US3556800A

US3556800A - Photographic silver halide emulsions

Info

Publication number: US3556800A
Application number: US747480A
Authority: US
Inventors: Shiro Kimura; Yoshiyuki Nakazawa; Masao Sawahara; Yasuharu Nakamura
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-07-25
Filing date: 1968-07-25
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19
Also published as: BE718499A; DE1772913B1; GB1210009A; FR1588846A

Abstract

A PHOTOGRAPHIC SILVER HALIDE EMULSION WHICH CONTAINS A NOVEL SENSITIZING DYE REPRESENTED BY THE FOLLOWING FORMULA F WHEREIN Z REPRESENTS THE NON-METALLIC ATOMS NECESSARY TO COMPLETE A HETEROCYCLIC RING OF THE TYPE EMPLOYED IN A CYANINE DYE; R AND R1 EACH REPRESENT A MEMBER SELECTED FROM THE GROUP CONSISTING OF A LOWER ALKYL GROUP, A SUBSTITUTED ALKYL GROUP, AN ALLYL GROUP, A BENZYL GROUP, A PHENETHYL GROUP AND A PHENOXYETHYL GROUP; X-REPRESENTS AN ANION; N MAY VARY FROM 0 TO 1 ; N1 MAY VARY FROM 0 TO 1; AND M MAY VARY FROM 1 TO 2. THE VARIOUS SPECIFIC DYES AND ILLUSTRATIVE PROCESSES OF FORMING THE DYES OF THIS INVENTION ARE DESCRIBED IN THE SPECIFICATION.

Description

United States Paten 3,556,800 PHOTOGRAPHIC SILVER HALIDE EMULSION S Shiro Kimura, Yoshiyuki Nakazawa, Masao Sawahara, and Yasuharu Nakamura, Kanagawa, Japan (all of 210 Nakanuma, Minami Ashigara-machi, Ashigara-Kamigun, Japan) No Drawing. Filed July 25, 1968, Ser. No. 747,480 Claims priority, application Japan, July 25, 1967, 42/47,721 Int. Cl. G03c 1/08 US. Cl. 96-120 2 Claims ABSTRACT OF THE DISCLOSURE A photographic silver halide emulsion which contains a novel sensitizing dye represented by the following formula and illustrative processes of forming the dyes of this invention are described in the specification.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates generally to a photographic silver halide emulsion, and more particularly, to a photographic silver halide emulsion containing a novel cyanine sensitizing dye in which a benzene ring forming the quinoline nucleus has a fluorine atom as a substituent.

Description of the prior art It is known, in the art of preparing photographic silver halide emulsions, that by incorporating a sensitizing dye in a photographic silver halide emulsion, the light-sensitive wave length spread of the silver halide emulsion can be increased, i.e., the silver halide emulsion can be spectrally sensitized.

However, the incorporation of a sensitizing dye in a light-sensitive silver halide emulsion tends to increase the formation of photographic fog in the photographic emulsion layer, especially, when a sensitizing dye having a quinoline nucleus is employed.

SUMMARY OF THE INVENTION It has been found that when a photographic silver halide emulsion has incorporated therein a sensitizing dye represented by the following general formula:

I R-N -en =cnon) n:oon=on) h n.

wherein Z represents the non-metallic atoms necessary to complete a heterocyclic ring of the type employed in a cyanine dye; R and R each represent a member selected Patented Jan. 19 1971 from the group consisting of a lower alkyl group, a substituted alkyl group, an allyl group, a benzyl group, a phenethyl group and a phenoxyethyl group; X- represents an anion; 11 may vary from 0 to 1; n may vary from 0 to l; and in may vary from 1 to 2.

The novel sensitizing dye of the present invention can spectrally sensitize a silver halide emulsion, and, in particular, it is quite effective in enlarging the spectral lightsensitive region of a gelatino silver halide emulsion.

An object of this invention is to provide a novel sensitizing dye having a quinoline nucleus.

Another object of this invention is to provide a lightsensitive silver halide emulsion, containing the novel sensitizing dye mentioned above, will well illustrate reduced fogging.

