Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D263/00—Heterocyclic compounds containing 1,3-oxazole or hydrogenated 1,3-oxazole rings
  • C07D263/52—Heterocyclic compounds containing 1,3-oxazole or hydrogenated 1,3-oxazole rings condensed with carbocyclic rings or ring systems
  • C07D263/54—Benzoxazoles; Hydrogenated benzoxazoles
  • C07D263/56—Benzoxazoles; Hydrogenated benzoxazoles with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached in position 2
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D235/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings
  • C07D235/02—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings condensed with carbocyclic rings or ring systems
  • C07D235/04—Benzimidazoles; Hydrogenated benzimidazoles
  • C07D235/06—Benzimidazoles; Hydrogenated benzimidazoles with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached in position 2
  • C07D235/08—Radicals containing only hydrogen and carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
  • C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
  • C07D277/08—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
  • C07D277/10—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
  • C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
  • C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
  • C07D277/22—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D293/00—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms
  • C07D293/10—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms condensed with carbocyclic rings or ring systems
  • C07D293/12—Selenazoles; Hydrogenated selenazoles
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/02—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/02—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups
  • C09B23/06—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups three >CH- groups, e.g. carbocyanines
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/10—Organic substances
  • G03C1/12—Methine and polymethine dyes

Definitions

• This invention relates to new methine dyes and to their preparation and use as sensitizers for photographic silver halide emulsions, and to methods of sensitizing such emulsions by means of such sensitizing dyes.
• methine dyes A great number of methine dyes are known and many of them have been found to sensitize photographic emulsions in a variety of useful manners. These sensitizing methine dyes, however, when used in such emulsions leave in general a residual stain in the colloid image-bearing layers and/ or in other photographic layers such as sublayers or even in the film support of developed and fixed photographic elements.
• the staining eifect is particularly troublesome in the case of photographic elements which are used in photo-mechanical processes, for example photographic negatives of the lithographic type which are to be corrected subsequently by a color mask image, and therefore a neutral tint is an absolute requirement.
• This staining effect is furthermore particularly objectionable in photographic papers since it is impossible, when such dye-sensitized emulsions are used, to obtain bright whites in a black-and-white picture or a true reproduction of the colors in a color picture.
• a light rose or yellow residual stain may further cause trouble when a finished photograph is exposed partly to full daylight, the other part being covered, so that under the influence of light the residual dye-stuff can bleach out, leaving an image which is partly white and partly colored.
• a further object is to provide methods for preparing these new dyes.
• Still another object is to provide silver halide emulsions sensitized with these new dyes.
• a still further object is to provide a practical and useful method for sensitizing silver halide emulsions which has the great advantage that, when such emulsions are coated on a suitable support, the exposed photographic element after development and fixing gives a finished photograph which is essentially free from any residual stain.
• the methine dyes are adsorbed on the silver halide crystals and on the particles of the colloid binder along the organic residue attached to the auxochrome nitrogen atom, that is the cyanine nitrogen atom which is linked through a conjugated carbon chain to another auxochrome group such as for example a nitrogen atom or a carbonyl, thiocarbonyl or cyano group.
• sensitizing methine dyes which are adsorbed on the silver halide crystals and on the hydrophilic water-permeable colloid binder along an organic residue bearing a hydrophilic group as defined more particularly hereinafter, do not leave an objectionable residual stain in the photographic layers after development and fixing of the exposed photographic element has been completed, independently of the Watersolubility of the new methine dyes involved. It has been 3,156,685 Patented Nov. 10, 1&64
• the readiness with which the new methine dyes can be removed from the exposed photographic element during processing consequently has no direct relation with the solubility of the dyes involved but is or may be regarded as a result of a desorption phenomenon whereby in aqueous medium the dye molecules are withdrawn from the surface of the silver halide crystals and/ or of the particles of the colloid binder on account of the great water-affinity of the organic residues containing the hydrophilic groups according to the invention.
• the existence of such desorption phenomena is known from adsorption chromatographic separation techniques where the solubility does not play a preponderant role either.
• methine dyes containing electro-negative groups in general are relatively poor sensitizers for photographic emulsions or even desensitizers for such emulsions and therefore not useful as practical photographic sensitizers.
• this shif ing is undesirable, it can be remedied by adaption of the other elements constituting the methine dye, for example by changing a heterocyclic nucleus or by introducing a substituent into a nucleus or in the conjugated chain.
