反应详情

3-Methoxyphthalic anhydride (17.8 g, 0.1 mole) was suspended in 100 ml. dry methylene chloride (previously distilled over anhydrous potassium carbonate). To the suspension was added anhydrous aluminum chloride (30.5 g, 0.23 mole) in one portion. The suspension quickly became bright yellow and was stirred at room temperature for 2 hours. A solution of p-dimethoxybenzene (27.6 g, 0.2 mole) in methylene chloride (100 ml) was added slowly to the vigorously stirred solution. The reaction mixture was stirred overnight at 25° and poured onto ice (300 g) and concentrated hydrochloric acid (50 ml). The slurry was stirred for 30 minutes and extracted with chloroform (4 × 150 ml). A white precipitate suspended in the aqueous layer is collected by filtration. The organic extract was washed once with water (200 ml) and washed with saturated sodium bicarbonate (4 × 150 ml). The aqueous bicarbonate extract was washed once with chloroform (150 ml) and acidified with concentrated hydrochloric acid, the mixture cooled on an ice bath and filtered. The residue was washed well with water and dried under reduced pressure and combined with the white precipitate to yield 2-(2',5'-dimethoxybenzoyl)-6-methoxybenzoic acid (I) as a pale yellow solid (13 g, 41% yield), m.p. 180°-182° C. (from ethanol); IR (KBr) 2.95, 5.72μ; NMR (CDCl3) δ, 7.60-6.80 (m, 6H), 6.10 (s, 1H), 3.75 (s, 3H), 3.70 (s, 3H), 3.49 (s, 3H).

1. distillationdry methylene chloride (previously distilled over anhydrous potassium carbonate)
2. stirringThe reaction mixture was stirred overnight at 25°
3. stirringThe slurry was stirred for 30 minutes
4. extractionextracted with chloroform (4 × 150 ml)
5. filtrationis collected by filtration
6. extractionThe organic extract
7. washwas washed once with water (200 ml)
8. washwashed with saturated sodium bicarbonate (4 × 150 ml)
9. extractionThe aqueous bicarbonate extract
10. washwas washed once with chloroform (150 ml)
11. temperaturethe mixture cooled on an ice bath
12. filtrationfiltered
13. washThe residue was washed well with water
14. customdried under reduced pressure