JPH0683000A - Novel photographic coupler - Google Patents

Abstract

PURPOSE:To provide a magenta or cyan dye image not causing change of hue due to heat, moisture, and light by using a specified coupler as the element of the silver halide color photographic sensitive material. CONSTITUTION:The color photographic sensitive material contains as the element the novel photographic coupler represented by general formula in which each of R1-R3 and Y is H or a substituent, X is H or group to be released by the reaction with the oxydation product of a color developing agent, (n) is integer of 0-2. The substituents of R1-R3 are typified by alkyl, preferably, such as 1-32C alkyl optionally straight or branched, aryl, preferably, such as phenyl, or anilino, acylamino, sulfonamide, and the like: X is H or a group to be released by coupling with the oxidation product of a color developing agent, such as halogen like Cl or Br.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel coupler used as a material for a silver halide color photographic light-sensitive material, and more specifically to a novel photographic material capable of forming a dye image having excellent fastness to heat, moisture and light. It is about couplers.

[0002]

BACKGROUND OF THE INVENTION Generally, in the production of color photographs, a silver halide color photographic light-sensitive material is exposed to light and then subjected to color development processing, whereby oxidized primary aromatic compounds are exposed in the exposed areas. Amine color developing agents and dye-forming couplers react to form dyes to form dye images, but in such photographic methods subtractive color reproduction is used, whereby yellow, magenta and cyan are used. Dye images are formed.

Conventionally, examples of photographic couplers used for forming the above yellow dye image include acylacetanilide type couplers, and examples of magenta dye image forming couplers include pyrazolone,
Pyrazolobenzimidazole, pyrazolotriazole or indazolone type couplers are known, and as a coupler for forming a cyan dye image, for example, a phenol or naphthol type coupler is generally used and obtained from these couplers. It is desired that the dye image does not discolor even when it is exposed to light for a long time or stored at high temperature and high humidity.

However, the above-mentioned phenol-based couplers and naphthol-based couplers, which have been studied and put into practical use as couplers for forming cyan dyes, have the spectral absorption characteristics of the formed cyan dye image,
It is still insufficient in terms of heat resistance and moisture resistance, and therefore various proposals have been made in the past, including the selection and search of substituents in couplers, with the aim of improving this. No coupler has been found that satisfies all requirements.

On the other hand, a dye formed from a 5-pyrazolone type coupler, which has been widely put into practical use as a magenta dye image forming coupler and has been studied, has excellent fastness to heat and light, but has a yellow component. In order to solve this, there are proposed couplers such as pyrazolobenzimidazole, indazolone, pyrazolotriazole, imidazopyrazole, pyrazolopyrazole, and pyrazolotetrazole, because they have unnecessary absorption that causes color turbidity. These couplers are preferable from the viewpoint of color reproducibility, but the dye formed from the coupler has a problem that the fastness to light is extremely low and fading easily occurs.

Therefore, as a result of further research in view of such circumstances, the present inventors have found a photographic coupler capable of forming a dye image which does not cause a hue change with respect to heat, humidity and light.

[0007]

Therefore, the first object of the present invention is to provide a novel photographic coupler used as a raw material of a silver halide color photographic light-sensitive material, and the second object of the present invention. It is an object of the present invention to provide a color photographic coupler capable of forming a dye image which does not cause a change in hue due to heat, humidity and light.

[0008]

The above objects of the present invention have been achieved by a photographic coupler represented by the general formula [I].

[0009]

[Chemical 2]

Where R ₁ , R ₂ , R ₃ and Y are each
Represents a hydrogen atom or a substituent, X represents a hydrogen atom or a group capable of splitting off upon reaction with an oxidized product of a color developing agent,
n represents an integer of 0 to 2.

The present invention will be described in more detail below.

In the general formula [I], R ₁ , R ₂ and R ₃
The substituent represented by is not particularly limited, but typically,
Alkyl, aryl, anilino, acylamino, sulfonamide, alkylthio, arylthio, alkenyl,
Each group such as cycloalkyl can be mentioned. In addition to these, a halogen atom and cycloalkenyl, alkynyl, heterocycle,
Sulfonyl, sulfinyl, phosphonyl, acyl, carbamoyl, sulfamoyl, cyano, alkoxy, aryloxy, heterocycleoxy, siloxy, acyloxy,
Sulfonyloxy, carbamoyloxy, amino, alkylamino, imide, ureido, sulfamoylamino, alkoxycarbonylamino, aryloxycarbonylamino, alkoxycarbonyl, aryloxycarbonyl, heterocyclic thio, thioureido, carboxyl, hydroxy, mercapto, nitro, Each group such as sulfo, a spiro compound residue, a bridged hydrocarbon compound residue and the like are also included.

