JPS59120655A - Fluoran derivative, production thereof and recording medium using said derivative - Google Patents

Abstract

NEW MATERIAL:Fluoran derivatives of formula I , wherein R1, R2, R3 are each H, (halogen, alkoxy-cyano-substd.) 1-18C alkyl, (halogen, alkyl, alkoxy-substd.) aralkyl group, R2 and R3 may be combined together to form a heterocyclic ring; X is H, halogen, alkyl; Y is X, a lower alkoxy group. EXAMPLE:3-N-Ethyl-N-cyclopentylamino-6-methyl-7-anilinofluoran. USE:Black color forming materials (color former) used for recording materials such as pressure-sensitive, thermal recording sheets. PREPARATION:A 2-(2-hydroxy-4-cyclopentylamino)-benzoyl benzoic acid derivative of formula II is condensed with a p-aminophenol derivative of formula III in the presence of a condensing agent such as sulfuric acid.

Description

[Detailed description of the invention]

The present invention relates to a fluoran derivative useful as a color-forming substance used in recording materials such as pressure-sensitive recording sheets, heat-sensitive recording sheets, and electrically conductive heat-sensitive recording sheets, a method for producing the same, and a recording material using the derivative. Conventionally, a method of recording information transmitted through energy media such as pressure, heat, electricity, etc., using a color reaction between a colorless or light-colored basic dye and an organic or inorganic electron-accepting substance. Various methods have been proposed for
Pressure-sensitive copying sheets, heat-sensitive recording sheets, electrically conductive heat-sensitive recording sheets, ultrasonic recording sheets, electron beam recording sheets, electrostatic recording sheets, such as those described on page 470 (1976),
Photosensitive recording sheet 1 - Furthermore, a large number of systems have been proposed for application to photosensitive printing materials, type ribbons, ballpoint inks, crayons, stamp inks, and the like. For these recording materials that utilize a color reaction between an electron-donating color-forming substance (hereinafter simply referred to as a color-forming agent) and an electron-accepting color-developing substance (hereinafter simply referred to as a color-forming agent), the type of color-forming agent must be selected. As a result, colored images exhibiting various hues are formed, but in recent years there has been a strong demand for recording media that can produce black colored images for the purpose of obtaining further copies from the obtained colored images. ing. In this case, in principle, a single prefecture color image can be obtained by mixing coloring agents that develop different colors such as red, iL yellow, and green11], but the coloring speed and light However, since the fastness to temperature and humidity differs, the color image that is initially developed cannot maintain its color tone. Therefore, research has been carried out to obtain black colored images using a single coloring agent, but all aspects such as stability, coloring speed, coloring density, fastness, hue, and cost of the coloring agent before coloring have been investigated. A black coloring agent that can add 1 to iη has not yet been found, and as a result, a black coloring recording material cannot necessarily add 1 to 2. However, the fluoran derivative represented by the following general formula (1) of the present invention [ In the formula, R7, R2, and R3 are each a hydrogen atom; a C7-Ct& alkyl group which may be substituted with a halogen atom, an alkoxyl group, or a cyano group; a halogen atom, a lower alkyl group, or a lower alkyl group; Rz and Ima3 are bonded to each other to form N
- It may constitute a heterocycle and may further contain an oxygen or nitrogen atom as a heterocycle member. Furthermore, R3 also represents a halogen atom, a lower alkyl group, a substituted alkyl group, a lower alkoxyl group, an amino group, a substituted amino group, an aryl group or a cycloalkyl group which may be substituted with an acyl group. X and Y each represent a hydrogen atom, a halogen atom, or a lower alkyl group, and Y also represents a lower alkoxyl group. ] is a colorless to light-colored stable compound that develops a highly concentrated hue when it comes into contact with a color developer, and recorded images obtained using this substance stably maintain their initial color δ1m even when exposed to sunlight. It has the characteristics of Among them, the following general formula (fV
) is a fluoran derivative represented by [where R, r &; IC7-Cz8 represents an alkyl group, R6 represents a phenyl group optionally substituted with a lower alkyl group, a halogen atom, or a dialkylamino group, and Z
