Azo compound, ink containing azo compound, display including said ink and electronic paper

Abstract

The present invention relates to an ink comprising: a solvent having a relative permittivity, measured at a frequency of 1 kHz and a temperature of 22 C., of 3 or less and a solubility in water at 25 C. of 20 mg/L or less; and a specific azo compound.

Claims

1. An ink comprising: a solvent having a relative permittivity, measured at a frequency of 1 kHz and a temperature of 22 C., of 3 or less and a solubility in water at 25 C. of 20 mg/L or less; and an azo compound represented by the following general formula (1): ##STR00073## wherein in the general formula (1), R.sup.1 represents any substituent, R.sup.2 represents a hydrogen atom or any substituent, R.sup.3 and R.sup.4 each independently represent an alkyl group which may have a substituent, ring A represents general formula (2), X represents a nitrogen atom, a methine group, or a methine group having a substituent, and general formula (2) is represented by the following formula: ##STR00074## wherein in the general formula (2), R.sup.5 represents a hydrogen atom or any substituent ##STR00075##

2. The ink according to claim 1, wherein the solvent comprises at least one member selected from the group consisting of hydrocarbon-based solvents, silicone oils, and fluorocarbon-based solvents.

3. The ink according to claim 1, wherein a product C of a molar extinction coefficient (Lmol.sup.1 cm.sup.1) at an absorption maximum wavelength in an n-decane solution of the azo compound and a saturation concentration C (molL.sup.1) at 5 C. of the solution is 1,000 cm.sup.1 or larger.

4. The ink according to claim 1, which further comprises at least one member selected from the group consisting of heterocyclic compounds, cyanovinyl compounds, and anthraquinone compounds.

5. The ink according to claim 4, wherein the heterocyclic compounds are at least one compound selected from the group consisting of the following general formulae (4) to (7): ##STR00076## wherein in the general formula (4), R.sup.101 and R.sup.102 each independently represent a hydrogen atom or any substituent, D.sup.3 and D.sup.4 each independently represent any substituent, e represents an integer of 0-5, and when e is 2 or larger, the two or more D.sup.3s present in the molecule may be the same or different, and g represents an integer of 0-4, and when g is 2 or larger, the two or more D.sup.4s present in the molecule may be the same or different; ##STR00077## wherein in the general formula (5), R.sup.201, R.sup.202, R.sup.203, R.sup.204, R.sup.205, R.sup.206, R.sup.207, and R.sup.208 each independently represent a hydrogen atom or any substituent, and Z represents a nitrogen atom, a methine group or a methine group having a substituent; ##STR00078## wherein in the general formula (6), R.sup.301, R.sup.302, D.sup.5, and D.sup.6 each independently represent any substituent, l represents an integer of 0-4, and when 1 is 2 or larger, the two or more D.sup.5s present in the molecule may be the same or different, and j represents an integer of 0-4, and when j is 2 or larger, the two or more D.sup.6s present in the molecule may be the same or different; ##STR00079## wherein in the general formula (7), R.sup.601, R.sup.602, D.sup.9, or D.sup.10 each independently represents any substituent, A.sup.1 represents a hydrogen atom or any substituent, p represents an integer of 0-5, and when p is 2 or larger, the two or more D.sup.9s present in the molecule may be the same or different, q represents an integer of 0-4, and when q is 2 or larger, the two or more D.sup.10s present in the molecule may be the same or different, X.sup.1 represents a nitrogen atom, a methine group, or a methine group having a halogen atom, a cyano group, or a COOR.sup.605 group as a substituent, and R.sup.605 represents a hydrogen atom, an alkyl group which has 1-20 carbon atoms and may have a substituent, an aryl group which has 6-20 carbon atoms and may have a substituent, or a heteroaryl group which has 2-20 carbon atoms and may have a substituent.

6. The ink according to claim 4, wherein the anthraquinone compounds are represented by the following general formula (8): ##STR00080## wherein in the general formula (8), D.sup.8 represents any substituent, and t represents an integer of 0-8, and when t is 2 or larger, the two or more D.sup.8s present in the molecule may be the same or different.

7. The ink according to claim 1, which is for displays or for optical shutters.

8. A display which comprises a display part including the ink according to claim 1, wherein an image is displayed by controlling voltage application to the display part.

9. The display according to claim 8, wherein the display part includes electrophoretic particles or an aqueous medium.

10. The display according to claim 8, wherein an image is displayed by causing a change in the coloration state by the voltage application.

11. The display according to claim 8, wherein an image is displayed in an electrowetting mode or an electrophoresis mode.

12. An electronic paper which comprises the display according to claim 8.

13. An azo compound represented by the following general formula (10): ##STR00081## wherein in the general formula (10), R.sup.21 represents any substituent, R.sup.22 and R.sup.23 each independently represent a hydrogen atom or any substituent, R.sup.24 and R.sup.25 each independently represent an alkyl group which may have a substituent, X.sup.2 represents a nitrogen atom or a methine group which may have a substituent, and n represents an integer of 0-5.

Description

EXAMPLES

(1) The invention will be explained below in more detail by reference to Examples and Comparative Examples, but the invention should not be construed as being limited to the following Examples in any way.