DESCRIPTION OF THE PREFERRED EMBODIMENT The aforesaid objects of this invention can be attained by incorporating in a photographic silver halide emulsion a sensitizing dye represented by general Formula I wherein R and R each may represent: lower alkyl group, such as a methyl group, an ethyl group, a propyl group, and a butyl group; a substituted alkyl group, such as a 2-hydroxyethyl group, a 2-acetoxyethyl group, a 3-hydroxypropyl group, a carboxymethyl group, a 2-carboxy ethyl group, a 3-carboxypropyl group, a 2-sulfoethyl group, a 3-sulfopropyl group, a 4-sulfobutyl group and the like; an allyl group; a benzyl group; a phenethyl group; or a phenoxyethyl group; Z represents the nonmetallic atoms necessary to complete a heterocyclic ring of the type' usually present in a cyanine dye, such as, a thiazole ring, a benzothiazole ring, a naphthothiazole ring, an oxazole ring, a benzoxazole ring, a naphthoxazole ring, a selenazole ring, a benzoselenazole ring, a naphthoselenazole ring, a thiazoline ring, anoxazoline ring, a selenazoline ring, a thiadiazole ring, an indolenine ring, a pyridine ring, a 2-quinoline ring, a 4-quin0line ring, or a benzoimidazole ring; X represents an anion such as a chlorine ion, a bromine ion, an iodine ion, a perchloric acid ion, a p-toluenesulfonic acid ion, or an ethyl sulfate ion; n is 0, 1, or 2; and m is 1 or 2; said dye forming an intramolecular salt when m is 1.

The sensitizing dye used in this invention may be prepared by known condensation methods using the compound (Compound II) shown by general Formula II wherein R and X" have the same meaning as heretofore defined. When R and X contain sulfonic acid or carboxylic acid, the compound may have a betaine structure by intermolecular ionization, or the compound may be an alkali metal salt.

Compound II may be prepared by reacting fluoroanilines and methylvinyl ketone using general methods of preparing 4-methylquinolines. The product may then be converted into its quaternary salt.

Practical methods of preparing the sensitizing dyes of this invention will be explained below.

(1) Preparation of 8-fluoro-4-methylquinoline:

Into a 1-liter three-necked flask equipped with a liquidsealed mechanical stirrer, a reflux condenser, a thermometer and a dropping funnel, there Were charged 150 g. of o-fluoroaniline, 95 g. of methyl vinyl ketone and 145 ml. of nitrobenzene. This was then diluted with sulfuric acid (concentrated sulfuric acid: 45 ml., and water: 22 ml.) which was added thereto dropwise. When heat was generated in the mixture, the temperature thereof rose to about 100 C. Thereafter, the system was. stirred for 2 hours at 100-105 C. in an oil bath to complete the reaction. After the reaction was finished, 300 ml. of water Was added to the product, and the mixture was then subjected to a steam distillation to distil ofi nitrobenzene. The residue was cooled, made alkaline by the addition of 100 g. of sodium hydroxide, extracted with benzene, and dried -With potassium carbonate. After removing benzene by a distillation, the residue was subjected to a reduced-pressure distillation, whereby fractions having a boiling point in the range of 137145 C./7 mm. Hg were collected. The product obtained was dissolved in 100 ml. of isopropanol by heating, and when the solution obtained was cooled by the addition of ice, 50 g. of the crystals of 8-fluoro-4-methylquinoline were obtained. The melting point of the crystals was 5658 C.

(2) Preparation of 6-fluoro-4-methylquinoline:

Into a 500 ml. three-necked flask equipped with a liquid-sealed mechanical stirrer, a reflux condenser, a thermometer and a dropping funnel, there were charged 90 g. of p-fluoroaniline, 57 g. of methyl vinyl ketone, and 100 ml. of nitrobenzene. This was then diluted with sulfuric acid (concentrated sulfuric acid: 35 ml.; water: ml.) which was added dropwise thereto. The system was then processed as in the above example (No. 1) to provide 28 g. of the crystals of 6-fluoro-4-methylquinoline, having a boiling point of 134136 C./l9 mm. Hg.

(3) Preparation of 1-ethyl-8-fluoro-4-methylquin0linium iodide:

A mixture of 4 g. of 8-fluoro-4-methylquinoline and 6 g. of ethyl iodide was refluxed under heat for 20 hours. After cooling, the product was mixed with acetone and filtered to provide 7 g. of the iodide of the quinoline, having a melting point of 153155 C.

