Cation radicals. XXXII. Reaction of N ‐ethylcarbazole with iodine‐silver salts. Nitration of N ‐ethylcarbazole

Reaction of N ‐ethylcarbazole ( 1 ) with iodine‐silver perchlorate gave a green solution having a singlet esr signal. Reduction of the solution with potassium iodide gave N,N ′ ‐diethyl‐3,3′‐dicarbazolyl ( 3 , 48%). Small amounts of 3‐iodo‐ ( 4 ) and 3,6‐diiodo‐ N ‐ethylcarbazole ( 5 ) were also obtained. Compounds 4 and 5 are believed to have been formed by electrophilic iodination of 1 by I 2 ‐AgCIO 4 , whereas 3 appears to have been formed via the dimerization of 1 .+ . In accord with this, reaction of 1 with iodine‐silver nitrite gave 3‐nitro‐ N ‐ethylcarbazole ( 6 , 61%), 9% of another nitro‐ N ‐ethylcarbazole ( 7 ), thought to be either 1‐ or 4‐nitro‐ N ‐ethylcarbazole, and 28% of 4. Thus, trapping of 1 .+ by nucleophilic nitrite ion occurred even though 1 .+ is not stable enough toward isolation as the perchlorate.