JP7519921B2 - Xanthene Compounds - Google Patents

Description

The present invention relates to a xanthene compound.

Xanthene compounds are widely used as light absorbers, sensitizers, dyes, etc. in photosensitive photographic materials, dyes, paints, inks, electrophotographic photoreceptors, toners, thermal recording paper, transfer ribbons, optical recording dyes, solar cells, photoelectric conversion elements, semiconductor materials, clinical test reagents, dyes for laser therapy, dyeing, etc.

Patent Document 1 discloses a xanthene compound having a specific structure. The document describes that the xanthene compound has excellent heat resistance and is useful as a pigment for a coloring composition.

JP 2018-053154 A

However, when a xanthene compound is used as a dye, it is required that it does not dissolve in organic solvents such as chloroform, acetone, and toluene at a concentration of more than 0.5% by mass. In other words, the xanthene compound is required to have high resistance to organic solvents. However, when the inventors conducted further tests, they found that the xanthene compound described in Patent Document 1 did not have sufficient resistance to organic solvents.

As a result of extensive investigations, the present inventors discovered that a xanthene compound having a specific structure can solve the above problems, and arrived at the present invention.
The present invention provides the following [1] to [16].

[1]
A xanthene compound represented by formula (I):

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, a hydroxy group, a nitro group, a cyano group, a halogen atom, a carboxy group, a sulfo group, a sulfamoyl group, a metallocenyl group, a hydrocarbon group having 1 to 30 carbon atoms, or a group in which one or more methylene groups in the hydrocarbon group have been replaced with a divalent group selected from Group I below, with the proviso that when two or more methylene groups have been replaced with a divalent group selected from Group I below, the divalent groups are not adjacent to each other,
The hydrogen atoms contained in the above-mentioned hydrocarbon groups may be substituted with halogen atoms, nitro groups, cyano groups, hydroxy groups, amino groups, carboxy groups, sulfo groups, phosphono groups, sulfamoyl groups, isocyanato groups, or heterocyclic groups.
R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, a heterocyclic group, a hydrocarbon group having 1 to 30 carbon atoms, or a group in which one or more methylene groups in the hydrocarbon group have been replaced with a divalent group selected from the following group I, with the proviso that when two or more methylene groups have been replaced with a divalent group selected from the following group I, the divalent groups are not adjacent to each other,
The hydrogen atom contained in the hydrocarbon group may be substituted with a heterocyclic group or a polar group.
one or more of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ is a group having a polar group as a substituent;
n represents an integer of 1 to 3;
A ^q- represents a q-valent anion, q represents an integer of 1 to 3, and p represents a coefficient for keeping the charge neutral.
Group I: -O-, -S-, -CO-, -COO-, -OCO-, -COS-, -OCS-, -SO ₂ -, -SO ₃ -, -NH-, -CONH-, -NHCO-, -SO ₂ NH-, -NH-SO ₂ - or -N=CH-.

[2]
The xanthene compound according to [1], wherein at least one group selected from the group consisting of ^R7 and ^R9 is each independently a hydroxy group, a nitro group, a cyano group, a halogen atom, a carboxy group, a sulfo group, a sulfamoyl group, a hydrocarbon group having 1 to 30 carbon atoms, or a metallocenyl group.

[3]
The xanthene compound according to [1] or [2], wherein at least one group selected from the group consisting of R ⁷ and R ⁹ is each independently a halogen atom, a nitro group, or a cyano group.

[4]
The xanthene compound according to any one of [1] to [3], wherein R ⁷ or R ⁹ is a halogen atom.

[5]
The xanthene compound according to any one of [1] to [4], wherein R ⁷ and R ⁹ are halogen atoms.

[6]
The xanthene compound according to any one of [1] to [5], wherein one or more of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ is a hydrocarbon group having 1 to 30 carbon atoms substituted with a carboxy group.

[7]
The xanthene compound according to any one of [1] to [6], wherein two or more of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are groups having a polar group.

[8]
The xanthene compound according to any one of [1] to [7], wherein R ¹¹ or R ¹² is a group having a polar group, and R ¹³ or R ¹⁴ is a group having a polar group.

[9]
The xanthene compound according to [8], wherein R ¹¹ and R ¹³ are groups having a polar group, and R ¹² , R ¹⁴ , R ¹⁵ and R ¹⁶ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms.