• a and B each represents a hydrocarbon group. That residue linked to an auxochrome heterocyclic nitrogen atom of methine dye salts may have a betaine structure by intra-rnolecular ionization of the sulphonic acid group:
• A preferably represents alkylene groups having from 14 carbon atoms such as methylene, ethylene, and propylene alone or coupled to .
• a mononuclear arylene radical such as benzylene (phenylene methylene) and 3 preferably represents an alkylene group having from 1-6 carbon atoms such as methylene, ethylene, propylene and butylene.
• the present invention further includes a process for preparing high sensitive photographic silver halide emulsions which give, after development and fixing of the exposed photographic element, a finished photograph which is essentially free from any residual stain, which comprises treating a photographic silver halide emulsion with a sensitizing polymethine dye as defined herein and a light sensitive photographic element containing at least one silver halide emulsion layer sensitized according to the foregoing process.
• the present invention also includes a method of preparing methine dyes, which method consists in treating a quaternary salt of a heterocyclic nitrogen base bearing at the nitrogen atom an organic residue of the following constitution:
• M represents an alkali metal atom, such as sodium, potassium or the like or an ammonium group and A and B have the same significance as set forth hereinbefore, by one of the methods known to be capable of converting the alkyl, aryl or aralkyl quaternary salt of such heterocyclic base into a methine dye.
• the word known is to be understood as designating methods in actual use or described in literature on the subject.
• the quaternary salts employed in the present invention can be obtained by treating the corresponding heterocyclic nitrogen base with a compound of the general formula:
• X represents an acid residue such as for example a halogen atom such as Cl and Br
• M A and B have the same significance as set forth hereinbefore.
• heterocyclic nitrogen base and the compound of Formula I above are merely heated together to form the quaternary halide. Crude quaternary halides prepared in this manner may be converted, if desired, into other quaternary salts before employing them to prepare our new methine dyes.
• the compounds of the general formula I wherein B represents a hydrocarbon radical containing a straight carbon chain of at least three carbon atoms may be prepared by heating together a compound of the general formula:
• B represents a hydrocarbon radical containing a straight chain of at least three carbon atoms and not more than 6 carbon atoms and containing preferably 3 or 4 carbon atoms and M, X and A have the same significance as set forth hereinbefore.
• the quaternary salts employed in the present invention can also be obtained by treating the corresponding quaternary salt, bearing at the nitrogen atom an organic residue of the following constitution:
• A has the same significance as set forth hereinbefore, and which may be prepared by treating the corresponding heterocyclic base with a compound of the general formula:
• B represents a hydrocarbon radical containing a straight carbon chain of at least three carbon atoms.
• heterocyclic nitrogen bases known to be convertible into a methine dyestuif
• the heterocyclic nitrogen bases containing in the alpha or gamma-position to the nitrogen atom of the heterocyclic ring an alkyl, thioalkyl, beta-alkylthiovinyl, betahalogenovinyl, beta (N-methylanilino)-vinyl or beta-acylanilidovinyl group, which vinyl groups may carry a substituent, such as a lower alkyl group.
• PREPARATION XX 2,5 -Dimethyl-3- (S odium S ulpho-Carbomethoxy-M ethyl Benzothiazolium Bromide A mixture consisting of 2,S-dimethyl-benzothiazole (4.5) g.) and sodium sulpho-carbomethoxy-methyl bromide (6 g.) is heated for 24 hours at C. in a drying oven. The product is washed with ether, ground, sucked off and dried in vacuum.
• the product obtained is washed with ether, ground and sucked oft. Melting point: 178 C.
• the new methine dyestufis according to the present invention may be obtained starting from the new heterocyclic quaternary salts by application of the usual condensation methods known to those skilled in thevart.
• the new asymmetric cyanine dyes according to the present invention can be prepared by condensing a cycloammonium quaternary salt of the following general formula:
• Z represents the non-metallic atoms to complete a heterocyclic nucleus containing to 6 atoms in the 'heterocyclic ring of the type known in cyanine dyes, such as those selected from the group consisting of those of the thiazole series (e.g.
• thiazole 4-methylthiazole, 4-phenyl thiazole, 5-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4.5-CliPhEi1Yl-4Zhifi20lfi, 4-(2-thienyl)-thiazole, etc), those of the benzothiaaole series (e.g.
