T-azo

Aono, K. et al., J. Chem. Soc., Dalton Trans., 1981, 1190-1195 In the preparation of l,T-azo-2-R-l,2-dicarbadodecaborane(14) by oxidation of the aminocarbaborane anions in liquid ammonia, toluene or other inert solvent must be added before evaporation of ammonia to prevent explosions. Individually indexed compounds are ... 

Oxidation of iV-aminoimidazo[l,2-a]pyrimidines 184 with bromine generally results in the corresponding l,T-azo compounds 185 (77JCS(P1)78). 

The preceding coppered or chromed. -> Cr or Cu present t Azo Salt Dyestuff after treated S g p .s f... 

HYDROXY-5-((p-SULPHOPHEN T,)AZO)-2-NAPHTHALENESULPHONIC ACID, DISODIUM SALTseeFAGlSO... 

Calvert et have made detailed studies on the l,T-azo- -butane and 1,1 -... 

Tetrazolylazo) -2-hydroxynaphthalene-3,6-disulfonic acid (T-azo-R) (Cj j[ HgOyNgS2) (Other reference in Vol.5, p.460)... 

When an aqueous solution of a diazonium salt is added to an alkaline solution of a phenol, coupling occurs with formation of an azo-compound (p. 188). If ho vc cr the ntiueous solution of the diazonium salt, t. . ., />-bromohenzene diazonium chloride, is mixed with an excess of an aromatic hydrocarbon, and aqueous sodium hydroxide then added to the vigorously stirred mixture, the diazotate which is formed, e.g., BrC,H N OH, dissolves in the hydrocarbon and there undergoes decomposition with the formation of nitrogen and two free radicals. The aryl free radical then reacts with the hydrocarbon to give a... 

H-acid, l-hydroxy-3,6,8-ttisulfonic acid, which is one of the most important letter acids, is prepared as naphthalene is sulfonated with sulfuric acid to ttisulfonic acid. The product is then nitrated and neutralized with lime to produce the calcium salt of l-nitronaphthalene-3,6,8-ttisulfonic acid, which is then reduced to T-acid (Koch acid) with Fe and HCl modem processes use continuous catalytical hydrogenation with Ni catalyst. Hydrogenation has been performed in aqueous medium in the presence of Raney nickel or Raney Ni—Fe catalyst with a low catalyst consumption and better yield (51). Fusion of the T-acid with sodium hydroxide and neutralization with sulfuric acid yields H-acid. Azo dyes such as Direct Blue 15 [2429-74-5] (17) and Acid... 

T artrazine, 4,5-dihydro-5 -oxo-1 -(4-sulfophenyl)-4-[(4-sulfophenyl)azo]-1// -pyrazole-3-carboxylic acid trisodium salt was discovered by Ziegler in 1884 and is used as a dye for wool and silk. It is used as a colour additive in foods, drugs and cosmetics, and is an adsorption-elution indicator for chloride estimations in biochemistry (B-76MI40404). 

B ) Coupling Orange T.—The procedure is the same as in (B) except that the alkaline solution of a-naphthol (Note 4) is cooled to 25 before adding the ice (Note 5). The azo dye in this case does not crystallize but forms a deep purple-red solution. 

Two low-molecular weight initiators with azo groups of different stability were used by Simionescu et al. [82,83] for polymerizations phenylformamidoethyl 4-/-butylazo-4-cyanovalerate (Scheme 20) and N,N -bis[(4-t-butylazo-4-cyanovaleryl)-oxoethyl]azo-bis-form-amide (Scheme 21) [84-86]. 

Unsymmetrical azo-compounds find application as initiators of polymerization in special circumstances, for example, as initiators of living radical polymerization [e.g. triphenylmethylazobenzene (30) (see 9.3.4)], as hydroxy radical sources [e.g. a-hydroperoxydiazene (31) (see 3.3.3,1)1, for enhanced solubility in organic solvents [e.g. f-butylazocyclohexanecarbonitrile (32)J, or as high temperature initiators [e.g. t-butylazoformamide (33)]. They have also been used as radical precursors in model studies of cross-termination in copolymerization (Section... 

The reaction between the PMMA and PS model radicals (4 and 5, generated from the unsymmetrical azo-compound 3) has been studied as a model for crosstermination in MMA-S copolymerization (Scheme 7.13).178,179 The value for tcross reaction was 0.56. In disproportionation, transfer of hydrogen from the PS model 5 to the PMMA radical 4 was ca 5.1 times more prevalent than transfer in the reverse direction (from 4 to 5). The value of kJklc(90°C) is between those of Atd/ tc(90oC) for the self-reaction of these radicals... 

T vo developments in the history of diazo and azo chemistry discussed in the previous section had important implications for the systematic nomenclature of these classes of compounds and for establishing their structural formulas ... 

The isomerization takes place because the excited states, both 5i and T, of many alkenes have a perpendicular instead of a planar geometry (p. 311), so cis-trans isomerism disappears upon excitation. When the excited molecule drops back to the So state, either isomer can be formed. A useful example is the photochemical conversion of c/s-cyclooctene to the much less stable trans isomer." Another interesting example of this isomerization involves azo crown ethers. The crown ether (5), in which the N=N bond is anti, preferentially binds NH4, Li, and Na, but the syn isomer preferentially binds and Rb (see p. 105). Thus, ions can be selectively put in or taken out of solution merely by turning a light source on or off." ... 

The conversion of azoxy compounds, (144) on acid treatment, to p-hydroxy azo compounds (145, or sometimes the o-hydroxy isomers ) is called the Wallach rearrangement. When both para positions are occupied, the t -hydroxy product... 

Kulla HG (1981) Aerobic bacterial degradation of azo dyes. In Microbial Degradation of Xenobiotics and Recalcitrant Compounds (Eds T Leisinger, AM Cook, R Hiitter, J Niiesch), pp. 387-399. FEMA Symposium 12. Academic Press, London. 

Zimmermann T, F Gasser, HG Kulla, T Leisinger (1984) Comparison of two bacterial azoreductases acquired during adaptation to growth on azo dyes. Arch Microbiol 138 37-43. 

Generation and deazetization of specifically dideuterated azo compound 22 in the presence of methyl (Z)-3-cyanoacrylate (T) gave mixtures of symmetric (S) and unsymmetric (U) Diels-Alder-type trapping products, whose ratio depended on the concentration of Larger [T] gave greater proportions of S-products. The... 

Azo-bridged ferrocene oligomers also show a marked dependence on the redox potentials and IT-band characteristics of the solvent, as is usual for class II mixed valence complexes 21,22). As for the conjugated ferrocene dimers, 2 and 241 the effects of solvents on the electron-exchange rates were analyzed on the basis of the Marcus-Hush theory, in which the t/max of the IT band depends on (l/Dop — 1 /Ds), where Dop and Ds are the solvent s optical and static dielectric constants, respectively (155-157). However, a detailed analysis of the solvent effect on z/max of the IT band of the azo-bridged ferrocene oligomers, 252,64+, and 642+, indicates that the i/max shift is dependent not only on the parameters in the Marcus-Hush theory but also on the nature of the solvent as donor or acceptor (92). 

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