Hereinafter, in each of the groups represented by R ₁ , R ₂ and R ₃ , the alkyl group preferably has 1 to 32 carbon atoms and may be linear or branched. A phenyl group is preferred as the aryl group.

Examples of the acylamino group include an alkylcarbonylamino group and an arylcarbonylamino group.

Examples of the sulfonamide group include an alkylsulfonylamino group and an arylsulfonylamino group.

Examples of the alkyl component and aryl component in the alkylthio group and arylthio group include the alkyl group and aryl group represented by R above. The alkenyl group preferably has 2 to 32 carbon atoms, and the cycloalkyl group preferably has 3 to 12 carbon atoms, particularly 5 to 7 carbon atoms, and the alkenyl group may be linear or branched.

The cycloalkenyl group has 3 to 10 carbon atoms.
12, especially 5 to 7, are preferred. Alkylsulfonyl group, arylsulfonyl group, etc. as sulfonyl group; alkylsulfinyl group, arylsulfinyl group, etc. as sulfinyl group; alkylphosphonyl group, alkoxyphosphonyl group, aryloxyphosphonyl group, arylphosphonyl group as phosphonyl group Etc .; as the acyl group, an alkylcarbonyl group, an arylcarbonyl group, etc .;
The carbamoyl group is an alkylcarbamoyl group, an arylcarbamoyl group or the like; the sulfamoyl group is an alkylsulfamoyl group, an arylsulfamoyl group or the like;
An alkylcarbonyloxy group as the acyloxy group,
Arylcarbonyloxy group, etc .; Sulfonyloxy group, alkylsulfonyloxy group, arylsulfonyloxy group, etc .; Carbamoyloxy group, alkylcarbamoyloxy group, arylcarbamoyloxy group, etc .; Ureido group, alkylureido group, arylureido group, etc. Etc .; as a sulfamoylamino group, an alkylsulfamoylamino group, an arylsulfamoylamino group, etc .; as a heterocyclic group, a 5- to 7-membered one is preferable, and specifically, a 2-furyl group, 2-thienyl group Group, 2-pyrimidinyl group, 2-benzothiazolyl group, 1-pyrrolyl group, 1-tetrazolyl group, etc .; The heterocyclic oxy group is preferably one having a 5- to 7-membered heterocycle, for example, 3,4,5,6 -Tetrahydropyranyl-2-oxy group, 1-phenyltetrazole-5-oxy group, etc .; as a heterocyclic thio group, 5 To 7-membered heterocyclic thio groups are preferable, for example, 2-pyridylthio group, 2-benzothiazolylthio group, 2,4-diphenoxy-1,3,5-triazole-6-thio group, etc .; siloxy group is trimethyl. Siloxy group, triethylsiloxy group, dimethylbutylsiloxy group, etc .; succinimide group as imide group, 3-heptadecyl succinimide group, phthalimide group, glutarimide group, etc .; spiro compound residue as spiro [3,3 ] Heptane
-1-yl and the like; bridged hydrocarbon compound residues include bicyclo [2,2,1] heptan-1-yl, tricyclo [3,
3,1,1 ^{3 7} ] Decan-1-yl, 7,7-dimethyl-bicyclo [2,
2,1] heptan-1-yl and the like can be mentioned.

The above groups may further have a substituent such as a long chain hydrocarbon group or a diffusion resistant group such as a polymer residue.

