Leuco quinoneimines

The leuco quinoneimine dyes are unstable to isolate but the substitution of an electron-withdrawing group such as acyl,13 carbamoyl,13 carboxy,13 or arylsulfonyl 12 group at the amino nitrogen atom stabilizes the... 

Polyhydroxybenzenes or aminophenol derivatives can be considered as leuco quinones or leuco quinoneimines. They are easily oxidized and couple... 

Polysulfide Melt. Cl Sulfur Black 1 [1326-82-5] (Cl 53185), derived from 2,4-dinitrophenol, is the most important dye in this group which also includes the indophenol-type intermediates. The latter are appHed in the stable leuco form. The derived dyes are usually confined to violet, blue, and green shades. Other members of this group are intermediates capable of forming quinoneimine (10) or phenazone stmctures (11) that produce red-brown or Bordeaux shades ... 

The initial cyclization of the quinones or quinoneimines may arise either by proton (249a) or hydride (249) abstraction.. The latter course is supported by the isolation of 255, exclusively, from the piperazine (254), since the second cyclization involves abstraction of the less acidic of the protons at the two available sites. The hydride lability of dihydroimidazoles and hydride reducibility of quinones are the probable reasons for the isolation of the leuco compound (261) and benzimidazole salt (262). Another possibility is an acid-catalyzed... 

In order to test if indeed PANI was an octaaniline, as proposed by Willstater and others and resurrected by Wnek, and in order to be able to make an oligomer with a known, specific number of quinoneimines we prepared, employing our condensation reaction mentioned above, a phenyl-capped octamer. We show below that three well defined oxidation slates leuco (white), per (magenta-violet), and emerald (blue) could be prepared and characterized. 

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