(2) [Synthesis of Intermediates TH1 to TH4]

(3) ##STR00062##

(4) <Synthesis of Intermediate TH1>

(5) 2,5-Dimethyl-1,4-dithiane-2,5-diol (10 g; 55.5 mmol) and malononitrile (7.33 g; 111 mmol) were dissolved in methanol (100 mL). Triethylamine (15.4 mL; 111 mmol) was gradually added thereto, and the mixture was stirred at room temperature for 1 hour. This liquid reaction mixture was concentrated, washed with water, and then filtered to obtain intermediate TH1 (9.32 g; yield, quantitative; .sup.1H-NMR (400 MHz, CDCl.sub.3): 6.00 (s, 1H), 4.87 (br-s, 2H), 2.19 (s, 3H)) as a solid.

(6) <Synthesis of Intermediate TH2>

(7) 1,4-Dithiane-2,5-diol (5.0 g: 32.8 mmol) and ethyl cyanoacetate (8.53 g; 75.4 mmol) were diluted with dimethylformamide (50 mL; 10 VR). Triethylamine (9.09 mL; 65.6 mmol) was dropped thereinto, and the mixture was allowed to react at room temperature for 30 minutes. Water (200 mL) was added to the liquid reaction mixture, and the resultant mixture was extracted with ethyl acetate (150 mL) twice. The organic layer was further washed with water (50 mL) three times. The organic layer was dried with magnesium sulfate and then filtered, and the filtrate obtained was concentrated to obtain intermediate TH2 (yield, quantitative) as a brown oil.

(8) <Synthesis of Intermediate TH3>

(9) Triethylamine (10.8 mL) was dropped into a mixture of propyl cyanoacetate (25.0 g; 0.19 mol), 1,4-dithiane-2,5-diol (16.45 g; 0.11 mol), and methanol (43 mL). In this operation, the reaction solution was kept at 30 C. or lower. After the dropping, the mixture was heated to 40 C. and stirred for 2 hours. This reaction solution was returned to room temperature and then concentrated. Ethyl acetate was added thereto, and the solid which had separated out was removed by filtration. The filtrate was concentrated to obtain intermediate TH3 (47.96 g) as a brown oil.

(10) <Synthesis of Intermediate TH4>

(11) Triethylamine (6.4 mL) was dropped into a mixture of butyl cyanoacetate (25.0 g; 0.18 mol), 1,4-dithiane-2,5-diol (14.81 g; 0.097 mol), and methanol (25 mL). In this operation, the reaction solution was kept at 30 C. or lower. After the dropping, the mixture was heated to 40 C. and stirred for 2 hours. This reaction solution was returned to room temperature and then concentrated. Ethyl acetate was added thereto, and the solid which had separated out was removed by filtration. The filtrate was concentrated to obtain intermediate TH4 (45.32 g; yield, quantitative).

(12) [Synthesis of Intermediates MA1 to MA7]

(13) ##STR00063##

(14) <Synthesis of Intermediate MA1>

(15) 4-Propylaniline (product of Tokyo Kasei: 5.87 g; 43.4 mmol) was diluted with water (60 mL). While this dilution was being cooled with ice, concentrated hydrochloric acid (12.0 mL; 130 mmol) was added thereto and sodium nitrite (3.14 g; 61.3 mmol) was further added gradually thereto. The resultant mixture was stirred for further 30 minutes with cooling with ice to obtain a diazotization solution. Intermediate TH1 (6.00 g; 43.4 mmol) was diluted with methanol (120 mL) in another flask, and the diazotization solution was gradually dropped thereinto. This mixture was stirred for 10 minutes and then heated to room temperature. The mixture was filtered, and the solid obtained was washed with a small amount of methanol to obtain intermediate MA1 (12.4 g; yield, quantitative).

(16) <Synthesis of Intermediate MA2>

(17) 4-Butylaniline (product of Tokyo Kasei: 8.72 g; 58.4 mmol) was diluted with water (90 mL). While this dilution was being cooled with ice, concentrated hydrochloric acid (15.9 mL; 175 mmol) was added thereto and sodium nitrite (4.23 g; 61.3 mmol) was further added gradually thereto. The resultant mixture was stirred for further 30 minutes with cooling with ice to obtain a diazotization solution. Intermediate TH1 (7.50 g; 54.2 mmol) was diluted with methanol (250 mL) in another flask, and the diazotization solution was gradually dropped thereinto. This mixture was stirred for 10 minutes and then heated to room temperature. The mixture was filtered, and the solid obtained was washed with a small amount of methanol to obtain intermediate MA2 (19.0 g; yield, quantitative).

(18) <Synthesis of Intermediate MA3>

(19) 4-Butylaniline (product of Tokyo Kasei: 8.72 g; 58.4 mmol) was diluted with water (90 mL). While this dilution was being cooled with ice, concentrated hydrochloric acid (15.9 mL; 175 mmol) was added thereto and sodium nitrite (4.23 g; 61.3 mmol) was further added gradually thereto. The resultant mixture was stirred for further 30 minutes with cooling with ice to obtain a diazotization solution. Intermediate TH2 (10.0 g; 58.4 mmol) was diluted with methanol (90 mL) in another flask, and the diazotization solution was gradually dropped thereinto. This mixture was stirred for 10 minutes and then heated to room temperature. The mixture was filtered, and the solid obtained was washed with methanol (200 mL) to obtain intermediate MA3 (12.1 g; yield, 62%).