represents a lower alkyl group. ] In particular, it has the property of being able to stably maintain a high density red-black, green-black or black color tone over a long period of time. For example, when applied to pressure-sensitive recording paper, it has particularly excellent initial color development. A recorded image can be obtained, and when applied to thermal recording paper, a recorded image with little background fog and excellent color development can be obtained. The fluoran derivative represented by the general formula (1) of the present invention having excellent properties as described above can be produced mainly by the following representative method Q. Immediately,
As shown below, first, m-cyclopentylaminophenol derivative (V) and phthalic anhydride derivative (Vl) are reacted to synthesize 2-(2-hydroxy-4-cyclopentylamino)benzoylbenzoic acid derivative (II). (R7 and Rz do not have the above-mentioned meanings.) Condensation of the obtained 1-(2-hydrogine-4-cyclobentylamino)-, -noylbenzoic acid derivative CI+) and p-aminephenol derivative (III) In this way, a fluoran derivative represented by the general formula [I] can be produced. [π]CM'J [Formula 1: 1iR4 represents a hydrogen atom or a lower alkyl group, and R, XR2, R3, X, , Y have the above-mentioned meanings. ] As a condensing agent in the condensation reaction between the 1-(2-hydroxy-4-cyclopentylamino)hendiylbenzoic acid derivative (n) and the p-aminophenol derivative CIll), sulfuric acid; phosphoric acid pentoxide; ; Water metal halides such as anhydrous tin chloride, anhydrous zinc chloride, anhydrous aluminum chloride, anhydrous soot bromide, anhydrous zinc bromide, anhydrous aluminum bromide, anhydrous iron bromide; phosphorus trichloride, tribasic ;Ii phosphorus chloride; phosphorus pentabromide; anhydrous three
Boron nitride; Friedel-Crafts catalysts such as hydrofluoric acid are used alone or in combination. Among these, sulfuric acid, which also serves as a solvent, is more preferably used. Also, as a solvent, carbon disulfide, monochlorobenzene, dichlorobenzene,

[・Hensen, trichlorobenzene, nitrobenzene, 2l・
Lomekune, nitroethane, etc. are useful. In addition, in the above reaction, when R4 of the p-aminephenol derivative is a lower alkyl group, 1 represented by the following general formula [■] which is a precursor of the desired fluoran derivative
-Riphenylmethane derivatives may be synthesized. [In the formula, R1, R, R, R, X, and Y have the above-mentioned meanings. ] In this case, the obtained triphenylmethane derivative is filtered if necessary, and the pH of the system is adjusted to 9.5 to 12 with an alkaline substance such as sodium hydroxide or potassium hydroxide.
The desired fluoran derivative can be obtained by heating to 0 to 100"C. If an organic solvent such as acetin, benzene, 1-luene, xylene, etc. is used in combination with the above aqueous medium, the yield will be increased. In particular, hydrophobic organic solvents such as benzene, toluene, and xylene are more preferably used because they prevent the formation of side reactions and provide favorable reaction conditions.In the general formula CI) of the present invention thus obtained, The fluoran derivatives expressed are colorless to light-colored basic dyes that have the same characteristics as described above, and are particularly useful for use in various recording media that utilize color reactions with color developers. The color developer used here is appropriately selected depending on the type of recording medium, but for example, it is suitable for recording media such as pressure-sensitive recording media, heat-sensitive recording media, and electrically conductive heat-sensitive recording media. For example, acid clay, activated clay, phthapulgide, hentonite, colloidal silica, aluminum silicate, magnesium silicate, zinc silicate, tin silicate, and calcined clay are preferably used. Inorganic color developers such as kaolin and cruzi, aliphatic carboxylic acids such as oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, and stearic acid, benzoic acid, paratertiary butylbenzoic acid, phthalic acid, gallic acid, and salicylic acid. , 3-isopropylsalicylic acid, 3-phenylsalicylic acid, 3-
Cyclohexylsalicylic acid, 3,5-Di-(α- methylhennru) salicyl M, 2-hydroxy-1-hennyl-3-naf I.1
Aromatic carbonic acids such as acids, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2
-chlorophenol), 4°4'-isopropylidenebis(2,6-dibromophenol), 4.4'-isopropylidenehis(2,6-dichlorophenol), 4.
