反应详情

To a mixture of HNO3 (95%, 80 mL) and H2SO4 (98%, 80 mL) was slowly added 3-methylbenzic acid (50 g, 0.37 mol) at 0° C. After addition, the mixture was stirred below 30° C. for 1.5 hours. The mixture was then poured into ice-water and stirred for 15 min. The precipitate solid was filtered and washed with water to give a mixture of 3-methyl-2,6-dinitro-benzoic acid and 5-methyl-2,4-dinitrobenzoic acid (70 g, 84%). To a solution of this mixture (70 g, 0.31 mol) in EtOH (150 mL) was added dropwise SOCl2 (54 g, 0.45 mol). The mixture was heated at reflux for 2 h before being concentrated to dryness under reduced pressure. The residue was partitioned between EtOAc (100 mL) and aq. Na2CO3 (10%, 120 mL). The organic layer washed with brine (50 mL), dried over Na2SO4, and concentrated to dryness to obtain ethyl 5-methyl-2,4-dinitrobenzoate (20 g), which was placed aside. The aqueous layer was acidified by HCl to pH 2-3 and the precipitated solid was filtered, washed with water, and dried in air to give 3-methyl-2,6-dinitrobenzoic acid (39 g, 47%).

1. customat 0° C
2. additionAfter addition
3. stirringstirred for 15 min
4. filtrationThe precipitate solid was filtered
5. washwashed with water
6. customto give
7. temperatureThe mixture was heated
8. temperatureat reflux for 2 h
9. concentrationbefore being concentrated to dryness under reduced pressure
10. customThe residue was partitioned between EtOAc (100 mL) and aq. Na2CO3 (10%, 120 mL)
11. washThe organic layer washed with brine (50 mL)
12. dry with materialdried over Na2SO4
13. concentrationconcentrated to dryness