• benzothiazole 4- chlorobenzothiazole, S-chlorobenzothiazole, 6-chloroben- Zothiazole, 7-chlorobenzothiazole, 4-rnethylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, 5-bromo benzothiazole, 6-bromobenzothiazole, 4-phenyl-benzothiazole, S-phenylbenzothiazole, 4-methoxybenzothiazole, 5- methoxybenzothiazole, dmethoxybenzothiazole, S-iodobenzothiazole, 6iodobenzothiazole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, 4,5,6,7-tetrahydrohenzothiazole, 5,G-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole, S-hydroxybenzothiazole, 6-hydroxybenzothiazole
• naphtho[2,l-d]thiazole naphtho[l, 2-d]thiazole, S-methoxynaphtho[1,2-d]thiazole, S-ethoxynaphtho[l,2 d]ithiazole, 8 rnethoxynaphtho [2,l-d]thia zole, 7-methoxyn-aphtho [2,1-d1thiazole), those of the thionaphtheno[7,6'-d]thiazole series (e.g. 4-me-thoxythio naphtheno [7',6-d]thiazole), those of the oxazole series (eg.
• benzoxazole S-chlorobenzoxazole, S-methylbenzoxazole, S-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbcnzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole, 6-methoxybenzoxazole, S-hydroxybenzoxazole, 6- hydroXy-benzoxazole), those of the naphthoxazole series (e.g. naphtho[2,l-d]oxazole, naphtho[1,2-d]oxazole), those of the selenazole series (e.g.
• thiazoline 4-1nethylthiazoline, 4-hydroxymethyl-4-methylthiazoline, 4,4-bishydnoxymethylthiazoline, 4-acetoxyrnethyl-4-rnethylthiazoline, 4,4 bis-acetoxymethylthiazoline), those of the t iazolidine series (e.g. 2-benzothiazolylidene-4-thi-azolidone), those of the oxazoline series (eg.
• benzimidazole series e.g. l-ethylbenzimidazole, 1- phenylbenzimidazole, 1-ethyl5,6-dichlorohenzimidazole, 1-hydroxyethyl-5,6-dichlorobenzimidazole, l-ethyl-S-chlorobenzimidazole, 1ethyl-5,6-di'bromohenzirnidazole, 1- ethyl-5-chloro-6-aminobenzimidazole, l-ethyl-S-chloro-G- bromobenzimidazole, l-ethyl-5-phenylbenzimidazole, lethyl 5 fluorobenzimidazole, l ethyl 5 cyanobenzimidazole, 1-(/3-acetoxyethyD-S-cyanobenzimidazole, 1- ethyl-5
• R represents an alkyl group of the formula C H wherein r represents a positive integer from 1 to 4 such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, an unsaturated aliphatic radical such as aliyl, a hydroxy substituted alkyl radical such as ,B-hydroxyethyl, an aralkyl radical such as benzyl, a substituted aralkyl radical such as carboxy benzyl, a mononuclear aryl group such as phenyl, a substituted mononuclear aryl group such as carboxyphenyl, or a radical of the formula as described above.
• r represents a positive integer from 1 to 4 such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, an unsaturated aliphatic radical such as aliyl, a hydroxy substituted alkyl radical such as ,B-hydroxy
• Z represents the non-metallic atoms to complete a heterocyclic nucleus containing 5 to 6 atoms in the heterocyclic ring such as those described for Z,
• X represents an acid residue as known in cyanine dyes and D represents an alkylmercapto, an arylmercapto, a betaarylaininovinyl, a delta-arylamino-1,3-butadienyl, a betaalkylmercaptovinyl, a beta-arylmercaptovinyl or a betaacetanilidovinyl group, which vinyl groups may carry a substituent, such as methyl, benzyl or phenyl.
• condensations are advantageously carried out in the presence of a basic condensing agent, for example a trialkylamine such as triethylamine, a dialkylaniline, a heterocyclic tertiary amine such as pyridine, N-alkylpiperidine or the like.
• a basic condensing agent for example a trialkylamine such as triethylamine, a dialkylaniline, a heterocyclic tertiary amine such as pyridine, N-alkylpiperidine or the like.
