5-nitro-2-phenylbenzimidazole

Nitro-2-nitrosaniline and benzaldehyde heated 2 hrs. at 95° in 50 -acetic acid 5-nitro-2-phenylbenzimidazole 3-oxide. Y 46%. D. W. Russell, Ghem. Commun. 1965, 498. 

Phenylbenzimidazole is nitrated first at the 5-position with mixed acid, and subsequent reaction produces 5-nitro-2-(4-nitrophenyl)-and 5-nitro-2-(3-nitrophenyl)-benzimidazole. 2-Phenyl-, 2-(4-nitro-phenyl)- and 5-nitro-2-phenyl-benzimidazole are nitrated as their conjugate acids. ... 

In the case of benzimidazole itself, nitration usually occurs at the 5-position (80MI1). Sterba and co-workers have studied the nitration of some arylbenzimidazoles and have showed that 2-phenyl benzimidazole, when treated with nitric acid sulfuric acid at 10°C, gives 6-nitro-2-phenyl-benzimidazole (75%). The 2-(3-nitrophenyl) and 2-(4-nitro phenyl) benzimidazoles similarly yield the 6-nitro products (57 and 97% respectively), and nitration of 6-nitro-2-phenylbenzimidazole gives the 2-(4-nitrophenyl) and 2-(3-nitrophenyl) products in 44% and 32.5% yields, respectively (65CCC1093). 

An interesting reaction has been described by Simonov and his colleagues [371], Studying the reaction of some aromatic rnt/zo-dinitro- and trinitrocompounds with benzylamine they have discovered that under special conditions the reaction of substitution of the nitro group with the benzylamine group is accompanied by reduction of the second nitro group and cyclization into 2-phenylbenzimidazole derivatives. In this case benzyl alcohol forming from benzylamine serves as a reducer. By the way it was obtained 4,5-dimethoxy-7-nitro-2-phenylbenzimidazole in 89% yield from 3,4,5-trinitroveratrole [371],... 

The mass spectra of nitro derivatives of 2-phenylbenzimidazoles show the dissociative ionization to be characterized by two trends involving the formation of [M-NO]+ and [M-N02]+ ions (Scheme 3.72) [1342] ... 

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