Ueber Formazylphenylketon

The Chemistry of Formazans and Tetrazolium Salts

“…The stability of these complexes depends largely on the nature of the substituents in the aromatic rings. The silver salt of 3-benzoyl-l,5-diphenylformazan (table 13) is very unstable (27, 28). The copper salts of formazans whose V-phenyl rings carry hydroxyl or carboxyl groups in the ortho position are particularly stable (56,168,199,201); they are not hydrolyzed by acids and have been used for dyeing.…”

“…Attempts to benzoylate triphenylformazan with benzoyl chloride (42) or to acetylate 3-methyl-1,5-diphenylformazan and other formazans with acetic anhydride (15, 60a) have been unsuccessful. Acetylation can be accomplished with acetic anhydride in the presence of zinc chloride (15,19,28,132), and can be achieved in special cases by the use of acetic anhydride alone (see page 365). C-Hydroxyalkylformazans have been found to react with warm acetic anhydride to give the O-acetyl derivatives only (60a).…”