Photographic Color Developers

J. Bailey u. L.A. Williams, The Photographic Color Development Process, in K. Venkataraman, The Che-... 

Sulfonyl chlorides have extensive uses in organic synthesis in the preparation of sulfonamides and sulfonate esters. Methanesulfonyl chloride is a key raw material in the synthesis of critical components for photographic color developing formulations, as well as for herbicides and pharmaceuticals. 

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Uses Shortstopping agent for SBR wax hardener emulsion polymerization of diene monomers intermediate for basic dyes for syn. fibers stabilizer for colloidal disps. of metal oxides in lubricants in photographic color developers... 

Sources of formaldehyde are numerous. Exposed people are mainly health workers, cleaners, painters, metalworkers, but also photographers (color developers) and carbonless copy-paper users. Formaldehyde can induce... 

For most color photographic systems, development is the rate determining step, and within that step the formation of semiquinone is the slow process (37). The fate of the highly reactive QDI is deterrnined by the relative rates of a number of competing processes (38). The desired outcome is reaction with ionized coupler to produce dye (eq. 3). Typically, the second-order rate constant for this process with ionized coupler is about 10 to 10 ... 

Dye release developers are themselves colored molecules, the presence of which in silver halide photographic materials could interfere with light capture by the light-sensitive silver halide. Less light would be available to the sensitizing dyes. Another approach has been reported in which the leuco dye is linked to the coupling-off position of conventional photographic color... 

For nonradioactive probe flnorescence or enzymatic color development For radioactive probe dip in photographic emulsion, expose, develop, stain Microscopic examination... 

Benzofuran derivatives such as 2-cyanobenzofuran-5-sulfonic acid esters and amides have found wide application as color developers in photographic processes (44USP2350127). The substituted benzofurans (507), (508) and (509) are used as brightening agents in textiles, wool, paper, cellulose and nylon (53MI31201). 

If photographic materials are processed by developing solutions containing heavy metal ions, in particular iron(III) or copper ions, stains often occur. The addition of an inositolpolyphosphoric add to a color-developing solution complexes iron(III) ion, thereby preventing stain.86 In addition, aerial fog caused by heavy-metal ion catalyzed oxidation of the p-phenylenediamine color devel-... 

Figure 5. Typical p-phenyl-enediamine color developing agents, known as CD1-CD4 in the photographic industry.

Sulfite ion has been used as a preservative in photographic developer solutions since 1882 [31]. It is present at a relatively low level in many modern color developers and can act as a preservative by removing oxygen from solution and also by removing developer oxidation products as shown in Eq. (21). 

This color developer can induce sensitization in photographers. 

Wet fixing chemistry turned out to be a bit more of a challenge. Hydroquinone and substituted hydroquinones could be employed to stabilize the exposed images, but inevitably, background color developed. A chance meeting with Ray Firmani, a photographer resulted in a solution. Firmani, who possessed limited... 

Other Borohydrides. Potassium borohydride was formerly used in color reversal development of photographic film and was preferred over sodium borohydride because of its much lower hygroscopicity. Because other borohydrides are made from sodium borohydride, they are correspondingly more expensive. Generally their reducing properties are not sufficiently different to warrant the added cost. Zinc borohydride [17611-70-0] Zn(BH 2> however, has found many appHcations in stereoselective reductions. It is less basic than NaBH, but is not commercially available owing to poor thermal stabihty. It is usually prepared on site in an ether solvent. Zinc borohydride was initially appHed to stereoselective ketone reductions, especially in prostaglandin syntheses (36), and later to aldehydes, acid haHdes, and esters (37). 

In most color photographic products, organic compounds such as couplers or redox dye releasers are added to the melted emulsions before coating. These compounds are essential to the development reactions that produce the dye molecules composing color images. 

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