N[C:2]1[CH:7]=[CH:6][C:5]([S:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)=[CH:4][N:3]=1.[ClH:15].N([O-])=O.[Na+].[OH-].[Na+]>O>[Cl:15][C:2]1[CH:7]=[CH:6][C:5]([S:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)=[CH:4][N:3]=1Alternatively, 2-amino-5-(phenylthio) pyridine (30 g., 0.15 moles) is added portionwise to 30 ml. of concentrated hydrochloric acid at 0°. The resultant suspension is cooled to -15° C and 20.7 g. of sodium nitrite in 40 ml. of water is added dropwise while keeping the temperature at -15° to -10° C. After stirring for an additional hour at -5° C, an aqueous 30% sodium hydroxide solution is slowly added to pH7 while not allowing the temperature to exceed 0° C. The resultant mixture is extracted with methylene chloride and the combined extracts are washed with water, dried and evaporated in vacuo to yield 2-chloro-5-(phenylthio) pyridine.
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