反应详情

A solution of 10.2 g (66.2 mmol) of 3-fluoro-4-methylbenzoic acid in 50 mL of EtOH and 25 mL of toluene containing 0.2 mL of H2SO4 was heated gradually to 120° C. (oil bath temperature), and the solvent was removed by distillation over a period of 2.25 h through a 10-cm Vigreux column. The residue was cooled, treated with a further 50 mL of EtOH and 25 mL of toluene, and the distillation was repeated. The residual solution, containing some white solid, was poured into 75 mL of aqueous NaHCO3 and extracted with hexane (75 mL, then 50 mL). The extract was washed with water (2×75 mL), dried (Na2SO4), and concentrated. The pale-yellow liquid was distilled, bp 49°-58° C. (0.01-0.05 mm) to give 11.1 g (92% yield) of ethyl 3-fluoro-4-methylbenzoate as a colorless liquid: IR (CHCl3) 1720 (C=O), 1580, 1420, 1370, 1290, 1190, 1130, 1090, 1020, 940, 895 cm-1 ; 1H NMR (CDCl3) δ 1.40 (t, J=7 Hz, 3, CO2CH2CH3), 2.32 (d, J=2 Hz, 3, ArCH3), 4.37 (q, J=7 Hz, 2, CO2CH2CH3), 7.22 (dd, J=8 Hz, J=8 Hz, 1, 6' H), 7.68 (m, 2, 3', 5' H); MS calcd for C10H11FO2 182.0743, found 182.0729.

1. customthe solvent was removed by distillation over a period of 2.25 h through a 10-cm Vigreux column
2. temperatureThe residue was cooled
3. additiontreated with a further 50 mL of EtOH and 25 mL of toluene
4. distillationthe distillation
5. additionThe residual solution, containing some white solid
6. additionwas poured into 75 mL of aqueous NaHCO3
7. extractionextracted with hexane (75 mL
8. washThe extract was washed with water (2×75 mL)
9. dry with materialdried (Na2SO4)
10. concentrationconcentrated
11. distillationThe pale-yellow liquid was distilled