反应详情

2,3-Dimethoxy-6-nitrobenzaldehyde from Procedure 6 (331 g) was added to acetone (2.5 l) in a 12 l flask. A saturated solution (approximately 60-65 g/l) of potassium permanganate was added until TLC showed no starting material. Approximately 7 l was required. The reaction mixture was filtered to remove the MnO2 and was washed with 2.5N KOH and acetone (2 l each). The combined filtrates were evaporated to dryness and acidified with concentrated HCl. The precipitated solid was collected on a filter, washed with water (250 ml) and dried overnight. The solid was dissolved in 2 l acetone, treated with MgSO4 and charcoal, evaporated to 500 ml and cooled to 5°. The crystals were filtered, washed with acetone and hexane and dried to afford dimethoxy acid (234 g, 65.7%) mp 187°-189° C.

1. filtrationThe reaction mixture was filtered
2. customto remove the MnO2
3. washwas washed with 2.5N KOH and acetone (2 l each)
4. customThe combined filtrates were evaporated to dryness
5. customThe precipitated solid was collected on a filter
6. washwashed with water (250 ml)
7. customdried overnight
8. dissolutionThe solid was dissolved in 2 l acetone
9. additiontreated with MgSO4 and charcoal
10. customevaporated to 500 ml
11. temperaturecooled to 5°
12. filtrationThe crystals were filtered
13. washwashed with acetone and hexane
14. customdried
15. customto afford dimethoxy acid (234 g, 65.7%) mp 187°-189° C.