Bromination of pyridine in fuming sulphuric acid

Abstract

Abstract When pyridine (4 moles) is heated at 130° in fuming sulphuric acid with bromine (1 mole), 1.6‐1.8 moles of pure 3‐bromopyridine are formed according to the equation 2 C 5 H 5 N + 2 SO 3 + Br 2 → 2 C 5 H 4 BrN + SO 2 + H 2 SO 4 . The reaction product contains but a small amount of dibromopyridines (less than 0.1 mole), 2,5‐dibromopyridine being the chief component in the mixture. The reaction products were analysed semiquantitatively by gas chromatography.