Anthraquinone Benzanthrone Dyes

Among anthraquiaoae dyes (see Dyes, anthraquinone). Acid Blue 78 [6424-75-5] C2 H25BrN20 S -Na, or Alizarin Pure Blue B, is a wool dye. Bromamine acid [116-81-4] (l-amiao-4-bromoanthraquiaoae-2-sulfonic acid), C24HgBrNO S, is a useful dye iatermediate. A number of bromo anthraquiaoae, pyrathroae, and benzanthrone dyes are known. 

On the basis of their chemical constitutions the anthraquinoid vat dyes may be classified in the following major groups acylaminoanthraquinones, anthraqui-noneazoles, anthrimides and other linked anthraquinones, anthrimidocarbazoles, phthaloylacridones, benzanthrone dyes, indanthrones, and other polycondensed ring systems. 

An example of industrial interest is the benzanthrone (9) synthesis. Benzan-throne derivatives are manufactured by cathodically reducing anthraquinone derivatives that may contain electronegative substituents [61]. In the cathode compartment the reduction of anthraquinone (7) in 85% H2S04 to oxanthrone (8) occurs which in presence of glycerol reacts to form benzanthrone (9), which is an important dye intermediate [40, 61]. 

Benzanthrone (6.73) is the source of various commercially important violet, blue and green vat dyes. This tetracyclic system can be prepared from a mixture of anthraquinone and propane-1,2,3-triol (glycerol) by heating with iron powder in concentrated sulphuric acid. The reaction involves reduction of anthraquinone to anthrone (6.74) followed by condensation (Scheme 6.14) with propenal (acrolein), the latter compound being generated... 

Vat dyes that do not contain all of the elements of the anthraquinone moiety include benzanthrone-based vat dyes such as C.I. Vat Orange 1 and Vat Green 1, which are made according to the routes shown in Figs. 13.127 and 13.128. The first synthesis is a three-step process (1) dibenzoylation of naphthalene, (2) Lewis acid-induced cyclization to the ben-zanthrone system, and (3) dibromination. The... 

Chemists at the rival Bayer company established the structure Indanthrone consists of two anthraquinone units joined through a heterocyclic bridge containing two nitrogens. This enabled industrial research laboratories to discover anthraquinone-based intermediates for other vat dyes. In 1904, an assistant of Bohn synthesized benzanthrone (48), later an important intermediate in processes involving aminoanthraquinone-derived colorants72. 

A typical use of 61 is, by fusion with potassium hydroxide at high temperature, in the production of flavanthrone (67) (Scheme 15). Fusion of 61 with potassium hydroxide under milder conditions affords the important anthraquinone azines known as indanthrones (Travis Chapter 1). The main vat-dye reactions proceed via anthrimides, which are both dyes and intermediates, since they are readily converted into cyclic carbazole derivatives. For example, benzanthrones, such as 68 and 69, dibenzanthrones, isodibenzanthrones, and their derivatives and substitution products, are important in vat-dye manufacture. An example of their use is in the synthesis of Cl Vat Olive T (70) (Scheme 16). Benzanthrone acridones made from 1-aminoanthraquinones are important green dyes. Certain vat-dye reactions require high-boiling organic solvents. 

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