4'-isopropylidenehis (2-methylphenol)
, 4.4'-impropylidene bis(2,6-dimedylphenol), 4. ．． 4'-isopropylidene bis(2
-tert-butylphenol), 4゜4'-secondary-butylidene diphenol, 4゜4'-cyclohexylidene bisphenol, 4゜4'-cyclohegylidene bis(2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, methyl-4-hydroxyhenzoe-1-, hensyl-4-
Vitrokidihenzoate, 2,2'-naobis(4,6
--dichlorophenol), 4-turn octylcatechol, 2,2'-methylene his (4-chlorophenol), 2,2'-methylene his (4-methyl-
Phenolic compounds such as 6-tert-butylphenol), 2,2'-dihydroxydiphenyl, rose
There are phenolic resins such as phenylphenol-formalin resin and para-butylphenol-acetylene resin! Color developer Furthermore, these organic color developers and zinc,
Salts with polyvalent metals such as magnesium, aluminum, calcium, titanium, manganese, tin, and nickel, hydrogen chloride, hydrogen bromide, hydrogen iodide, boric acid, silicic acid, phosphoric acid, sulfuric acid, nitric acid, and perchloric acid. and halides such as aluminum, zinc, nickel, soot, titanium, and boron. Regarding various typical recording materials using such a color developer and a fluoran derivative represented by the general formula C1) of the present invention,
This will be explained in more detail below. For example, the pressure-sensitive recording medium is U.S. Pat. No. 2,505,470,
No. 2,505,471, No. 2,505,489, No. 2,548,366, No. 2,712,507, No. 2
゜730.4 s C1, 2,730,457,
3,418.250, 3,924,027, 4,010,038, etc., and the fluoran derivatives of the present invention are available in various forms. This can be applied to pressure-sensitive recording media. Generally, the fluoran derivatives of the present invention are used alone or in combination, and if necessary, trinoenylnocun lactones,
Spiropyrans, fluorans, diphenylmethanes,
Consists of basic dyes such as leucomethylene blue, synthetic oils such as alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, and alkylated terphenyl, vegetable oils such as cotton oil and castor oil, animal oils, mineral oils, or mixtures thereof. A dispersion liquid in which dirt is dissolved in a solvent and dispersed in a binder, or the above solution is contained in microcapsules by various capsule manufacturing methods such as coacerhesion method, interfacial polymerization method, and 1n-situ method, and the binder is The pressure-sensitive recording medium of the present invention is produced by coating the dispersion dispersed therein on a support such as paper or Plastic Seat 1-1 resin coated paper. Of course, there are the so-called upper sheets in which one side of the support is coated with the above-mentioned dispersion, and the so-called top sheet in which one side of the support is coated with a color developer coating liquid mainly consisting of a color developer, and the other side is coated with the above-mentioned dispersion. sheet for,
Furthermore, the capsules and the developer can be coated on the same side of the support by applying a coating liquid containing a mixture of the capsules and the color developer, or by applying a developer coating liquid on top of the capsule dispersion. As mentioned above, various forms such as so-called single copy sorting in which a color developer is present are included. The amount of fluorane derivative to be used varies depending on various conditions such as the desired coating amount, the form of the pressure-sensitive recording medium, the capsule manufacturing method, the composition of the coating liquid including various auxiliaries, and the coating method. You can select it as appropriate. In any case, by using the fluorane derivative represented by the general formula CI) of the present invention as a basic dye in various conventional pressure-sensitive recording materials, it is possible to form recorded images with excellent light resistance and reduce pressure sensitivity. It is a record that can be obtained]. A heat-sensitive recording medium” analogy
4 27880■, same a 5-14039 month, lid]
48-43830 Rishi, 49-691), 49-
70 Tomi, No. 52-20142 etc. 3
There are various forms of sea urchins, and the fluoran derivatives of the present invention can be applied to these various forms of heat-sensitive recording media.7. A heat-sensitive recording material (4) that exhibits a recorded image of its own nature.Generally, a binder is dissolved or dispersed, and fine particles of the fluorane derivative of the present invention and a color developer are dispersed in the medium. The heat-sensitive recording material of the present invention is produced by applying the coating solution obtained by applying the coating solution to a suitable support such as paper, plastic film, synthetic paper, &J woven fabric sheet, molded product, etc. There is no particular limitation on the ratio of the basic dye mainly composed of fluoran derivatives and the color developer used in the recording layer, but in general, dye 1
1 to 50 parts by weight 1, preferably 2 to 10 parts by weight
Parts by weight of color developer are used. In addition, for the purpose of improving coloring ability, matting the surface of the recording layer, and improving writing properties7, polyvalent metal oxides, hydroxides,
Inorganic gold+2 compounds such as carbonates and inorganic pigments are generally added in an amount of 0.1''5 parts by weight, preferably 0 parts by weight per 1 part by weight of color developer.
