反応 #955922

反応方程式

4-Chloro-2-methylbenzoic acid

H2SO4

MeOH

→

methyl 4-chloro-2-methylbenzoate

収率 92.0%

反応条件

後処理

1. 1
   温度The mixture was refluxed overnight
2. 2
   その他MeOH was evaporated
3. 3
   抽出the residue was extracted with EtOAc
4. 4
   乾燥dried over MgSO4
5. 5
   ろ過filtered
6. 6
   その他evaporated

実験手順

4-Chloro-2-methylbenzoic acid (3 g, 17.6 mmol) was suspended in 12 ml of MeOH with 1 ml of concentrated H2SO4. The mixture was refluxed overnight, MeOH was evaporated and the residue was extracted with EtOAc, dried over MgSO4 filtered and evaporated to give methyl 4-chloro-2-methylbenzoate as a colorless viscous liquid (2.96 g, 92%) that was used in the next step without further purification. The ester (2.96 g, 16 mmol) was, under inert atmosphere, dissolved in THF (100 mL) and NMP (9 mL) and Iron (III) acetylacetonate (318 mg, 0.9 mmol) was added giving a red solution. Then EtMgBr (7 ml of 1M solution in ether) was added dropwise under vigorous stirring. The mixture turned dark brown and then violet and then was stirred for 15 more min. The reaction was diluted with ether and quenched upon the addition of aq. HCl (1M, 10 ml). The crude product was extracted with ether. The combined organic layers were washed with water and brine, dried over MgSO4 and evaporated. The residue was purified on silica gel (30% EtOAc/hexanes) to give methyl 4-ethyl-2-methylbenzoate as an oil (2.37 g, 83%). (1H NMR (500 MHz, CDCl3): δ 1.26 (t, 3H), 2.63 (dd, 2H), 3.9 (s, 3H), 7.1 (b, 2H), 7.85 (d, 1H)).

出典