(20) <Synthesis of Intermediate MA4>

(21) 4-Pentylaniline (product of Tokyo Kasei: 2.33 g; 14.3 mmol) was diluted with water (25 mL; 10 VR), and 35% hydrochloric acid (3.9 mL; 42.9 mmol; 3.0 MR) was added thereto. Sodium nitrite (1.03 g; 15.0 mmol) was added thereto with cooling with ice to obtain a diazotization solution. Intermediate TH2 (4.5 g; 13.0 mmol) and methanol (45 mL; 10 VR) were introduced into another flask. While this flask was being cooled with an ice bath, the diazotization solution was gradually dropped thereinto. In the course of the dropping, methanol (50 mL) was added. The liquid reaction mixture was heated to room temperature, and the solid which had separated out was taken out by filtration. The solid obtained was suspended in and washed with methanol (100 mL), and the suspension was filtered to obtain intermediate MA4 (4.84 g; yield, quantitative) as a yellow solid.

(22) <Synthesis of Intermediate MA5>

(23) A mixture of 4-butylaniline (10 mL; 62.9 mmol), desalted water (78 mL), and 35% hydrochloric acid (19.4 mL) was cooled to 0 C. or below, and an aqueous solution (21 mL) of sodium nitrite (4.563 g; 66.13 mol) was dropped thereinto. After the dropping, the mixture was stirred for 30 minutes while keeping the temperature thereof at 0 C. or below. Thus, a diazotization solution was obtained. A mixture of TH3 (11.668 g; 0.153 mol), methanol (520 mL), and sulfamic acid (0.611 g; 6.29 mmol) was cooled to 0 C. or below, and the diazotization solution was dropped thereinto. After the dropping, the mixture was stirred for 30 minutes while keeping the temperature thereof at 0 C. or below. The reaction solution was returned to room temperature, and the sediment which had separated out was taken out by filtration and rinsed by pouring a water/methanol=1/1 solution (300 mL) thereon. Thus, intermediate MA5 (13.81 g; yield, 63%) was obtained.

(24) <Synthesis of Intermediate MA6>

(25) A mixture of 4-butylaniline (10 mL; 62.9 mmol), desalted water (78 mL), and 35% hydrochloric acid (19.4 mL) was cooled to 0 C. or below, and an aqueous solution (21 mL) of sodium nitrite (4.563 g; 66.13 mol) was dropped thereinto. After the dropping, the mixture was stirred for 30 minutes while keeping the temperature thereof at 0 C. or below. Thus, a diazotization solution was obtained. A mixture of TH4 (12.55 g; 62.9 mmol), methanol (188 mL), and sulfamic acid (0.611 g; 6.29 mmol) was cooled to 0 C. or below, and the diazotization solution was dropped thereinto.

(26) In the course of the dropping, a solid separated out to render the stirring difficult, and methanol (260 mL) was hence added. After the dropping of the diazotization solution, the mixture was stirred for 30 minutes while keeping the temperature thereof at 0 C. or below. The reaction solution was returned to room temperature, and the sediment which had separated out was taken out by filtration and rinsed by pouring a water/methanol=1/1 solution (300 mL) thereon. Thus, intermediate MA6 (12.87 g; yield, 57%) was obtained.

(27) <Synthesis of Intermediate MA7>

(28) A mixture of 8.02 g (54 mmol) of 4-n-butylaniline and 80 mL of 7% aqueous hydrochloric acid solution was stirred and cooled with ice, and an aqueous solution obtained by dissolving 3.76 g (55 mmol) of sodium nitrite in 25 mL of water was thereafter dropped thereinto. This mixture was stirred to obtain a diazotization solution. Into another vessel were introduced 6.68 g (54 mmol) of 2-amino-3-cyanothiophene and 100 mL of methanol. On an ice bath, the diazotization solution was dropped into the mixture to cause coupling. The sediment yielded was taken out by filtration and dried to obtain intermediate MA7 (14 g; yield, 92%).

(29) [Synthesis of Intermediates CP1 to CP7]

(30) ##STR00064## ##STR00065##

(31) <Synthesis of Intermediate CP1>

(32) A mixture of m-toluidine (51.1 g; 477 mmol), 1-bromo-2-ethylhexane (357.3 g; 1.86 mol), and potassium carbonate (221.5 g; 1.6 mol) was stirred at 140 C. for 17 hours. This mixture was allowed to cool and then filtered. The organic layer obtained was concentrated and then purified by silica gel column chromatography to obtain intermediate CP1 (52 g: yield, 33%).

(33) <Synthesis of Intermediate CP2>

(34) A mixture of 3-ethylaniline (10.0 g; 83 mmol), N,N-dimethylformamide (50 mL), 1-bromo-2-ethylhexane (47.8 g; 248 mmol), and potassium carbonate (45.6 g; 330 mmol) was stirred at 110 C. for 24 hours. The mixture was allowed to cool and then filtered. Water was added to the filtrate, and the resultant mixture was extracted with toluene. The organic layer obtained was concentrated and then purified by silica gel column chromatography to obtain CP2 (6.3 g; yield 22%).

(35) <Synthesis of Intermediate CP3>

(36) A mixture of m-aminoacetanilide (13.0 g; 87 mmol), N,N-dimethylformamide (60 mL), 1-bromo-2-ethylhexane (50.4 g; 261 mmol), and potassium carbonate (49.5 g; 358 mmol) was stirred at 140 C. for 14 hours. The mixture was allowed to cool and then filtered. Water was added to the filtrate, and the resultant mixture was extracted with toluene. The organic layer obtained was concentrated and then purified by silica gel column chromatography to obtain CP3 (17.4 g; yield 54%).