[10]
The xanthene compound according to any one of [1] to [8], wherein R ¹⁵ and R ¹⁶ are groups having a polar group.

[11]
The xanthene compound according to [10], wherein R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms.

[12]
The xanthene compound according to any one of [1] to [7], wherein two or more of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are groups having a polar group, and R ¹⁵ and R ¹⁶ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms.

[13]
The xanthene compound according to any one of [1] to [7], wherein R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms, and R ¹⁵ and R ¹⁶ are groups having a polar group.

[14]
The xanthene compound according to any one of [1] to [13], wherein R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently an alkyl group having 1 to 10 carbon atoms, which may or may not have a polar group.

[15]
The xanthene compound according to any one of [1] to [14], wherein n is 1, q is 1, and A ^q- is a halide ion, an imide ion, or a sulfonate ion.

[16]
The xanthene compound according to any one of [1] to [15], wherein the polar group is a carboxy group.

According to the present invention, a xanthene compound having high resistance to organic solvents can be provided.

Hereinafter, the xanthene compound of the present invention will be described based on a preferred embodiment. The xanthene compound of the present invention has a structure represented by the above formula (I).

In formula (I), the halogen atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R 7 , R ⁸ , R ⁹ and R ¹⁰ and the halogen atoms that may replace the hydrogen atoms contained in the hydrocarbon groups represented by R ^{1 ,} R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ include fluorine, chlorine, bromine and iodine. The halogen atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different. In the present invention, the halogen atom is preferably chlorine because the width of the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed.

In the present invention, when a group such as a hydrocarbon group has a substituent, the number of carbon atoms of the group defined in the present invention includes the number of carbon atoms of the substituent, unless otherwise specified.

In formula (I), the hydrocarbon group having 1 to 30 carbon atoms represented by R ¹ , R ² , R ³ , R 4 , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ is not particularly limited, and examples thereof include an alkyl group ^having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms and an arylalkenyl group having 8 to 30 carbon atoms. The hydrocarbon groups having 1 to 30 carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different. In the present invention, the hydrocarbon group having 1 to 30 carbon atoms is preferably an alkyl group having 1 to 20 carbon atoms, since this narrows the wavelength range of the ultraviolet-visible absorption spectrum of the compound and increases the extinction coefficient per weight of the compound.

The alkyl group having 1 to 20 carbon atoms may be linear or branched. Examples of linear alkyl groups include methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, hexadecyl, octadecyl, and icosyl. Examples of branched alkyl groups include isopropyl, isobutyl, s-butyl, t-butyl, isoamyl, t-amyl, isooctyl, 2-ethylhexyl, t-octyl, isononyl, and isodecyl. In the present invention, linear alkyl groups are preferred because they make it easier to synthesize the compound. In addition, alkyl groups having 1 to 10 carbon atoms are preferred because they increase the extinction coefficient per weight of the compound, and alkyl groups having 1 to 4 carbon atoms are more preferred.

The alkenyl group having 2 to 20 carbon atoms may be linear or cyclic. When the alkenyl group is linear, it may be a terminal alkenyl group having an unsaturated bond at the end, or an internal alkenyl group having an unsaturated bond inside. Examples of terminal alkenyl groups having 2 to 20 carbon atoms include vinyl, 2-propenyl, 3-butenyl, 4-pentenyl, and 5-hexenyl. Examples of internal alkenyl groups include 2-butenyl, 3-pentenyl, 2-hexenyl, 3-hexenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 3-octenyl, 3-nonenyl, 4-decenyl, 3-undecenyl, and 4-dodecenyl. Examples of cyclic alkenyl groups include 3-cyclohexenyl, 2,5-cyclohexadienyl-1-methyl, and 4,8,12-tetradecatrienyl allyl. In the present invention, an alkenyl group having 2 to 10 carbon atoms is preferred because the synthesis of the compound becomes easier. In addition, the position of -C=C- in the alkenyl group is preferably a terminal portion because the wavelength range of the ultraviolet-visible absorption spectrum of the compound becomes narrower. The number of -C=C- is preferably 1 to 2 from the viewpoint of the generation of isomers.

