N-1',3'-dimethylbutylaniline (melting point 64-65.5°C) was used. and operated in the same manner. 4.86 g of 3-diethylamino-6-chloro-7-1',3'-dimethylbutylamino-benzofluorane having the above structural formula was obtained and recrystallized from isopropanol to obtain white crystals with a melting point of 108-112°C. Ta. Example 5 Instead of 2-chloro-4-hydroxy-N-isopropylaniline in Example 3, 4.55 g of 2-chloro-4-hydroxy-N-1'-methyl-2'-acetylethylaniline (melting point 62-64°C) The same operation was performed using . 3-diethylamino-6-chloro-7-1'-methyl-2'- of the above structural formula
Acetylethylamino-benzofluorane 5.25g
was obtained and recrystallized from isopropanol to reduce the melting point to
White crystals were obtained at 215-216.5°C. Example 6 2-chloro-4-methoxy-N-isopropylaniline was used instead of 2-chloro-4-hydroxy-N-isopropylaniline in Example 3.
3.99 g were used to condense with 2-(4'-diethylamino-2'-hydroxybenzoyl)-3-naphthoic acid in concentrated sulfuric acid. The crystals obtained by pouring into ice water and making alkaline were dried. This was heated to 170°C with the same amount of orthodichlorobenzene, and after cooling was diluted with isopropanol to produce a 3-diethylamino-
6-chloro-7-isopropylamino-benzofluorane was obtained.

Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 8 carbon atoms, and R ₃ represents an alkyl group, an alkoxyalkyl group, or a phenyl alkyl group having 1 to 8 carbon atoms. R ₄ represents an alkyl group having 1 to 8 carbon atoms. ~10 alkyl groups, alkoxyalkyl groups, alkoxyalkoxyalkyl groups,
Cycloalkoxyalkyl group, cycloalkoxyalkoxyalkyl group, phenylalkoxyalkyl group, phenylalkoxyalkoxyalkyl group, phenoxyalkyl group, phenoxyalkoxyalkyl group, cycloalkyl group, phenylalkyl group, acylalkyl group, cyanoalkyl group,
It represents a carboamide alkyl group, furyl alkyl group, furyl alkyloxyalkyl group, tetrahydrofuryl alkyl group or tetrahydrofuryl alkyloxyalkyl group, and the phenyl group contained in R ₃ or R ₄ is substituted with an alkyl group or a halogen. Good too. Further, R ₃ and R ₄ may be combined with -CH to form a cycloalkyl group, a tetralinyl group or an indanyl group. X is hydrogen, halogen or nitro group, n is 1
Or represents the number 2. ) A fluoran compound represented by 2 General formula () (In the formula, R ₁ and R ₂ are alkyl groups having 1 to 8 carbon atoms,
X represents hydrogen, halogen or a nitro group, and n represents a number of 1 or 2. ) A compound represented by the general formula () (In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, R ₃ is an alkyl group having 1 to 8 carbon atoms,
Represents an alkoxyalkyl group or a phenylalkyl group. R ₄ is an alkyl group having 1 to 10 carbon atoms, an alkoxyalkyl group, an alkoxyalkoxyalkyl group,
cycloalkoxyalkyl group, cycloalkoxyalkoxyalkyl group, phenylalkoxyalkyl group, phenylalkoxyalkyl group, phenylalkoxyalkoxyalkyl group, phenoxyalkyl group, phenoxyalkoxyalkyl group,
Represents a cycloalkyl group, phenylalkyl group, acylalkyl group, cyanoalkyl group, carboamidoalkyl group, furylalkyl group, furyloxyalkyl group, tetrahydrofurylalkyl group or tetrahydrofurylalkyloxyalkyl group, and R ₃ or R The phenyl group contained in ₄ may be substituted with an alkyl group or a halogen. Further, R ₃ and R ₄ may be combined with -CH to form a cycloalkyl group, a tetralinyl group or an indanyl group. General formula () characterized by reacting the compound represented by ) in the presence of a dehydration condensation agent. (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , X, and n have the above-mentioned meanings.) A method for producing a fluoran compound represented by the following.