Photographic dyes

Condensed aromatic compounds (benzoselenazoles) are considered much more stable, and they are in fact more commonly used in the area of cyanine-type photographic dyes. 

The Knorr pyrazole synthesis has been extensively utilized in the preparation of a number of pyrazoles as metal chelators, photographic dyes, herbicides, and biologically active... 

The following uses have been claimed for compounds containing the 1,2,4,5-tetrazine skeleton as herbicides, insecticides, bactericides, as pharmaceuticals, as explosives and rocket propellants, as photographic dyes and additives to photographic layers, as reducing agents, as inhibitors of steel corrosion and as fuel additives. 

There are a large number of reasons to discount the simple photon-stereomeric approach, that is endothermic, in favor of considering available modem choices based on quantum-mechanics. The field of photographic dyes provides a well-understood alternative based on resonant conjugated carbon chemistry. This approach is energy neutral (marginally exothermic). When combined with the solid state physics derived from the transistor, it offers an alternate hypothesis that is confirmable in the laboratory. 

Fig. 13.42. Structures of yellow (left), magenta (center), and cyan (right) photographic dyes.

For chemical and physical processes across microdroplet/solution interfaces, obs having dimensions of s or dm mor s is often proportional to r " ( = 0, 1 or 2). A linear relationship between obs and has been reported for the extraction of a neutral compound such as ferrocene derivatives from water into a micro-oil-droplet without adsorption at the microdroplet/water interface [18,19] and for a photographic dye formation reaction in an oil-in-water emulsion [23]. The proportionality of a kobs versus r plot has been reported for a relatively slow process such as a photographic dye formation reaction [23,29,42], electron transfer [43-45] and adsorption at the micro-oil-droplet/water interface [19,20]. For the chemical reaction with the rate-determining step in a solution phase or a microdroplet in a microdroplet/solution system, fcobs is independent of r[23]. Based on the droplet size dependence of the reaction rate, the rate-determining step of the overall reaction processes across a microdroplet/solution interface is analysed and the reaction mechanism can be discussed in detail. 

Aromatic indolizines are very rare in nature, but the fully reduced (indolizidine) nucleus is widespread, particularly in alkaloids, of which swainsonine is a typical example. Synthetic indolizines have found use in photographic dyes. 

Dehydration of sulfonamides 192 using CCI4 and PPha has been used as a route to 3-alkylated-2//-benzo-l-thia-2,4-diazine 1,1-dioxides 193, which are useful intermediates for photographic dyes (Equation 40) <2004JPP2004035415>. 

Treatment of substituted 2-aminobenzenesulfonamides with 1,1,1-triethoxyethane serves as a route to the precursor of 232 <2004JPP2004224957> and similar chemistry using more highly substituted orthoesters leads to ZH-benzo-l-thia-2,4-diazine 1,1-dioxides 233 <2005JPP2005289982>. Compounds such as 232 and 233 are of interest as yellow photographic dyes. 

Coumarin-linked benzo-47/-l-thia-2,4-diazine 1,1-dioxides 283, where X is a cryptand or crown ether, have been studied for their potential in measuring metal cation concentrations <1998EPP861843>. 3,4-Dialkylated benzo-477-l-thia-2,4-diazine 1,1-dioxides 284 are useful as couplers in the formation of photographic dyes <2002JPP2002318441>. Bis(3-substituted-47/-benzo-l-thia-2,4-diazine 1,1-dioxides) such as 285 are useful as materials in the recording layers of optical disks that use lasers in the 300-900 nm range <2006JPP2006076209>. 

Related but more complex processes occur when indole is treated with p-toluenesulfonic acid <88JCS(Pi)2377, 88JCS(Pi)2387). Indoles also undergo acid-catalyzed addition to lactols to form derivatives such as (95), which are precursors of a range of photographic dyes (Equation (24)) <9i JOC4576). 

The chemistry of oxazoles continues to be an important focus of academic and industrial laboratories around the world. Indeed, this small-ring heterocycle has elicited extraordinary creativity from medicinal and process chemists, polymer chemists, materials scientists, photographic dye chemists, and natural products chemists engaged in basic and applied research. 

The majority of odd, heteroconjugated systems are isoconjugate with carbanions. Here introduction of heteroatoms has very drastic effects on the spectrum, effects which have been used extensively in the dye industry in general, and the photographic dye industry in particular, to modify the... 

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