The above cycloalkyl group having 3 to 20 carbon atoms means a saturated monocyclic or saturated polycyclic alkyl group having a total of 3 to 20 carbon atoms. Examples of saturated monocyclic alkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl. Examples of saturated polycyclic alkyl groups include adamantyl, decahydronaphthyl, octahydropentalene, bicyclo[1.1.1]pentanyl, and tetradecahydroanthracenyl. In the present invention, a cycloalkyl group having 3 to 10 carbon atoms is preferred because it increases the absorption coefficient per weight of the compound. In addition, a monocyclic alkyl group is preferred because it narrows the wavelength range of the ultraviolet and visible absorption spectrum of the compound.

The cycloalkylalkyl group having 4 to 20 carbon atoms means a group in which a hydrogen atom of an alkyl group is replaced with a cycloalkyl group and which has a total of 4 to 20 carbon atoms. The cycloalkylalkyl group may be a monocyclic or polycyclic cycloalkyl group. In addition, a methylene group of the alkyl group in the cycloalkylalkyl group may be replaced with -CH=CH-.
Examples of cycloalkylalkyl groups having 4 to 20 carbon atoms and in which the cycloalkyl group is a single ring include cycloalkylmethyl such as cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, cycloheptylmethyl, cyclooctylmethyl, cyclononylmethyl, and cyclodecylmethyl; cycloalkylethyl such as 2-cyclobutylethyl, 2-cyclopentylethyl, 2-cyclohexylethyl, 2-cycloheptylethyl, 2-cyclooctylethyl, 2-cyclononylethyl, and 2-cyclodecylethyl; cycloalkylpropyl such as 3-cyclobutylpropyl, 3-cyclopentylpropyl, 3-cyclohexylpropyl, 3-cycloheptylpropyl, 3-cyclooctylpropyl, 3-cyclononylpropyl, and 3-cyclodecylpropyl; and cycloalkylbutyl such as 4-cyclobutylbutyl, 4-cyclopentylbutyl, 4-cyclohexylbutyl, 4-cycloheptylbutyl, 4-cyclooctylbutyl, 4-cyclononylbutyl, and 4-cyclodecylbutyl. Examples of the cycloalkylalkyl group having 4 to 20 carbon atoms and in which the cycloalkyl group is a polycyclic ring include bicyclo[1.1.0]butyl, bicyclo[1.1.1]pentyl, bicyclo[2.1.0]pentyl, bicyclo[3.1.0]hexyl, bicyclo[2.1.1]hexyl, bicyclo[2.2.0]hexyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.0]heptyl, bicyclo[3.1.1]heptyl, bicyclo[2.2.1]heptyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.0]heptyl, bicyclo[3.1.1]heptyl, bicyclo[2.2.1]heptyl, Examples of such aryl groups include cyclo[5.1.0]octyl, bicyclo[4.2.0]octyl, bicyclo[4.1.1]octyl, bicyclo[3.3.0]octyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, spiro[4.4]nonanyl, spiro[4.5]decanyl, decalin, tricyclodecanyl, tetracyclododecanyl, and cedrol, cyclododecanyl 3-3-adamantylpropyl, and decahydronaphthylpropyl.
In the present invention, a cycloalkylalkyl group having 4 to 10 carbon atoms is preferred because the compound has a high absorption coefficient per weight. The cycloalkyl group in the cycloalkylalkyl group having 4 to 10 carbon atoms is preferably a monocyclic group because the compound can be synthesized more easily.

The aryl group having 6 to 30 carbon atoms may have a monocyclic structure or a condensed ring structure. Furthermore, the aryl group may be a combination of an aryl group having a monocyclic structure and an aryl group having a monocyclic structure, an aryl group having a monocyclic structure and an aryl group having a condensed structure, or an aryl group having a condensed structure and an aryl group having a condensed structure. Examples of the aryl group having a monocyclic structure include phenyl and biphenylyl. Examples of the aryl group having a condensed ring structure include naphthyl, anthryl, and phenanthrenyl. The aryl group having 6 to 30 carbon atoms may have one or more substituents. Examples of the substituents include the alkyl group, the alkenyl group, the carboxy group, and a halogen atom. Examples of substituted aryl groups having 6 to 30 carbon atoms include substituted aryl groups having a monocyclic structure, such as tolyl, xylyl, ethylphenyl, 4-chlorophenyl, 4-carboxylphenyl, 4-vinylphenyl, 4-methylphenyl, and 2,4,6-trimethylphenyl. In the present invention, aryl groups having 6 to 10 carbon atoms are preferred because the absorption coefficient per weight of the compound is increased. In addition, the aryl group preferably has a monocyclic structure because the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed.

