Hydrochloric Acid → 2-Chloro-3-phenylpyridine

Participants

Reaction Steps

A solution of 2-chloro-3-cyanopyridine (VII; 2.0 g, 0.01 mole) in methylene chloride was treated dropwise with a 1M solution of DABAL-H in methylene chloride (0.03 mole, 33 mL) at -78°. The solution turned from a colorless to a bright yellow-orange color during the addition, and the stirring was continued for 3 hr at -78°. The mixture was treated with 3N HCl (75 mL) which rapidly warmed the reaction to -10°. The rate of addition was regulated so as to maintain the reaction temperature below 0°. The solution was treated dropwise with 10% sodium hydroxide solution which formed a bright yellow emulsion which was filtered through sintered glass. The collected aluminum salts were exhaustively washed with methylene chloride, filtered, and the filtrate dried (MgSO4). Concentration of the organic solution in vacuo gave a yellow solid which was purified by Kugelrohr distillation (60°/0.4 Torr.) affording 0.46 g (33%) of 2-chloro-3-pyridinecarboxaldehyde (VI) as a white solid, m.p. 48°.

Provenance & Evidence