(4) Preparation of 1-ethyl-6-fluoro-4-methylquinolinium iodide. The basic procedures outlined above (No. 3) Were followed:

Cir

(5) Preparation of l-ethyl-8-fiuoro-4-methylquinolinium p-toluenesulfonate: A mixture of 30 g. of 8-fluoro-4- methylquinoline and 42 g. of ethyl p-toluenesulfonate was heated to 140 C. for 4 hours in an oil bath. After cooling, the product was mixed with acetone and the mixture was stirred to form crystals, which were recovered by filtration. 62 g. of the crystals of the iodide having a melting point of 123-125 C. were obtained.

(6) Preparation of 1-ethyl-6-fluoro-4-rnethylquino1inium p-toluenesulfonate:

A mixture of g. of 6-flu0r0-4-methylquinoline and ethyl-p-toluenesulfonate was heated to 140 C. for 4 hours in an oil bath. After cooling, the product was mixed with ether and acetone, stirred and filtrated to provide g. of the hygroscopic crystal of the sulfonate.

(7) Preparation of 4-(2-acetanilidovinyl)-1-ethyl-8 fluoroquinolinium p-toluenesulfonate:

COCH3 A mixture of g. of 1-ethyl-8-fiuoro-4-methylquinolinium p-toluenesulfonate and 35 g. of diphenyl formamidine was heated to C. for 10 minutes in an oil bath with intermittent stirring. After cooling, the product was mixed with acetone and the precipitates formed were recovered by filtration and boiled in acetone to provide 38 g. of the crystal of 4-(2-anilinovinyl)-1-ethyl-8- fluoroquinolinium p-toluenesulfonate, having a melting point of 192-193 C. The product (35 g.) and 200 ml. of acetic anhydride were heated for 8 minutes to C. in an oil bath. After cooling, the product was mixed with ether and the precipitate formed was recovered by filtration and washed with ether to provide 35 g. of the crystals of the sulfonate, having a melting point of 12S 127 C.

(8) Preparation of 4-(2-anilinovinyl)-1-ethyl-6-flu0roquinolinium p-toluenesulfonate:

A mixture of 30 g. of 1-ethyl-6-fiuor0-4-methylquinolinium p-toluenesulfonate and 19.5 g. of diphenyl formamidine was heated to 140 C. for 10 minutes in an oil bath, with intermittent stirring. After cooling, the prod uct Was mixed with ether and acetone to cause crystallization, and the precipitate formed was recovered by filtration, washed with acetone and recrystallized from a mixed solvent of methanol and isopropanol to provide 11.5 g. of the sulfonate, having a melting point of 218220 C.

(9) Preparation of 1,3'-diethyl-8-fluorothia-4-cyanine iodide:

A mixture of 2.8 g. of 1-ethyl-8-fluoro-4-methylquinolinium p-toluenesulfonate and 2 g. of 3-ethyl-2- methylthiobenzothiazolium ethyl sulfate was dissolved in 60 ml. of ethanol by heating. After adding 4 ml. of triethylamine, the mixture was boiled for 30 minutes under conditions of reflux. After the reaction was finished, an aqueous solution of potassium iodide was added to the system, precipitating the dye. After cooling, the percipitate was recovered by filtration, washed with water, and recrystallized (twice) from a mixed solvent of methanol and chloroform to provide 1.9 g. of the dye, having a melting point of 281-282 C. (decomposed). The absorption maximum of the dye, in methanol, was 508 m (10) Preparation of l,1-diethyl-8,8 difluoro-4,4- carbocyanine iodide:

A mixture of 4 g. of 1-ethyl-8-fluoro-4amethylquinolinium, 8 ml. of ethyl o-formate, and 1 ml. of triethylamine was boiled for 3 minutes with refluxing. After the reaction was finished, the dye thus formed was recovered by filtration, washed with acetone and recrystallized (twice) from a mixed solvent of methanol and chloroform to provide 0.8 g. of the dye, having a melting point of 276-277 C. (decomposed). The absorption maximum of the dye in methanol was 709 mg.

(11) Preparation of 1,1' diethyl-8-fluoro-2',4-carbocyanine iodide:

Into 120 ml. of ethanol were dissolved, by heating, 3 g. of l-ethyI-S-fluoro-4-methylquinolinium p-toluenesulfonate and 2.9 g. of 2-(2 acetanilidovinyl) l-ethylquinolinium iodide. The solution was then mixed with ml. of triethylamine and the mixture was boiled, with refluxing for 30 minutes. After the reaction was finished,

the dye thus formed was filtered, washed with ethanol and recrystallized from a mixed solvent of methanol and chloroform to provide 1.9 g. of the dye having a melting point of 258-259 C. (decomposed). The maximum absorption maximum of the dye in methanol was 656 my.