The arylalkyl group having 7 to 30 carbon atoms means a group in which one or more hydrogen atoms of the alkyl group are substituted with the aryl group and which has a total of 7 to 30 carbon atoms. Examples of the arylalkyl group having 7 to 30 carbon atoms include phenyl alkyl groups such as benzyl, α-methylbenzyl, α,α-dimethylbenzyl, 2-phenylethyl, 2-phenylpropyl, 3-phenylpropyl, diphenylmethyl, triphenylmethyl, and triphenylpropyl; and naphthyl alkyl groups such as naphthylpropyl. In the present invention, an arylalkyl group having 7 to 20 carbon atoms is preferred because the absorption coefficient per weight of the compound is high. In addition, the aryl group in the arylalkyl group is preferably a phenyl group or a naphthyl group because the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed. The number of aryl groups in the arylalkyl group is preferably 1 to 3 because the absorption coefficient per weight of the compound is high. The aryl group in the arylalkyl group is preferably an alkyl group having 1 to 4 carbon atoms because the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed, and a linear alkyl group having 1 to 4 carbon atoms is preferred. The aryl group in the arylalkyl group is preferably located at the terminal of the alkyl group, since this makes the synthesis of the compound easier.

The above arylalkenyl group having 8 to 30 carbon atoms means a group in which the hydrogen atoms of the alkenyl group are replaced with aryl groups and which has a total of 8 to 30 carbon atoms. Examples of the arylalkenyl group having 8 to 30 carbon atoms include styrenyl, cinnamyl, 2-phenyl-2-propenyl, 3-phenyl-2-propenyl, 2-phenyl-4-pentenyl, 2-phenyl-4-hexenyl, 2,2-diphenylethylenyl, 3,3-phenyl-2-propenyl, 2-naphthyl-2-propenyl, 3-naphthyl-2-propenyl, 3-naphthyl-2-phenyl-2-propenyl, 5-anthracenyl-2-phenyl-4-hexenyl, and 5-anthracenyl-2-naphthyl-4-hexenyl. In the present invention, an arylalkenyl group having 8 to 20 carbon atoms is preferred because it increases the absorption coefficient per weight of the compound. The aryl group in the arylalkenyl group is preferably a phenyl group or a naphthyl group, since the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed. The number of aryl groups in the arylalkenyl group is preferably 1 or 2, since the absorption coefficient per weight of the compound is high. The aryl group in the arylalkenyl group is preferably an alkyl group having 1 to 6 carbon atoms, since the absorption coefficient per weight of the compound is high. The aryl group in the arylalkenyl group is preferably located at the terminal of the alkyl group, since the synthesis of the compound is easier. The alkenyl group in the arylalkenyl group is preferably a chain-like group, since the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed. When the alkenyl group is a chain-like group, it may be a terminal alkenyl group having an unsaturated bond at the terminal, or an internal alkenyl group having an unsaturated bond inside.

The heterocyclic groups represented by R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ may be monocyclic or may have a condensed ring structure. Furthermore, the heterocyclic group may be a group in which a monocyclic heterocyclic group is linked to a monocyclic heterocyclic group, a monocyclic heterocyclic group is linked to a heterocyclic group having a condensed structure, or a heterocyclic group having a condensed structure is linked to a heterocyclic group having a condensed structure. Examples of monocyclic heterocyclic groups include pyridyl, pyrimidyl, pyridazyl, piperazyl, piperidyl, pyranyl, pyrazolyl, triazyl, pyrrolidyl, imidazolyl, triazolyl, furyl, furanyl, thienyl, thiophenyl, thiadiazolyl, thiazolyl, oxazolyl, isothiazolyl, isoxazolyl, yulolidyl, morpholinyl, thiomorpholinyl, 2-pyrrolidinone-1-yl, 2-piperidon-1-yl, 2,4-dioxyimidazolidin-3-yl, and 2,4-dioxyoxazolidin-3-yl. Examples of heterocyclic groups having a condensed ring structure include heterocyclic groups having a condensed ring structure such as quinolyl, isoquinolyl, benzimidazolyl, benzofuranyl, benzothiophenyl, benzothiazolyl, benzoxazolyl, and indolyl. The same explanation applies to the heterocyclic groups which can substitute for hydrogen atoms in the hydrocarbon groups represented by R ¹ , R ² , R ³ , R ^{4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 ,} R ¹⁵ and R ¹⁶ .

