Naphthoquinone dyes

P. Novotna, V. Pacakova, Z. Bosakova and K. Stulik, High performance liquid chromato graphic determination of some anthraquinone and naphthoquinone dyes occurring in historical textiles, J. Chromatogr. A, 863, 235 241 (1999). 

From about 1930 onwards, developments in the field of naphthoquinone dyes concentrated on the use of naphthazarin and intermediates for the preparation of violet, blue, and green acid and disperse dyes [1]. More recently there has been interest in the synthesis and color and constitution properties of simple colored naphthoquinones, stimulated by the fact that such dyes have similar tinctorial properties to the anthraquinones but a smaller molecular size. The naphthoquinones provide a useful alternative to the anthraquinones for certain specialized applications, e g., as pleochroic dyes with improved solubility for liquid-crystal displays. As a result, research interest in these chromogens remains unabated, even though they have failed to make any major impact as textile dyes [2-8],... 

A different class of polycyclic naphthoquinone dyes is based on the n apht h 12,361 i ndolizine -6,11 -dione system 14, which is readily accessible by condensation of 2,3-dichloro-l,4-naphthoquinone with active methylene compounds in the presence of pyridine [22], or by reaction of 2-methoxy-3-pyridino-1,4-naphthoquinone with an active methylene compound [23], In 14, the bridgehead nitrogen atom acts as an effective auxochrome, and hence orange to red colors are observed without further substitution. Derivatives of 14 (R = amide group) are of particular value as vat dyes and pigments. Related isomeric heterocyclic structures have also attracted interest, e.g., 15, a yellow disperse dye for polyester [24],... 

More than 50% of disperse dyes are simple azo compounds, about 25% are anthraquinones, and the rest are methine, nitro, and naphthoquinone dyes (see Sections 2.2, 2.3, 2.6, 3.12). 

Henna dye is used on nails, skin and hair by married women in the Islamic community and, traditionally, it is used by the major participants in marriage ceremonies. Henna consists of the dried leaves of Lawsonia alba, and the coloring matter, lawsone, is a hydroxy-naphthoquinone. Dyeing hair or skin with powdered henna is a lengthy procedure and, to speed up this process, Sudanese women mix a black powder (p-phenylenediamine) with henna to accelerate the fixing. The combination of henna and p-phenylenediamine is particularly toxic, and over 20 cases of such toxicity, some fatal, were noted in Khartoum alone over a 2-year period. Initial symptoms are those of angioneurotic edema with massive edema of the face, lips. 

Novotnd et al. [261] studied a set of eight historical anthroquinone and naphthoquinone dyes (carminic acid, laccaic acid A and B, lawsone, juglone, alizarin, lapachol, emodin). They were well resolved in 12 min on a C]g column (A — 270 nm) using a 15-min exponential gradient from 40/60 -y 95/5 methanol/ water (0.1 M citrate pH 2.5). Separately, alizarin and purpurin were resolved on a C]g column (A = 245 ran) using a 72/25 methanol water (0.2 M acetate pH 4.3) mobile phase. Detection limits of 0.6-12 ng injected (analyte dependent) were reported. Linear curves up to the solubility limit of l mM were also used. 

The photostability of dichroic dyes is one of the most important considerations for their use in LCDs [16, 43 -46,49, 62 -67]. The photostability of many classes of dye is not sufficient for display applications [46, 64-66], this being particularly true for monoazo dyes with triazole and benztria-zole rings, as well as bis(azo)dyes with the-ophelline and naphthalene fragments [46]. Monoazo and bis(azo) dyes without triazole and benztriazole rings have a sufficiently long lifetime [46]. Anthraquinone dyes are much more stabe than azo compounds. Naphthoquinone dyes have a photostability... 

A iridine traces in aqueous solution can be determined by reaction with 4-(p-nitroben25l)pyridine [1083-48-3] and potassium carbonate [584-08-7]. Quantitative determination is carried out by photometric measurement of the absorption of the blue dye formed (367,368). Alkylating reagents interfere in the determination. A iridine traces in the air can be detected discontinuously by absorption in Folin s reagent (l,2-naphthoquinone-4-sulfonate) [2066-93-5] (369,370) with subsequent chloroform extraction and hplc analysis of the red dye formed (371,372). The detection limit is ca 0.1 ppm. Nitrogen-specific thermal ionisation detectors can be used for continuous monitoring of the ambient air. 

Alkannin occurs in the roots of the plant as the alkah-sensitive ester of angelic acid (62). It may be extracted from the roots by using boiling light petroleum ether. Treatment of this extract with dilute sodium hydroxide gives a blue solution from which the dye is precipitated by the addition of acid. The cmde product is purified by vacuum sublimation (63). Its stmcture (11) is a hydroxylated naphthoquinone with a long, unsaturated side chain (64,65) it has the (3)-configuration. 

Primary amines and substances with reactive methylene groups react with 1,2-naphthoquinone-4-sulfonate to yield intensely colored p-quinoid derivatives, which, in the case of aryl amines, are indophenol dyes [12, 13]. 

Anthraquinone is widely use in the manufacture of a range of dyes. Two possible routes for manufacturing anthraquinone are (1) from the reaction of 1,4-naphthoquinone with butadiene and (2) reaction of benzene with phthalic anhydride. Describe mechanisms for both these reactions and identify likely reaction conditions and any other reagents required. Compare the atom economy of the two routes. Identify three factors for each route that may influence the commercial viability. 

In the case of the naphthoquinone methine-type near-IR dye 55, reduction with tin(II) chloride under acidic conditions gives the leuco dye 56, which has weak absorption maxima at 350-359nm in methanol. The leuco dye 56 can be isolated as a stable pale yellow compound. The oxidation behavior of 56 has been studied by adding benzoquinone as oxidant in methanol solution. Compound 56 immediately produced new absorption at 760 nm which is consistent with the absorption maximum of 55 (Scheme 19).30 The absorption spectra of the leuco, quinone, and metal complex forms are summarized in Table 3. 

Other Quinones.—Look up o-quinones and the three naphthoquinones the best method of preparing a- and / -naphthoquinone is froml 4-andl 2-aminonaphthol respectively, which are obtained from azo-dyes of the two naphthols by reduction (see p. 302). 

Uses Intermediate for phthalic anhydride, naphthol, 1,4-naphthoquinone, 1,4-dihydro-naphthalene, 1,2,3,4-tetrahydronaphthalene (tetralin), decahydronaphthalene (decalin), 1-nitro-naphthalene, halogenated naphthalenes, naphthol derivatives, dyes, explosives mothballs manufacturing preparation of pesticides, fungicides, detergents and wetting agents, synthetic resins, celluloids, and lubricants synthetic tanning preservative emulsion breakers scintillation counters smokeless powders. 

Naphthoquinone Derivatives, These dyes are generally not very colorfast and sometimes also fade. Anthraquinone derivatives have better properties (see Dyes, ANTHRAQUINONE). New developments are based on compounds that combine the chemical structure of phenothiazine or phenoselenazine derivatives with benzoquinone or naphthoquinone units (16). These dyes show good chemical stability. Naphthoquinone derivatives have yet to find a practical application as dyes in WORM disks because of the high expenditure for synthesis due to low yields. 

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