反应详情

温度

0 °C

A solution of sodium nitrite (3.16 g, 45.8 mmol) in water (30 ml) was added dropwise over 30 minutes to a stirred, cooled (-5° C.) suspension of 4-amino-2-bromoanisole (Description 7a) (7.31 g, 36.2 mmol) in concentrated hydrochloric acid (50 ml), maintaining the temperature below 0° C. The mixture was stirred at ca. 0° C. for 30 minutes then added portionwise to a suspension of tin (II) chloride dihydrate (36.87 g, 163 mmol) in concentrated hydrochloric acid (50 ml) at -10° C. The resulting thick paste was stirred at -2° C. for 15 min., allowed to warm to room temperature over 20 minutes and stirred at room temperature for a further 20 min. The reaction mixture was recooled, basified with aqueous sodium hydroxide (10M) and extracted with ethyl acetate (2×250 ml). The ex-tracts were washed with brine (250 ml), combined, dried (MgSO4) and the solvent was evaporated under reduced pressure to give 3-bromo-4-methoxphenylhydrazine (7.27 g, 93%). 1H NMR (250 MHz, CDCl3) δ 3.84 (3H, s), 6.75 (1H, dd, J=8.8, 2.6 Hz), 6.83 (1H, d, J=8.8 Hz), and 7.11 (1H, d, J=2.6 Hz).

1. temperaturecooled
2. temperaturemaintaining the temperature below 0° C
3. stirringThe resulting thick paste was stirred at -2° C. for 15 min.
4. temperatureto warm to room temperature over 20 minutes
5. stirringstirred at room temperature for a further 20 min
6. extractionextracted with ethyl acetate (2×250 ml)
7. washThe ex-tracts were washed with brine (250 ml)
8. dry with materialdried (MgSO4)
9. customthe solvent was evaporated under reduced pressure
10. customto give 3-bromo-4-methoxphenylhydrazine (7.27 g, 93%)