Examples of the metallocenyl group represented by ^R1 , ^R2 , ^R3 , R4, ^R5 , ^R6 , ^R7 , ^R8 , ^R9 and ^R10 include ferrocenyl, ^nickelocenyl , cobaltyl, ferrocene alkyl and ferrocene alkoxy.

In the xanthene compound of the present invention, at least one of the groups represented by R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ in formula (I) is a group having a polar group as a substituent. In the present invention, the polar group means a polar atomic group. Specific examples of the polar group include a carboxy group, a hydroxy group, an amino group, and a sulfonyl group. Among these, a carboxy group is preferred because the compound has high resistance to organic solvents.

Xanthene compounds in which n in formula (I) is 1 are preferred from the standpoint of ease of synthesis.

The anion represented by A ^q- in formula (I) can be a monovalent, divalent or trivalent anion depending on the value of q. When A ^q− is a monovalent anion A ⁻ , examples of the A ⁻ include halide ions such as chloride ion (Cl ⁻ ), bromide ion (Br ⁻ ), iodide ion (I ⁻ ), and fluoride ion (F ⁻ ); inorganic ions such as perchlorate ion (ClO ₄ ⁻ ), chlorate ion (ClO ₃ ⁻ ), nitrate ion (NO ₃ ⁻ ), nitrate ion (NO ₃ ⁻ ), thiocyanate ion (SCN ⁻ ), hexafluorophosphate ion (PF ₆ ⁻ ), hexafluoroantimony ion (SbF ₆ ⁻ ), tetrachloroaluminate ion (AlCl ₄ ⁻ ), and tetrafluoroborate ion (BF ₄ ⁻ ); carboxylate ions such as acetate ion (CH ₃ CO ₂ ⁻ ) and trifluoroacetate ion (CF ₃ CO ₂ ⁻ ₎ ; Examples of the monovalent anion _include sulfonate ions ^such as benzenesulfonate ion, toluenesulfonate ion, trifluoromethanesulfonate ion, and vinylsulfonate ion; alkyl sulfate ions such as methyl sulfate ion, ethyl sulfate ion, and butyl sulfate ion; alkyl phosphate ions such as methyl phosphate ion, ethyl phosphate ion, and butyl phosphate ion; and imide ions such as bis(trifluoromethanesulfonyl)imide ion ((CF ₃ SO ₂ ) ₂ N ⁻ ), bis(perfluorobutanesulfonyl)imide ion ((C ₄ F ₉ SO ₂ ) ₂ N ⁻ ), and dicyanimide ion ((CN) ₂ N ⁻ ). The monovalent anion is preferably a halide ion, imide ion, or sulfonate ion. As the halide ion, chloride ion is preferred from the viewpoint of ease of synthesis. As the imide ion, bis(trifluoromethanesulfonyl)imide ion is preferred from the viewpoint of high resistance to organic solvents. As the sulfonate ion, a benzenesulfonate ion such as 3-sulfobenzoate ion is preferred because it has high resistance to organic solvents.
When A ^q− is a divalent anion A ²⁻ , examples of A ²⁻ include a tungstate ion, a molybdate ion (MoO ₄ ²⁻ ), and a chromate ion.
When A ^q− is a trivalent anion A ³⁻ , examples of A ³⁻ include a phosphomolybdate ion, a phosphotungstate ion, a phosphotungstomolybdate ion, and a vanadate ion.

In the xanthene compound of the present invention, since the wavelength region of the ultraviolet-visible absorption spectrum of the compound is narrowed, at least one group selected from the group consisting of R ⁷ and R ⁹ in formula (I), particularly R ⁷ and R ⁹ , is preferably a hydroxy group, a nitro group, a cyano group, a halogen atom, a carboxy group, a sulfo group, a sulfamoyl group, a hydrocarbon group having 1 to 30 carbon atoms, or a metallocenyl group, more preferably a halogen atom, a nitro group, or a cyano group, further preferably a halogen atom, and particularly preferably a chlorine atom.
From the same viewpoint, it is preferable that at least one group selected from the group consisting of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ¹⁰ is a hydrogen atom, and it is preferable that all of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ¹⁰ are hydrogen atoms.

