Anthraquinones special

The anthraquinones are useful in acrylics and are compatible with polystyrene and ceUulosics. Solvent Red 111 has a special affinity for poly(methyl methacrylate) as the red in automobile taillights exposure for a year in Florida or Arizona produces only a very slight darkening. Acid types are usehil for phenohcs (see Dyes, anthraquinone). 

In the anthraquinone series, apart from the special case of the amination of leucoquinizarin, sulfonic acid and nitro are the preferred leaving groups. 1-Aminoanthraquinone is manufactured from anthraquinone-l-sulfonic acid or 1-nitroanthraquinone, and 2-amino anthraquinone (betamine) from anthraquinone-2-sulfonic acid. 

Pigment Red 177 [4051-63-2] has the chemical structure of 4,4 -diaminol,l -dianthraquinonyl and is prepared by intermolecular copper-catalyzed debromination of l-amino-4-bromoanthraquinone-2-sulfonic acid followed by desulfonation. It is the only known pigment with unsubstituted amino groups which are involved in both intra- and intermolecular hydrogen bonding (19). The bluish red pigment is used in plastics, industrial and automotive paints, and specialized inks (see Dyes, ANTHRAQUINONE). 

This reaction is specially interesting since many of the above compounds readily yield the corresponding anthraquinone derivatives (see p. 82), e.g., 4-chloro-l-hydroxy-anthraquinone has been obtained from p-chloro-phenol substituted anthraquinones of this type are becoming increasingly important. 

Compared to direct azo dyes, the direct anthraquinone dyes have lower tinctorial strengths and are therefore far less economical to use. They have lost most of their importance. Only a few special green dyes have retained their importance. Direct green cotton dyes can be produced by coupling a blue bromamine acid dye and a yellow azo dye via ureido or diaminotriazine bridges. 

Other Acid Anthraquinone Dyes. In addition to the dyes in the preceding classes, a whole series of specially developed products is available. For instance, derivatives of the anthrimide or carbazole series are known to be very light-fast gray and brown wool dyes. The post-sulfonation products of 1,5- and 1,8-diarylami-noanthraquinones are violet dyes commonly applied as mixtures. 

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],... 

The features of chemical constitution associated with the special requirement of solvent solubility include a number of chemical groups on the chromophores. Sulfo groups are often absent, and only hydroxy or amine groups are present. There are mostly cationic and neutral and sometimes also anionic azo, 1 2 azo metal-complex, and a few anthraquinone dyes. An example is C.I. Solvent Yellow 21, 18690 [5601-29-6] (22, 1 2 Chrome alsoC.7. Acid Yellow 121). 

The specially synthesized l-arylcyanomethyl-9,10-anthraquinones with a long lifetime for the photoinduced form showed photodegradation in alcohols as well.36 It was found that despite the variable lifetime of the photoinduced form of the different compounds of this type, the dark reaction of its interaction with alcohol dominated over the hydrogen atom transfer, which was due to the photochromic process. The efficiency of the photochromic transformations depended on the nature of the... 

In special cases, chlorination is brought about by replacement of a sulfonic group by chlorine. This reaction is particularly important with anthraquinone compounds, but it is also known in the benzene series (see page 236). 

Instead of the amino group, other amine residues can be introduced. Of special importance are the dianthraquinonylamines, which can be converted by condensation into brown carbazole-anthraquinone vat dyes. This condensation is usually brought about by aluminum... 

These few examples give some small indication of the chemistry of the Indigoid and Anthraquinone vat dyes, but the subject covers a wide range and the molecular structure of many is far from simple. For further information, Fox J.S.D.C., 1949, 65, 508), Bradley (R.I.C. Special Publication, No. 5, 1958), or Thomson J.S.D.C., 1936, 52, 237 and 247), should be consulted. 

Of special interest to the dyestuff chemist is the 9,10-dihydroxyanthracene stmcmre since its red, water-soluble sodium salt forms the basis for applying anthraquinone dyes to cotton (qv). Because the reductions were originally carried out in large mbs or vats, the operation became known as "vatting" and the dyes as "vat" dyes. The most commonly used reducing agent is alkaline hydrosulfite, also known as dithionite (Na S O]). Use of thiourea... 

Catalyst decomposition depends heavily on the specific process conditions employed. Producers operate under two different regimes the all-tetra system, in which no specific actions are taken to either suppress the formation of tetra or to dehydrogenate it back to anthraquinone, and the anthra system, in which efforts are made to minimize the tetra content. Tetra formation can be reduced by the use of selective hydrogenation catalysts and specific operating conditions (i.e., solvent choice and specialized quinones). In addition, tetra can be dehydrogenated in the presence of activated alumina (AI2O3) in the catalyst regenerator (Eq. (14.12)). 

A study in IS patients taking azapropazone 300 mg three times daily found that antacids (dihydroxyaluminium sodium carbonate, aluminium magnesium silicate), bisacodyl or anthraquinone laxatives only caused a minor (S to 7%) reduction in azapropazone plasma levels. No special precautions would seem to be needed if any of these drugs are given together with azapropazone. Consider also NSAIDs Miscellaneous + Antacids , p.l42. 

Of paramount importance to structure elucidation of the flavoman-nin derivatives and of the other groups of dimeric pre-anthraquinones discussed below was the use of n.m.r. spectroscopy. Of special significance in this regard have been the shifts arising as a consequence of the anisotropic influence of the biaryl linkages and the position of... 

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