(37) <Synthesis of Intermediate CP4>

(38) A mixture of 3-amino-4-methoxyacetanilide (25.0 g; 139 mmol), N,N-dimethylformamide (125 mL), 1-bromo-2-ethylhexane (80.4 g; 416 mmol), and potassium carbonate (76.7 g; 554 mmol) was stirred at 140 C. for 14 hours. The mixture was allowed to cool and then filtered. Water was added to the filtrate, and the resultant mixture was extracted with toluene. The organic layer obtained was concentrated and then purified by silica gel column chromatography to obtain intermediate CP4 (9.82 g; yield 18%).

(39) <Synthesis of Intermediate CP5>

(40) Into a flask were introduced 2,5-diethoxyanilne (product of Tokyo Kasei: 50 g; 276 mmol), 2-ethylhexyl bromide (286 mL), potassium iodide (4.58 g), and potassium carbonate (153 g). The contents were heated and stirred for 26 hours in total at an internal temperature of about 125 C. This liquid reaction mixture was cooled to room temperature and filtered. Water (400 mL) was added to the filtrate obtained, and the resultant mixture was extracted with hexane (300 mL). The hexane layer was further washed with water (400 mL) twice and dried with magnesium sulfate, and the solvent was thereafter distilled off. The crude product obtained was purified by silica gel column chromatography to obtain intermediate CP5 (23.6 g; yield, 22%) as oily matter.

(41) <Synthesis of Intermediate CP6>

(42) A mixture of 3-amino-4-methoxyacetanilide (7.51 g; 41.7 mmol), 4-tert-butylbenzyl bromide (28.4 g; 125 mmol), potassium carbonate (11.5 g; 83.4 mmol), and N,N-dimethylformamide (25 mL) was stirred for 1.5 hours at an internal temperature of 75 C. This mixture was cooled to room temperature, and water was added thereto. The resultant mixture was extracted with a mixed solvent composed of toluene and ethyl acetate. The extract was dried with anhydrous sodium sulfate and concentrated under vacuum. The solid was washed with hexane to obtain intermediate CP6 (17.7 g; yield, 90%).

(43) <Synthesis of Intermediate CP7>

(44) A mixture of methanol (36 mL) and sodium thiocyanate (15.5 g; 191 mmol) was heated to 60 C., and 1-chloropinacolone (25 mL; 191 mmol) was dropped thereinto over 15 minutes. This mixture was heated at 60 C. for 2.5 hours, allowed to cool to room temperature, and then cooled to 10 C. or below with an ice bath. Water (32 mL) was dropped thereinto, and the resultant mixture was stirred at 5 C. for 1 hour. The resultant crystals were taken out by filtration and air-dried to obtain intermediate 1 (amount yielded, 27 g; yield, 90%).

(45) A mixture of the intermediate 1 (13 g; 83 mmol), toluene (65 mL), and acetic acid (2.5 g; 41 mmol) was heated to 80 C., and di(2-ethylhexyl)amine (20 g; 83 mmol) was dropped thereinto over 10 minutes. This mixture was heated at 80 C. for 4 hours and then allowed to cool to room temperature. Thereafter, water was added to the organic layer, and the resultant mixture was subjected to liquid separation. Furthermore, the organic layer was washed with water three times and with saturated aqueous sodium chloride solution once. This organic layer was dried with anhydrous sodium sulfate, and the solvent was distilled off. The residue was purified by column chromatography to obtain intermediate CP7 as a colorless viscous liquid (amount yielded, 21.77 g; yield, 69.1%).

Example 1

Synthesis of Compound 1

(46) Intermediate MA2 (7.50 g; 25.1 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (375 mL), and this dilution was cooled to 5 C. with a freezing mixture. While holding the dilution at 0 C. or below, 40% nitrosylsulfuric acid (8.77 g; 1.1 eq.) was gradually dropped thereinto to prepare a diazotization solution. Intermediate CP3 (9.39 g; 25.1 mmol), THF (275 mL), and sodium acetate (13.2 g) were introduced into another flask and cooled to 5 C. While holding the contents at 0 C. or below, the diazotization solution was gradually dropped thereinto.

(47) The liquid reaction mixture was heated to room temperature, and water was added thereto. Thereafter, this mixture was extracted with hexane, and the organic layer was washed twice with 10% aqueous sodium hydroxide solution (200 mL). The organic layer was dried with magnesium sulfate, and the solvent was distilled off. The resultant residue was purified by silica gel column chromatography, and methanol was added thereto. This mixture was cooled, and the solid obtained was taken out by filtration to obtain compound 1 (yield, 14%).

Example 2

Synthesis of Compound 2

(48) Intermediate MA2 (2.50 g; 8.38 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (125 mL), and the dilution was cooled to 5 C. or below with a freezing mixture. Thereinto was gradually dropped 40% nitrosylsulfuric acid (2.93 g; 9.05 mmol), thereby preparing a diazotization solution. Intermediate CP1 (2.78 g; 8.38 mmol), THF (125 mL), and sodium acetate (4.5 g) were introduced into another flask and cooled to 5 C. Thereinto was gradually dropped the diazotization solution prepared as described above.

(49) The liquid reaction mixture was heated to room temperature, and water (200 mL) was added thereto. Thereafter, this mixture was extracted with hexane (300 mL), and the organic layer was washed twice with 10% aqueous NaOH solution (100 mL). The organic layer was dried with magnesium sulfate and concentrated under vacuum. The concentrate was purified by silica gel column chromatography, and the solid was washed with methanol to obtain compound 2 (1.40 g; yield, 26%).

