反应详情

To a solution of ethyl 4-(2,4-dichlorophenoxy)-butyrate (57 g, crude from last step, about 0.2 mol) in THF (500 mL) and water (500 mL) was added LiOH.H2O (12.6 g, 0.3 mol), and the reaction mixture was stirred for 5 h at RT. The mixture was washed with Et2O (3×200 mL), and the aqueous layer was acidified by addition of HCl (20%) to pH ˜2. The mixture was extracted with EtOAc (3×400 mL), the combined organic extracts were washed with water and brine, dried over Na2SO4 and concentrated in vacuo to give the butyric acid (37 g, 74.3% from 2,4-dichlorophenol) as a white solid. 1H-NMR (CDCl3): δ 7.36 (d, 1H, J=8.8 Hz), 7.18 (dd, 1H, J1=8.8 Hz, J2=2.4 Hz), 6.84 (d, 1H, J=8.8 Hz), 4.07 t, 2H, J=7.2 Hz), 2.64 (t, 2H, J=7.2 Hz), 2.17 (p, 2H, J=6.4 Hz).

1. washThe mixture was washed with Et2O (3×200 mL)
2. additionthe aqueous layer was acidified by addition of HCl (20%) to pH ˜2
3. extractionThe mixture was extracted with EtOAc (3×400 mL)
4. washthe combined organic extracts were washed with water and brine
5. dry with materialdried over Na2SO4
6. concentrationconcentrated in vacuo