Dyestuff yellow

Can be coupled in the 4-position with dia-zotized bases to give a series of azo dyestuffs more usually it is first sulphonated to give a valuable series of intermediates for solubilized azo dyestuffs. The nitro-l-naphthols are themselves dyestuffs, e.g. 2,4-dinitro-l-naph-thol ( naphtol yellow ). 

Bright yellow needles m.p. 45 C, b.p. 2 4°C. Prepared together with 4-nitrophenol by careful nitration of phenol. Sodium sulphide reduces it to 2-aminophenol which is used in dyestuffs and photographic processes. 

Qumones are colored p benzoqumone for example is yellow Many occur natu rally and have been used as dyes Alizarin is a red pigment extracted from the roots of the madder plant Its preparation from anthracene a coal tar derivative m 1868 was a significant step m the development of the synthetic dyestuff industry... 

Many hydrazones and azines are colored and useful as dyestuffs. Examples are 2-hydroxynaphthazine, a yellow fluorescent dye (Lumogen LT Bright Yellow), and the pyridon—azino—quinone class of red-violet dyes. Numerous hydrazine derivatives are antioxidants and stabilizers by virtue of their reducing and chelating powers. 

Flavones. These compounds are the most widely distributed natural coloring matter formerly used as dyestuffs. The term flavone was first suggested in 1895 (69), and is indicative of their yellow color ijlavus, Latin for yellow). They have lost their commercial value as dyes since the advent of synthetic dyes in 1856. 

Fig. 60 Chromatogram of a 6 dyestuff mixture made up (according to falling Rf values) of Sudan red 7B, Sudan orange G, Sudan black B, Sudan yellow, Artisil blue 2RP and Sudan black B (2 components) under different humidity conditions. From left to right 72, 65, 47, 42, 32,18, 14 and 9% relative humidity layer silica gel 60 mobile phase toluene.

Uric acid couples with 2,6-dichloroquinone-4-chloroimide in position N-7 to yield a yellow dyestuff. 

Bromopyrogallol red. This metal ion indicator is dibromopyrogallol sulphon-phthalein and is resistant to oxidation it also possesses acid-base indicator properties. The indicator is coloured orange-yellow in strongly acidic solution, claret red in nearly neutral solution, and violet to blue in basic solution. The dyestuff forms coloured complexes with many cations. It is valuable for the determination, for example, of bismuth (pH = 2-3. nitric acid solution endpoint blue to claret red). 

The presence of free bromine, and consequently the end-point, can be detected by its yellow colour, but it is better to use indicators such as methyl orange, methyl red, naphthalene black 12B, xylidine ponceau, and fuchsine. These indicators have their usual colour in acid solution, but are destroyed by the first excess of bromine. With all irreversible oxidation indicators the destruction of the indicator is often premature to a slight extent a little additional indicator is usually required near the end point. The quantity of bromate solution consumed by the indicator is exceedingly small, and the blank can be neglected for 0.02M solutions. Direct titrations with bromate solution in the presence of irreversible dyestuff indicators are usually made in hydrochloric acid solution, the concentration of which should be at least 1.5-2M. At the end of the titration some chlorine may appear by virtue of the reaction ... 

Hofenk de Graff, J. H. and W. G. T. Roelofs (1978), The analysis of flavonoids in natural yellow dyestuffs occurring in ancient textiles, Proc. bit. Council of Museums Committee for Conservation, 5th Trienial Mtg., Zagreb. 

For example, the dye. Solvent Yellow 14 has a sublimation temperature of about 125 °C whereas its melting point is 134 °C. The reaction temperature of the chlorate-lactose composition is in excess of 500 °C, which often results in chemical reactions bringing about the destruction of a large proportion of the dye. For example, strong reduction brings about cleavage as shown in Scheme 10.2, whereas pyrolysis leads to decomposition as in Scheme 10.3 Hence, a typical orange smoke composition contains up to 50% of dyestuff in order to offset losses due to the above reactions. 

The main aromatic amines used as diazo components are substituted anilines or naphthylamines and the coupling components substituted iV-aUcylanilines, phenols, naphthylamines and naphthols. Heteroaromatic diazo and coupling components are widely used in commercial azo dyestuffs. The main heterocyclic conpling components are pyrazalones (2.6) and, especially, pyridones (2.8). These are nsed to prodnce bright yellow and orange monoazo dyes, such as Cl Acid Yellow 72 (2.7) and Cl Disperse Orange 139 (2.9). ... 

The largest usage is in polyester and many dyestuff companies have disperse dye ranges for this purpose, some of which are also applied to polyamide fibres. The main colours are in the yellow, orange, red, pink and violet areas with coumarins, methines and perylene dominating the structural classes. 

Solvent Yellow 94 [51847-8] 45350 1 uranine American Cyanimid Co. Leeben Color, Div. of Tricon Colors, Inc. International Dyestuffs Corp. HUton-Davis Chemical Group of Sterling Drug, Inc. 

Many other dyestuffs may be used. Paranitraniline Yellow gives a canary yellow smoke, and Flaming Red B gives a crimson-colored smoke by comparison with which the smoke from Para-nitranilinc Red appears to be scarlet. None of the colored smoke compositions are adapted to indoor use. All the smokes are unpleasant and unwholesome. 

Nitrobenzene is a pale yellow liquid, b.p. 208.0°, which is poisonous and has an almondlike odor closely resembling that of benzaldehyde (which is not poisonous). It is used as a component of certain Sprengel explosives and as a raw material for the preparation of aniline and of intermediates for the manufacture of dyestuffs and medicinals. Its preparation, familiar to every student of organic chemistry, is described here in order that the conditions for the substitution of one nitro group in benzene may serve us more conveniently as a standard for judging the relative ease and difficulty of the nitration of other substances. 

Metal complexes of tetradentate azomethines, e.g. (199), are reported136 to have very high light-fastness but to be tinctorially weak and dull in hue. Despite this they are of technical interest as very fast yellow to brown pigments. They find no application as dyestuffs, however, because of these deficiencies for example, the chromium complex of (200) gives dull, tinctorially weak dyeings on wool possessing poor wet-fastness properties. 

Quinoline yellow (spirit sol.). Colour remains un- 1 changed Quino line Class 1 The dyestuff dissolves in 95 P r cent alcohol. Reduce the alcoholic solution with zino-dust, and acetic acid. The dyestufljis insoluble in caustic soda. Boll with 95 per cent alcohol. 

Autochrome orange, mercerol yellow 2 R, mercerol orange 2 R, salicine orange G, salicine yellow G, metachrome yellow, etc. Cotton is stained Salt mordant Dyestuff, ... 

Of water. Safranine, after reduction and oxidation, does not return to Its original shade, but to a violet (methylene derivative), into this division. It reduces more slowly than the triphcnylmethane dyestuffs and is similar to the fast acid violets of Table split up into classes by treatment of the fibre with concentrated sulphuric add, when various colours are obtained (red, violet, yellow, which is permanent In air but changed on boiling with persulphate to a pale violet-brown. Div. 35,—Many of the red should fall hito this group, are, when fixed upon wcol, extremely difficult to reduce. This is especially the case with eriochroptQ... 

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