Examples of the group capable of splitting off upon reaction with the oxidation product of the color developing agent represented by X include a halogen atom (chlorine atom, bromine atom, fluorine atom, etc.) and alkylene, alkoxy, aryloxy, heterocyclic oxy, acyloxy. , Sulfonyloxy, alkoxycarbonyloxy,
Aryloxy carbonyl, alkyl oxalyl oxy, alkoxy oxalyl oxy, alkyl thio, aryl thio, heterocyclic thio, alkyloxy thiocarbonyl thio, acylamino, sulfonamide, nitrogen atom-containing heterocyclic ring bonded by N atom, alkyloxy carbonylamino, aryloxy Carbonylamino, carboxyl,

[0020]

[Chemical 3]

[0021] _{(R '1, R' 2} , R '3, Y' and n '
Has the same meaning as R ₁ , R ₂ , R ₃ , Y and n, and Ra and Rb represent a hydrogen atom, an aryl group, an alkyl group or a heterocyclic group. ) And other groups, but a halogen atom is preferable.

Y represents a hydrogen atom or a substituent, and a preferable substituent is, for example, one which is eliminated after reacting with an oxidized product of a developing agent. For example, the substituent represented by Y is described in JP-A-61-228444. Substituents that are coupled off by a group capable of splitting off under alkaline conditions such as those described in JP-A No. 2003-134, or by reaction with an oxidized product of a developing agent as described in JP-A-56-133734. Etc., but preferably Y is a hydrogen atom. Therefore, among the compounds of the present invention represented by the general formula [I], the compound represented by the general formula [II] is particularly preferable.

[0023]

[Chemical 4]

[0024] In the _{formula, R 1, R 2, R} 3, X and n have the same meanings as _{R 1, R 2, R 3} , X and n in the general formula [I].

Next, typical examples of the compound of the present invention are shown below, but the present invention is not limited thereto.

[0026]

[Chemical 5]

[0027]

[Chemical 6]

[0028]

[Chemical 7]

[0029]

[Chemical 8]

[0030]

[Chemical 9]

The above-mentioned coupler of the present invention is a known compound such as Jo
urnal of Chem.Resarch (M) (Journal of Chemical Research), 1989, including compounds described on pages 1501 to 1523, and can be synthesized according to the described synthesis method.

The above cited document does not describe that the compound described in the document is useful as a coupler for color photography.

(Synthesis Example) Exemplified compound (4) was synthesized according to the following synthetic scheme.

[0034]

[Chemical 10]

I) Intermediate (Synthesis of 4b ) 5 g of the intermediate (4a) is dissolved in 20 ml of chloroform and 20 ml of triethylamine, and 20 ml of a chloroform solution of 5 g of 2-methoxycarbonylacetyl chloride is added dropwise at 0 ° C.
Then react at room temperature for 20 minutes. After completion of the reaction, the product is washed with water, dried, dried under reduced pressure, and recrystallized with ethanol water to obtain 5 g of intermediate (4b) (yield 62%).

Ii) A synthetic intermediate (4b ) of Exemplified Compound (4) (5.2 g) is reacted in 30 ml of a methanol solution of methanol methoxide (prepared by reacting 1 g of sodium with 30 ml of methanol) under heating under reflux for 3 hours. After completion of the reaction, the reaction solution is poured into acetic acid-water (3 g-30 ml), and the formed crystals are collected by filtration. After that, recrystallization from acetone-methanol gives 3.9 g (yield 87%) of the target compound (4).

The structure was confirmed by ¹ H-NMR and MASS spectrum.

The coupler of the present invention can be used usually in the range of 1 × 10 ^-3 mol to 1 mol, preferably 1 × 10 ^-2 mol to 8 × 10 ^-1 mol per mol of silver halide.

The coupler of the present invention can also be used in combination with other types of cyan couplers and magenta couplers. The methods and techniques used in conventional dye-forming couplers are likewise applied to the couplers of this invention.

The coupler of the present invention can be used as a material for forming a color photograph by any coloring method, and specific examples thereof include an external coloring method and an internal coloring method. When used as an external color-developing method, the coupler of the present invention can be dissolved in an aqueous alkali solution or an organic solvent (eg alcohol) and added to the developing solution for use.

When the coupler of the present invention is used as a material for color photographic formation by the internal color forming method, the coupler of the present invention is used by incorporating it in a photographic light-sensitive material.

Typically, a method in which the coupler of the present invention is blended with a silver halide emulsion and the emulsion is coated on a support to form a color light-sensitive material is preferably used.

The coupler of the present invention is used in color photographic light-sensitive materials such as color negative and positive films and color photographic paper.

