Picolinic acid → 2-(2-Pyridinyl)benzothiazole

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Reaction Steps

To a solution of polyphosphoric acid ethyl ester (PPE) 360 g in 600 ml of CHCl3 is added o-aminothiophenol 36.9 g, 0.30 mole and picolinic acid 55.5 g, 0.45 mole. The resulting solution is heated at reflux for 1 hour. The solvent is removed in vacuo, and the residue poured onto 1500 cc of ice-water. The pH of the aqueous mixture is adjusted to 10, and it is then extracted three times with 500 cc portions of CHCl3. The extracts are dried (MgSO4); filtered; and concentrated to dryness. Recrystallization from acetonitrile yields 47.4 g of the title A compound in the form of white needles, m.p. 133°-134°.

Provenance & Evidence