C.I. natural yellow

Fustic Yellow Maclurin, Morin C.I. Natural Yellow 8, 11, resp. 

Exceptions are dyeings with safflower (C.I.1 Natural Red 26) (38) made from the leaves of the dyer s thistle (Carthamus tinctorius L.). The red dye carthamin (C.I. 75140) (38) goes into solution when it is boiled in water. When this solution is poured through a paper filter after it has cooled, the paper is stained red, whereas the filtrate is colorless or is stained light yellow by safflower yellow (C.I. Natural Yellow 5), a second dye of the safflower. When the red stained filter is boiled in 1% ammonia, it becomes irreversibly colorless. 

The glacial acetic acid extract can be stained by indigo (C.I. Natural Blue 1) in a blue shade, by berberine (C.I. Natural Yellow 18), the only basic natural dye, and sometimes by madder (C.I. Natural Red 8) in a yellow shade. 

Natural dyes belonging to the class of thehydroxyflavones (C.I. Natural Yellow 1,2,4,10,11,12, and 13) become almost colorless. Upon addition of ammonia to the previously washed dyeing, the original yellow shade returns. Upon subsequent boiling, after addition of a small amount of sodium dithionite, the yel-... 

Figure 1 shows the shades of these color lakes obtained from dyeings produced with the principal yellow natural dyes dyer s rocket (C.I. Natural Yellow 2), quercitron (C.I. Natural Yellow 10), unripe buckthorn berries (C.I. Natural Yellow 13), fustic (C.I. Natural Yellow 11), curcuma (C.I. Natural Yellow 3), and kamala (C.I. Natural Yellow 25). These lakes, which differ markedly in their shades from the others, are marked with a cross. They are the tin lakes of quercitron and curcuma, the curcuma iron lake, and the copper lakes of dyers rocket, unripe buckthorn berries, and fustic. A report on these methods has been published (15). The natural yellow dyes are shown in Figure 1 as examples of the lakes produced. 

Testing of Yellow Natural Dyeings. When a yellow dyeing is boiled in glacial acetic acid (cf. solvent stripping tests), berberine (C.I. Natural Yellow 18), the only natural basic yellow, is dissolved. This dye can be identified by TLC comparison on silica gel with the solvent butanol-glacial acetic acid-water (5 1 2). 

When the dyeing treated in this manner is heated with tin, aluminum, iron, copper, and uranyl salts after it has been washed out with water, flavone dyes that contain luteolin as the main component can be identified fairly easily from the color of the lakes. In such cases, one can assume that dyer s plants such as dyer s rocket and dyer s greenwood (both C.I. Natural Yellow 2) were mainly used. 

Figure 5. TLC of hydroxyflavone dyes. I, dyers rocket (Reseda luteola L., C.L Natural Yellow 2) 2, young fustic (Cotinus coggygria SCOP., C.I. Natural Brown 1) 3, buckthorn berries (Rhamnus cathartica L., fructi immaturi, C.I. Natural Yellow 13) 4, old fustic (Chlorophora tinctoria GAUD., C.I. Natural Yellow 1 5, osage orange wood (Maclura pomifera, C.L Natural Yellow 8) and 6, bastard hemp (Datisca cannabina L., C.L...

These dyes are now of only minor commercial importance, but are of interest for their small molecular structures. The early nitro dyes were acid dyes used for dyeing natural animal fibers such as wool and silk. They are nitro derivatives of phenols, e.g., picric acid (4) or naphthols, e.g., C.I. Acid Yellow 1, 10316 [846-70-8] (5). 

Testing of Black Natural Dyeings. Black dyeings are first boiled in tin(II) chloride solution (15). During this treatment, dyeings with iron tannate (C.I. Natural Brown 6) become almost colorless, whereas dyeings with tanners sumach (Rhus coriaria L., Herba, C.I. Natural Brown 6) turn yellow-orange because of their quercetin content. 

If the violet dyeing becomes only somewhat paler when treated with 102 sulfuric acid, the specimen is washed out with water and vatted with sodium dithionite and ammonia. If the dyeing then turns yellow and is reoxidized in the air to a blue, this dyeing is one with alkanna (C.I. Natural Red 20) on alum mordant. 

When a brown natural dyeing turns yellow upon vatting with sodium dithionite and ammonia and the original shade returns upon reoxidation, the dyeing probably was produced with walnut shells (C.I. Natural Brown 7) or some other hydroxynaphthoquinone. 

The flavonoids, derivatives of flavone (353) and of isoflavone (354), are widely distributed among plants of many kinds. They provide colour (from pale yellow to orange) in flowers and their potential as dyes is being revived now that awareness of the toxicity of some synthetic dyes is increasing, for example morin (355 C.I. Natural Red) is one of many possible hydroxylated flavones with dyeing properties. 

Cellulosic fibres have, for all practical purposes, no affinity for basic dyes. A few such as Auramine (C.I. basic yellow 2), Magenta (C.I. basic VIOLET 14), and Methyl Violet (C.I. basic violet 1) have some affinity for cotton, but the wet-fastness leaves very much to be desired. In the case of the protein fibre there is substantial evidence that the affinity is of a chemical nature. The reaction is essentially one of salt formation as shown ... 

The flavone morin (700) (Natural Yellow C.I. 75660) dyes wool yellow, the actual shade being determined by the mordant which is used. It has also been mentioned as a spot test reagent for salts of aluminum, beryllium, zinc and other metals (B-54MI22401). 

Cuprous Oxide. Red copper oxide C.I. 77402 Perenex Yellow Cuprocide Copper-Sandoz Caocobre. CujO mol wt 143.08. Cu 88.82%, O 11.18%. Occurs in nature as the mineral cuprite (red to reddisli-brown octahedral or cubic crystals). Prepd commercially by furnace reduction of mixtures ot copper oxides with Cu Drapeau, Johnson, U.S. pats. 2,758,014 2,891,842 (1956, 1959 to Glidden) by decompn of copper ammonium carbonate Rowe, U.S. pat. 2,474,497 Klein, U.S. pat. 2.474,533 (both 1949 to Lake Chemical) Rowe, U.S. pat. 2,536,096, Munn, U.S. pat. 2,670,273 (1951, 1954 to Mountain Copper) by treatment of Cu(OH)j with S02 Rowe, U pat. 2,665,192 (1954 to Mountain Chemical) or by electrolysis of an aq soln of NaCI between Cu electrodes Arend, Paint Technology 13, 265 (1948). Laboratory prepns Glemser, Seuer in Handbook of Preparative Inorganic Chemistry, vol. 2, G. 

Luteolln (3, 4, 5,7-tetrahydroxyflavone C. I. 75590, natural yellow 2). Formula see flavones. CisHioO, Mr 286.23, fine yellow crystals with silk-like luster, mp. 329 °C (decomp.), poorly soluble in water, soluble in alkalis to give deep yellow solutions. The bitter-tasting L. has anticonvulsant activity. L. occurs in leaves, flowers, and stems of dyer s weld Reseda luteola), in the flowers of the yellow foxglove (Digitalis lutea thus also the name digitoflavone for L.), and in other... 

---