Benzene, 4-Aminoazo

As might be expected, the stability and reactivity of diazonium salts are affected by substituents as well as by the anion. The rate of coupling and the location of the azo bond are influenced by substituents on the coupling reagent. Some primary and secondary aromatic amines derived from benzene initially form A-azo compounds, which rearrange to p-aminoazo compounds in acidic media [8b, c]. Tertiary amines, on the other hand, behave normally. Preparation 2-3, while of a rather complex molecule, illustrates the simple techniques commonly used in coupling in an aqueous system. Note the presumed preferential tendency of coupling to take place predominantly in the para position. 

Reaction of a similar triazine component with I acid (1-hydroxy-6-amino-naphthalene-3-sulfonic acid), followed by coupling with diazotized 4-aminoazo-benzene gives the cationic substantive azo dye 4 [71032-95-6], which colors paper in red hues. 

Aminoazo Benzene from Nitroazo Benzene.— Another method of preparing aminoazo compounds is analogous to the preparation of aniline, i.e.f by the reduction of the corresponding nitro compound. When azo benzene is nitrated we obtain nitro azo benzene and this on reduction yields amino azo benzene. 

Richardson HL, Stier AR, Borsos-Natch-Nebel E. 1952. Liver tumor inhibition and adrenal histologic responses in rats to which 3 -methyl-4-dimethyl-aminoazo-benzene and 20-methylcholanthrene were simultaneously administered. Cancer Res. 12 356-61... 

Figure 1.2. Schematic of typical absorbance spectra for trans-azobenzenes. The azobenzene-type molecules solid line) have a strong absorption in the UV, and a low intensity band in the visible (barely visible in the graph). The aminoazo-benzenes dotted line) and pseudo-stilbenes dashed line) typically have strong overlapped absorptions in the visible region.

The diazo-compounds form the starting point of numerous organic compounds, including the azo-dyes, the first representative of which (amino-azobenzene hydrochloride, aniline yellow ) was prepared and shown to be a dye by Mene. What was called aniline yellow is the oxalate of aminoazo-benzene (CeH5 N N-CeH4 NH2), introduced as a dye by Simpson, Maule, and Nicholson in 1863 its constitution was established by C. A. Martius and Griess, and the isomeric change of diazoaminobenzene into aminoazobenzene was explained by Kekule. ... 

Figure 2.15 Some 7t-electron charge density differences between the ground and first excited states calculated by the PPP-MO method for 4-aminoazo-benzene, 2.1c.

Dimethyl-4-aminoazo- benzene 4-o-Tolylazo-o-toluidine C14H15N3 97-56-3 225.289 ye If (al) 102 vs eth, EtOH... 

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