反应详情

温度

85 °C

A mixture of 4-(2-ethylhexyl)-2-thiophenecarboxaldehyde (17.3 g, 77.1 mmol) and hydroxylamine hydrochloride salt (8.04 g, 116 mmol) in pyridine/ethanol (40 mL, 1/1, v/v) was refluxed at 85° C. for overnight. After cooling down to room temperature, the solution was rotary evaporated to remove most of the solvent. In a separatory funnel, the residue was taken up with chloroform (100 mL) and washed with distilled water (2×75 mL). After drying over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation to give a yellowish liquid, which was dissolved in acetic anhydride (60 mL). To the resulting solution was added potassium acetate (0.4 g). The solution was then heated up to 140° C. and refluxed for 4 h. After cooling, the yellow solution was dropped into 100 mL of cold water and was extracted with hexane (2×100 mL). The combined organic layers were washed with distilled water twice and then dried over magnesium sulfate. The solvent was removed by rotary evaporation and the residue was subject to a silica-gel column chromatography (EtOAc/Hex=1/10, v/v, Rf=0.5) to yield a colorless liquid product (15.6 g, 91% yield). 1H NMR (400 MHz, CDCl3) δ (ppm): 7.40 (d, 1H, J=1.2 Hz), 7.15 (d, 1H, J=1.2 Hz), 2.54 (d, 2H, J=6.8 Hz), 1.52 (m, 1H), 1.20-1.29 (m, 8H), 0.86 (m, 6H). (3-substitution isomer can be removed in chromatography.)

1. temperatureAfter cooling down to room temperature
2. customthe solution was rotary evaporated
3. customto remove most of the solvent
4. customIn a separatory funnel, the residue was taken up with chloroform (100 mL)
5. washwashed with distilled water (2×75 mL)
6. dry with materialAfter drying over anhydrous magnesium sulfate
7. customthe solvent was removed by rotary evaporation
8. customto give a yellowish liquid, which
9. temperatureThe solution was then heated up to 140° C.
10. temperaturerefluxed for 4 h
11. temperatureAfter cooling
12. extractionwas extracted with hexane (2×100 mL)
13. washThe combined organic layers were washed with distilled water twice
14. dry with materialdried over magnesium sulfate
15. customThe solvent was removed by rotary evaporation