• the new symmetrical cyanine dyes according to the present invention can be prepared by condensing a cyclammonium quaternary salt represented by the general Formula II above with an ortho car boxylic acid alkyl ester, such as ethyl ortho-formate and ethyl ortho-acetate, advantageously in the presence of a carboxylic acid anhydride, for example acetic anhydride.
• a cyclammonium quaternary salt represented by the general Formula II above with an ortho car boxylic acid alkyl ester, such as ethyl ortho-formate and ethyl ortho-acetate, advantageously in the presence of a carboxylic acid anhydride, for example acetic anhydride.
• t represents an integer from 1 to 3
• Ar represents an aryl group and L and L each represents a methine group.
• aryl-amino-vinyl intermediates, or vinylene homologues thereof thus obtained can be transformed into the corresponding acetarylido derivatives by boiling with acetic anhydride, which can be condensed to unsymmetrical cyanine dyes with cyclammonium quaternary salts containing a methyl group in alpha or gamma position to the nitrogen atom.
• the condensations are advantageously carried out in the presence of a basic condensing agent as set forth above.
• the most valuable methine dyes of the present invention may be represented by one of the two general Formulae A and B:
• E -z' m n E --Z Z" and Z each represents the non-metallic atom necessary to complete a heterocyclic nitrogen nucleus of the type contained in cyanine dyes,
• n and n each represents a positive integer from 1 to 2
• ! represents a positive integer from 1 to 3
• R represents a member selected from the group consisting of a hydrogen atom, and lower alkyl radical
• X represents an acid radical of the type used in cyanine dyes
• R represents a radical of the type contained in cyanine dyes as substituent on the cyanine nitrogen atom
• R represents a radical of the formula in said radicals, R and R' 2 representing a positive integer from 1 to 6, M representing an alkali metal atom or cation such as ammonium and A representing a member selected from the group consisting of a lower alkylene radical or an arylene alkylene radical such as a benzylene radical.
• a silver chloride emulsion containing per kg. 20 mg. of this dyestuff is sensitized to 5 mg with a broad maximum at 540545 mg.
• a silver bromo-iodide emulsion containing per kg. 15 mg. of this dyestuif is sensitized to 655 ITLLL With a broad maximum at 600 111 1..
• a silver chloride emulsion containing per kg. 20 mg. of this dyestutf is sensitized to 580 m with a maximum at .530 III/1..
• EXAMPLE 11 The dyestuif anhydro-[2-(3-ethylthiazoline)]- ⁇ 2-[3- 16 (sulpho carbomethoxy-rnethyl) 5 methyl-benzothiasucked off and crystallized from ethanol. Absorption zole] ⁇ -trirnethinecyanine hydroxide, having the formula: maximum: 506 me.
• triethylamine are added drop by drop and after phonate (3.1 g.) and 2-methyl-3-[p-(omega-sulphoone hour stirring under ice-cooling the dyestuif is sucked carbobutoxy) benzyl]-benzothiazo1ium bromide (2.6 g.) off and recrystallized three times from a mixture ethanolare dissolved in ethanol (25 cm?) and after adding triwater.
• Absorption maximum 508 m ethylamine (1.4 cm?) boiled for fifteen minutes. After A silver chloride emulsion containing per kg. 15 mg.
• the dyestuff is precipitated with water and reof this dyestuff is sensitized to 590 m with a broad maxicrystallized three times from diacetone alcohol. Absorpmum at 540 mg. tion maximum: 610 mg.
• EXAMPLE 12 A silver bromo-iodide emulsion containing per kg. 30 The dyestuff anhydm [z (3 ethylthiazoline)1 mg. of this dyestulf is sensitized to 690 my.
• N are 0 o CH -S 03- (lhHs l i is prepared as follows: y *CH:CH CH: 2,6-dimethyl 3-(sodiumsulpho-carbomethoxy-methyl)- N t benzothiazolium bromide (4.2 g.) and Z-(fi-acetanilidoz Hz)i a- 52115 I vinyl)-3-ethylthiazolinium bromide (3.5 g.) are dissolved in methanol (35 cm?) and the solution is cooled at 0 C. 2.8 cm. triethylamine are added drop by drop and after Prepared as follows: one hour stirring under ice-cooling the dyestutf is sucked 2 methyl 3 (omeg?
• trimethinecyanine hydroxide having the formula: mg. of this dyestulf is sensitized to 690 mg with a broad maximum at 635-640 III/L.
