Thionyl Chloride → 2-Chloro-4-methyl-5-nitropyridine

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Reaction Steps

A mixture of 4-methyl-5-nitro-1H-pyridine-2-one (5.00 g, 32.44 mmol), thionyl chloride (20 ml), and two drops of dimethylformamide was heated at reflux under nitrogen for 52 hours. The resultant orange colored solution was evaporated under reduced pressure, and a small amount of anhydrous toluene was added and then removed via evaporation under reduced pressure to remove traces of thionyl chloride. The residual oil then passed through a silica gel filter (dried at 150° C. under vacuum overnight, approximately 100 g) followed by methylene chloride (1 1). This filtrate was evaporated under reduced pressure to afford 2-chloro-4-methyl-5-nitropyridine (5.30 g, 30.71 mmol, 95%) as an orange oil, which crystallized below 0° C.; IR (CHCl3) 1,605, 1,550, 1,520, 1,450, 1,360, 1,345 cm-1 ; 1H NMR (CDCl3) δ 9.03 (s, 1H), 7.83 (s, 1H), 2.60 (s, 3H); LRMS (m/z, relative intensity) 174 (25), 173 (19), 172 (M+, 68), 157 (74), 155 (100), 128 (27), 101 (47), 100 (55), 99 (74), 90 (43), 75 (36).

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