反应详情

A solution of 10 g of 2,6-dimethylbenzoic acid in 22 g thionyl chloride was stirred at reflux temperature for 2 hours. Removal of the excess thionyl chloride afforded the crude acid chloride as a yellow oil. This intermediate was added to a stirred solution of 4 mL of methanol in 10.8 mL pyridine at 65°-70° C. After completion of the addition, the resulting mixture was stirred at room temperature for 2 hours and then poured into 75 mL ice-water. The aqueous layer was extracted with four 50-mL portions of ether and the combined organic extracts were backwashed with saturated sodium bicarbonate solution, 5% aqueous hydrochloric acid, and water. Drying and evaporation of the solvent gave a pale yellow oil which was purified by bulb-to-bulb distillation (40°-50° C., 0.5 mm Hg) to afford 9.5 g of pure 2,6-dimethylbenzoic acid, methyl ester as a colorless liquid; IR (film) 1725 cm-1 ; NMR(CDCl3) δ 2.3 (s, 6H), 3.9 (s, 3H), 7.0-7.4 (m, 3H).

1. temperatureat reflux temperature for 2 hours
2. customRemoval of the excess thionyl chloride
3. customafforded the crude acid chloride as a yellow oil
4. additionAfter completion of the addition
5. extractionThe aqueous layer was extracted with four 50-mL portions of ether
6. customDrying
7. customevaporation of the solvent
8. customgave a pale yellow oil which
9. distillationwas purified by bulb-to-bulb distillation (40°-50° C., 0.5 mm Hg)