．． 2 to 2 commercially available parts] (-7 as appropriate (
Can be used for jf. The heat-sensitive recording material of the present invention is generally produced by coating a support with a coating liquid in which fine particles of a fluorane derivative, i#, and i colorant are dispersed, as described in L. Two types of coating liquids in which a fluoran derivative and a color developer are separately dispersed may be overcoated onto a support, and it is of course also possible to manufacture the coating by impregnation or pouring. There are no particular restrictions on the preparation method or application method of the coating liquid, and the amount of application is usually 2 to 12% in terms of dry jF amount.
g/r+? Level coating 4j Sane Ru. Examples of binders include starches, celluloses, proteins, gum arahia, polyvinyl alcohol, styrene-male anhydride and inic acid co-merite salt, styrene-butadiene copolymer emulsion, and acetic acid-vinyl maleic anhydride copolymer. Polymer salts, polyacrylates, etc. are appropriately selected and used. The electrically conductive heat-sensitive recording material is manufactured, for example, by the method described in JP-A-49-11344 and JP-A-50-48930. In general, a coating liquid in which a conductive substance, a basic dye mainly composed of the fluoran derivative of the present invention, and a color developer are dispersed together with a binder is applied to a support such as paper, or a conductive substance is applied to the support. The current-carrying heat-sensitive recording material of the present invention is produced by forming a layer and applying a coating liquid containing a dye, a color developer, and a binder dispersed thereon. In addition, the dye and developer are both 70~! If the material does not melt in the preferred temperature range of 20 DEG C., the sensitivity to Joule heat can be adjusted by using an appropriate thermofusible substance in combination. Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to stiff materials unless it goes beyond the gist of the present invention. Further, parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified. [Example 1] 2-(2-hydroxy-4-N-ethyl-N-cyclopentylamino)benzoylbenzoin 1o. 11 moles and 2-methyl-4methquin hisoenylamine 0
．． 010 mol was reacted with 15 mβ concentrated sulfuric acid at room temperature for 24 hours. The obtained reaction product was poured into ice water of 100 mρ, and a 20% hydroxide solution was added at room temperature to bring the pH to 11, followed by 50 m7 of l-luene. Add 8
It was heated at 5°C for 3 hours. Next, 1-luene li was separated, toluene was distilled off under reduced pressure, and recrystallized from ethyl alcohol to obtain 3-N-ethyl-N-cyclopentylamino-6-methyl-7-anilinofluorane in the form of colorless needles. Obtained as crystal. In addition, yield 83%, m, p,: 169 ~
A black color developed on silica gel at 170°C. [Example 2] 2-(1-Hydroquine-4-N-methyl-N-cyclopentylamino)benzoylbenzoic io. 1 mole and 0.01 mole of 2-methyl-4-hydroxy-4'-methylhyphenylamine. The mixture was reacted indoors in concentrated sulfuric acid for 17 hours. The obtained reaction product was poured into 100 mβ ice water, and the pH was adjusted to 9 by adding a 20% aqueous sodium hydroxide solution at room temperature, and the resulting precipitate was filtered, washed with water, and dried. Then, recrystallization was carried out using Hensen's method to obtain 3-N-methyl-N-1-pentylamino-6-methyl-7-toluidinofluoran as colorless crystals. In addition, yield 75%, TIl, l): 182-185
°C, a black color developed on silica gel. [Example 3] 2-(2-hydroxy-4-N-n-octyl-N--
shift 1 pentylamino) hexyl 3゜4,. 5.
