Quinone dye

Quinone dyes Quinoneimine Quinoneimine dye Quinone methides Quinonemonoimine Quinones... 

The chemistry of quinone dyes has been discussed in a series of books entitled The Chemistry of Synthetic Dyes, edited by Venkataraman.1 The general chemistry of quinoid compounds has been discussed by Patai.2 There have been many books that cover quinoid compounds as dyes and pigments but very few discuss the chemistry of the corresponding leuco dyes. Traditional vat dyes are applied to cellulosic fiber in the leuco form. The chemistry of the leuco form of vat dyes is rather simple. Some leuco quinones are quite stable in the solid state and can be stored for a year. Other leuco dyes are unstable in solution and gradually undergo aerial oxidation. 

Another noted and prolific Japanese author in the field of functional dyes, Masaru Matsuoka of the Laboratory of Materials Science, Kyoto Women s University, has written the second chapter, dealing with leuco-quinone dyes. These are the traditional redox leuco systems employed for so many years in the vat dyeing industry, and this chapter is an invaluable review of the chemistry of these systems, drawing on recent mechanistic and structural investigations. Applications considered include not only textile dyeing, but also other more specialized areas, such as hair dyeing, color formers, and photoimaging materials. 

Quinone dyes, 9 503 Quinone ketals, anodic oxidation of hydroquinone ethers to, 21 264 Quinone methides, 2 209-211 Quinone Michael addition chemistry, 21 248-249, 250, 252 Quinone monoacetals, 21 251 Quinone monoimine (QMI), 19 246 Quinone oximes, formation of,... 

Fig. 3.6 Cathodic SWV curves for three quinone dyes and pigments lawson (1, a quasireversible process), alizarin lake (2, a reversible process) and cochineal red (3, a quasireversible process). Scans from open-circuit potential toward negative potentials. Insets the net, forward and backward current components are shown for alizarin lake and cochineal red (reprinted from [186] with permission)...

The photoreduction of carboxylic acids and their derivatives has not been widely reported, although cyclic imides do behave like ketones in such reactions (4.39). Quinones are readily photore-duced, and this is of particular importance for anthraquinone dyes or pigments used on cellulose materials such as cotton. Some quinone dyes cause what is known as phototendering—the fabric progressively weakens and can be torn easily after exposure of the dyed... 

Quinone dyes Qumoneimine Qumoneimme dye Quinone methides Qumonemonoimine Quinones... 

ACETATE DYE. One group comprises waler insoluble azo or antlira-quinone dyes that have be highly dispersed to make them capable of penetrating and dyeing acetate fibers. A second class consists of water-insoluble amino azo dyes that are made water soluble by treatment with formaldehyde and bisulfite. After absorption by the fiber, the resulting sulfonic acids hydrolyze and regenerate the insoluble dyes,... 

Many solvent-soluble dyes have been examined, particularly azo and anthra-quinone dyes. The latter tend to be used on account of their higher light stability. Typical dyes [3] are the yellow (44), the red (45), and the blue (46). Fluorinated disazo dyes such as (47) have good solubility and high order parameters (0.79) [39],... 

Photoreduction of benzophenone by primary and secondary amines leads to the formation of benzpinacol and imines [145]. Quantum yields greater than unity for reduction of benzophenone indicated that the a-aminoalkyl radical could further reduce the ground state of benzophenone. Bhattacharyya and Das confirmed this in a laser-flash photolysis study of the benzophenone-triethylamine system, which showed that ketyl radical anion formation occurs by a fast and a slow process wherein the slow process corresponds to the reaction of a-aminoalkyl radical in the ground state of benzophenone [148]. Direct evidence for similar secondary reduction of benzil [149] and naphthalimides [150] by the a-aminoalkyl radical have also been reported. The secondary dark reaction of a-aminoalkyl radicals in photo-induced electron-transfer reactions with a variety of quinones, dyes, and metal complexes has been studied by Whitten and coworkers [151]. 

Table 10.5 Variation of colour with increasing conjugation of anthra quinone dyes...

Just briefly mentioned should be quinone dyes 28 [201], cyanine SAMs 29 where the cyanine dye forms highly ordered 2D J-aggregates on a cysteamine SAM with a 7 X V3 superlattice [ 145,146] and a perylene bisimide dye 30, which shows J-type aggregation as demonstrated by the bathochromic shift of the fluorescence spectra [202] (Fig. 33). 

Such display has been realized by using low-molar-mass liquid crystals and anthra-quinone dyes (62]. One limilalioa is the poor solubility of such dyes in liquid crystals. A 0.S wt% solutioo was investigated. 

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