• the dyestufl is 1-ethyl-2-methyl-3-(sodium sulpho-carbomethoxy- 17 methyl)-5,6-dichlorobenzimidazolium bromide (2.4 g.) and Z-(phenylimino ethylidene) 3 ethylbenzoxazoline (1.65 g.) are dissolved in acetic anhydride (20 0111. and, after the addition of triethylamine (1.4 cm?) left overnight at 20.
• the dyestuii' is precipitated with ether and recrystallized twice from ethanol and once from diacetone alcohol-water. Absorption maximum: 491 mu.
• the new methine dyes are useful especially for extending the spectral sensitivity of the customarily employed gelatino silver chloride, gelatino silver chloro-bromide, gelatin silver bromide, gelatino silver bromoidine and gelatin'o silver chloro-bromo-iodine emulsions
• photographic emulsions containing water-permeable colloids other than gelatin such as agar-agar, zeine, collodion, water-soluble cellulose derivatives, polyvinyl alcohol or other hydrophilic synthetic or natural resins or polymeric compounds, may equally well be sensitized according to the present invention.
• the dye, or dyes can be incorporated in the photographic emulsion by one of the methods customarily employed in the art.
• the dyes are advantageously incorporated in the finished, washed emulsions and should be uniformly distributed throughout the emulsion.
• the concentration of the dyes in the emulsion can vary widely, for example from 1 to 100 mg. per kg. of flowable emulsion and will vary according to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customarily used in the art of emulsion making.
• the new methine dyes can be incorporated in photographic emulsions the general sensitivity of which has been increased by physical and chemical ripening.
• An suitable chemical sensitizers may be mentioned the well known sulphur sensitizers such as allylisothiocyanate, allylthiourea, sodium thiosulphate, potassium selenocyanide and the natural sensitizers originating in the gelatin, reducing sensitizers such as the imino-aminomethanesulphinic acid and the derivatives thereof, and the salts of noble metals such as gold, platinum and palladium.
• photographic emulsions optically sensitized ac cording to the invention may further be supersensitized and/ or hypersensitized by one of the methods known to those skilled in the art.
• the usual addenda such as antifogging agents, stabilizers, anti-bronzing agents, hardeners, wetting agents, plasticizers, development accelerators, color couplers, fluorescent brighteners and ultra-violet screening compounds can moreover be incorporated in the emulsion in the manner customarily employed in the art.
• the sensitivity of the silver halide emulsions sensitized according to the process of the present invention is not adversely affected but rather enhanced by the presence therein of certain fluorescent compounds.
• Another advantage of the process for sensitizing silver halide emulsions according to the present invention is the compatibility of the new methine dyes with anionic wetting agents and with color couplers which is of great importance in the application of the new methine dyes for sensitizing the silver halide emulsion of a light-sensitive element for color photography.
• Emulsions sensitized with the new methine dyes can be coated in the usual manner on a suitable support such as glass, cellulose derivative film, resin film or paper.
• Z constitutes the atoms necessary to complete a heterocyclic system selected from the group consisting of benzothiazole, 6 methoxybenzothiazole, 6 methyl benzothiazole, S-methyl benzothiazole, 5,6-dimethyl benzothiozole, benzoselenazole, benzoxazole, S-phenyl benzoxazole, 6-methoxybenzoxazole, benzimidazole, 5,6-dichlorobenzimadazole, thiazole and 4- methyl thiazole;
• Z constitutes the atoms necessary to complete a heterocyclic system selected from the group consisting of benzothiazole, benzoselenazole, benzoXazole, benzirnidazole, thiazole, naphthothiazole, selenazoline and thiazoline;
• d is a positive integer from 1 to 3;
• R is a member selected from the group consisting of hydrogen and methyl
• R is a radical of the formula wherein A is lower alkylene, p a positive integer from 1 to 6 and M an alkyl metal atom.

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• Thiazole And Isothizaole Compounds (AREA)
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• 0
  • DE DENDAT1072476D patent/DE1072476B/de active Pending
  • BE BE568759D patent/BE568759A/xx unknown
• 1957
  • 1957-06-20 GB GB19425/57A patent/GB886271A/en not_active Expired
• 1958
  • 1958-06-20 FR FR768402A patent/FR1239318A/fr not_active Expired
• 1961
  • 1961-07-03 US US121372A patent/US3156685A/en not_active Expired - Lifetime

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