2-Amino-3-nitro-6-(phenylmercapto)pyridine → 2,3-Diamino-6-(phenylmercapto)pyridine

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Reaction Steps

2,3-Diamino-6-(phenylmercapto)pyridine was prepared by hydrogenating 2-amino-3-nitro-6-(phenylmercapto)pyridine (107.1 g, 0.433 mol) under 5 atm of H2 in the presence of 30 g of Raney-Ni in 1200 mL of 2-propanol at 70° C. After 4 hours (29.1 L of hydrogen) the reaction mixture was cooled to 4° C. while stirring continuously. The precipitate was collected by vacuum filtration, washed with 2-propanol and dried at 50° C. under vacuum. The combined filtrates were concentrated under reduced pressure and recrystallized from 2-propanol. After washing the hydrogenation apparatus twice with 1000 mL of THF, evaporation under reduced pressure and recrystallization from 2-propanol, the precipitate was collected and dried at 50° C. under vacuum to give 80.4 g (87.1% yield) of 2,3-diamino-6-(phenylmercapto)pyridine, m.p. 119-122° C.).

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