The light-sensitive material using the coupler of the present invention, such as this color photographic paper, may be monochromatic or multicolor. In the multi-color light-sensitive material, the coupler of the present invention may be contained in any layer, but it is usually contained in the green-sensitive silver halide emulsion layer and / or the red-sensitive silver halide emulsion layer. Multicolor photosensitive material has a spectrum of 3
Each of the primary color regions has a photosensitive dye image-forming constituent unit. Each building block can consist of a single layer or multiple emulsion layers sensitive to certain regions of the spectrum. The constituent layers of the light-sensitive material, including the layers of the image-forming constituent units, can be arranged in various orders as known in the art.

A typical multicolor light-sensitive material contains at least one cyan dye image-forming structural unit consisting of at least one red-sensitive silver halide emulsion layer containing at least one cyan coupler, and at least one magenta coupler. At least one magenta dye image-forming structural unit comprising one green-sensitive silver halide emulsion layer, (at least one of cyan coupler and / or magenta coupler is a coupler of the present invention) and at least one yellow coupler. A yellow dye image-forming structural unit consisting of two blue-sensitive silver halide emulsion layers supported on a support.

The light-sensitive material can have additional layers such as filter layers, intermediate layers, protective layers, subbing layers and the like.

In order to incorporate the coupler of the present invention into an emulsion, a conventionally known method may be used. For example, tricresyl phosphate, a high boiling point organic solvent having a boiling point of 175 ° C. or higher such as dibutyl phthalate or a low boiling point solvent such as butyl acetate or butyl propionate, alone or as necessary in a mixed solution thereof, the coupler of the present invention. Is dissolved alone or in combination, then mixed with an aqueous gelatin solution containing a surfactant, then emulsified with a high-speed rotating mixer or colloid mill, and then added to silver halide to be used in the present invention. Emulsions can be prepared.

The silver halide composition preferably used for the light-sensitive material using the coupler of the present invention is silver chloride, silver chlorobromide or silver chloroiodobromide. Further, it may be a combination mixture such as a mixture of silver chloride and silver bromide. That is, when the silver halide emulsion is used for color photographic paper, particularly fast developing property is required. Therefore, it is preferable that the halogen composition of the silver halide contains a chlorine atom, and at least 1% of silver chloride is contained. Particularly preferred is silver chloride, silver chlorobromide or silver chloroiodobromide.

The silver halide emulsion is chemically sensitized by a conventional method. Further, it can be optically sensitized to a desired wavelength range.

The silver halide emulsion contains an antifoggant or stabilizer in the photographic industry for the purpose of preventing fog during the manufacturing process of the light-sensitive material, storage or photographic processing, and / or keeping the photographic performance stable. Compounds known as can be added.

The color light-sensitive material using the coupler of the present invention includes a color fog-preventing agent, a dye image stabilizer, an anti-UV agent, an antistatic agent, a matting agent, which are usually used in light-sensitive materials.
A surfactant or the like can be used.

Regarding these, for example, Research Disclosure Vol. 176, 22-31
The description on page (December 1978) can be referred to.

The color photographic light-sensitive material using the coupler of the present invention can form an image by performing color development processing known in the art.

The color photographic light-sensitive material using the coupler of the present invention may contain a color developing agent in the hydrophilic colloid layer as the color developing agent itself or as a precursor thereof, and can be processed with an alkaline activating bath. .

The color photographic light-sensitive material using the coupler of the present invention is subjected to bleaching treatment and fixing treatment after color development.
The bleaching process may be performed simultaneously with the fixing process.

After the fixing process, a washing process is usually performed. Further, a stabilizing treatment may be performed as an alternative to the water washing treatment, or both may be used in combination.

[0057]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1 A red light-sensitive color light-sensitive material sample 1 was prepared by sequentially coating the following layers from the support side on a paper support laminated on both sides with polyethylene. In addition, the addition amount of a compound is per 1 m ² unless otherwise specified (silver halide is a silver conversion value).

First Layer: Emulsion Layer 1.2 g of gelatin, 0.30 g of red-sensitive silver chlorobromide emulsion (containing 96 mol% of silver chloride) and comparative cyan coupler a 9.1 × 10 ^-4 mol dissolved in 1.35 g of dioctyl phosphate. Red-sensitive emulsion layer.

