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2.5-Dichloro-3-picoline (II). A stirred solution of 5-amino-2-chloro-3-picoline (I) (3.0 g, 0.021 mol) (7) in concentrated hydrochloric acid (153 ml) was diazotized at 0-5 0 by the slow, dropwise addition of a solution of sodium nitrite (8.3 g) in water (23 ml). Copper powder (16.6 g) was cautiously added to the freshly diazotized solution, and the mixture was allowed to reach room temperature where stirring was continued for 21/2 h. The solution was again cooled to ice bath temperature and slowly neutralized with chilled 30% sodium hydroxide. Indirect steam distillation of the neutralized solution afforded the dihalopicoline II as a white solid. Further purification was achieved by recrystallization (Table I).2-Chloro-5-iodo-3-picoline (III). A stirred solution of I (2.0 g, 0.014 mol) in concentrated hydrochloric acid (7 ml) was diazotized at 0 0 by the slow, dropwise addition of sodium nitrite (1.7 g) in water (4 ml). The freshly diazotized solution was poured into a solution of potassium iodide (8.0 g) in water (6 ml). The resulting mixture was warmed on a steam cone for 5 min, cooled to room temperature, and made basic with 25% sodium hydroxide. Sodium bisulfite was added to the dark suspension which was then stirred overnight. The dihalopicoline III was isolated by indirect steam distillation and purified as described in Table I.

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