0.01 mol of 6-detrachlorobenzoic acid and 2-methyl-
001 mole of 4-dioxybiphenylamine and 10 m
B was reacted in concentrated sulfuric acid at room temperature for 24 hours. The obtained reaction product was poured into 100 ml of ice water, and 1 volume of 20% sodium hydroxide to 1+'l of 20% sodium hydroxide solution was added at room temperature.
l 1 and acetone 30 m 7! 2 for 3 hours after adding the water. Then, the crystalline precipitate obtained was filtered, washed with water, and recrystallized with isopropyl alcohol to give 3-N-n-octyl-N-cyclobennalamino-6- Methyl-7-anilinofluorane was obtained as colorless needles. Note that the yield was 71%, m. 0.
7165-168°C, black color developed on silica gel. [Examples 4 to 17] Benzophenone derivatives shown in Table 1 were used instead of 2-(2-hydroxy-4-N-methyl-N-cyclopentylamino)hendiylbenzoic acid, and 2-methyl-4
- Example 1 except that p-aminophenol derivatives shown in Table 1 were used instead of methoxybiphenylamine.
Various fluorane derivatives were obtained in the same manner as above. The yield of iM derivatives and the color tone on silica gel are shown in Table 1.
I wrote M. Table 1 [Example 18] Thermal writing@paper was produced by the following method using 1-N-ethyl-j<-cyclopentylamino-6-methyl-7-anilinofluorane obtained in Example 1. did. Fluoran derivative of Δliquid Preparation Example 1 5 parts Stearic acid amide 1 part 2% aqueous solution of hydroxyethyl cellulose 25 parts This composition was ground with a sand grinder to an average particle size of 2 microns. Solution B was prepared using 50 parts of 4.4'-isopropylidenediphenol, 1 part of stearic acid amide, and 250 parts of a 2% aqueous solution of hydroxyethyl cellulose.This composition was ground to an average particle size of 2 microns using a sand grinder. C wave preparation solution A 62 parts B? li
31RH ultra-particle anhydrous silica (trade name Thyroid 244, manufactured by Fuji Dewison Chemical Co., Ltd.) 25 parts 20% aqueous solution of styrene-maleic anhydride copolymer salt 175 parts Zinc stearate 5; s, +s water
100
A coating liquid was prepared by mixing the above parts in the above proportions. A heat-sensitive recording paper was obtained by applying 50 g/n of the coating liquid obtained on the base paper so that the dry coating amount was 6 g/rr+ on the base paper.The obtained recording paper had no background fog. It has a good blank appearance and is heated to 125 kg at a pressure of 4 kg/crA.
When pressed for 5 seconds on a hot plate at °C, a deep black color developed. This colored image has excellent light resistance and will not change color or disappear even when exposed to light. Note that the thermal recording paper of this example was scanned at a scanning speed of 0.05 mm using a carbon dioxide laser (output 1 W, beam diameter 150 mm).
When recording was performed using a 7 m/sec cylindrical scanning recording tester, a recorded image exhibiting a high density black color was obtained. [Example 19] 5 parts of the fluorane derivative obtained in Example 1 were dissolved in 100 parts of isopropylated naphthalene, and 350 parts of warm water (50 1000 parts of warm water was added to this emulsion, the pH was adjusted to 4 with acetic acid, the pH was adjusted to 4, and the mixture was cooled to 10'C. was added to cure the capsules. This capsule-containing coating liquid was coated on one side of a 45 g/rrf base paper so that the dry weight was 5 g/r+(. - A developer coating liquid containing 20 parts of zinc salt of (methylhensyl) salicylic acid, 80 parts of kaolin, and a styrene-butadiene copolymer emulsion (50% solids content > 30 parts) was applied to a dry weight of 5 g/cd. A pressure-sensitive recording paper (inner paper) was obtained. When I wrote on several sheets with the capsule-coated side and developer-coated side facing each other and applied pressure, a black colored image was obtained on the developer-coated side. This colored image had a faster color development rate than the initial stage of color development, a higher density than the initial stage of printing, and no discoloration or fading was observed even when exposed to sunlight. [Example 20] 200 parts of 1% polyvinyl alcohol aqueous solution 200 parts of cupric iodide and 5 parts of 10% monolithium sulfite aqueous solution were added to the mixture and ground with a sand grinder until the average particle size was 2 microns.To this, 8 parts of polyacrylic acid ester emulsion and fHl tan were added. After adding 20 parts and thoroughly dispersing it, it was coated on a 50 g/m base paper at a dry coating weight of 7 g/m'. Except that 1-N-methyl-N-cyclopentylamino-6-methyl-71-luidinofluorane obtained in Example 2 was used instead of 1-pentylamino-6-methyl-7-anilinofluorane. A heat-sensitive coating liquid prepared in the same manner as in Example 4 was applied to give a dry coating amount of 5 g/M to obtain an electrically conductive heat-sensitive recording paper.
