Yellow dye

A number of yellow dyes were known in antiquity weld and saffron seem to have been the most widely used, but barberry root, turmeric, Persian berries, and safflower have also been identified in ancienf fibers. Weld, probably the oldest European-known yellow dye, is derived from fhe herbaceous plant Roseda luteola, which is indigenous to central Europe. The dye is distributed throughout the entire plant, although it is concentrated in the upper 

Safflower, also known as bastard saffron, is a yellow dye that has been used for well over three millennia, having been identified in fabrics from the Egyptian twelfth dynasty. It is derived from the safflower plant, carthamus tinctoria, native to southern Asia and the Middle East The coloring matter in the plants is a mixture of two components one is yellow, known as safflower yellow B the other, carthamin, is red. Safflower yellow B dissolves in water when fresh safflower flowers are washed with acidulated water. Evaporating the water from the filtered solution leaves the dye as a residue in the form of a powder. Following removal of the yellow component, the red constituent of safflower, carthamin, can be extracted from the flowers by washing them with hot water. In the East, carthamin was widely used in the past, mainly for making cosmetic preparations. 

Turmeric, also known as curcuma, is an easily fading yellow dye that was used in Mesopotamia many centuries b.c.e. and later became popular in ancient Rome. It is derived from the turmeric plant. Curcuma longa, and other varieties of Curcuma indigenous to China and Southwest Asia. The dye is extracted with hot water from the shredded rhizomes of the plant and then dried into a yellow powder. The coloring matter in turmeric is the organic compound curcumin. 

Barberry root is a yellow-red dye that has been used since prehistoric times it is extracted with hot water from the stems, bark, and roots of Berberis vulgaris, a bush that grows indigenously in Europe as well as in North America. The coloring matter in the dye is the organic compound berberine. Silk and wool can be dyed directly with barberry root, yielding a yellow color however, for dyeing cotton, a mordant is required to attach the dye to the substrate fibers. 

Persian berries is the common name of a yellow-greenish dye, well known in antiquity. It is extracted from the seed-bearing fruits of a variety of species of Rltamnus plants that grow indigenously in the Middle East and southern 

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The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

A high concentration of the fluorescent dye itself in a solvent or matrix causes concentration quenching. Rhodamine dyes exhibit appreciable concentration quenching above 1.0%. Yellow dyes, on the other hand, can be carried to 5 or even 10% in a suitable matrix before an excessive dulling effect, characteristic of this type of quenching, occurs. Dimerization of some dyes, particularly those with ionic charges on the molecules, can produce nonfluorescent species. 

Various methods of home-dyeing cotton and wool materials using natural dyes made from hulls of butternut, hickory nut, pecan, eastern black walnut, and Knglish walnut have been described (149). As far back as during the Civil War, butternut hulls have been used to furnish the yellow dye for uniforms of the Confederate troops. More recent attempts have been made to manufacture yellow and brown dyes from filbert shells on a commercial scale. The hulls are treated with copper sulfate and concentrated nitric acid to produce a yellow color, with ferrous sulfate to produce oHve-green, or with ammonia to produce mby-red (150) (see Dyes AND DYE INTERMEDIATES Dyes, natural). 

Stilbene dyes of importance aie mosdy direct yellow dyes for ceUulosic fibers, especially paper. There have been several red and blue stilbene-containing dyes reported, but they have not (ca 1996) been developed to commercial importance. There are brown leather dyes which are stilbene-based. The most important stilbene dyes are those known siace the 1880s. The commercial importance of Direct Yellow 11 (1883), Direct Orange 15 (1888), Direct Yellow 4 (1886), and Direct Yellow 106 (1936) attest to the value, properties, and durabiUty of stilbene yellow dyes. 

Pyrazolone dyes are particularly versatile yellow chromophores the yellow dye developer used in Polacolor, the first instant color film, was based on a pyrazolone dye. The stmctures of the three Polacolor dyes are shown in Figure 3. The study of azo dyes derived from 4-substituted 1-naphthols led to the chromophore used in the Polacolor magenta dye developer. The Polacolor cyan dye developer contained a 1,4,5,8-tetra-substituted anthraquinone as chromophore (20). 

Discrimination between exposed and unexposed areas in this process requires the selection of thia zolidine compounds that do not readily undergo alkaline hydrolysis in the absence of silver ions. In a study of model compounds, the rates of hydrolysis of model /V-methyl thia zolidine and A/-octadecyl thiazolidine compounds were compared (47). An alkaline hydrolysis half-life of 33 min was reported for the /V-methyl compound, a half-life of 5525 min (3.8 days) was reported for the corresponding V/-octadecyl compound. Other factors affecting the kinetics include the particular silver ligand chosen and its concentration (48). Polaroid Spectra film introduced silver-assisted thiazolidine cleavage to produce the yellow dye image (49), a system subsequentiy used in 600 Plus and Polacolor Pro 100 films. 

Fig. 14. Schematic cross section of Spectra integral film. The 600 Plus film has a similar stmcture. In these films the yellow image is formed by silver-assisted cleavage of a yellow dye releaser. A colorless developer reduces exposed silver hahde in the blue-sensitive emulsion in unexposed areas dissolved silver diffuses to the dye releaser layer and triggers the release of the yellow image dye.

In hair coloring a light ash blond shade may require as Httie as 0.5—1% of intermediates, whereas a tme black may require up to about 5%. In principle, the formulator blends precursors that yield red, blue, and yellow dyes. The base in which the components are dissolved or suspended is similar to that used in simple bleaches and may include alkanolamides, various types of surfactants, thickening agents, and solvents. Removal of undesirable dyes is achieved by treating the discolored hair with a powerful reductant of the sulfite family. 

Azacarbocyanines. A cyanine containing three carbon atoms between heterocychc nuclei is called a carbocyanine (n = 1 in (46)). Replacing these carbon atoms by one, two, and three nitrogen atoms produces azacarbocyanines, diazacarbocyanines, and triazacarbocyanines, respectively. Dyes of these three classes are important yellow dyes for polyacrylonitrile, eg. Cl Basic Yellow 28 [52757-89-8J (Cl 48054) (47). 

Quinophthalones provide important dyes for the coloration of plastics (eg, Cl Solvent Yellow 33 (71), R = H [5662-03-3]) and for the coloration of polyester. For example. Cl Disperse Yellow 54 (71) R = OH, is the lea ding yellow dye for the transfer printing of polyester. 

The yellow dye curcumin, [458-37-7] (Cl Natural Ye//oii> 3 Cl 75300) (41), also known as tumeric, occurs in the roots of the plant Curcuma tinctoria found growing wild in Asia. The dye was well known to the ancient Romans and Greeks who used it to dye wool, cotton, and silk. The dye is an oil-soluble bright yellow material, and is the only natural yellow dye that requires no mordant. It finds use as a colorant for baked goods such as cakes. 

Betalaines. In 1968, the term betalaines was used to describe collectively two groups of plant pigments the red betacyanins and the yellow betaxanthins. The red and yellow dyes found in beets. Beta vulgaris, fall into this category. An interesting history has been written about these dyes (133). 

Noda, N. et ah. Determination of natural yellow dye from the fruits of gardenia by detecting geniposide, J. Hygenic Chem. (Eisei Kagaku), 29, 7, 1983. 

Azure A can be reduced to an air sensitive intermediate 71 and acylated in one step to produce the ballasted leuco 72 which can be isolated and capped with the dye chloroformate 69 to give the ballasted yellow dye release developer 73. 

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