Second layer: protective layer A protective layer containing 0.50 g of gelatin. As a hardening agent, 2,4-dichloro-6-hydroxy-s-triazine sodium salt was added so that the amount was 0.017 g per 1 g of gelatin.

Next, in the same manner as in Sample 1 of the present invention, except that the comparative coupler a in Sample 1 was replaced by the coupler shown in Table 1 (the addition amount was the same molar amount as that of Comparative coupler a).
~ 8 were produced.

The samples 1 to 8 obtained above were subjected to wedge exposure according to a conventional method, and then developed in the next step.

(Development processing step) Color development 38 ° C. 3 minutes 30 seconds Bleach fixing 38 ° C. 1 minute 30 seconds Stabilization treatment / or water washing treatment 25 ° C.-30 ° C. 3 minutes Drying 75-80 ° C. 2 minutes In each processing step The composition of the treatment liquid used is as follows.

(Color developer) Benzyl alcohol 15.0 ml Ethylene glycol 15.0 ml Potassium sulfite 2.0 g Potassium bromide 0.7 g Sodium chloride 0.2 g Potassium carbonate 30.0 g Hydroxylamine sulfate 3.0 g Polyphosphoric acid (TPPS) 2.5 g 3-Methyl- 4-Amino-N-ethyl-N- (β-methanesulfonamidoethyl) aniline sulfate 5.5g Optical brightener (4,4'-diaminostilbenedisulfonic acid derivative) 1.0g Potassium hydroxide 2.0g Add water Adjust the total volume to 1000 ml and the pH to 10.20. (Bleach-fixing solution) ethylenediaminetetraacetate ferric ammonium dihydrate 60.0g ethylenediaminetetraacetic acid 3.0g ammonium thiosulfate (70% aqueous solution) 100.0ml ammonium sulfite (40% aqueous solution) 27.5ml pH 7.1 with potassium carbonate or glacial acetic acid And add water to bring the total volume to 1000 ml.

(Stabilizing Solution) 5-Chloro-2-methyl-4-isothiazolin-3-one 1.0 g Ethylene glycol 10.0 g Water is added to make 1000 ml.

The concentrations of the above-treated samples 1 to 8 were measured using a densitometer (KD-7 type manufactured by Konica Corporation), and the treated samples were subjected to high temperature and high humidity (60 ° C, 80
% RH) and left for 14 days to examine the heat and humidity resistance of the dye image.

The results are shown in Table 1. However, the heat resistance and humidity resistance of the dye image are expressed by the percentage of dye residue after the heat and humidity resistance test with respect to the initial density of 1.0.

[0068]

[Table 1]

[0069]

[Chemical 11]

As is clear from the results in Table 1, the samples using the couplers of the present invention have a higher dye residual rate than the samples using the comparative couplers, and the color fading occurs even when exposed to high heat and high humidity. It turns out that is unlikely to occur.

Example 2 The red-sensitive silver chlorobromide emulsion (silver chloride) in Sample 1 of Example 1 was used.
96 mol%) 0.30 g was used in place of 0.35 g of a green-sensitive silver chlorobromide emulsion (containing 85 mol% of silver bromide), and a cyan cyan coupler a of the present invention was used instead of 9.1 × 10 ^-4 mol. Samples 9, 10 and 11 were prepared in the same manner as in Example 1 except that the couplers (11), (16) and (24) were used in an amount of 5.1 × 10 ⁻⁴ mol, respectively. Development processing was performed. With respect to each of the treated samples, heat resistance and humidity resistance were examined in the same manner as in Example 1. After irradiating each sample with a xenon fade meter for 3 days, the density was measured and the light fastness of the dye image was examined from the residual ratio of the dye after the light fastness test for an initial density of 1.0.

As a result, it was found that the magenta dye image obtained was extremely resistant to heat and humidity and relatively fast to light, and had the effect of the present invention.

Example 3 The following layers were sequentially coated on the triacetyl cellulose film from the support side to prepare red-sensitive color reversal photographic light-sensitive materials 12 to 16 containing the couplers shown in Table 2.

First layer: Emulsion layer 1.4 g of gelatin, 0.5 g of red-sensitive silver chlorobromide emulsion (containing 96 mol% of silver chloride) and 1.5 g of dibutyl phthalate dissolved in Table 2
A red-sensitive emulsion layer consisting of 9.1 × 10 ⁻⁴ mol of the coupler shown in FIG.