(12) Preparation of 1,3 diethyl 8-fluoro-5',6-dimethylthia-4-carbocyanine iodide:

Into 50 ml. of ethanol were dissolved, by heating, 1 g. of 4-(2-acetanidovinyl) 1-ethyl-8-fluoroquinolinium p-toluenesulfonate and 0.66 g. of 3-ethyl-2,5,6-trirnethylbenzothiazolium iodide. After the addition of 3 ml. of tri ethylamine to the solution, the mixture was refluxed for 30 minutes. After the reaction was finished, the dye thus precipitated was recovered by filtration, washed with ethanol and recrystallized from a mixed solvent of methanol and chloroform to provide 0.9 g. of the dye having a melting point of 266267 C. (decomposed). The absorption maximum of the dye in methanol was 651 III/1..

(13) Preparation of 6',7 benzo 1,3'-diethy1-6- fluorothia-4-carbocyanine p-toluenesulfonate:

A mixture of 2 g. of l-ethyl-6-fluoro-4-methylquinolinium p-toluenesulfonate, 1.6 g. of 2-(2-anilinovinyl)-3- ethyl-naphtho [2,1-a] thiazolium p-toluenesulfonate, ml. of ethanol, and 6 ml. of acetic anhydride was heated with the addition of 5 ml. of triethylamine and the mixture was refluxed for one hour. After the reaction was finished, the product was concentrated, cooled and mixed with ether, and the dye thus precipitated was filtered and recrystallized from a mixed solvent of ethanol, chloroform and isopropanol (three times) to provide 1.3 g. of the dye, having a melting point of 259 C. (decomposed). The absorption maximum of the dye in methanol was 660 m (14) Preparation of 1,3'-diethyl 8 fluoro-5,6-dimethylselena-4-carbocyanine iodide:

Into 70 ml. of ethanol were dissolved 1 g. of 4-(2- acetanilidovinyl) 1-ethyl-8-fluoroquinolinium p-toluenesulfonate and 0.75 g. of 3 ethyl-2,5,6-trimethylbenzoselanazolium iodide. After adding 4 ml. of triethylamine, the mixture was refluxed for 30 minutes. After the reaction was finished, the dye thus formed was filtered and recrystallized from a mixed solvent of methanol and chloroform to provide 0.8 g. of the dye, having a melting point of 266-267" C. The absorption maximum of the dye in methanol was 657 mp.

(15) Preparation of anhydro 6,7 benzo-3-ethyl- 8-fluoro-l(3 sulfopropyl)thio 4 carbocyanine hydroxide:

A mixture of 2 g. of 8-fluoro-4-methylquinoline and 2.3 g. of propane sulfone was heated to -160 C. for 2 hours in an oil bath. After the reaction was finished, acetone was added to the product with stirring to cause crystallization and the crystals thus formed were filtered and washed with ethanol to provide 2.2 g. of anhydro-S- fluoro-4-methyl-1 (3-sulfopropyl)-quinolinium hydroxide. A mixture of 0.7 g. of the product, 150 ml. of 2- (2-anilinovinyl) 3 ethylnaphtho [2,1-a] thiazolium p-toluenesulfonate, 150 ml. of ethanol, and 3 ml. of acetic anhydride was heated, and, after adding ml. of triethylamine, the resulting mixture was refluxed for 30 minutes. After the reaction was finished, the dye thus precipitated was filtered and recrystallized from a mixed solvent of acetic acid and pyridine to provide 0.5 g. of the dye having a melting point of 300 C. (decomposed). The absorption maximum of the dye in methanol was 663 mg.

(16) Preparation of anhydro-6,7' benzo 3'-carboxy-methyl 1 ethyl-8-fluorothia-4-carbocanine hydroxide:

A mixture of 2.5 g. of 4-(2-acetanilidovinyl)-l-ethyl-8- fluoro-quinolinium p-toluenesulfonate, 1.65 g. of 3-carboxyrnethyl-Z-methylnaphtho [2,1-a]thiazolium bromide, and 100 ml. of ethanol was heated, and after the addition of 4 ml. of triethylamine, the resulting mixture was refluxed for 30 minutes. After the reaction was finished, the product was concentrated, cooled and mixed with ether while stirring. After removing the ether layer which formed by decantation, a small amount of isopropanol and ether was added to precipitate the dye, which was filtered and recrystallized from a mixed solvent of methanol and chloroform to provide 1.1 g. of dye having a melting point of 193-194 C. (decomposed). The absorption maximum of the dye in methanol was 662 m (17) Preparation of 6,7'-benzo '-carboxyethyl-1- ethyl-8-fluorothia-4-carbocyanine bromide:

A mixture of 2 g. of 4-(Z-acetanilidovinyl)-1-ethyl-8 fluoro-quinolinium p-toluenesulfonate, 1.3 g. of 3-carboxyethyl-Z-methylnaphtho [2,l-oc] thiazolium bromide, and 50 ml. of ethanol was heated, After adding 2 ml. of triethylamine, the mixture Was refluxed for 3 minutes. After the reaction was finished, the product was concentrated, cooled, and mixed with ether to precipitate the dye, which was filtered and recrystallized (twice) from a mixed solvent of methanol and chloroform to provide 1.5 g. of dye having a melting point of 203205 C. (decomposed). The absorption maximum of the dye in methanol was 662 my.

(18) Preparation of anhydro-6,7'-benzo-l-ethyl-6- fluoro-3 3-sulfopropyl thia-4-carbocyanine hydroxide:

ro-quinolinium p-toluenesulfonate, 0.69 g. of anhydro-Z- 1nethyl-3-(3-sulfopropyl) naphtho[2,1a]thiazolium hydroxide, 200 ml. of ethanol, and 4 ml. of acetic anhydride was heated, and, after adding 5 ml. of triethylamine, the mixture was refluxed for 30 minutes. After the reaction was finished, the dye thus formed was filtered and recrystallized from a mixed solvent of acetic acid and pyridine to provide 0.8 g. of dye having a melting point above 300 C. (decomposed). The absorption maximum of the dye in methanol was 663.5 m

(19) Preparation of 6',7-benzo-l-(3-carboxypropyl)- 3-ethyl-8-fluorothia-4-carbocyanine bromide:

A mixture of 5 g. of 8-fluoro-4-methy1quinoline and 4.6 g. of a-butylonitrile was heated to 140 C., for 6 hours, in an oil bath. After reaction was completed, the product was cooled, mixed with ether and acetone with stirring to cause crystallization. The crystals thus formed were recovered by filtration and recrystallized from a mixed solvent of ethanol and isopropanol to provide 3.6 g. of 1-(3-cyanopropyl) 8 fluoro-4-methylquinolinium bromide, having a melting point of 180-181 C. The product (3.6 g.) was then refluxed for 6 hours with ml. of hydrobromic acid (48%), concentrated under reduced pressure and cooled to cause crystallization. The crystals thus formed were filtered to provide 2.5 g. of 1-(3-carboxypropyl) 8 fluoro 4 methylquinolinium bromide. A mixture of 1.2 g. of the product, 1.5 g. of 2- (2-anilinovinyl) 3 ethyl 6,7 benzobenzothiazolium p-toluenesulfonate, 150 ml. of ethanol, and 4 ml. of acetic anhydride was heated, and, after adding 5 ml. of triethylamine, the mixture was refluxed for 30 minutes. After the reaction was finished, the product was concentrated, cooled, and mixed with ether to cause crystallization. The dye thus formed was filtered and recrystallized (twice) from a mixed solvent of methanol and isopropanol to provide 0.6 g. of the crystals of dye having a melting point of 193-195 C. The absorption maximum of the dye in methanol was 662 m Preparation of 1,3'-diethyl-8-fluorothia-4-dicarbocyanine iodide:

Into 150 ml. of ethanol there were dissolved, by heating, 2.8 g. of 1-ethyl-8-fluoro-4-methylquinolinium p-tolucnesulfonate and 2.6 g. of 2-(4-acetanilido-1,3-butadienyl)-3-ethylbenzothiazoliurn iodide. After adding 4 ml. of triethylamine, the mixture was refluxed for minutes. After the reaction was finished, the product was cooled and the dye thus formed was obtained by filtration and recrystallized from a mixed solvent of methanol and chloroform to provide 1.6 g. of dye having a melting point of 214-215 C. The absorption maximum of the dye in methanol Was 736.5 m

In addition to the aforesaid sensitizing dyes, the following dyes are within the scope of the present invention and it is believed that the preparation of these dyes will be easily Understand fmm Hm aimm mmtmn..- -..1.

