Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
  • C07D487/04—Ortho-condensed systems
• • 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
  • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression
  • G03C1/346—Organic derivatives of bivalent sulfur, selenium or tellurium

Definitions

• the present invention relates to photographic materials comprising light-sensitive silver halide emulsions. More particularly, this invention is directed to stabilized silver halide emulsions which have less tendency to fog and which still possess substantially the same light sensitivity.
• Fogging in general, and chemical fogging in particular may be defined as a uniform deposit of silver extending over and either partially or wholly obliterating the image and is caused in a number of Ways namely, the nature of the emulsion, its age and the conditions under which it has been stored, the nature of the developer, impurities in the developing solution and the time and temperature of the development.
• chemical fogging is promoted when such active agents as metal are employed in a concentrated solution or are used in the presence of an excess of alkali.
• the oxidation of certain developing agents such as metol and hydroquinone exerts a powerful fogging action.
• R represents a hydrogen atom, alkyl groups containing from one to eighteen carbon atoms, aromatic groups and halogen and X-represents a hydrogen atom, a carboxyalkyl group or the roup S-A wherein A represents the pyrazolopyrimidine structure shown above.
• the antifogging effect is generally due to the presence in the emulsion of the pyrazolopyrimidine structure and not necessarily to the size of configuration of substituents R and X.
• R represents an alkyl group
• substituents wherein R represents an alkyl group include groups such as methyl, ethyl propyl. butyl, hexyl, octyl, decyl, dodecyl, octadecyl and the like.
• the substituent R can also represent aromatic radicals such as phenyl, naphthyl and anthryl radicals as well as a halogen atom such as chlorine.
• the substituent X can represent a hydrogen atom, a halo radical such as a chloro radical, carboxy-allcyl radicals such as carboxymethyl, carboxyethyl, carboxybutyl and carboxyhexyl radicals, and the disulfides corresponding thereto.
• the antifogging agents which have been found to exert such beneficial effects to light-sensitive silver halide emulsions for the prevention of chemical fogging can be readily prepared in accordance with known procedures. such as described in J. Am. Chem. Soc, vol. 79, 6407-15 (1957).
• 4-mercapto-6-methyl pyrazolo (3,4-d) pyrimidine is conveniently prepared by reacting under refiux conditions S-aminoi-cyanopyrazole with acetic anhydride to provide 5-acetylamino-4-cyanopyrazole which is subsequently reacted with potassium hydroxide and hydrogen peroxide to yield 4-hydroxy-6-methyl pyrazolo (3,4-d) pyrimidine.
• the hydroxide is then converted to the mercapto derivative by reaction with phosphorous pentasulfide.
• the addition of the antifoggants can be made before, during or after the addition of the soluble silver salt to the soluble halide in the presence of a suitable carrier or colloid such as gelatin, polyvinyl alcohol, solubilized casein, albumin and the like.
• the antifoggants of the present invention can also be employed as components of the developing solution.
• the amount of antifogging agent employed as additives to the light-sensitive emulsions varies from about 0.1 to about 50 milligrams of antifoggant per 0.6 mole of silver halide.
• antifogging agents When the antifogging agents are employed as ripening finals it has been found advantageous to employ them in amounts in the range of from about 0.1 to about 25 milligrams per 0.6 mole of silver halide whereas when the antifogging agents are employed in coating finals it has been found advantageous to employ amounts in the range of from about 0.5 to about 50 milligrams of antifoggant per 0.6 mole of silver halide.
• the development of optimum characteristics within the range set forth above will depend, in part, upon the type of,
• the antifogging agents of the invention in adjacent layers, for example, in a separate undercoating layer or in the antiabrasion gelatin surface.
