Magenta dyes

Reaction of 2-pyrazoloneselenazoles with p-nitrosodialkylanilines leads to a series of azomethinep>Tazolones (Scheme 47) used as purple magenta dyes in color photography (34). The main regions of absorption are ... 

Other classes of magenta dye-forming couplers reported in the Hterature include the pyra2oloben2imidazoles (90) and the inda2olones (91). The latter are unique because they do not contain an active methylene group and are proposed to form magenta dyes with a 2witterionic stmcture. 

For light fade the magenta dye has usually been limiting. Numerous studies support the hypothesis that the fading mechanism is photooxidative... 

Pyrazolone dyes are particularly versatile yellow chromophores the yellow dye developer used in Polacolor, the first instant color film, was based on a pyrazolone dye. The stmctures of the three Polacolor dyes are shown in Figure 3. The study of azo dyes derived from 4-substituted 1-naphthols led to the chromophore used in the Polacolor magenta dye developer. The Polacolor cyan dye developer contained a 1,4,5,8-tetra-substituted anthraquinone as chromophore (20). 

Fig. 5. Reflection spectra of magenta dye developers (—) a xanthene (1) and (--) a metallized azo (Fig. 4b) compound. The lower blue absorption of the...

Polacolor. The first instant color film, Polacolot, was introduced by Polaroid Corporation in 1963. Polacolot was replaced in 1975 by Polacolot 2, a film with improved light stabiUty, which utilizes the metallized dye developers shown in Eigute 4. An extended range version, Polacolot ER, introduced in 1980, utilizes the cyan and yeUow metallized dye developers together with a magenta dye developer that incorporates a xanthene dye having reduced blue absorption (see Eig. 5). 

Green-sensitized sliver halide layer Metallized magenta dye developer layer Spacer... 

The Time-Zero film process has an efficient receiving layer consisting of a graft copolymer of 4-vinylpyridine and a vinylhenzyltrimethylammonium salt grafted to hydroxyethylceUulose (81,82). The accuracy of color rendition was improved in the Time-Zero SX-70 film by the use of the xanthene magenta dye-developer (1). 

Table 8. Examples of Magenta Dyes for Sublimation Thermal-Transfer Printing...

The chlorophenazinium salt 60 (15.5 g) was dissolved in 2.5 liters of acetonitrile, filtered, and 12.6 g of benzylmethylamine was added. The mixture was stirred for 20h and solvent was removed by rotary evaporation. The resulting solid was dissolved in 600ml of ethanol and reprecipitated by pouring into 3 liters of ether to yield 11.1 g (58%) of the magenta dye 3-(iV-benzyl-iV-methyl)amino-9-ethylphenazinium iodide (61). 

Twelve grams of the magenta dye 61 was dissolved in 250ml of methylene chloride and stirred gently with a solution of 12.2g of sodium dithionite in 250 ml of water. A solution of 5 g of benzoyl chloride in 10 ml of dichloromethane was added slowly to the lower organic layer. The pH of the upper aqueous layer was maintained at 5 to 6. The organic layer was separated, washed with dilute aqueous NaOH and brine. The solution was absorbed onto silica gel and rotary evaporated to dryness. The product was washed from the silica with ether. The ether solution was evaporated to yield 8.2 g of the leuco dye 3-(A-benzyl-A-methyl)amino-9-ethyl-l0-ben-zoyl-9,10-dihydrophenazine (62). 

In the traditional silver halide dye-forming and dye-bleach processes, metal complex dyes are not normally used.62,63 However, metal complex azo dyes have been claimed15 for use in color diffusion transfer photography employing non-diffusible magenta dye-releasing dyes which, upon development of the silver halide layer, release a diffusible magenta dye (Scheme 7). 

Evans. S. Elwood, J. K. (Eastman Kodak Co.) Photographic Products and Processes Employing Novel Non-Diffusable Magenta Dye-releasing Compounds and Precursors Thereof. U.S. Patent 4,420,550, Dec. 13, 1983. 

Two kinds of pyrazolotriazole magenta dyes are used in color photographic materials. One is the I //-pyrazolo[5,1 -r]-[l,2,4]triazole skeleton, and the other is the l//-pyrazolo[ 1,5+][ 1,2,4]triazole skeleton as shown in the representative azomethine dye 1 (Figure 1) <1994J(P2)531>. 

Magenta azo dye developer, 19 287 Magenta couplers, in chromogenic chemistry, 19 254-256 Magenta dyes... 

Several other classes of heterocyclic compound have been identified as alternatives to 2-pyrazolin-5-ones. Both the pyrazolo[2,3-a]benzimidazole (53) (59GEP1070030) and the pyrazolo[3,2-c]-s-triazoles (54 A, B = alkyl, aryl) (77JCS(P1)2047) give magenta dyes with low blue absorption. 

The indazolin-3-ones (55) yield magenta dyes formulated as zwitterionic structures (56) (69USP3486894). On the other hand, the related benzisoxazolones (57) give yellow azo dyes (58) with p-phenylenediamines (57BRP778089). 

The azo dyes employed in the system can be carefully chosen from a wide range of available compounds, so that optimum hue and stability characteristics are attained. Occasionally, dyes containing a heterocyclic ring are reported, the thiophene (70) being a specific example of a magenta dye (72GEP2147560). 

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