Dye 21-6,7 benzo-l,3'-diethyl-8-fluorothia-4-carbocyanine iodide:

Melting point 266 C. (decomposed); absorption maximum 660 mg. (in methanol).

Dye 221,3-diethyl 5 ethoxy 8 fluoro 6- rnethylthia-4-carbocyanlne iodide:

Melting point 264 C. (decomposed); absorption maximum 660 ITl/L. (in methanol).

Dye 23-Anhydro 1 ethyl 5,6' dimethyl 8- fluoro 3' (3-sulfopropyl)selena 4 carbocyanine hydroxide:

Melting point 297 C. (decomposed); absorption maximum 658.5 mg (in methanol).

Dye 24anhydro-1-ethyl-5,6'-dimethyl-8-fluoro-3'-(3- sulfopropyl thiacarbocyanine hydroxide Melting point 298 C.; absorption maximum 652 mp. (in methanol).

The novel sensitizing dye used in this invention can spectrally sensitize a silver halide emulsion, and, in particular, is quite elfective for enlarging the spectral lightsensitive region of a gelatino silver halide emulsion.

The sensitizing dye of this invention will also sufficiently sensitize a photographic emulsion containing hydrophilic colloids other than gelatin, such as agar agar, collodon, water-soluble cellulose derivatives, polyvinyl alcohol and other synthetic or natural hydrophilic resins.

In the silver halide emulsion of this invention, there may be employed various silver salts, such as, silver chloride, silver bromide, silver iodo-bromide, silver chlorobromide, silver chloroido-bromide, and the like.

The sensitizing dye of this invention may also be added to a photographic silver halide emulsion which has been preliminarily sensitized by a physical ripening or a chemical ripening.

To prepare the sensitized photographic silver halide emulsion of this invention, one or more sensitizing dyes of this invention may be incorporated in a photographic emulsion by conventional methods. In practice, the sensitizing dye is incorporated into the photographic emulsion as a solution in a suitable solvent, such as methanol or ethanol. The amount of the sensitizing dye may be widely varied. For most commercial purposes, a range of 1-150 mg. of dye per one kg. of emulsion, according to the final use, will be acceptable.

The photographic silver halide emulsion of this invention, containing the sensitizing dye, may be further subjected to super-sensitization and hyper-sensitization, if desired.

In the preparation of the silver halide emulsion of this invention, additives that are usually employed in the field, such as, sensitizers, stabilizers, color toning agents, hardening agents, surface active agents, antifoggants, plasticizers, developing accelerators, couplers, and fluorescent whitening agents may be incorporated into the photographic silver halide emulsion.

In addition, when the silver halide emulsion of this invention also contains at least one of the following materials: Compound A-I, Compound A-II, Compound A- III or Compound B, described in Japanese patent publication No. 4,724/53, Japanese patent application No. 11,- 669/ 67, Japanese patent application No. 52,488/65, and Japanese patent publication No. 81,697/ 65, respectively, the sensitivity of the spectral sensitizing regions can be increased. That is, a super-sensitizing effect can be obtained, and further, the spectral sensitivity decrease during preservation of light sensitive elements having the light-sensitive layers of the silver halide emulsions of this invention can be halted to a great extent.

Compound A-I is represented by the general formula:

I I X X wherein R and R each may represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an acyl group, an alkoxyl group, an unsubstituted or substituted carbamyl group, a hetercyclic ring; and X and X each represent a hydrogen atom or SO I-I.

Compound A-II is represented by the following general formula:

Compound AIII is represented by the following general formula:

wherein R and R each represents a halogen atom, a hydroxyl group, or NHR (where R represents an aryl group or an aralkyl group); D represents a hydogen atom, an alkali metal, an ammonium group or an amine salt.

1 1 Compound B is a condensation product of formaldehyde and a compound represented by the following formula:

The sensitizing dyes of this invention were incorporated in a silver chlor-bromide emulsion (AgBr 40 moles; AgCl 60 moles). The photographic emulsion thus prepared was applied to a cellulose triacetate film and dried to provide a light-sensitive film. The light sensitive emulsion layer was exposed to the light of a tungsten lamp, using a diffraction grating spectrograph, developed. The spectral sensitivity characteristics were then measured. During the development, a developer having the composition shown below (Table 1) was used:

TABLE 1 G. N-methyl-p-aminophenol sulfate 20 Hydroquinone 4.0 Sodium carbonate (anhydrous) 24 Potassium bromide 1 Sodium sulfite 40 Water to make In Table 2, the sensitization maximums of each of the sensitizing dyes of this invention are shown when each dye was added to the photographic emulsion described above.

