Phosphorus pentachloride → 4'-Chloro-2,2':6',2''-terpyridine

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Reaction Steps

A mixture of 3.99 g (16 mmol) of 1′H-[2,2′;6′,2″]terpyridin-4′-one (L1) and 8.0 g (38 mmol) of phosphorus pentachloride is boiled at reflux in 200 ml of phosphorus oxychloride for sixteen hours. The mixture is allowed to cool and concentrated to dryness. 200 ml of ice-water are then added cautiously to the residue, and the solution is then adjusted to pH 9 with aqueous potassium hydroxide solution. Extracton is carried out three times using chloroform and the organic extracts are dried over sodium sulfate, filtered and concentrated. After recrystallisation from ethanol, 4′-chloro-[2,2′;6′,2″]terpyridine is obtained in the form of white needles. 1H-NMR (CDCl3, 360 MHz): 7.20–7.29 (m, 2H); 7.70–7.79 (tm, 2H); 8.37 (s, 2H); 8.47 (d, 2H; 7.6 Hz); 8.56–8.63 (dm, 2H).

Provenance & Evidence