34237-98-4Relevant articles and documents
A search for blues brothers: X-ray crystallographic/spectroscopic characterization of the tetraarylbenzidine cation radical as a product of aging of solid magic blue
Talipov, Marat R.,Hossain, Mohammad M.,Boddeda, Anitha,Thakur, Khushabu,Rathore, Rajendra
supporting information, p. 2961 - 2968 (2016/03/12)
Magic blue (MB+? SbCl6- salt), i.e. tris-4-bromophenylamminium cation radical, is a routinely employed one-electron oxidant that slowly decomposes in the solid state upon storage to form so called 'blues brothers', which often complicate the quantitative analyses of the oxidation processes. Herein, we disclose the identity of the main 'blues brother' as the cation radical and dication of tetrakis-(4-bromophenyl)benzidine (TAB) by a combined DFT and experimental approach, including isolation of TAB+? SbCl6- and its X-ray crystallography characterization. The formation of TAB in aged magic blue samples occurs by a Scholl-type coupling of a pair of MB followed by a loss of molecular bromine. The recognition of this fact led us to the rational design and synthesis of tris(2-bromo-4-tert-butylphenyl)amine, referred to as 'blues cousin' (BC: Eox1 = 0.78 V vs. Fc/Fc+, λmax(BC+?) = 805 nm, εmax = 9930 cm-1 M-1), whose oxidative dimerization is significantly hampered by positioning the sterically demanding tert-butyl groups at the para-positions of the aryl rings. A ready two-step synthesis of BC from triphenylamine and the high stability of its cation radical (BC+?) promise that BC will serve as a ready replacement for MB and an oxidant of choice for mechanistic investigations of one-electron transfer processes in organic, inorganic, and organometallic transformations.
ortho-Substituent effects on the in vitro and in vivo genotoxicity of benzidine derivatives
You,Brezzell,Das,Espadas-Torre,Hooberman,Sinsheimer
, p. 19 - 30 (2007/10/03)
Benzidine and its 3,3'-diamino, 3,3'-dimethyl, 3,3'-dimethoxy, 3,3'-difluoro, 3,3'-dichloro, 3,3'-dibromo, 3,3'-dicarbomethoxy and 3,3'-dinitro derivatives together with 2-nitrobenzidine and 3-nitrobenzidine were compared for their in vitro and in vivo genotoxicity. Relative mutagenicity was established with Salmonella strains TA98, TA98/1,8-DNP6 and TA100 with and without S9 activation. All the derivatives in the presence of S9 were more mutagenic than benzidine with 3,3'-dinitro- and 3-nitro-benzidine having the greatest mutagenicity. Mutagenicity in all 3 strains with S9 activation could be correlated to electron-withdrawing ability of substituent groups, as measured by the basicity of the amines. This correlation was explained on the basis that electron-withdrawing groups could favor the stability of the mutagenic intermediate N-hydroxylamine and also enhance the reactivityof the ultimate mutagenic species, the nitrenium ion. Mutagenicity was also correlated to the energy of the lowest unoccupied molecular orbitals (E(LUMO)). Hydrophibicity was found to have very limited effect on the relative mutagenicity of our benzidine derivatives. The in vivo endpoint was chromosomal aberrations in the bone-marrow cells of mice following intraperitoneal administration of benzidine and its derivatives. In contrast to the in vitro results, while all the amines were genotoxic in vivo, only the 3-nitro derivative had a significant increase in toxicity over benzidine.
