Functional Yellow Dyes

Chitosan-clay bio-nanocomposites showing the ability to incorporate anionic species can be used to prepare functionalized biohybrids. An example is the uptake of anionic dyes such as fast green and naphthol yellow S which are low-toxicity... 

These dyes are invariably monoazo compounds with the reactive system attached to the diazo component, owing to the ready availability of monosulphonated phenylenediamine intermediates. Pyrazolone couplers are most commonly used, as in structure 7.82 (where Z is the reactive grouping), and this is particularly the case for greenish yellow vinylsulphone dyes. Catalytic wet fading by phthalocyanine or triphenodioxazine blues is a characteristic weakness of azopyrazolone yellows (section 3.3.4). Pyridones (7.83), barbituric acid (7.84) and acetoacetarylide (7.85 Ar = aryl) coupling components are also represented in this sector, with the same type of diazo component to carry the reactive function. 

Fig. 3.124. Chromatograms of a 1 1 dye mixture (a) 40 min before addition of Na2C03, (b) 10 min after addition of Na2C03, and (c) 60 min after addition of Na2C03 flow rate = 0.6 ml/min, other conditions are described in the text. The peak at 4.57 min in (a) and the same peak (smaller in size) at 4.54 min in (b) are both attributed to the functional group of cibacron yellow ( — F) the peak at 7.54 min in (a) and the same peak (smaller in size) at 7.40 min in (b) are both attributed to the hydrolysed part of the functional group of cibacron yellow the peaks at 5.07 min in (b) and 5.22 min in (c) are attributed to the hydrolysed part of the functional group of cibacron blue. Reprinted with permission from A. Zotou et al. [175].

In xanthenes, even if all one-photon allowed transitions are also two-photon allowed, the shape of the bands and their relative intensities are very different in the IPA and 2PA spectra [76,78]. This is not the case for other laser dyes and chromophores, for which the two spectra are almost identical (if represented as a function of the total transition energy), showing peaks in the same position and with very similar band shapes. Some example of chromophores in this category are coumarin 307 [78], coumarin 102 [80], 7-hydroxycoumarin [81], lucifer yellow [78], and cascade blue [78]. 

R are used to control the Amax of the chromophore. Interaction of the dye releaser with ETAox yields the corresponding quinoneimine (84) which is hydrolyzed in alkali to give the sulfamoyl-solubilized yellow image dye (85). Derivatives of l-phenyl-3-pyrazolidinone (see Section 1.14.2.1.4) can function as electron transfer agents. 

To investigate the response of the optode membrane to NH4+, its absorption spectrum was monitored as a function of the NH4+ concentration after immersing the freshly prepared PVC film in 0.1 M aqueous HC1 to pro-tonate the dye. The absoption data are shown in Fig. 14. The absorption maximum shifted from 475 to 610 nm, and the color of the optode membrane changed from yellow (10-6—10 5 M) — light yellow (10 M) —> fight green (10 3 M) —> cyan (10 2 M) — blue (10-1 -1 M). The absorption spectra have a clear isosbestic point. 

The simple anthraquinone dyes, containing hydroxy or amino functions as their major auxochromes, are used for brilliant red to blue shades. Yellow and orange shades are obtained by other dye classes. Choosing appropriate substituents allows the best dyes for various fibers and colors to be obtained. 

X-ray analysis of the washed specimen from which the yellow color leached out showed some slight diminishing of aluminum and virtually no sulfur, whereas sulfur was present in the remnant fabric. Although it is possible that sulfur was in some way connected with the yellow dyestuff molecule, it may also be that a sulfur-containing acid was used to affix the yellow dyestuff on the cloth. Acid dyes are so-named because they are set with acids, and sulfuric acid commonly was used at this time to serve this function (8-12). 

Table 3.13 Plate number as the function of the packing pressure. Conditions column 50 X 1 71 mm, Kro-masil 100, dp = 1 3 im (EKA Nobel AB, Bohus, Sweden), linear flow velocity v = 0.3 mm s 1, injection volume 100 pi, solvent dichloromethane HPLC grade, solute Ceres yellow R (dye).

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