The mercuration of pyridine‐N‐oxide

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Abstract
By heating pyridine‐N‐oxide with mercuric acetate in acetic acid solution at 130°, a reaction product was obtained, which afforded, after reacting successively with sodium chloride solution and bromine, a mixture containing 2‐bromo‐ and 2,6‐dibromopyridine‐N‐oxide. The structure of the dibromo‐compound was proved by converting it via 2,6‐dibromo‐4‐nitro‐pyridine‐N‐oxide into the known 4‐amino‐2,6‐dibromopyridine. Our result differs from that obtained by Ukai, Yamamoto and Hirano who record the 4‐monosubstituted derivative as the sole product of reaction under the same conditions 2).2,6‐Dibromopyridine‐N‐oxide is an excellent intermediate for the preparation of derivatives of pyridine and its N‐oxide, especially for those substituted in positions 2, 4 and 6.