Example 3

Synthesis of Compound 3

(50) Intermediate MA1 (3.00 g; 10.5 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (180 mL), and the dilution was cooled to 5 C. or below with a freezing mixture. Thereinto was gradually dropped 40% nitrosylsulfuric acid (3.67 g; 9.05 mmol), thereby preparing a diazotization solution. Intermediate CP3 (3.95 g; 10.5 mmol), THF (180 mL), and sodium acetate (5.5 g) were introduced into another flask and cooled to 5 C. Thereinto was gradually dropped the diazotization solution prepared as described above.

(51) The liquid reaction mixture was heated to room temperature, and water (200 mL) was added thereto. Thereafter, this mixture was extracted with hexane (300 mL), and the organic layer was washed twice with 10% aqueous sodium hydroxide solution (100 mL). The organic layer was dried with magnesium sulfate and concentrated under vacuum. The concentrate was purified by silica gel column chromatography, and the solid was washed with methanol (50 mL) to obtain compound 3 (770 mg; yield, 11%).

Example 4

Synthesis of Compound 4

(52) Intermediate MA2 (3.58 g; 10.5 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (215 mL), and the dilution was cooled to 5 C. or below with a freezing mixture. Thereinto was gradually dropped 40% nitrosylsulfuric acid (4.19 g; 13.2 mmol), thereby preparing a diazotization solution. Intermediate CP5 (4.87 g; 12.0 mmol), THF (215 mL), and sodium acetate (6.5 g) were introduced into another flask and cooled to 5 C. Thereinto was gradually dropped the diazotization solution prepared as described above.

(53) The liquid reaction mixture was heated to room temperature, and water (100 mL) was added thereto. Thereafter, this mixture was extracted twice with n-hexane (200 mL), and the organic layer was washed twice with 10% aqueous NaOH solution (100 mL). The organic layer was dried with magnesium sulfate and concentrated under vacuum. The concentrate was purified by silica gel column chromatography, and methanol was added thereto. This mixture was cooled, and the solid obtained was taken out by filtration to obtain compound 4 (630 mg; yield, 8%).

Example 5

Synthesis of Compound 5

(54) Intermediate MA4 (2.40 g; 6.95 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (144 mL), and the dilution was cooled to 5 C. or below with a freezing mixture. Thereinto was gradually dropped 40% nitrosylsulfuric acid (2.65 g; 8.34 mmol), thereby preparing a diazotization solution. Intermediate CP2 (2.30 g; 6.95 mmol), THF (150 mL), and sodium acetate (5.0 g) were introduced into another flask and cooled to 5 C. Thereinto was gradually dropped the diazotization solution prepared as described above.

(55) The liquid reaction mixture was heated to room temperature, and water (400 mL) was added thereto. Thereafter, this mixture was extracted twice with n-hexane (200 mL), and the organic layer was washed twice with 1-N NaOH (200 mL). The organic layer was dried with magnesium sulfate and concentrated under vacuum. The concentrate was purified by silica gel column chromatography, and methanol was added thereto. This mixture was cooled, and the solid obtained was taken out by filtration to obtain compound 5 (190 mg; yield, 4%).

Example 6

Synthesis of Compound 6

(56) Intermediate MA3 (2.50 g; 7.54 mmol) was diluted with acetic acid/propionic acid=17/8 (V/V) (250 mL), and the dilution was cooled to 5 C. or below with a freezing mixture. Thereinto was gradually dropped 40% nitrosylsulfuric acid (2.87 g; 9.05 mmol), thereby preparing a diazotization solution. Intermediate CP1 (2.50 g; 7.54 mmol), THF (250 mL), and sodium acetate (5.0 g) were introduced into another flask and cooled to 5 C. Thereinto was gradually dropped the diazotization solution prepared as described above.

(57) The liquid reaction mixture was heated to room temperature, and water (300 mL) was added thereto. Thereafter, this mixture was extracted twice with hexane (400 mL), and the organic layer was washed twice with 10% aqueous NaOH solution (100 mL). The organic layer was dried with magnesium sulfate and concentrated under vacuum. The concentrate was purified by silica gel column chromatography, and methanol was added thereto. This mixture was cooled, and the solid obtained was taken out by filtration to obtain compound 6 (150 mg; LC area, 98.8%; yield, 3%).

Example 7

Synthesis of Compound 7

(58) A mixture of intermediate MA5 (3.00 g; 8.68 mmol), 85% phosphoric acid (38 mL), acetic acid (25 mL), and propionic acid (13 mL) was cooled to 0 C. or below, and 40% nitrosylsulfuric acid (2.89 g; 9.11 mmol) was dropped thereinto. After the dropping, the mixture was stirred for 30 minutes while holding the mixture at 0 C. or below, thereby obtaining a diazotization solution. A mixture of intermediate CP1 (2.879 g; 8.68 mmol), tetrahydrofuran (18 mL), methanol (2 mL), desalted water (3 mL), and urea (52 mg; 0.868 mmol) was cooled to 0 C. or below, and the diazotization solution was dropped thereinto.

(59) During this operation, the pH was kept at 2.8-3.6 by suitably adding a saturated aqueous solution of sodium acetate. After the diazotization solution had been dropped, the resultant mixture was stirred for 30 minutes while holding the mixture at 0 C. or below. This reaction solution was returned to room temperature, and the aqueous layer was extracted with hexane. The organic layer was dried with anhydrous sodium sulfate and filtered, and the resultant filtrate was concentrated. The crude product obtained was purified by silica gel column chromatography and solidified by cooling in a freezer. Thus, compound 7 was obtained as a powder.