In the xanthene compound of the present invention, one or more, preferably two or more hydrogen atoms among R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ in formula (I) are preferably a hydrocarbon group having 1 to 30 carbon atoms substituted with a carboxy group, since this increases the resistance of the compound to organic solvents.
In the xanthene compound of the present invention, it is preferred that two or more of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ in formula (I) are groups having a polar group, since this increases the resistance of the compound to organic solvents.
In the xanthene compound of the present invention, it is preferable that R ¹¹ or R ¹² in formula (I) is a group having a polar group, and R ¹³ or R ¹⁴ is a group having a polar group, since the compound has high resistance to organic solvents. From the same viewpoint, it is preferable that R ¹⁵ and R ¹⁶ are groups having a polar group.
In the xanthene compound of the present invention, since the compound has high resistance to organic solvents, it is preferable that two or more of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in formula (I) are groups having a polar group, and R ¹⁵ and R ¹⁶ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms. From the same viewpoint, it is preferable that R ¹¹ and R ¹³ in formula (I) are groups having a polar group, and R ¹² , R ¹⁴ , R ¹⁵ and R ¹⁶ are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms. From the same viewpoint, it is preferable that R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in formula (I) are unsubstituted hydrocarbon groups having 1 to 30 carbon atoms, and R ¹⁵ and R ¹⁶ are groups having a polar group.
In the xanthene compound of the present invention, since the wavelength range of the ultraviolet-visible absorption spectrum of the compound is narrowed, it is preferable that R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ in formula (I) are each independently a hydrocarbon group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, still more preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably an alkyl group having 1 to 4 carbon atoms.

In the xanthene compound of the present invention, it is preferable that n and q in formula (I) are 1, that is, A ^q- is a monovalent anion, since this facilitates the synthesis of the compound. When A ^q- is a monovalent anion, it is preferable that A ^q- is a halide ion, an imide ion, or a sulfonate ion. As the halide ion, a chloride ion is preferable. As the imide ion, a bis(trifluoromethanesulfonyl)imide ion is preferable. As the sulfonate ion, a benzenesulfonate ion such as a 3-sulfobenzoate ion is preferable.

Specific examples of the xanthene compounds of the present invention include compounds (I-1) to (I-30).

The xanthene compound of the present invention has high resistance to organic solvents such as chloroform, acetone, and toluene, i.e., the xanthene compound of the present invention is poorly soluble in organic solvents. High resistance to organic solvents means that the compound is substantially insoluble in organic solvents, or even if it dissolves, the dissolution amount is as small as less than 0.5 mass%.
In particular, the xanthene compound of the present invention is preferably substantially insoluble in chloroform, or if it does dissolve, the amount of dissolution is preferably less than 0.5% by mass, more preferably 0 to 0.4% by mass.
In addition, the xanthene compound of the present invention is preferably not substantially soluble in acetone, or if it is soluble, the amount of solubility is preferably less than 0.5% by mass, more preferably 0 to 0.2% by mass, and even more preferably 0 to 0.1% by mass.
In addition, the xanthene compound of the present invention is preferably substantially insoluble in toluene, or if soluble, the solubility is less than 0.5 mass%, more preferably 0 to 0.2 mass%, and further preferably insoluble in toluene. In this specification, "insoluble in organic solvents" means that the solubility in organic solvents is 0.01 mass% or less.
The solubility of a xanthene compound in an organic solvent can be measured by the method described in the Examples.

The xanthene compound represented by the above formula (I) can be suitably produced, for example, by the following method.

First, an aniline derivative having a polar group is formylated, and then dehydration condensation is carried out with an aminophenol derivative to obtain a leuco compound. The obtained leuco compound is then oxidized and salt-exchanged with various anions to obtain the desired xanthene compound. Known reaction conditions can be used.

The xanthene compounds of the present invention can be used as light absorbers, sensitizers, etc. in applications such as photosensitive photographic materials, dyes, paints, inks, electrophotographic photoreceptors, toners, thermal recording paper, transfer ribbons, optical recording dyes, solar cells, photoelectric conversion elements, semiconductor materials, clinical test reagents, dyes for laser therapy, and dyeing.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by mass" and "% by mass", respectively.