• antifogging agents of the invention can be compatibly employed in combination with other known antifoggants and stabilizers; with sulfur-, reduction and 1netal-, and noble metal sensitizers as well as in combination with polyoxyalkylene polyols, their derivatives; polyvinylpyrrolidones and other accelerators.
• Example I A silver halide emulsion in gelatin containing 2% silver iodide and 98% silver bromide was prepared in a conventional manner and brought up to its maximum light sensitivity. It was then readied for coating, finals were added such as sensitizing dyes, and hardening agents. A 0.1% solution of 4-mercapto-6-anethylpyrazolo (3,4-d) pyrimidine was prepared and added to the emulsion as an antifoggant and stabilizer. The emulsion samples contained about 0.6 mole of silver halide. The so prepared emulsion samples were coated on a suitable cellulose ester base' and dried. Samples of these film coatings where then G exposed in a Type 113 'sensitomete-r and developed in a developer of the following composition:
• the stabilizer used in this example was prepared as follows:
• Example II The procedure used was the same as in Example I except that there was used as the stabilizer 4-carboxymethyl thioether of the 6-methyl-pyrazolo (3,4-d) pyrimidine. The results of the experiment indicated that 80 milligrams of the compound provided the same effectiveness as 8.0 milligrams of the compound of Example I.
• the carboxymethyl thioether is prepared by heating equimoleoular portions of the mercapto compound and bromoacetic acid and sufiicient 2 N sodium hydroxide solution to take up the hydrogen bromide split-off during the reaction under reflux for two and one-half hours. After cooling the reaction mixture is acidified and yields the compound.
• Example 111 The procedure was the same as Example I except that there was used the disulfide corresponding to 4-mercapto- 6-methyl-pyrazolo (3,4-d) pyrimidine. The results obtained were similar to those obtained in Example I.
• the stabilizer was prepared from the mercapto compound by oxidizing it in ethanol solution with hydrogen peroxide.
• Example IV Exposed samples of a photographic film were developed .for twelve minutes at 65 F. in a standard metol-hydroquinone developer. Two tests were made, one with the normal developing solution and one with a developer containing 200 m'gs. of 4-mercapto-6-methyl-pyrazolo (3,4-d) pyrimidine to one liter of developer. Sensitometric strips, developed in the normal developer (control) for twelve minutes showed a fog of .30, whereas those strips, which were developed in the developer containing the antifoggant, had a fog of .20.
• a light-sensitive photographic material comprising a light-sensitive silver halide emulsion, a carrier therefor and an antifogging agent characterized by the general formula:
• a light-sensitive photographic material comprising a light-sensitive silver halide emulsion, a carrier therefor, said emulsion containing, as an antifog-gant, 4-mercapto- 6-methyl-pyrazolo (3,4-d) pyrimidine.
• a light-sensitive photographic material comprising a light-sensitive silver halide emulsion, a carrier therefor, said emulsion containing, as an antifoggant, 4-mercapto- 6-chloro-pyrazolo (3,4-d) pyrimidine.
• a light-sensitive photographic material comprising a light-sensitive silver halide emulsion, a carrier therefor, said emulsion containing, as an antifoggant, a compound of the formula:
• a light-sensitive photographic material comprising a light-sensitive silver halide emulsion, a carrier therefor, said emulsion containing, as an antifoggant, a compound of the formula:
• R is the same as the radical represented by R in the foregoing general formula.
• R represents a member selected firom the group consisting of hydrogen chloro, alkyl aromatic radicals and X represents a member selected from the group consisting of hydrogen, carboxyalkyl radicals containing up to six carbon atoms in the alkyl group and a radical having the formula N ll i N wherein R is the same as the radical represented by R in the foregoing general formula.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

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• 0
  • BE BE624110D patent/BE624110A/xx unknown
• 1961
  • 1961-11-02 US US149520A patent/US3244521A/en not_active Expired - Lifetime
• 1962
  • 1962-09-18 GB GB35484/62A patent/GB965047A/en not_active Expired
  • 1962-10-27 DE DEG36249A patent/DE1182060B/de active Pending

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