反応 #1076001

反応方程式

charcoal

2,5-Dibromo-3-picoline

2-amino-5-bromo-3-methylpyridine

Acetyl chloride

2,5-dibromo-3-picoline

sodium iodide

→

5-bromo-2-iodo-3-methylpyridine

収率 70.0%

溶媒

hexane

Br2 HBr

acetonitrile

反応条件

後処理

1. 1
   温度the reaction mixture was gently refluxed for 18 h
2. 2
   その他The cooled reaction mixture
3. 3
   ろ過was filtered
4. 4
   洗浄the solid was washed with acetonitrile until colorless
5. 5
   workup.ADDITIONtreated with aq. Na2CO3 until the pH was 10-11
6. 6
   その他The organic layer was separated
7. 7
   乾燥dried over anhydrous sodium sulfate
8. 8
   濃縮concentrated
9. 9
   その他to give a brown oil
10. 10
    温度as above (reflux time 6 h)
11. 11
    その他A dark brown oil was obtained
12. 12
    ろ過filtered
13. 13
    濃縮concentrated
14. 14
    その他to give a light brown oil

実験手順

2,5-Dibromo-3-picoline is commercially available or may be prepared from 2-amino-5-bromo-3-methylpyridine by standard diazotization followed by bromination in Br2/HBr. Acetyl chloride (0.68 mol, 52.7 mL) was added to a stirring solution of 2,5-dibromo-3-picoline (0.45 mol, 113 g) in acetonitrile (600 mL) followed by sodium iodide (1.66 mol, 250 g) and the reaction mixture was gently refluxed for 18 h. The cooled reaction mixture was filtered and the solid was washed with acetonitrile until colorless. It was suspended in methylene chloride and treated with aq. Na2CO3 until the pH was 10-11. The organic layer was separated, dried over anhydrous sodium sulfate and concentrated to give a brown oil. It was subjected to iodination a second time as above (reflux time 6 h). A dark brown oil was obtained using the same work-up as above. A solution of this oil in hexane was treated with charcoal, filtered and concentrated to give a light brown oil. It slowly solidified on standing to give 5-bromo-2-iodo-3-methylpyridine as a light brown solid (95.0 g, 0.32 mol). Yield: 70%.

出典