When recording was performed using a cylindrical scanning recording tester at a speed of /sec, a deep black recorded image was obtained. This recorded image had excellent light resistance and did not change color or fade even when exposed to sunlight. Patent Applicant: Kanzaki Paper Co., Ltd. Procedural Amendment March 22, 1980 Director General of the Patent Office 1. Case Description Patent Application No. 233077, 1982. 2. Title of Invention: Fluoran Derivatives, Process for Producing the Same, and Use of the Derivatives. Record 3゜Relationship with the case of the person making the amendment Patent applicant representative Fukuo Endo 4, agent residence (660) Kanzaki Paper Co., Ltd. 1-11 Jokoji Motomachi, Amagasaki City 6 Target of amendment Details Column 7 of “Detailed Description of the Invention” of the book, ? jli Correct contents As shown in the attached sheet (Contents of amendment) (1) The table on page 26 of the specification is amended as follows.

Claims (3)

[Claims] (1) Fluorane represented by the following general formula El) [In the formula, R1, R2, and R3 are each a hydrogen atom;
7-C1 Any alkyl group; represents an aralkyl group optionally substituted with a halogen atom, a lower alkyl group, or a lower alkoxyl group; R2XR, may be combined with each other to form an N-heterocycle; It may further contain an oxygen or nitrogen atom as a member. Furthermore, R3 also represents a halokene atom, a lower alkyl group, a substituted alkyl group, a lower alkoxyl group, an amine group, a substituted amino group, an aryl group or a cycloalkyl group which may be substituted with an acyl group. X and Y each represent a hydrogen atom, a halogen atom, or a lower alkyl group, and Y also represents a lower alkoxyl group. ] (2) A 2-(2-hydroxy-4-cyclopentylamino)hendiylbenzoic acid derivative represented by the following general formula Cl1) [wherein R/ is a hydrogen atom; substituted with a halogen atom, an alkoxyl group, or a cyan group] p-aminophenol derivative Y represented by the following general formula CIl+) [In the formula, R, =, R3 are each a hydrogen atom; a halogen atom, an alkyl group of C/-C/l? which may be substituted with an alkyl group, a cyano group; a halogen atom, a lower alkyl group, a lower It represents an aralkyl group which may be substituted with an alkoxyl group, which may be bonded to each other to form an N-hetero ring, and may further contain an oxygen or nitrogen atom as a het-I ring member. Further, I also represents an aryl group or a cycloalkyl group which may be further substituted with a halogen atom, a lower alkyl group, a substituted alkyl group, a lower alkoxyl group, an amino group, a substituted amino group, or an acyl group. R< represents a hydrogen atom or a lower alkyl group. X,
Y represents a hydrogen atom; a halogen atom; a lower alkyl group, and Y further represents a lower alkoxyl group. ] A method for producing a fluoran derivative represented by the following general formula CI3. [In the formula, R7,)72, R3, X, and Y have the above-mentioned meanings. ] (3) Fluorane derivative represented by the following general formula CI) [where RI, R<, and lλ3 are each a hydrogen atom; an alkyl group of cl to C/g that may be substituted with a halogen atom, an alkoxyl group, or a cyan group : Indicates an aralkyl group optionally substituted with a halogen atom, a lower alkyl group, or a lower alkoxyl group, and R2 and R3 are bonded to each other to form N-
[hetaI: ] ring, and may further contain an oxygen or nitrogen atom as a heterocyclic ring member. Furthermore, R3 is a halogen atom, a lower alkyl group, a substituted alkyl group,
It also represents a lower alkoxyl group, an amine group, a substituted amine group, an aryl group or a cycloalkyl group which may be substituted with an acyl group. X and Y each represent a hydrogen atom, a halogen atom, or a lower alkyl group, and Y also represents a lower alkoxyl group. ] A recording medium containing at least one of the following as an electron-donating coloring substance.