The mercuration of pyridine-N-oxide (ii)

✍ Scribed by M. van Ammers; H. J. den Hertog

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 360 KB
• Volume: 81
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19620810207

✦ Synopsis

Abstract

Pyridine‐N‐oxide has been mercurated with different reagents, i.e. mercuric acetate in acetic acid, mercuric sulphate, mercuric sulphate in sulphuric acid, mercuric chloride and mercuric bromide.

Mercuration with mercuric acetate in acetic acid yields mainly derivatives substituted at positions 2 or 2 and 6, together with the compound substituted at the 3‐position. It is shown that the supposition of Ukai, Yamamoto and Hirano^4^ that the compound substituted at position 4 is formed in this reaction as the chief product, is incorrect.

The 3‐ and 4‐isomers are obtained together with the 2‐isomer as chief product, however, when pyridine‐N‐oxide is heated with mercuric sulphate. Addition of sulphuric acid lowers the yield of this mercuration and changes the substitution pattern. Together with the derivative substituted at position 2 a considerable amount of the 3‐isomer is formed. Also in mercuration with mercuric chloride and mercuric bromide the nucleus is attacked at the 3‐ and 4‐positions, but here the reaction mixture consists preponderately of the 2‐isomer again.