Example 1 Synthesis of Xanthene Compound (I-1) 15.0 parts of 3-aminophenol and 187 parts of methanol were mixed and stirred at -5°C to obtain a reaction liquid. 8.8 parts of propylaldehyde were added to the obtained reaction liquid and stirred for 10 minutes, and then 11.4 parts of sodium borohydride were added little by little and stirred for 4 hours. 2N hydrochloric acid was added to the reaction liquid until the pH became 4, and then the precipitated solid was separated by filtration. The methanol in the filtrate was distilled off, and ethyl acetate was added to the residue and washed three times with water, and then the solvent was distilled off from the organic layer. The obtained liquid was dried in a reduced pressure oven at 60°C to obtain 11.24 parts (54%) of compound S-2. LC/MS: 150 [M ⁺ ].

10.0 parts of compound S-2, 19.4 parts of ethyl 4-bromobutyrate, and 66.2 parts of tetrabutylammonium bromide were mixed and heated and stirred at 95°C for 2 hours. After cooling to room temperature, the reaction product was extracted with toluene, and the extracted reaction product was washed three times with 50 parts of water. The organic layer was distilled off and the residue was purified by silica gel column chromatography (developing solvent: chloroform:hexane = 1:1) to obtain 8.1 parts of compound S-3 (yield 23%). LC/MS: 264 [M+].

4.3 parts of compound S-3, 2.0 parts of compound S-1, and 49.1 parts of trifluorosulfonic acid were mixed and stirred at 100 ° C for 3 hours to obtain a reaction solution. Compound S-1 is represented by the following formula. After the reaction solution was cooled to room temperature, 100 parts of water was added to the reaction solution, followed by extraction with chloroform and ethyl acetate, and each organic layer was washed with water. The washed organic layers were combined and the solvent was distilled off. 3.5 parts of p-chloranil and 100 parts of acetonitrile were added to the residue and stirred at room temperature for 12 hours. After the solvent was distilled off from the reaction solution, 100 parts of chloroform were added and the precipitated solid was filtered off. After concentrating the filtrate, 100 parts of 4% aqueous sodium hydroxide solution was added and stirred at room temperature for 12 hours. The liquid was neutralized to pH 4 with 2N hydrochloric acid, and the precipitated solid was filtered off. The obtained solid was dispersed and washed with a mixed solution of ethyl acetate-hexane (3:1) for 3 hours, and then dried. The dried solid was dissolved in 20 parts of concentrated hydrochloric acid to obtain a solution. The obtained solution was filtered, and the filtrate was crystallized with 20% saline and neutralized with 25% aqueous sodium hydroxide solution until the pH reached 4. The precipitated solid was collected by filtration and dried in a reduced pressure oven at 60° C. to obtain 2.3 parts (yield 39%) of the xanthene compound represented by formula (I-1). LC/MS: 683 [M+].

Example 2 Synthesis of Xanthene Compound (I-2) 0.44 parts of the xanthene compound (I-1), 0.35 parts of bis(trifluoromethanesulfonyl)lithium, and 6.7 parts of N,N-dimethylsulfoxide were mixed and stirred at 50°C for 3 hours to obtain a reaction solution. The obtained reaction solution was dropped into 40 parts of 20% saline, and the precipitated solid was collected by filtration. The solid was dissolved in chloroform, and the organic layer was washed with water, and then sodium sulfate was added and dried, followed by distillation to remove the solvent, and the mixture was dried in a reduced pressure oven at 60°C to obtain 0.43 parts (yield 74%) of the xanthene compound represented by formula (I-2).

Example 3 Synthesis of xanthene compound (I-3) 0.50 parts (yield 72%) of the xanthene compound represented by formula (I-3) was obtained in the same manner as in Example 2, except that bis(trifluoromethanesulfonyl)lithium was changed to sodium 3-sulfobenzoate.

[Example 4] Synthesis of xanthene compound (I-4) 0.4 parts of N,N-diethylamino-3-phenol, 0.5 parts of compound S-X, and 7.4 parts of trifluorosulfonic acid were mixed and stirred at 100 ° C. for 3 hours to obtain a reaction solution. Compound S-X is represented by the following formula. After cooling the reaction solution to room temperature, the reaction solution was added to 50 parts of water, extracted with chloroform and ethyl acetate, and each organic layer was washed with water. The washed organic layers were combined and the solvent was distilled off. 0.9 parts of p-chloranil and 50 parts of acetonitrile were added to the residue and stirred at room temperature for 12 hours. After distilling off the solvent from the reaction solution, 50 parts of chloroform were added and the precipitated solid was filtered off. The filtrate was concentrated, and 50 parts of 4% aqueous sodium hydroxide solution was added to the concentrated filtrate and stirred at room temperature for 12 hours. The reaction solution was neutralized to pH 4 with 2N hydrochloric acid, and the precipitated solid was collected by filtration. The obtained solid was dispersed and washed with a mixed solution of ethyl acetate-hexane (3:1) for 3 hours, dried, and then dissolved in 5 parts of concentrated hydrochloric acid to obtain a solution. The obtained solution was filtered, and the filtrate was crystallized with 20% saline and neutralized with 25% aqueous sodium hydroxide solution until the pH became 4. The precipitated solid was collected by filtration and dried in a reduced pressure oven at 60°C to obtain 0.21 parts (yield 24%) of the xanthene compound represented by formula (I-4). LC/MS: 655 [M+].