Second layer: protective layer A protective layer containing 0.5 g of gelatin. As a hardening agent, 2,4-dichloro-6-hydroxy-s-triazine sodium salt was added to 0.017 g per 1 g of gelatin.

[Reversal Treatment Process] Process Treatment temperature Treatment time First development 38 ° C. 3 minutes Water washing 38 ° C. 2 minutes Inversion 38 ° C. 2 minutes Color development 38 ° C. 6 minutes Adjustment 38 ° C. 2 minutes Bleach 38 ° C. 6 minutes Settled at 38 ℃ for 4 minutes Washed at 38 ℃ for 4 minutes Stabilized at 38 ℃ for 1 minute Dry at room temperature Use the following composition of the processing solution.

[First developer] sodium tetrapolyphosphate 2.0 g sodium sulfite 20.0 g hydroquinone monosulfonate 30.0 g sodium carbonate (monohydrate) 30.0 g 1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone 2.0 g Potassium bromide 2.5g Potassium thiocyanate 1.2g Potassium iodide (0.1% solution) 2ml Add water 1000ml [Reversal liquid] Nitrilotrimethylenephosphonic acid hexasodium salt 3.0g Stannous chloride (dihydrate) 1.0g p-Aminophenol 0.1 g Sodium hydroxide 5.0 g Glacial acetic acid 15 ml Water added 1000 ml [Color developer] Sodium tetrapolyphosphate 3.0 g Sodium sulfite 7.0 g Sodium triphosphate (decahydrate) 36.0 g Potassium bromide 1.0 g Potassium iodide (0.1% solution) 90 ml Sodium hydroxide 3.0 g Citrazine acid 1.5 g N-ethyl-N-β-methanesulfonamidoethyl-3-methyl-4-aminoanili・ Sulfate 11.0g Ethylenediamine 3.0g Water added 1000ml [Solution] Sodium sulfite 12.0g Sodium ethylenediaminetetraacetate (dihydrate) 8.0g Thioglycerine 0.4ml Glacial acetic acid 3.0ml Water added 1000ml [Blend] Ethylenediamine Sodium tetraacetate (dihydrate) 2.0g Ethylenediaminetetraacetic acid iron (III) ammonium (dihydrate) 120.0g Potassium bromide 100.0g Add water 1000ml [Fixer] Ammonium thiosulfate 80.0g Sodium sulfite 5.0g Sodium bisulfite 5.0g Water added 1000ml [Stabilizer] Formalin (37% by weight) 5ml Conidax (Konica Corporation) 5ml Water added 1000ml For each sample treated above, heat resistance of dye image as in Example 1 -The moisture resistance was examined. The results are shown in Table 2.

However, in this embodiment, the KD-
The transmission density was measured using a 7R type densitometer.

[0079]

[Table 2]

As is clear from the results shown in Table 2, the samples using the coupler of the present invention have a higher residual ratio of dye and excellent heat and humidity resistance than the samples using the comparative coupler. I understand.

Example 4 A red-sensitive silver chlorobromide emulsion (silver chloride) in Sample 12 of Example 3 was used.
0.5 g of green-sensitive silver chlorobromide emulsion (containing 85 mol% of silver bromide) was used in place of 0.5 g of 96 mol%), and magenta of the present invention was used in place of the comparative cyan coupler a9.1 × 10 ^-4 mol. Coupler (1
Samples 17 and 18 were prepared in the same manner as in Example 3 except that 5.1 × 10 ⁻⁴ mol of 2) and (21) were used, and the same exposure and development processes as in Example 3 were performed.

The processed sample was examined for heat resistance, humidity resistance and light resistance in the same manner as in Example 2. The obtained magenta dye image was fast against heat, humidity and light, and the effect of the present invention was obtained. Found to have.

[0083]

The cyan or magenta color image formed from the novel photographic coupler of the present invention is fast against heat, humidity and light and is useful for a color photographic light-sensitive material.

Claims (1)

[Claims] 1. A photographic coupler represented by the general formula [I]: [Wherein R ₁ , R ₂ , R ₃ and Y each represent a hydrogen atom or a substituent, X represents a hydrogen atom or a group capable of splitting off upon reaction with an oxidant of a color developing agent, and n represents 0-2
Represents the integer. ]