Hydrochloric Acid → 2,3-Dichloro-5-(chloromethyl)pyridine

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Reaction Steps

To a stirred solution of 2,3-dichloro-5-hydroxymethylpyridine (4.4 g, 25 mmol) and pyridine (2.61 g, 33 mmol) in dichloromethane (75 mL) was added rapidly phosphorous oxychloride (4.91 g, 32 mmol). An exothermic reaction sufficient to boil the reaction mixture ensued. After stirring at room temperature for 2 h, 1 N HCl aqueous solution (50 mL) was carefully added to the reaction mixture and the stirring continued for 10 min. The organic phase was separated and the aqueous phase extracted with dichloromethane (50 mL). The combined organic phase was washed successively with water (25 mL), 1 N aqueous NaOH solution (25 mL) and saturated aqueous NaCl solution (25 mL), dried over anhydrous MgSO4, filtered, and concentrated to give 3.80 g of the desired 2,3-dichloro-5-chloromethylpyridine as yellow oil (77.4% yield) which solidified upon standing at room temperature. GC-MS: mass calcd for C6H5Cl2NO [M]+ 178. Found 178

Provenance & Evidence