Example 5 Synthesis of xanthene compound (I-5) 0.55 parts (yield 67%) of the xanthene compound represented by formula (I-5) was obtained in the same manner as in Example 2, except that the xanthene compound (I-1) was changed to the xanthene compound (I-4).

Example 6 Synthesis of xanthene compound (I-6) 0.51 parts (yield 76%) of the xanthene compound represented by formula (I-6) was obtained in the same manner as in Example 3, except that the xanthene compound (I-1) was changed to the xanthene compound (I-4).

[Comparative Example 1] Comparative xanthene compound 1
As comparative xanthene compound 1, the following compound was used.

Comparison between Xanthene Compound (I-1) of Example 1 and Comparative Example 1 The solubility of Xanthene Compound 1 in an organic solvent was measured by the following method.
0.10 g each of xanthene compound (I-1) and comparative xanthene compound 1 was weighed into a 50 mL sample tube. Chloroform was added to the sample tube, and the tube was shaken for 3 minutes and then allowed to stand for 1 minute to determine the concentration at which crystals did not precipitate, which was taken as the solubility of the xanthene compound in chloroform. Measurement was performed by continuing the addition of chloroform to a solution containing 10% by mass of the xanthene compound until crystals did not precipitate. The measurement was performed at room temperature (23° C.). The results are shown in Table 1.
The solubilities of the xanthene compounds in acetone and toluene were measured by the same procedure, and the results are shown in Table 1.

As is clear from the results shown in Table 1, the xanthene compound (I-1) of Example 1 has a solubility of 0.5% or less in organic solvents such as chloroform, acetone, and toluene, and has improved resistance to organic solvents, making it suitable for use as a dye. In contrast, the comparative xanthene compound 1 has a solubility in organic solvents of more than 0.5%, making it less suitable as a dye than the xanthene compound (I-1) of Example 1.

Claims (2)

A xanthene compound represented by formula (I):

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ¹⁰ each independently represent a hydrogen atom, a hydroxy group, a nitro group, a cyano group, a halogen atom, a carboxy group, a sulfo group, a sulfamoyl group, a metallocenyl group, a hydrocarbon group having 1 to 30 carbon atoms, or a group in which one or more methylene groups in the hydrocarbon group have been replaced with a divalent group selected from Group I below, with the proviso that when two or more methylene groups have been replaced with a divalent group selected from Group I below, the divalent groups are not adjacent to each other,
The hydrogen atoms contained in the above-mentioned hydrocarbon groups may be substituted with halogen atoms, nitro groups, cyano groups, hydroxy groups, amino groups, carboxy groups, sulfo groups, phosphono groups, sulfamoyl groups, isocyanato groups, or heterocyclic groups.
R ⁷ and R ⁹ each independently represent a halogen atom;
R ¹¹ and R ¹³ each independently represent a hydrocarbon group having 1 to 30 carbon atoms substituted with a carboxy group;
R ¹² , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represent an unsubstituted hydrocarbon group having 1 to 30 carbon atoms ;
n represents an integer of 1 to 3;
A ^q- represents a q-valent anion, q represents an integer of 1 to 3, and p represents a coefficient for keeping the charge neutral.
Group I: -O-, -S-, -CO-, -COO-, -OCO-, -COS-, -OCS-, -SO ₂ -, -SO ₃ -, -NH-, -CONH-, -NHCO-, -SO ₂ NH-, -NH-SO ₂ - or -N=CH-. 2. The xanthene compound according to claim 1 , wherein n is 1, q is 1, and ^Aq- is a halide ion, an imide ion, or a sulfonate ion.