Acid orange 7, oxidation

Hexenal is determined by photocolorimetry after oxidation with nitric acid. The yellow-orange oxidation product explodes on heating. 

Various industrial sectors related to textiles, paper, and photography use dyes of synthetic origin with a complex aromatic molecular structure, which are frequently discharged in industrial effluents. One solution to these environmental problems is to use oxidative enzymes that destroy colored compounds and that may be of practical interest for the decolorization of synthetic dyes. Enzymes such as LiPX and MnPX are involved in the decolorization of synthetic azo dyes, such as Acid Orange II. 

It has already been pointed out that this compound may be prepared by hydrolysis of the selenocyanate it may also be obtained by the interaction of sodium selenide and 1-chloroanthraquinone. By the latter process orange-red plates, M.pt. 212° C., result. If 2-chloroanthra-quinone be used in the reaction, 2-anihraquinone selenophenol is obtained as an orange-yellow product, which gives a violet-red solution in sulphuric acid. Concentrated nitric acid causes oxidation to the seleninic acid. 

Fig (11) Camosic acid (89) is an abietane diterpene and has been isolated from the leaves of sage as pale-yellow powder, m.p. 194.5 - 195°C (crystallized from acetic acid). Its oxidation products have been identified as (92), an orange powder, m.p. 129°C and (93), a yellow powder, m.p. 172 - 173°C. 

It now remains to separate out the ruthenium. This is accomplished by fusing with potassium hydroxide and nitrate, best in a silver crucible, and subsequently dissolving in water. The solution obtained has an orange-yellow colour in consequence of the presence of potassium ruthenate. This colour is removed by the addition of nitric acid, ruthenium oxide separating out. Ignition in a graphite crucible with a little chalk yields the free ruthenium, the chalk combining with any silicon, chromium, and osmium that may have been present. 

PoRADA T, Gade R, Fassler D, Gunther K (1999) Quantum Yield of the Ti02-Photo-catalyzed Degradation of Acid Orange 7, J. Adv. Oxid. Technol. 4, No. 203-208. 

Additionally to phenolic intermediates, upon the aromatic ring opening, a series of carboxylic acids can be formed. Maleic acid, for instance, has been detected in the oxidation of byphenyls (Bouquet-Somrani et al., 1996), 1,2,4-THB (Li et al., 1991a), 1,2-dimethoxybenzene (Pichat, 1997), and acid orange 7 (Stylidi et al., 2003). Similarly, muconic acid has been reported as an intermediate of byphenyls oxidation (Bouquet-Sormani et al., 1996), while succinic and malonic acids were identified in polycarboxylic benzoic acid oxidation (Assabane et al., 2000). It is therefore expected that these or similar acids be formed during phenol oxidation. 

It forms orange needles, which are soluble in alcohol but insoluble in benzene. Its M.P. is above 330° [25]. It yields no phthalic acid on oxidation, and therefore probably contains the third OH-group in the second benzene ring. Isopurpurin is the principal constituent of the commercial alizarin for red. It dyes a fine scarlet red on alumina its iron lake is greyish violet, and of little value. 

The azo dyes used in this study were l-phenylazo-2-naphthol-6-sulfonate (2) and seven derivatives with substituents in the meta or para positions of the phenyl ring (3-9). These were selected as representative l-azo-2-naphthol sulfonate dyes and because the substituents on phenyl ring would allow a systematic study of the mechanism of their oxidation by metalloporphyrin-catalysed systems in aqueous solution. Dye 2 is commercially available (as Acid Orange 12) and was purified by reciystallisation whilst the others (3-9) were prepared by standard diazonium ion/2-naphthol coupling reactions. The purities of all the dyes were checked by TLC, MS and H NMR spectroscopy. Table 1 reports the measured pl values of all the azo dyes used in this study. 

Characterisation of the kinetic equation for the oxidation of Acid Orange 12 by oxoiron(IV) tetra(2,6-dichloro-3-sulfonatophenyI)porphyrin... 

The effect of substituents, on the phenyl group of Acid Orange 12, on the second order rate constants of dye oxidation... 

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