Benzanthrones

It is used in the preparation of benzanthrone by heating with glycerol and sulphuric acid (Skraup s reaction). 

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. 

Benzanthrone and Related Compounds. Ben2anthrone [82-05-3] (71) is prepared by the reaction of anthraquiaone (15) with glycerol, sulfuric acid, and a reduciag agent such as iron. 

The anthraquiaone vat dyes can be classified into several groups on the basis of their chemical stmctures (/) benzanthrone dyes, (2) indanthrones, (3) anthrimides, (4) anthrimidocarbazoles, (5) acylaminoanthraquinones, (6) anthraquinoneazoles, (7) anthraquiaone acridones, (8) anthrapyrimidines, and 9) highly condensed ring systems. Most currendy (1993) available dyes have been known for many decades, and very few new dyes have been commercialized since the 1970s. Recendy, research and development efforts have focused on improved manufacturing of traditional vat dyes. 

Benzanthrone Dyes. Vat dyes derived from benzanthrone may be divided into two groups violanthrones and isoviolanthrones, dyes that have the perylene ring in their molecular stmcture and benzanthrone pyrazolanthrones and benzanthrone acridones, the peri ring closure products of 3-anthra quin onyl amino-ben zanthrone. 

Benzanthrone Pyrazolanthrones andBenzanthrone Acridones. Ben2anthrone pyra2olanthrones give from navy blue to gray shades and have good fastness. However, the only example of industrial use is Cl Vat Black 8 [2278-50-4] (141) (Cl 71000). Cl Vat Blue 25 [6247-39-8] (Cl 70500) has the basic stmcture of this dye class, but it is not produced today. 

In order to secure a pure product the above material is dissolved in 175 cc. of tetrachloroethane by boiling and the solution is boiled under reflux for fifteen minutes with 12 g. of decolorizing carbon, and then filtered by suction into an Erlenmeyer flask, washing the charcoal with about 50 cc. of hot solvent. The filtrate is kept hot, treated with 750 cc. of boiling alcohol, and set aside to crystallize. The benzanthrone separates as pure yellow needles melting at r7o-i7r° yield, 48-52 g. (60-65 per cent of the theoretical amount) (Note 7). 

Benzanthrone has been prepared by three general methods, the first of which is generally regarded as the best (i) by heating a reduction product of anthraquinone with sulfuric acid and glycerol,1 or with a derivative of glycerol, or with acrolein. The anthraquinone is usually reduced in sulfuric acid solution, just prior to the reaction, by means of aniline sulfate, iron, , or copper. It has also been prepared (2) by the action of aluminum or ferric chloride on phenyl-a-naphthyl ketone, and (3) from i-phenylnaphthalene-2-carboxylic acid. ... 

Acridine and compounds Aniline and compounds Benzanthrone and compounds Benzidine and compounds Chloro compounds... 

Lauer and Irie154 also reported two sets of unitless rate coefficients for the sulphonation of 1,8-benzanthrone in 80.6-99.0 wt. % acid. First-order rate coefficients (believed to be in min-1 and extrapolated to ca. 95 °C from rates obtained at temperatures up to 170 °C) and activation energies relating to acid strengths (in parentheses) were 12, 30.1 (91 %) 110, 26.6 (95.6%), 2500, 24.8 (99%). With... 

Figure 6.10. Rate constants for quenching of sensitizers by cis- and trans-stilbenes (open and filled circles, respectively). Sensitizers are as follows (1) tri-phenylene, (2) thioxanthone, (3) phenanthrene, (4) 2-acetonaphthone, (3) 1-naphthyl phenyl ketone, (6) crysene, (7) fluorenone, (8) 1,2,5,6-dibenzanthracene, (9) benzil, (10) 1,2,3,4-dibenzanthracene, (11) pyrene, (12) 1,2-benzanthracene, (13) benzanthrone, (14) 3-acetyl pyrene, (15) acridine, (16) 9,10-dimethyl-l,2-benzanthracene, (17) anthracene, (18) 3,4-benzpyrene.<57> Reprinted by permission of the American Chemical Society.

Reaction of benzanthrone with nitrogen dioxide alone or in admixture with ozone gives a mixture of nitrated products including 3-nitrobenzanthrone, which is a new class of powerful direct-acting mutagens of atmospheric origin (Eq. 2.12).26... 

When dibenzal diperoxide 3 was added, at 200°, to a solution of di-benzanthrone a red chemiluminescence was observed67) this is also seen in the reaction of violanthrone (dibenzanthrone) with alkaline hydrogen peroxide/chlorine. 

In the case of chemiluminescence occurring on treatment of di-benzanthrone with hypochlorite, as mentioned above, an endo peroxide might well be a key intermediate formed from 4 and singlet oxygen. The emitting species, however, is trichloro-dibenzanthrone, not 4 itself 70h... 

Aqueous solubility values for the samples analyzed compared favorably with results obtained by traditional methods. The solubility values for amiodarone HC1, reserpine, and benzanthrone were lower than the LOQ of the, uPLC system used for the evaluation. Results of the evaluation of compound solubility employing no-filtration /iPLC were compared with those obtained by two traditional methods (1) multiscreen filtration followed by a UV plate reader, and (2) the shake flask method followed by a UV plate reader. As shown in Figure 6.31, the solubility values determined by the different methods are comparable for most compounds examined. Figure 6.32 shows the results of evaluations of aqueous solubility at four different pH levels for phenazopyridine and piroxicam samples. 

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... 

The benzanthrone system is susceptible to both electrophilic and nucleophilic attack. The most reactive sites towards electrophiles are the 3- and 9-positions, which can be compared with the 4,4 -positions in biphenyl. The 9-position is somewhat deactivated by the carbonyl group, however. Thus, for example, monobromination takes place at the 3-position and further substitution gives 3,9-dibromobenzanthrone. Nitration and benzoylation similarly give rise to the 3-substituted product. The 3-position is in fact peri-hindered (compare naphthalene) so that sulphonation yields the 9-sulphonic acid. Electron withdrawal by the carbonyl group activates the 4- and 6-positions towards nucleophilic attack for example, hydroxylation occurs at these sites. 

In 1904 Bally obtained a bluish violet solid by alkali fusion of benzanthrone at approximately 220 °C. Two isomeric compounds were isolated by vatting the reaction mixture and filtering off a sparingly soluble sodium salt. Oxidation of the filtrate gave a blue vat dye, violanthrone (6.75 Cl Vat Blue 20), as the main component. The less soluble residue similarly afforded a violet product, isoviolanthrone (6.76 Cl Vat Violet 10). The formation of isoviolanthrone can be suppressed by carrying out the fusion in a solvent such as naphthalene or a polyethylene glycol in the presence of sodium acetate and sodium nitrite. Dyes of this type are often referred to as dibenzanthrones. 

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