反应详情

温度

72.5 °C

In a 20 L 4 necked RB flask, fitted with a mechanical stirrer, reflux condenser, add 4-difluoro methoxy-8-nitro-1-formyl dibenzo[b,d]furan (1 kg, 3.25 M), acetone (7.2 L) and heat to temp. 70-75° C. under stirring. Add a slurry of potassium permanganate (0.48 kg) in water (3 L) to the reaction mixture at 70-75° C. under stirring and maintain for 1 hr. After 1 hr maintenance, the second lot of potassium permanganate (0.120 kg) in water (400 ml) was added at 70-75° C. under stirring and maintain for 1 hr. After 2 hr maintenance, the third lot of potassium permanganate (0.120 kg) in water (400 ml) was added at 70-75° C. under stirring and maintain for 1 hr. The progress of the reaction was monitored by HPLC. After ascertaining the completion of the reaction, acetone (7.2 L) was added at temp. of 70-75° C. under stirring and maintained for 30 min. The reaction mixture was brought to 25-35° C., filtered. The inorganic salt cake was washed with acetone (2 L) collect and combine all the acetone washings. The acetone MLS were distilled at temp. below 75° C. under vacuum, cool the residue to 25-35° C. and maintain under stirring for 30 min. The precipitated product was filtered, dried and the wet cake was subjected to reflux with a solvent mixture of (5 L acetone and 1.25 L water) and maintained for 3 h. Cool the reaction mass to 10-15° C. maintain for 30 min under stirring, filter the precipitated product, wash the product with water (1 L). The wet cake was subjected to azeotropic removal of water by refluxing with toluene (10 L) After complete removal of water, the reaction mixture was brought to 25-35° C., maintained for 30 min, filtered and dried in vacuum oven below 70° C. till LOD<1%. The dried product appears as cream color, solid, weighs about 840-850 g, yield 80-81%, purity˜95% by HPLC, m.p.>270° C. The IR (KBr) spectrum shows 3100 (C—H str), 1695 (—COOH str), 1100 (C—F str) cm−1. The 1H-NMR spectrum shows δ 9.8 (s, 1H), 8.6 (d, 1H), 8.2 (m, 2H), 7.3 (m, 3H), 7.6 (m, 1H). The CI mass shows m/z 322 (M+) The elemental analysis shows calculated % C, 52.03; % H, 2.18; % N, 4.33. Observed % C, 52.04; % H, 2.03; % N, 4.45%.

1. temperaturereflux condenser
2. temperatureheat to temp
3. stirringunder stirring
4. temperaturemaintain for 1 hr
5. stirringunder stirring
6. temperaturemaintain for 1 hr
7. waitAfter 2 hr maintenance
8. stirringunder stirring
9. temperaturemaintain for 1 hr
10. additionwas added at temp
11. stirringof 70-75° C. under stirring
12. temperaturemaintained for 30 min
13. customwas brought to 25-35° C.
14. filtrationfiltered
15. washThe inorganic salt cake was washed with acetone (2 L)
16. customcollect
17. distillationThe acetone MLS were distilled at temp
18. temperaturebelow 75° C. under vacuum, cool the residue to 25-35° C.
19. temperaturemaintain
20. stirringunder stirring for 30 min
21. filtrationThe precipitated product was filtered
22. customdried
23. temperatureto reflux with a solvent mixture of (5 L acetone and 1.25 L water)
24. temperaturemaintained for 3 h
25. temperatureCool the reaction mass to 10-15° C.
26. temperaturemaintain for 30 min
27. stirringunder stirring
28. filtrationfilter the precipitated product
29. washwash the product with water (1 L)
30. customThe wet cake was subjected to azeotropic removal of water
31. temperatureby refluxing with toluene (10 L)
32. customAfter complete removal of water
33. customwas brought to 25-35° C.
34. temperaturemaintained for 30 min
35. filtrationfiltered
36. customdried in vacuum oven below 70° C. till LOD<1%