反应详情

Methyl iodide (10.0 mL, 160 mmol) was added to a mixture of 4-bromo-2-methylbenzoic acid (25.0 g, 116 mmol) and potassium carbonate (20.0 g, 145 mmol) in anhydrous dimethylformamide (75 mL) at room temperature under a nitrogen atmosphere and stirred for 18 h. The mixture was poured into water and extracted with ethyl acetate (3×50 mL). The organic phases were combined, washed with copper sulfate solution (50 mL) and brine (50 mL), dried and evaporated. Purification by column chromatography on silica gel using 9:1 hexane/ethyl acetate as eluant provided 21.0 g (79%) of methyl 4-bromo-2-methylbenzoate as a clear liquid: 1H NMR (CDCl3) δ7.85 (d, 1H), 7.42-7.47 (m, 2H), 3.95 (s, 3H), 2.64 (s, 3H); IR (neat) 1726 cm-1 ; Mass spectrum m/z 197, 199 (M+H--OCH3).

1. extractionextracted with ethyl acetate (3×50 mL)
2. washwashed with copper sulfate solution (50 mL) and brine (50 mL)
3. customdried
4. customevaporated
5. customPurification by column chromatography on silica gel using 9:1 hexane/ethyl acetate as eluant