Example 8

Synthesis of Compound 8

(60) A mixture of intermediate MA6 (3.00 g; 8.34 mmol), 85% phosphoric acid (38 mL), acetic acid (25 mL), and propionic acid (13 mL) was cooled to 0 C. or below, and 40% nitrosylsulfuric acid (2.78 g; 8.8 mmol) was dropped thereinto. After the dropping, the mixture was stirred for 30 minutes while holding the mixture at 0 C. or below, thereby obtaining a diazotization solution. A mixture of intermediate CP1 (2.767 g; 8.34 mmol), tetrahydrofuran (18 mL), methanol (2 mL), desalted water (3 mL), and urea (50 mg; 0.834 mmol) was cooled to 0 C. or below, and the diazotization solution was dropped thereinto.

(61) During this operation, the pH was kept at 2.8-3.6 by suitably adding a saturated aqueous solution of sodium acetate. After the diazotization solution had been dropped, the resultant mixture was stirred for 30 minutes while holding the mixture at 0 C. or below. This reaction solution was returned to room temperature, and the aqueous layer was extracted with hexane. The organic layer was dried with anhydrous sodium sulfate, concentrated under vacuum, and purified by silica gel column chromatography. Thereafter, the purified product was solidified by cooling in a freezer, thereby obtaining compound 8 as a powder.

Example 9

Synthesis of Compound 9

(62) Intermediate MA3 (3.31 g; 10 mmol), phosphoric acid (30 mL), acetic acid (24 mL), and propionic acid (6 mL) were cooled with an ice-acetone bath, and 40% nitrosylsulfuric acid (3.49 g; 11 mmol) was added thereto. This mixture was stirred for 20 minutes to obtain a diazotization solution. Intermediate CP4 (4.05 g; 10 mmol), amidosulfuric acid (0.29 g; 3 mmol), tetrahydrofuran (50 mL), and water (100 mL) were introduced into another vessel. While cooling this mixture with an ice bath, the diazotization solution was added thereto.

(63) During this operation, the internal temperature was kept at 7 C. or below, and the pH was kept at 2-3 by dropping an aqueous sodium acetate solution. After the dropwise addition, the mixture was stirred for further 3 hours with cooling, and then extracted with toluene. The toluene layer was washed with water and concentrated under vacuum. The concentrate was purified by silica gel column chromatography and washed with methanol. Thus, compound 9 (2.2 g; yield, 29%) was obtained as a black powder.

Example 10

Synthesis of Compound 10

(64) A mixture of intermediate MA7 (2.50 g; 8.79 mmol), 85% phosphoric acid (31 mL), acetic acid (20 mL), and propionic acid (10 mL) was cooled to 5 C., and 40% nitrosylsulfuric acid (2.9 g; 9.2 mmol) was dropped thereinto.

(65) After the dropping, the mixture was stirred for 15 minutes while holding the mixture at 5 C. or below, thereby obtaining a diazotization solution. A mixture of intermediate CP7 (3.34 g; 8.79 mmol), tetrahydrofuran (22 mL), methanol (2 mL), desalted water (3 mL), and urea (0.052 g; 0.87 mmol) was cooled to 5 C. or below in another vessel, and the diazotization solution was dropped thereinto. During this operation, the pH was kept at 2.8-3.2 by adding an aqueous sodium acetate solution (110 mL in total).

(66) After the diazotization solution had been dropped, the resultant mixture was stirred for 30 minutes while holding the mixture at 5 C. or below. This reaction solution was returned to room temperature, and the aqueous layer was extracted with hexane. The organic layer was dried with anhydrous sodium sulfate, concentrated under vacuum, and purified by silica gel column chromatography. Methanol was added thereto, and the mixture was cooled. The resultant solid was taken out by filtration to obtain compound 10 (1.97 g; yield, 33%).

(67) <Synthesis of Compound 11>

(68) A mixture of intermediate MA8 (5.0 g; 16.7 mmol), 85% phosphoric acid (63 mL), acetic acid (24 mL), and propionic acid (21 mL) was cooled to 5 C. or below, and 40% nitrosylsulfuric acid (5.85 g; 18.4 mmol) was dropped thereinto. After completion of the dropping, the mixture was stirred at 5 C. or below for 30 minutes to obtain a diazotization solution. A mixture of CP7 (6.37 g; 16.7 mmol), tetrahydrofuran (41 mL), methanol (6 mL), desalted water (6 mL), and urea (0.100 g; 1.67 mmol) was introduced into another vessel, and the diazotization solution was dropped thereinto while keeping the internal temperature at 5 C. or below.

(69) During this operation, the pH was kept at 2.8-3.2 by adding an aqueous sodium acetate solution. After completion of the dropping, the resultant mixture was stirred at 5 C. for 30 minutes and then returned to room temperature. Thereafter, water was added thereto, and this mixture was extracted with hexane. The hexane layer was dried with anhydrous sodium sulfate, concentrated under vacuum, and purified by silica gel column chromatography. Methanol was added thereto, and the resultant solid was taken out by filtration to obtain compound 11.

(70) ##STR00066## ##STR00067## ##STR00068##

Comparative Example 1

(71) <Synthesis of Intermediate TD>

(72) A mixture of 2-amino-5-mercapto-1,3,4-thiadiazole (12.9 g; 96.8 mmol), 1-bromohexane (16.8 g; 102 mmol), ethanol (100 mL), and potassium hydroxide (8.15 g; 145 mmol) was heated with refluxing for 4 hours and then poured into ice water. The sediment was taken out by filtration and washed with methanol/water (1/1 by volume) to obtain intermediate TD (12.3 g; yield, 58%).

