Photographic reagents

Podbielniak extractor, 20 780-781 Pods, photographic-reagent-containing, 29 275... 

Grade Free from chlorine (FFC), technical, NF, textile, photographic, reagent, FCC. 

This update covers material that appeared in Chemical Abstracts in the 10-year period to the end of 1993, with limited reference to subsequent papers. Over 7600 references to pyridazines or to phthalazines, cinnolines, and their benzo derivatives were identified for this period. While many are not concerned primarily with pyridazine and its benzo derivatives, it is interesting to consider their composition. The majority, about two thirds, refer to pyridazine derivatives, while the remainder are concerned mainly with phthalazines, cinnolines, and their benzo derivatives, with a few containing material common to both pyridazine and its benzo derivatives. Approximately a quarter of all of the references are to patent applications, and while these include some in which a pyridazine function is a nonessential part of the invention, a significant number include pyridazine and benzo derivatives as an important part of the invention. The patent activity is an indication of the expansion of industrial interest in these heterocyclic derivatives. Analysis of a representative sample of patent applications in the early 1990s revealed that in approximately 30% the diazine was an important part of the invention, while the distribution of end uses was pharmaceuticals (43%), agrochemicals (31%), other materials such as photographic reagents and liquid crystals (18%), and analytical applications (8%). 

The dibydrochloride salt is used as a photographic developer. It also is employed as an intermediate in the manufacture of fur dyes, in hair dyeing, as a reagent in testing for ammonia and formaldehyde, and as an oxygen scavenger in water to prevent boiler corrosion (173). 

Fig. 1 Chromatogram of a lily of the valley extract - left before and right after treatment with Jensen s reagent, photographed in long-wavelength UV light (X = 365 nm) [13].

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