Synthesis and properties of 3-nitrosocarbazole

The synthesis of 3-nitrosocarbazole (I) by the Fischer-Hepp rearrangement of 9-nitrosocarbazole has been described. The resistance of I to oxidation provides evidence that it cannot be the intermediate in the conversion of 9-nitrosocarbazole to the C-nitro compounds. It has also been shown that I and its derivatives cannot be synthesized by the action nitrosyl chloride on carbazoles. Methylation of I yields 9-methyl-3-nitrosocarbazole, 9,9′-dimethyl-3-azocarbazole and 9,9′-dimethyl-3-azoxycarbazole as the main products. The mechanism of this disproportionation process has been proposed. The spectral data of I are given.