(73) <Synthesis of Comparative Compound 1>

(74) A mixture of 44% nitrosylsulfuric acid (2.52 g; 10 mmol), acetic acid (30 mL), and propionic acid (10 mL) was prepared with cooling with an ice bath. Intermediate TD (2.17 g; 10 mmol) was added thereto, and this mixture was stirred for 1 hour with cooling with an ice bath to obtain a diazotization solution. Intermediate CP6 (4.73 g; 10 mmol), sodium acetate (16.4 g; 100 mmol), and tetrahydrofuran (60 mL) were introduced into another vessel, and the diazotization solution was dropped thereinto with cooling with an ice bath. The resultant mixture was stirred at room temperature. Thereafter, water was added thereto, and this mixture was extracted with toluene. The toluene layer was washed with water and concentrated under vacuum. The concentrate was purified by silica gel column chromatography to obtain comparative compound 1 (1.79 g; yield, 26%).

(75) ##STR00069##

(76) [Production of Inks of the Compounds]

(77) With respect to each of compounds 1 to 11 and comparative compound 1, an ink was prepared using n-decane (relative permittivity, 2.0; solubility in water, 1 mg/L or less) as a solvent. The solution color, absorption maximum wavelength (.sub.max), solubility C in 5 C. n-decane, molar extinction coefficient , and C of each ink are summarized in Table 4.

(78) <Method of Determining Relative Permittivity of Solvent>

(79) Precision LCR Meter 4284A, manufactured by Agilent Technologies, Inc., was used to make a measurement by the impedance meter method. The solvent and the ink were each sandwiched between flat glass substrates which each had an ITO electrode and which had been arranged opposite and in parallel so as to result in an electrode spacing of 30 Thereafter, at 22 C., the equivalent parallel capacitance was measured under the conditions of a frequency of 1 kHz and application of a test signal voltage of 0.1 V. The relative permittivity was determined through a calculation using the following equation and evaluated.
Relative permittivity=(equivalent parallel capacitance)(electrode spacing)/(electrode area)/(permittivity of vacuum (.sub.0))

(80) <Method of determining Solubility of Solvent in Water>

(81) Into a 110-mL vial were introduced 30 g of pure water and 8 g of the solvent. This vial was shaken for 4 hours at a frequency of 200 times per minute in a 25 C. thermostatic chamber. The liquid which had undergone the shaking was centrifuged (6,000g; for 5 minutes), and the aqueous layer was sampled. The concentration of the solvent dissolved therein was determined by gas chromatography.

(82) <Method of determining Absorption Maximum Wavelength .sub.max and Molar Extinction Coefficient >

(83) One milligram of each of compound 1 and comparative compounds 1 and 2 was dissolved in 100 mL of the solvent, and the solution was examined for absorption spectrum with Hitachi Spectrophotometer U-4100 using a quartz cell having a measuring optical-path length of 10 mm. From the spectrum obtained, the absorption maximum wavelength .sub.max (nm) and the molar extinction coefficient E (L.Math.mol.sup.1.Math.cm.sup.1) were determined.

(84) <Method of Determining Solubility C and C>

(85) The solubility C of each compound in n-decane was determined in the following manner. Each of compounds 1 to 11 and comparative compound 1 was added to n-decane until some of the compound came to remain undissolved, and the mixture was subjected to an ultrasonic treatment at 30 C. for 30 minutes. Compounds 1, 3 to 5, and 11 were highly soluble and, hence, the addition thereof was stopped at the time when a specific solubility was ascertained.

(86) After the addition, each mixture was subjected to a 30-minute ultrasonic treatment at 30 C. This mixture was allowed to stand at 5 C. for 24 hours and then subjected to centrifugal filtration with a 0.1-m filter using a miniature centrifugal machine (centrifugal force, 5,200g). The saturated solution obtained was diluted to an adequate concentration and examined for absorption spectrum with Hitachi Spectrophotometer U-4100 using a quartz cell having a measuring optical-path length of 10 mm. The concentration of each compound was determined from a relationship between the absorbance at the absorption maximum wavelength .sub.max (nm) and the molar extinction coefficient (L.Math.mol.sup.1.Math.cm.sup.1) determined beforehand, and the solubility C (mol.Math.L.sup.1) thereof was calculated. Furthermore, the product C of the molar extinction coefficient (L.Math.mol.sup.1.Math.cm.sup.1) and the solubility C (mol.Math.L.sup.1) was determined.

(87) TABLE-US-00004 TABLE 4 Absorption maximum Solubility Color wavelength C (L .Math. mol.sup.1 .Math. C Compound tone .sub.max (nm) (mass %) cm.sup.1) (cm.sup.1) Compound 1 blue 617 28.8 70000 20000 Compound 2 blue 608 1.7 62000 1220 Compound 3 blue 617 34.3 70000 20000 Compound 4 blue 638 10.5 54000 6000 Compound 5 blue 591 20.1 50000 10000 Compound 6 blue 575 5.2 55000 3100 Compound 7 blue 590 17.4 51000 9500 Compound 8 blue 591 11.0 52000 6000 Compound 9 blue 653 33.9 65000 22000 Compound 10 blue 595 15 57000 9000 Compound 11 blue 595 19.7 59000 12000 Comparative red 526 9.1 50000 4700 compound 1

(88) <Method of Light Fastness Test>

(89) The light fastness of compounds 1 to 3, 5, and 7 to 11 and comparative compound 1 was determined in the following manner. In 0.99 g of n-decane was dissolved 0.01 of each compound. This solution was introduced into a cell having an optical-path length of 0.004 mm, and this cell was sealed with an epoxy resin. Using a weatherometer (Atlas Ci4000), the cell was irradiated with xenon light (340 nm; irradiance, 0.55 W/m.sup.2) for 40 hours. During the irradiation, the internal temperature of the test chamber was kept at 33 C.