Table 3 shows the results of a comparison of the fog densities when employing the silver halide emulsions of this invention and when employing identical silver halide emulsions containing the conventional sensitizing dyes shown below (not the novel dyes of the present invention).

TABLE 2 Sensitization sensitizing dye Amount* Ag halide maximum, my

0.03 AgCl/Br 530 0.006 AgGl/Br 690 0.006 AgCl/Br 675 0.006 AglC/Br 080 0.006 AgCl/Br 680 0.006 AgCl/Br 690 0.006 AgCl/Br 685 0.006 AgCl/Br 680 0.006 AgCl/Br 685 0.006 AgCl/Br 685 0. 006 AgCl/Br 685 0.006 AgCl/Br 685 0.006 AgCl/Br 690 0.006 AgCl/Bl' 675 The conventional sensitizing dyes (comp) used in the above experiments are shown below:

| C3115 What is claimed is: 1. A photographic silver halide emulsion containing a sensitizing dye represented by the general formula wherein Z represents the non-metallic atoms necessary to complete a heterocyclic ring of the type employed in a cyanine dye; R and R each represents a member selected from the group consisting of a lower alkyl group, a substituted alkyl group, an allyl group, a benzyl group, a phenethyl group and a phenoxyethyl group; X- represents an anion; u may vary from 0 to 1; 11 may vary from 0 to l; and in may vary froml to 2.

2. The photographic silver halide emulsion claimed in claim 1 wherein said sensitizing dye is selected from the group consisting of 8-fluoro-4-methylquinoline; 6-fluoro-4-methylquinoline; 1-ethyl-8-fluoro-4-methylquinolinium iodide; 1-ethyl-6-fluoro-4-methyl-quinolinium iodide; 1-ethyl-8-fiuoro-4-methylquinolinium p-toluenesulfonate; 1-ethyl-6-fluoro-4-methylquinolinium p-toluenesulfonate; 4- Z-acetanilidovinyl) l -ethyl-8-fluoro-quinolinium p-toluenesulfonate; 4-(Z-anilinovinyl)-1-ethyl-6-fluoro-quinolinium n-toluenesnlfnmrp- 13 1,1'-diethy1-8,8'-difiuoro-4,4'-carb0cyanine iodide; 1,1-diethy1-S-fluoro-Z,4-carbocyanine iodide; 1,3'-diethy1-8-fiuoro-5 ',6'-dimethy1thia-4-carbocyanine iodide; 6,7-benzo-1,3'-diethy1-6-fluor0thia-4-carbocyanine p-toluenesulfonate; 1,3-diethyl-8-fluoro-5',6-dimethy1selena-4-carbocyanine iodide; anhydro-6',7-benzo-3'-ethyl-8-fiuoro-1-(3-su1fopropy1) thia-4-carbocyanine hydroxide; anhydro-6,7-benZo-3'-carboxymethy1-1-ethy1-8- fluorothia-4-carbocyanine hydroxide; 6,7'-ben2o-3'-carboxyethy1-1-ethy1-8-fluorothia-4- carbocyanine bromide; anhydro-6,7'-benzo-1-ethy1-6-fiuoro-3 3-sulfopropy1) thia-4-carbocyanine hydroxide; 6',7'-benzo-1-(3-carboxypropy1)-3-ethyl-8-fluoro-thia-4- carbocyanine bromide; 1,3'-diethyl-8-fiuorothia-4-dicarbocyanine iodide; 6,7'-benzo-1,3'-diethyl-8-fluorothia-4-carbocyanine 14 iodide; 1,3-diethy1-5'-ethoxy-8-fluoro-6-methy1thia-4- carbocyanine iodide; anhydro-1-ethyl-5',6-dimethy1-8-fluoro-3'-(3-sulfopropy1) selena-4-carbocyanine hydroxide; and anhydro-l-ethy1-5',6-dimethyl-8-fluoro-3'-(S-sulfopropyl) thia-4-carbocyanine hydroxide.

References Cited UNITED STATES PATENTS 2,912,329 11/1959 Jones et a1. 96--106 NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, Assistant Examiner US. Cl. X.R. 96-106