(90) The retention of each compound was calculated using the following equation. The compounds which had a retention of 100-90% were rated as A, those having a retention of 89-80% as B, those having a retention of 80-50% as C, and those having a retention of 49% or less as D.
*Retention (%)=(absorbance at absorption maximum wavelength after irradiation)/(absorbance at absorption maximum wavelength before irradiation)100

(91) The results of the light fastness test are summarized in Table 5 below.

(92) TABLE-US-00005 TABLE 5 Compound Light fastness Compound 1 A Compound 2 A Compound 3 A Compound 4 A Compound 5 A Compound 6 A Compound 7 A Compound 8 A Compound 9 A Compound 10 A Compound 11 A Comparative D compound 1
<Preparation of Black Inks>

(93) Composition 1, which was composed of compound 3 and the yellow compound A, red compound A, and blue compound A that are described below, was dissolved in n-decane (relative permittivity, 2.0; solubility in water, 1 mg/L or less; manufactured by Tokyo Kasei Kogyo Co., Ltd.) to prepare black ink 1 in accordance with Table 6. Furthermore, composition 2, which was composed of compound 10 and the yellow compound A, red compound A, and blue compound A that are described below, and composition 3, which was composed of the yellow compound A, red compound A, and blue compound A that are described below, were each dissolved in the same n-decane as in the case of composition 1 to prepare black ink 2 and a comparative black ink in accordance with Table 6.

(94) Incidentally, when the black inks 1 and 2 and comparative black ink were prepared, the addition amounts of the compounds were regulated so as to result in an optical density (OD), measured at an optical-path length of 0.010 mm, of 2.7.

(95) TABLE-US-00006 TABLE 6 Com- Com- Yellow com- Red com- Blue com- Total weight pound 3 pound 10 pound A pound A pound A of compounds n-Decane (g) (g) (g) (g) (g) (g) (g) Black ink 1 composition 1 0.035 0.083 0.052 0.226 0.396 1.604 Black ink 2 composition 2 0.035 0.084 0.044 0.229 0.392 1.608 Comparative composition 3 0.0956 0.05 0.356 0.502 1.498 black ink

(96) <Yellow Compound A>

(97) The compound (1-1) described in International Publication WO 2009/063880.

(98) ##STR00070##

(99) <Red Compound A>

(100) A mixture of H-1 (0.50 g; 3.3 mmol), glacial acetic acid (3 mL), propionic acid (0.7 mL), sulfuric acid (2.7 mL), and desalted water (0.3 mL) was cooled with an ice bath, and 44 wt % nitrosylsulfuric acid (1.0 g; 3.6 mmol) was dropped thereinto at an internal temperature of 1 C. Thereafter, the resultant mixture was stirred for 1 hour while keeping the internal temperature at 05 C., thereby obtaining a diazotization solution. Intermediate CP1 (0.81 g; 3.1 mmol), tetrahydrofuran (40 mL), sulfamic acid (0.06 g; 0.6 mmol), and sodium acetate (5.7 g) were introduced into another vessel, and the diazotization solution was dropped thereinto while keeping the internal temperature at 05 C. with cooling with ice.

(101) In the course of the dropping, ice and tetrahydrofuran (40 mL) were added. After completion of the dropping, the pH was adjusted to 4 by adding an aqueous sodium acetate solution. This mixture was extracted with toluene, and the extract was concentrated under vacuum and purified by silica gel column chromatography. The solid yielded was washed with methanol/water (1/1 (by volume)). Thus, red compound A (0.45 g; yield, 32%) was synthesized.

(102) ##STR00071##

(103) <Blue Compound A>

(104) The compound described in JP-A-2000-313174.

(105) ##STR00072##

(106) <Hue Evaluation>

(107) The black inks and the comparative ink were each examined for spectrum using a cell having a measuring optical-path length of 0.01 mm. The hue thereof was quantitatively evaluated by conducting a color measurement using the color calculation program which belonged to the Hitachi Spectrophotometer U-4100, under the conditions of illuminant D65 and a viewing angle of 2 degrees. The results of the hue evaluation of black ink 1 and the comparative ink are shown in Table 7.

(108) <Viscosity Measurement>

(109) Black inks 1 and 2 and the comparative black ink were examined for viscosity at 25 C. using a rotational viscometer (BROOKFIELD LV-1). The results of the measurement are shown in Table 7.

(110) TABLE-US-00007 TABLE 7 Measuring optical-path Results of hue evaluation length (mm) L* a* b* C* OD Black ink 1 0.01 1.33 0.38 0.08 0.4 2.7 Black ink 2 0.01 1.78 0.33 0.27 0.4 2.7 Comparative 0.01 1.94 0.21 1.79 1.8 2.7 black ink

(111) Although equal in OD to the comparative black ink, black inks 1 and 2 each had a small value of L* and a value of C* of 1 or less. Black inks 1 and 2 were found to be satisfactory black inks having an excellent black hue. Black inks 1 and 2 further had a lower ink viscosity than the comparative ink, and were found to be inks having excellent properties.

(112) While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. This application is based on a Japanese patent application filed on Nov. 28, 2012 (Application No. 2012-260019) and a Japanese patent application filed on Nov. 28, 2012 (Application No. 2012-260020), the entire contents thereof being incorporated herein by reference.